Wang, Li; Zhu, Chen; Jin, Lin; Xiao, Aihua; Duan, Jie; Ma, Luyi
Kalanchoe (K.) daigremontiana is important for studying asexual reproduction under different environmental conditions. Here, we describe a novel KdNOVEL41 (KdN41) gene that may confer drought resistance and could thereby affect K. daigremontiana development. The detected subcellular localization of a KdN41/Yellow Fluorescent Protein (YFP) fusion protein was in the nucleus and cell membrane. Drought, salt, and heat stress treatment in tobacco plants containing the KdN41 gene promoter driving β-glucuronidase (GUS) gene transcription revealed that only drought stress triggered strong GUS staining in the vascular tissues. Overexpression (OE) of the KdN41 gene conferred improved drought resistance in tobacco plants compared to wild-type and transformed with empty vector plants by inducing higher antioxidant enzyme activities, decreasing cell membrane damage, increasing abscisic acid (ABA) content, causing reinforced drought resistance related gene expression profiles. The 3,3'-diaminobenzidine (DAB) and nitroblue tetrazolium (NBT) staining results also showed less relative oxygen species (ROS) content in KdN41-overexpressing tobacco leaf during drought stress. Surprisingly, by re-watering after drought stress, KdN41-overexpressing tobacco showed earlier flowering. Overall, the KdN41 gene plays roles in ROS scavenging and osmotic damage reduction to improve tobacco drought resistance, which may increase our understanding of the molecular network involved in developmental manipulation under drought stress in K. daigremontiana.
Jørgensen, Jørgen Helms
/(4) in all tests. They were also resistant to field populations of the pathogen when scored in disease nurseries at more than 78 locations in 29 countries in Europe, the Near East, North and South America. New Zealand, and Japan. This indicates that the 11 genes confer the same, world-wide spectrum...
Luo, Hong-Yan; Liu, Ma-Feng; Wang, Ming-Shu; Zhao, Xin-Xin; Jia, Ren-Yong; Chen, Shun; Sun, Kun-Feng; Yang, Qiao; Wu, Ying; Chen, Xiao-Yue; Biville, Francis; Zou, Yuan-Feng; Jing, Bo; Cheng, An-Chun; Zhu, De-Kang
The Gram-negative bacterium Riemerella anatipestifer CH-2 is resistant to lincosamides, having a lincomycin (LCM) minimum inhibitory concentration (MIC) of 128 µg/mL. The G148_1775 gene of R. anatipestifer CH-2, designated lnu(H), encodes a 260-amino acid protein with ≤41% identity to other reported lincosamide nucleotidylyltransferases. Escherichia coli Rosetta TM (DE3) containing the pBAD24-lnu(H) plasmid showed four- and two-fold increases in the MICs of LCM and clindamycin (CLI), respectively. A kinetic assay of the purified Lnu(H) enzyme for LCM and CLI showed that the protein could inactive lincosamides. Mass spectrometry analysis demonstrated that the Lnu(H) enzyme catalysed adenylylation of lincosamides. In addition, an lnu(H) gene deletion strain exhibited 512- and 32-fold decreases in LCM and CLI MICs, respectively. The wild-type level of lincosamide resistance could be restored by complementation with a shuttle plasmid carrying the lnu(H) gene. The transformant R. anatipestifer ATCC 11845 [lnu(H)] acquired by natural transformation also exhibited high-level lincosamide resistance. Moreover, among 175 R. anatipestifer field isolates, 56 (32.0%) were positive for the lnu(H) gene by PCR. In conclusion, Lnu(H) is a novel lincosamide nucleotidylyltransferase that inactivates LCM and CLI by nucleotidylylation, thus conferring high-level lincosamide resistance to R. anatipestifer CH-2. Copyright © 2017. Published by Elsevier B.V.
Kawashima, Cintia G; Guimarães, Gustavo Augusto; Nogueira, Sônia Regina; MacLean, Dan; Cook, Doug R; Steuernagel, Burkhard; Baek, Jongmin; Bouyioukos, Costas; Melo, Bernardo do V A; Tristão, Gustavo; de Oliveira, Jamile Camargos; Rauscher, Gilda; Mittal, Shipra; Panichelli, Lisa; Bacot, Karen; Johnson, Ebony; Iyer, Geeta; Tabor, Girma; Wulff, Brande B H; Ward, Eric; Rairdan, Gregory J; Broglie, Karen E; Wu, Gusui; van Esse, H Peter; Jones, Jonathan D G; Brommonschenkel, Sérgio H
Asian soybean rust (ASR), caused by the fungus Phakopsora pachyrhizi, is one of the most economically important crop diseases, but is only treatable with fungicides, which are becoming less effective owing to the emergence of fungicide resistance. There are no commercial soybean cultivars with durable resistance to P. pachyrhizi, and although soybean resistance loci have been mapped, no resistance genes have been cloned. We report the cloning of a P. pachyrhizi resistance gene CcRpp1 (Cajanus cajan Resistance against Phakopsora pachyrhizi 1) from pigeonpea (Cajanus cajan) and show that CcRpp1 confers full resistance to P. pachyrhizi in soybean. Our findings show that legume species related to soybean such as pigeonpea, cowpea, common bean and others could provide a valuable and diverse pool of resistance traits for crop improvement.
Springer, Burkhard; Kidan, Yishak G.; Prammananan, Therdsak; Ellrott, Kerstin; Böttger, Erik C.; Sander, Peter
Chromosomally acquired streptomycin resistance is frequently due to mutations in the gene encoding the ribosomal protein S12, rpsL. The presence of several rRNA operons (rrn) and a single rpsL gene in most bacterial genomes prohibits the isolation of streptomycin-resistant mutants in which resistance is mediated by mutations in the 16S rRNA gene (rrs). Three strains were constructed in this investigation: Mycobacterium smegmatis rrnB, M. smegmatis rpsL3+, and M. smegmatis rrnB rpsL3+. M. smegmatis rrnB carries a single functional rrn operon, i.e., rrnA (comprised of 16S, 23S, and 5S rRNA genes) and a single rpsL+ gene; M. smegmatis rpsL3+ is characterized by the presence of two rrn operons (rrnA and rrnB) and three rpsL+ genes; and M. smegmatis rrnB rpsL3+ carries a single functional rrn operon (rrnA) and three rpsL+ genes. By genetically altering the number of rpsL and rrs alleles in the bacterial genome, mutations in rrs conferring streptomycin resistance could be selected, as revealed by analysis of streptomycin-resistant derivatives of M. smegmatis rrnB rpsL3+. Besides mutations well known to confer streptomycin resistance, novel streptomycin resistance conferring mutations were isolated. Most of the mutations were found to map to a functional pseudoknot structure within the 530 loop region of the 16S rRNA. One of the mutations observed, i.e., 524G→C, severely distorts the interaction between nucleotides 524G and 507C, a Watson-Crick interaction which has been thought to be essential for ribosome function. The use of the single rRNA allelic M. smegmatis strain should help to elucidate the principles of ribosome-drug interactions. PMID:11557484
Genetic engineering and transformation offer the possibility of modifying the genetic material of insects. These techniques will make it possible, for example, to transfer genes conferring resistance to insecticides into the genome of beneficial species, or to develop new methods of combating insect pests and disease carrying insects. We cloned two genes which contain the code for proteins that detoxify insecticides. The first, esterase B1 from Culex quinquefasciatus, is amplified approximately 250 times in Californian mosquitoes resistant to organic phosphate insecticides. A second esterase gene was cloned from bacteria which break down various organic phosphates. Experiments are in progress to transfer these genes to Drosophila and beneficial insects. These same genes could also serve as selection markers for the purpose of developing transformation techniques for different insects whose genome one wishes to modify using genetic engineering techniques. (author). 5 refs
Full Text Available In the present climate change scenario, controlling plant disease through exploitation of host plant resistance could contribute toward the sustainable crop production and global food security. In this respect, the identification of new sources of resistance and utilization of genetic diversity within the species may help in the generation of cultivars with improved disease resistance. Begomoviruses namely, Tomato yellow leaf curl virus (TYLCV and Chilli leaf curl virus (ChLCV are known to cause major yield losses in several economically important crop plants of the family Solanaceae. Though co-occurrence, association and synergistic interactions among these viruses in the host plants is reported, whether orthologous genetic loci in related host plants could be responsible for conferring resistance to these viruses has not been investigated yet. Several loci including Ty1, Ty2, Ty3, Ty4, and ty5 have been reported to confer resistance to leaf curl viruses in tomato. Here, we examined the pepper orthologous markers, corresponding to these QTL regions, for polymorphism between ChLCV susceptible and resistant genotypes of pepper. Further, to examine if the polymorphic markers are segregating with the disease resistance, Bulk Segregant Analysis (BSA was performed on F2 population derived from crosses between resistant and susceptible lines. However, none of the markers showed polymorphism in BSA suggesting that the tested markers are not linked to genes/QTLs responsible for conferring resistance to ChLCV in the selected genotypes. In silico analysis was performed to study the synteny and collinearity of genes located within these QTL regions in tomato and pepper genomes, which revealed that more than 60% genes located in Ty2 and Ty4, 13.71% genes in Ty1, 23.07% in Ty3, and 44.77% genes located within ty5 QTL region in tomato are conserved in pepper genome. However, despite such a high conservation in gene content, the linkage relationship in these
Jain, Parul; Tar'an, Bunyamin
Chickpea (Cicer arietinum L.) production in the Canadian prairies is challenging due to a lack of effective weed management mainly because of poor competition ability of the crop and limited registered herbicide options. Chickpea genotype with resistance to imidazolinone (IMI) herbicides has been identified. A point mutation in the acetohydroxyacid synthase1 (AHAS1) gene at C581 to T581, resulting in an amino acid substitution from Ala194 to Val194 (position 205, standardized to arabidopsis), confers the resistance to imazamox in chickpea. However, the molecular mechanism leading to the resistance is not fully understood. In many plant species, contrasting transcription levels of AHAS gene has been implicated in the resistant and susceptible genotypes in response to IMI. The objectives of this research were to compare the AHAS gene expression and AHAS enzyme activity in resistant and susceptible chickpea cultivars in response to imazamox herbicide treatment. Results from RT-qPCR indicated that there is no significant change in the transcript levels of AHAS1 between the susceptible and the resistant genotypes in response to imazamox treatment. Protein hydrophobic cluster analysis, protein-ligand docking analysis, and AHAS enzyme activity assay all indicated that the resistance to imazamox in chickpea is due to the alteration of interaction of the AHAS1 enzyme with the imazamox herbicide.
Yano, Tatsuya; Inukai, Masatoshi; Isono, Fujio
Sphingolipids have been reported to regulate the growth and death of mammalian and yeast cells, but their precise mechanisms are unknown. In this paper, it was shown that the deletion of the oxysterol binding protein homologue 3 (OSH3) gene confers hyper resistance against ISP-1, an inhibitor of sphingolipid biosynthesis, in the yeast Saccharomyces cerevisiae. Furthermore, the overexpression of the ROK1 gene, which directly binds to Osh3p, conferred resistance against ISP-1, and the deletion of the KEM1 gene, which regulates microtubule functions, exhibited ISP-1 hypersensitivity. And yet, an ISP-1 treatment caused an abnormal mitotic spindle formation, and the ISP-1-induced cell cycle arrest was rescued by the deletion of the OSH3 gene. Taken together, it is suggested that the expression levels of the OSH3 gene influence the ISP-1 sensitivity of S. cerevisiae, and the sphingolipids are necessary for normal mitotic spindle formation in which the Osh3p may play a pivotal role.
Saintenac, Cyrille; Zhang, Wenjun; Salcedo, Andres; Rouse, Matthew N; Trick, Harold N; Akhunov, Eduard; Dubcovsky, Jorge
Wheat stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is a devastating disease that can cause severe yield losses. A previously uncharacterized Pgt race, designated Ug99, has overcome most of the widely used resistance genes and is threatening major wheat production areas. Here, we demonstrate that the Sr35 gene from Triticum monococcum is a coiled-coil, nucleotide-binding, leucine-rich repeat gene that confers near immunity to Ug99 and related races. This gene is absent in the A-genome diploid donor and in polyploid wheat but is effective when transferred from T. monococcum to polyploid wheat. The cloning of Sr35 opens the door to the use of biotechnological approaches to control this devastating disease and to analyses of the molecular interactions that define the wheat-rust pathosystem.
Brotman, Y.; Silberstein, L.; Kovalski, I.; Perin, C.; Dogimont, C.; Pitrat, M.; Klingler, J.; Thompson, A.; Perl-Treves, R.
Genomic and cDNA fragments with homology to known disease resistance genes (RGH fragments) were cloned from Cucumis melo using degenerate-primer PCR. Fifteen homologues of the NBS-LRR gene family have been isolated. The NBS-LRR homologues show high divergence and, based on the partial NBS-fragment sequences, appear to include members of the two major subfamilies that have been described in dicot plants, one that possesses a TIR-protein element and one that lacks such a domain. Genomic organization of these sequences was explored by DNA gel-blot analysis, and conservation among other Cucurbitaceae was assessed. Two mapping populations that segregate for several disease and pest resistance loci were used to map the RGH probes onto the melon genetic map. Several NBS-LRR related sequences mapped to the vicinity of genetic loci that control resistance to papaya ringspot virus, Fusarium oxysporum race 1, F. oxysporum race 2 and to the insect pest Aphis gossypii. The utility of such markers for breeding resistant melon cultivars and for cloning the respective R-genes is discussed.
Li, Linghong; Lin, Feng; Wang, Weidong; Ping, Jieqing; Fitzgerald, Joshua C; Zhao, Meixia; Li, Shuai; Sun, Lianjun; Cai, Chunmei; Ma, Jianxin
RpsUN1 and RpsUN2 were fine mapped to two genomic regions harboring disease resistance-like genes. The haplotypes and instability of the regions and candidate genes for the two resistance loci were characterized. Phytophthora root and stem rot caused by Phytophthora sojae, is one of the most destructive diseases of soybean. Deploying soybean cultivars carrying race-specific resistance conferred by Rps genes is the most practical approach to managing this disease. Previously, two Rps genes, RpsUN1 and RpsUN2 were identified in a landrace PI 567139B and mapped to a 6.5 cM region on chromosome 3 and a 3.0 cM region on chromosome 16, corresponding to 1387 and 423 kb of the soybean reference genome sequences. By analyzing recombinants defined by genotypic and phenotypic screening of the 826 F 2:3 families derived from two reciprocal crosses between the two parental lines, RpsUN1 and RpsUN2, were further narrowed to a 151 kb region that harbors five genes including three disease resistance (R)-like genes, and a 36 kb region that contains four genes including five R-like genes, respectively, according to the reference genome. Expressional changes of these nine genes before and after inoculation with the pathogen, as revealed by RNA-seq, suggest that Glyma.03g034600 in the RpsUN1 region and Glyma.16g215200 and Glyma.16g214900 in the RpsUN2 region of PI 567139B may be associated with the resistance to P. sojae. It is also suggested that unequal recombination between/among R-like genes may have occurred, resulting in the formation of two recombinants with inconsistent genotypic and phenotypic observations. The haplotype variation of genomic regions where RpsUN1 and RpsUN2 reside in the entire soybean germplasm deposited in the US soybean germplasm collection suggests that RpsUN1 and RpsUN2 are most likely novel genes.
Núñez de Cáceres González, Francisco F; Davey, Michael R; Cancho Sanchez, Ester; Wilson, Zoe A
Transgenic Lilium lines have been generated by Agrobacterium -mediated transformation that have enhanced resistance to Botrytis cinerea as a consequence of ectopic expression of a rice chitinase gene. The production of ornamentals is an important global industry, with Lilium being one of the six major bulb crops in the world. The international trade in ornamentals is in the order of £60-75 billion and is expected to increase worldwide by 2-4% per annum. The continued success of the floriculture industry depends on the introduction of new species/cultivars with major alterations in key agronomic characteristics, such as resistance to pathogens. Fungal diseases are the cause of reduced yields and marketable quality of cultivated plants, including ornamental species. The fungal pathogen Botrytis causes extreme economic losses to a wide range of crop species, including ornamentals such as Lilium. Agrobacterium-mediated transformation was used to develop Lilium oriental cv. 'Star Gazer' plants that ectopically overexpress the Rice Chitinase 10 gene (RCH10), under control of the CaMV35S promoter. Levels of conferred resistance linked to chitinase expression were evaluated by infection with Botrytis cinerea; sporulation was reduced in an in vitro assay and the relative expression of the RCH10 gene was determined by quantitative reverse transcriptase-PCR. The extent of resistance to Botrytis, compared to that of the wild type plants, showed a direct correlation with the level of chitinase gene expression. Transgenic plants grown to flowering showed no detrimental phenotypic effects associated with transgene expression. This is the first report of Lilium plants with resistance to Botrytis cinerea generated by a transgenic approach.
Phytophthora root and stem rot (PRR), caused by the soil-borne oomycete pathogen Phytophthora sojae, is one of the most destructive diseases of soybean. PRR can be effectively controlled by race-specific genes conferring resistance to P. sojae (Rps). However, the Rps genes are usually non-durable, a...
Paul, Jean-Yves; Becker, Douglas K; Dickman, Martin B; Harding, Robert M; Khanna, Harjeet K; Dale, James L
Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc), is one of the most devastating diseases of banana (Musa spp.). Apart from resistant cultivars, there are no effective control measures for the disease. We investigated whether the transgenic expression of apoptosis-inhibition-related genes in banana could be used to confer disease resistance. Embryogenic cell suspensions of the banana cultivar, 'Lady Finger', were stably transformed with animal genes that negatively regulate apoptosis, namely Bcl-xL, Ced-9 and Bcl-2 3' UTR, and independently transformed plant lines were regenerated for testing. Following a 12-week exposure to Foc race 1 in small-plant glasshouse bioassays, seven transgenic lines (2 × Bcl-xL, 3 × Ced-9 and 2 × Bcl-2 3' UTR) showed significantly less internal and external disease symptoms than the wild-type susceptible 'Lady Finger' banana plants used as positive controls. Of these, one Bcl-2 3' UTR line showed resistance that was equivalent to that of wild-type Cavendish bananas that were included as resistant negative controls. Further, the resistance of this line continued for 23-week postinoculation at which time the experiment was terminated. Using TUNEL assays, Foc race 1 was shown to induce apoptosis-like features in the roots of wild-type 'Lady Finger' plants consistent with a necrotrophic phase in the life cycle of this pathogen. This was further supported by the observed reduction in these effects in the roots of the resistant Bcl-2 3' UTR-transgenic line. This is the first report on the generation of transgenic banana plants with resistance to Fusarium wilt. © 2011 The Authors. Plant Biotechnology Journal © 2011 Society for Experimental Biology, Association of Applied Biologists and Blackwell Publishing Ltd.
Biadglegne, Fantahun; Tessema, Belay; Rodloff, Arne C; Sack, Ulrich
Resistance to drugs is due to particular genomic mutations in the specific genes of Mycobacterium tuberculosis. Timely genetic characterization will allow identification of resistance mutations that will optimize an effective antibiotic treatment regimen. We determine the magnitude of gene mutations conferring resistance to isoniazid (INH), rifampicin (RMP) and ethambutol (EMB) among tuberculosis (TB) lymphadenitis patients. A cross sectional prospective study was conducted among 226 M.tuberculosis isolates from culture positive lymph node aspirates collected from TB lymphadenitis patients between April 2012 and May 2012. Detection of mutations conferring resistance to drugs was carried out using GenoType(®) MTBDRplus and GenoType® MTBDRsl assay. Out of the 226 strains, mutations conferring resistance to INH, RMP, multidrug resistance tuberculosis (MDR-TB) and EMB were 8, 3, 2 and 2 isolates, respectively. There was no isolated strain that showed mutation in the inhA promoter region gene. All INH resistant strains had mutations in the katG gene at codon 315 with amino acid change of S315T1. Among rifampicin resistant strains, two isolates displayed mutations at codon 531 in the rpoB gene with amino acid change of S531L and one isolate was by omission of wild type probes at Q513L. According to mutations associated with ethambutol resistance, all of the isolates had mutations in the embB gene with aminoacid change of M306I. All isolates resistant to INH, RMP and MDR using BacT/AlerT 3D system were correctly identified by GenoType® MTBDRplus assay. We observed mutations conferring resistance to INH at S315T1 of the katG gene, RMP at S531L and Q513L in the rpoB genes and EMB at M306I of the embB gene. In the absence of conventional drug susceptibility testing, the effort to develop easy, rapid and cost effective molecular assays for drug resistance TB monitoring is definitely desirable and the GenoType® MTBDRplus assay was found to be a useful method for diagnosis
Ahmad, B.; Ambreen, S.; Khan, I.
Brassica juncea (Czern and Coss., L.) is an important oilseed crop. Since it is attacked by several bacterial and fungal diseases, therefore, we developed an easy and simple protocol for the regeneration and transformation of B. juncea variety RAYA ANMOL to give rise to transgenic plants conferring resistance against various fungal diseases. The transformation was carried out using Agrobacterium with Chitinase gene. This gene was isolated from Streptomyces griseus HUT6037. We used two types of explants for transformation i.e. hypocotyls and cotyledons. Only hypocotyls explants showed good results regarding callus initiation. Different hormonal concentrations were applied i.e. BAP 2, 4 and 6 mgL-1 and NAA 0.1, 0.2 and 0.3 mgL-1. However, high transformation efficiency was observed by supplementing the medium with combination of 2 mgL-1 BAP and 0.2 mgL-1 for initiation of callus. Similarly 10 mgL-1 kanamycin and 200 mgL-1 cefotaxime also proved successful for the selection of transformed callus. In order to confirm the presence of transgenic callus Polymerase chain reaction was performed using specific primers for Chitinase gene. (author)
Bolton, Lance F.; Kelley, Lynda C.; Lee, Margie D.; Fedorka-Cray, Paula J.; Maurer, John J.
Salmonella enterica serotype typhimurium (S. typhimurium) DT104 (DT104) first emerged as a major pathogen in Europe and is characterized by its pentadrug-resistant pattern. It has also been associated with outbreaks in the United States. The organism typically carries resistance to ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline. The mechanism of chloramphenicol resistance in DT104 was determined by producing antibiotic-resistant Escherichia coli host strain clones from DT104 DNA. DNA from chloramphenicol-resistant clones was sequenced, and probes specific for the genes floS. typhimurium (floSt), int, invA, and spvC were produced for colony blot hybridizations. One hundred nine Salmonella isolates, including 44 multidrug-resistant DT104 isolates, were tested to evaluate the specificities of the probes. The gene floSt, reported in this study, confers chloramphenicol and florfenicol resistance on S. typhimurium DT104. Florfenicol resistance is unique to S. typhimurium DT104 and multidrug-resistant S. typhimurium isolates with the same drug resistance profile among all isolates evaluated. Of 44 DT104 isolates tested, 98% were detected based on phenotypic florfenicol resistance and 100% had the floSt-positive genotype. Resistances to florfenicol and chloramphenicol are conferred by the gene floSt, described in this paper. Presumptive identification of S. typhimurium DT104 can be made rapidly based on the presence of the floSt gene or its resulting phenotype. PMID:10203484
Sandhu, K S; Forrest, K L; Kong, S; Bansal, U K; Singh, D; Hayden, M J; Park, R F
Genetic studies were undertaken to determine the inheritance and genomic location of uncharacterised seedling resistance to leaf rust, caused by Puccinia hordei, in the barley cultivar Ricardo. The resistance was shown to be conferred by a single dominant gene, which was tentatively designated RphRic. Bulk segregant analysis (BSA) and genetic mapping of an F(3) mapping population using multiplex-ready SSR genotyping and Illumina GoldenGate SNP assay located RphRic in chromosome 4H. Given that this is the first gene for leaf rust resistance mapped on chromosome 4H, it was designated Rph21. The presence of an additional gene, Rph2, in Ricardo, was confirmed by the test of allelism. The seedling gene Rph21 has shown effectiveness against all Australian pathotypes of P. hordei tested since at least 1992 and hence represents a new and useful source of resistance to this pathogen.
Full Text Available Abstract Background Phytophthora sojae is the primary pathogen of soybeans that are grown on poorly drained soils. Race-specific resistance to P. sojae in soybean is gene-for-gene, although in many areas of the US and worldwide there are populations that have adapted to the most commonly deployed resistance to P. sojae ( Rps genes. Hence, this system has received increased attention towards identifying mechanisms and molecular markers associated with partial resistance to this pathogen. Several quantitative trait loci (QTL have been identified in the soybean cultivar ‘Conrad’ that contributes to the expression of partial resistance to multiple P. sojae isolates. Results In this study, two of the Conrad QTL on chromosome 19 were dissected through sequence and expression analysis of genes in both resistant (Conrad and susceptible (‘Sloan’ genotypes. There were 1025 single nucleotide polymorphisms (SNPs in 87 of 153 genes sequenced from Conrad and Sloan. There were 304 SNPs in 54 genes sequenced from Conrad compared to those from both Sloan and Williams 82, of which 11 genes had SNPs unique to Conrad. Eleven of 19 genes in these regions analyzed with qRT-PCR had significant differences in fold change of transcript abundance in response to infection with P. sojae in lines with QTL haplotype from the resistant parent compared to those with the susceptible parent haplotype. From these, 8 of the 11 genes had SNPs in the upstream, untranslated region, exon, intron, and/or downstream region. These 11 candidate genes encode proteins potentially involved in signal transduction, hormone-mediated pathways, plant cell structural modification, ubiquitination, and basal resistance. Conclusions These findings may indicate a complex defense network with multiple mechanisms underlying these two soybean QTL conferring resistance to P. sojae. SNP markers derived from these candidate genes can contribute to fine mapping of QTL and marker assisted breeding for
Hasman, Henrik; Aarestrup, Frank Møller
B protein from Enterococcus hirae. The tcrB gene was found in E. faecium isolated from pigs (75%), broilers (34%), calves (16%), and humans (10%) but not in isolates from sheep. Resistant isolates, containing the tcrB gene, grew on brain heart infusion agar plates containing up to 28 mM CuSO4 compared......A newly discovered gene, designated tcrB, which is located on a conjugative plasmid conferring acquired copper resistance in Enterococcus faecium, was identified in an isolate from a pig. The tcrB gene encodes a putative protein belonging to the CPx-type ATPase family with homology (46%) to the Cop...... for resistance to these two antimicrobial agents. The frequent occurrence of this new copper resistance gene in isolates from pigs, where copper sulfate is being used in large amounts as feed additive, suggests that the use of copper has selected for resistance....
Chintamanani, Satya; Multani, Dilbag S; Ruess, Holly; Johal, Gurmukh S
The maize Hm2 gene provides protection against the leaf spot and ear mold disease caused by Cochliobolus carbonum race 1 (CCR1). In this regard, it is similar to Hm1, the better-known disease resistance gene of the maize-CCR1 pathosystem. However, in contrast to Hm1, which provides completely dominant resistance at all stages of plant development, Hm2-conferred resistance is only partially dominant and becomes fully effective only at maturity. To investigate why Hm2 behaves in this manner, we cloned it on the basis of its homology to Hm1. As expected, Hm2 is a duplicate of Hm1, although the protein it encodes is grossly truncated compared with HM1. The efficacy of Hm2 in conferring resistance improves gradually over time, changing from having little or no impact in seedling tissues to providing complete immunity at anthesis. The developmentally specified phenotype of Hm2 is not dictated transcriptionally, because the expression level of the gene, whether occurring constitutively or undergoing substantial and transient induction in response to infection, does not change with plant age. In contrast, however, the Hm2 transcript is much more abundant in plants homozygous for this gene compared with plants that contain only one copy of the gene, suggesting a transcriptional basis for the dosage-dependent nature of Hm2. Thus, different mechanisms seem to underlie the developmentally programmed versus the partially dominant resistance phenotype of Hm2.
Simko, Ivan; Ochoa, Oswaldo E; Pel, Mathieu A; Tsuchida, Cayla; Font I Forcada, Carolina; Hayes, Ryan J; Truco, Maria-Jose; Antonise, Rudie; Galeano, Carlos H; Michelmore, Richard W
Many cultivars of lettuce (Lactuca sativa L.) are susceptible to downy mildew, a nearly globally ubiquitous disease caused by Bremia lactucae. We previously determined that Batavia type cultivar 'La Brillante' has a high level of field resistance to the disease in California. Testing of a mapping population developed from a cross between 'Salinas 88' and La Brillante in multiple field and laboratory experiments revealed that at least five loci conferred resistance in La Brillante. The presence of a new dominant resistance gene (designated Dm50) that confers complete resistance to specific isolates was detected in laboratory tests of seedlings inoculated with multiple diverse isolates. Dm50 is located in the major resistance cluster on linkage group 2 that contains at least eight major, dominant Dm genes conferring resistance to downy mildew. However, this Dm gene is ineffective against the isolates of B. lactucae prevalent in the field in California and the Netherlands. A quantitative trait locus (QTL) located at the Dm50 chromosomal region (qDM2.2) was detected, though, when the amount of disease was evaluated a month before plants reached harvest maturity. Four additional QTL for resistance to B. lactucae were identified on linkage groups 4 (qDM4.1 and qDM4.2), 7 (qDM7.1), and 9 (qDM9.2). The largest effect was associated with qDM7.1 (up to 32.9% of the total phenotypic variance) that determined resistance in multiple field experiments. Markers identified in the present study will facilitate introduction of these resistance loci into commercial cultivars of lettuce.
Okawa, Hiromi; Motohashi, Hozumi; Kobayashi, Akira; Aburatani, Hiroyuki; Kensler, Thomas W.; Yamamoto, Masayuki
Nrf2 is a key regulator of many detoxifying enzyme genes, and cytoplasmic protein Keap1 represses the Nrf2 activity under quiescent conditions. Germ line deletion of the keap1 gene results in constitutive activation of Nrf2, but the pups unexpectedly died before weaning. To investigate how constitutive activation of Nrf2 influences the detoxification system in adult mice, we generated mice bearing a hepatocyte-specific disruption of the keap1 gene. Homozygous mice were viable and their livers displayed no apparent abnormalities, but nuclear accumulation of Nrf2 is elevated. Microarray analysis revealed that, while many detoxifying enzyme genes are highly expressed, some of the typical Nrf2-dependent genes are only marginally increased in the Keap1-deficient liver. The mutant mice were significantly more resistant to toxic doses of acetaminophen than control animals. These results demonstrate that chronic activation of Nrf2 confers animals with resistance to xenobiotics without affecting the morphological and physiological integrity of hepatocytes
Fei, Yun-Yan; Gai, Jun-Yi; Zhao, Tuan-Jie
Glyphosate is a widely used herbicide that inhibits 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) activity. Most plants and microbes are sensitive to glyphosate. However, transgenic-resistant crops that contain a modified epsps obtained from the resistant microbes have been commercially successful and therefore, new resistance genes and their adaptive regulatory mechanisms are of great interest. In this study, a soil-borne, glyphosate-resistant bacterium was selected and identified as Enterobacter. The EPSPS in this strain was found to have been altered to a resistant one. A total of 42 differentially expressed genes (DEGs) in the glyphosate were screened using microarray techniques. Under treatment, argF, sdhA, ivbL, rrfA-H were downregulated, whereas the transcripts of speA, osmY, pflB, ahpC, fusA, deoA, uxaC, rpoD and a few ribosomal protein genes were upregulated. Data were verified by quantitative real-time PCR on selected genes. All transcriptional changes appeared to protect the bacteria from glyphosate and associated osmotic, acidic and oxidative stresses. Many DEGs may have the potential to confer resistance to glyphosate alone, and some may be closely related to the shikimate pathway, reflecting the complex gene interaction network for glyphosate resistance. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.
Mao, Chanjuan; Xie, Hongjie; Chen, Shiguo; Valverde, Bernal E; Qiang, Sheng
Liriope spicata (Thunb.) Lour has a unique LsEPSPS structure contributing to the highest-ever-recognized natural glyphosate tolerance. The transformed LsEPSPS confers increased glyphosate resistance to E. coli and A. thaliana. However, the increased glyphosate-resistance level is not high enough to be of commercial value. Therefore, LsEPSPS was subjected to error-prone PCR to screen mutant EPSPS genes capable of endowing higher resistance levels. A mutant designated as ELs-EPSPS having five mutated amino acids (37Val, 67Asn, 277Ser, 351Gly and 422Gly) was selected for its ability to confer improved resistance to glyphosate. Expression of ELs-EPSPS in recombinant E. coli BL21 (DE3) strains enhanced resistance to glyphosate in comparison to both the LsEPSPS-transformed and -untransformed controls. Furthermore, transgenic ELs-EPSPS A. thaliana was about 5.4 fold and 2-fold resistance to glyphosate compared with the wild-type and the Ls-EPSPS-transgenic plants, respectively. Therefore, the mutated ELs-EPSPS gene has potential value for has potential for the development of glyphosate-resistant crops. Copyright © 2016 Elsevier Inc. All rights reserved.
Somerville, Chris R [Portola Valley, CA; Scheible, Wolf [Golm, DE
Cellulose synthase ("CS"), a key enzyme in the biosynthesis of cellulose in plants is inhibited by herbicides comprising thiazolidinones such as 5-tert-butyl-carbamoyloxy-3-(3-trifluromethyl)phenyl-4-thiazolidinone (TZ), isoxaben and 2,6-dichlorobenzonitrile (DCB). Two mutant genes encoding isoxaben and TZ-resistant cellulose synthase have been isolated from isoxaben and TZ-resistant Arabidopsis thaliana mutants. When compared with the gene coding for isoxaben or TZ-sensitive cellulose synthase, one of the resistant CS genes contains a point mutation, wherein glycine residue 998 is replaced by an aspartic acid. The other resistant mutation is due to a threonine to isoleucine change at amino acid residue 942. The mutant CS gene can be used to impart herbicide resistance to a plant; thereby permitting the utilization of the herbicide as a single application at a concentration which ensures the complete or substantially complete killing of weeds, while leaving the transgenic crop plant essentially undamaged.
Sunflower broomrape (Orobanche cumana Wallr.) is a root holoparasitic angiosperm considered as being one of the major constraints for sunflower production in Mediterranean areas. Breeding for resistance has been crucial for protecting sunflowers from broomrape damage. The Or5 gene, which confers re...
Wu, Dan, E-mail: email@example.com [Department of Medical Genetics, Peking University Health Science Center, No 38 Xueyuan Road, Haidian district, Beijing 100191 (China); Liu, Jing; Wu, Baiyan [Department of Medical Genetics, Peking University Health Science Center, No 38 Xueyuan Road, Haidian district, Beijing 100191 (China); Tu, Bo; Zhu, Weiguo [Department of Biochemistry and Molecular Biology, Peking University Health Science Center, No 38 Xueyuan Road, Haidian district, Beijing 100191 (China); Luo, Jianyuan, E-mail: firstname.lastname@example.org [Department of Medical Genetics, Peking University Health Science Center, No 38 Xueyuan Road, Haidian district, Beijing 100191 (China); Department of Medical and Research Technology, School of Medicine, University of Maryland, Baltimore 21201 (United States)
Highlights: • The work reveals a protective properties of CLN3 towards TM-induced apoptosis. • CLN3 regulates expression of the GRP78 and the CHOP in response to the ER stress. • CLN3 plays a specific role in the ERS response. - Abstract: Mutations in CLN3 gene cause juvenile neuronal ceroid lipofuscinosis (JNCL or Batten disease), an early-onset neurodegenerative disorder that is characterized by the accumulation of ceroid lipofuscin within lysosomes. The function of the CLN3 protein remains unclear and is presumed to be related to Endoplasmic reticulum (ER) stress. To investigate the function of CLN3 in the ER stress signaling pathway, we measured proliferation and apoptosis in cells transfected with normal and mutant CLN3 after treatment with the ER stress inducer tunicamycin (TM). We found that overexpression of CLN3 was sufficient in conferring increased resistance to ER stress. Wild-type CLN3 protected cells from TM-induced apoptosis and increased cell proliferation. Overexpression of wild-type CLN3 enhanced expression of the ER chaperone protein, glucose-regulated protein 78 (GRP78), and reduced expression of the proapoptotic protein CCAAT/-enhancer-binding protein homologous protein (CHOP). In contrast, overexpression of mutant CLN3 or siRNA knockdown of CLN3 produced the opposite effect. Together, our data suggest that the lack of CLN3 function in cells leads to a failure of management in the response to ER stress and this may be the key deficit in JNCL that causes neuronal degeneration.
Montes, Maria Jesus; Andrés, María Fe; Sin, E.; Lopez Braña, Isidoro; Martín-Sánchez, J.A.; Romero, M.D.; Delibes Castro, Angeles
Cereal cyst nematode (CCN; Heterodera avenae Woll.) is a root pathogen of cereal crops that can cause severe yield losses in wheat (Triticum aestivum). Differential host–nematode interactions occur in wheat cultivars carrying different CCN resistance (Cre) genes. The objective of this study was to determine the CCN resistance conferred by the Cre7 gene from Aegilops triuncialis in a 42-chromosome introgression line and to assess the effects of the Cre1, Cre3, Cre4, and Cre8 genes present in A...
Ngo, The D; Malone, Jenna M; Boutsalis, Peter; Gill, Gurjeet; Preston, Christopher
Five glyphosate-resistant populations of Chloris truncata originally collected from New South Wales were compared with one susceptible (S) population from South Australia to confirm glyphosate resistance and elucidate possible mechanisms of resistance. Based on the amounts of glyphosate required to kill 50% of treated plants (LD 50 ), glyphosate resistance (GR) was confirmed in five populations of C. truncata (A536, A528, T27, A534 and A535.1). GR plants were 2.4-8.7-fold more resistant and accumulated less shikimate after glyphosate treatment than S plants. There was no difference in glyphosate absorption and translocation between GR and S plants. The EPSPS gene did not contain any point mutation that had previously been associated with resistance to glyphosate. The resistant plants (A528 and A536) contained up to 32-48 more copies of the EPSPS gene than the susceptible plants. This study has identified EPSPS gene amplification contributing to glyphosate resistance in C. truncata. In addition, a Glu-91-Ala mutation within EPSPS was identified that may contribute to glyphosate resistance in this species. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.
Zhao, Xue; Teng, Weili; Li, Yinghui; Liu, Dongyuan; Cao, Guanglu; Li, Dongmei; Qiu, Lijuan; Zheng, Hongkun; Han, Yingpeng; Li, Wenbin
Soybean (Glycine max L. Merr.) cyst nematode (SCN, Heterodera glycines I,) is a major pest of soybean worldwide. The most effective strategy to control this pest involves the use of resistant cultivars. The aim of the present study was to investigate the genome-wide genetic architecture of resistance to SCN HG Type 2.5.7 (race 1) in landrace and elite cultivated soybeans. A total of 200 diverse soybean accessions were screened for resistance to SCN HG Type 2.5.7 and genotyped through sequencing using the Specific Locus Amplified Fragment Sequencing (SLAF-seq) approach with a 6.14-fold average sequencing depth. A total of 33,194 SNPs were identified with minor allele frequencies (MAF) over 4%, covering 97% of all the genotypes. Genome-wide association mapping (GWAS) revealed thirteen SNPs associated with resistance to SCN HG Type 2.5.7. These SNPs were distributed on five chromosomes (Chr), including Chr7, 8, 14, 15 and 18. Four SNPs were novel resistance loci and nine SNPs were located near known QTL. A total of 30 genes were identified as candidate genes underlying SCN resistance. A total of sixteen novel soybean accessions were identified with significant resistance to HG Type 2.5.7. The beneficial alleles and candidate genes identified by GWAS might be valuable for improving marker-assisted breeding efficiency and exploring the molecular mechanisms underlying SCN resistance.
The Puccinia graminis f. sp. tritici (Pgt) Ug99 race group is virulent to most stem rust resistance genes currently deployed in wheat and poses a serious threat to global wheat production. The durum wheat (Triticum turgidum ssp. durum) gene Sr13 confers resistance to Ug99 in addition to virulent rac...
Ping, Jieqing; Fitzgerald, Joshua C; Zhang, Chunbao; Lin, Feng; Bai, Yonghe; Wang, Dechun; Aggarwal, Rajat; Rehman, Maqsood; Crasta, Oswald; Ma, Jianxin
Rps11 confers excellent resistance to predominant Phytophthora sojae isolates capable of defeating major Rps genes deployed into soybean production, representing a novel source of resistance for soybean cultivar enhancement. Phytophthora root and stem rot (PRSR), caused by the soil-borne pathogen Phytophthora sojae, is a devastating disease of soybean [Glycine max (L.) Merr.] throughout the world. Deploying resistant soybean cultivars is the most effective and environmentally friendly approach to managing this disease. The soybean landrace PI 594527 was found to carry excellent resistance to all P. sojae isolates examined, some of which were capable of overcoming the major Rps genesp, such as Rps1-k, Rps1-c, and Rps3-a, predominantly used for soybean protection in the past decades. A mapping population consisting of 58 F2 individuals and 209 F2:3 families derived from a cross between PI 594527 and the susceptible cultivar 'Williams' was used to characterize the inheritance pattern of the resistance to P. soja (Rps) in PI 594527. It was found that the resistance was conferred by a single Rps gene, designated Rps11, which was initially defined as an ~5 Mb genomic region at the beginning of chromosome 7 by bulked segregant analysis (BSA) with a nucleotide polymorphism (SNP) chip comprising 7039 SNP markers. Subsequently, simple sequence repeat (SSR) markers in the defined region were used to genotype the F2:3 mapping population to map Rps11 to a 225.3 kb genomic region flanked by SSR markers BARCSOYSSR_07_0286 and BARCSOYSSR_07_0300, according to the soybean reference genome sequence. Particularly, an SSR marker (i.e., BARCSOYSSR_07_0295) was found to tightly co-segregate with Rps11 in the mapping population and can be effectively used for marker-assisted selection of this gene for development of resistant soybean cultivars.
Somerville, Chris R.; Scieble, Wolf
Cellulose synthase ('CS'), a key enzyme in the biosynthesis of cellulose in plants is inhibited by herbicides comprising thiazolidinones such as 5-tert-butyl-carbamoyloxy-3-(3-trifluromethyl) phenyl-4-thiazolidinone (TZ), isoxaben and 2,6-dichlorobenzonitrile (DCB). Two mutant genes encoding isoxaben and TZ-resistant cellulose synthase have been isolated from isoxaben and TZ-resistant Arabidopsis thaliana mutants. When compared with the gene coding for isoxaben or TZ-sensitive cellulose synthase, one of the resistant CS genes contains a point mutation, wherein glycine residue 998 is replaced by an aspartic acid. The other resistant mutation is due to a threonine to isoleucine change at amino acid residue 942. The mutant CS gene can be used to impart herbicide resistance to a plant; thereby permitting the utilization of the herbicide as a single application at a concentration which ensures the complete or substantially complete killing of weeds, while leaving the transgenic crop plant essentially undamaged.
Full Text Available Rice black-streaked dwarf virus (RBSDV belongs to the genus Fijivirus in the family of Reoviridae and causes severe yield loss in rice-producing areas in Asia. RNA silencing, as a natural defence mechanism against plant viruses, has been successfully exploited for engineering virus resistance in plants, including rice. In this study, we generated transgenic rice lines harbouring a hairpin RNA (hpRNA construct targeting four RBSDV genes, S1, S2, S6 and S10, encoding the RNA-dependent RNA polymerase, the putative core protein, the RNA silencing suppressor and the outer capsid protein, respectively. Both field nursery and artificial inoculation assays of three generations of the transgenic lines showed that they had strong resistance to RBSDV infection. The RBSDV resistance in the segregating transgenic populations correlated perfectly with the presence of the hpRNA transgene. Furthermore, the hpRNA transgene was expressed in the highly resistant transgenic lines, giving rise to abundant levels of 21–24 nt small interfering RNA (siRNA. By small RNA deep sequencing, the RBSDV-resistant transgenic lines detected siRNAs from all four viral gene sequences in the hpRNA transgene, indicating that the whole chimeric fusion sequence can be efficiently processed by Dicer into siRNAs. Taken together, our results suggest that long hpRNA targeting multiple viral genes can be used to generate stable and durable virus resistance in rice, as well as other plant species.
Yao, Hong; Liu, Dejun; Wang, Yang; Zhang, Qijing; Shen, Zhangqi
Campylobacter is a major foodborne pathogen, and previous studies revealed that Campylobacter isolates from food-producing animals are increasingly resistant to gentamicin in China. The molecular epidemiology and genetic mechanisms responsible for gentamicin resistance in China have not been well understood. In this study, 607 Campylobacter isolates of chicken and swine origins collected in 2014 were analyzed, revealing that 15.6% (25/160) of the Campylobacter jejuni isolates and 79.9% (357/447) of the Campylobacter coli isolates were resistant to gentamicin. PCR detection of the gentamicin resistance genes indicated that aph(2″)-If was more prevalent than the previously identified aacA/aphD gene and has become the dominant gentamicin resistance determinant in Campylobacter Transformation and whole-genome sequencing as well as long-range PCR discovered that aph(2″)-If was located on a chromosomal segment inserted between two conserved genes, Cj0299 and panB Cloning of aph(2″)-If into gentamicin-susceptible C. jejuni NCTC 11168 confirmed its function in conferring high-level resistance to gentamicin and kanamycin. Molecular typing by pulsed-field gel electrophoresis suggested that both regional expansion of a particular clone and horizontal transmission were involved in the dissemination of the aph(2″)-If gene in Campylobacter To our knowledge, this is the first report describing the high prevalence of a chromosomally encoded aph(2″)-If gene in Campylobacter The high prevalence and predominance of this gene might be driven by the use of aminoglycoside antibiotics in food animal production in China and potentially compromise the usefulness of gentamicin as a therapeutic agent for Campylobacter -associated systemic infection. Copyright © 2017 American Society for Microbiology.
Munir, I.; Hussan, W.; Kazi, M.; Mian, A.
Brassica juncea is an important oil seed crop throughout the world. The demand and cultivation of oil seed crops has gained importance due to rapid increase in world population and industrialization. Fungal diseases pose a great threat to Brassica productivity worldwide. Absence of resistance genes against fungal infection within crossable germplasms of this crop necessitates deployment of genetic engineering approaches to produce transgenic plants with resistance against fungal infections. In the current study, hypocotyls and cotyledons of Brassica juncea, used as explants, were transformed with Agrobacterium tumefacien strain EHA101 harboring binary vector pEKB/NIC containing synthetic chitinase gene (NIC), an antifungal gene under the control of cauliflower mosaic virus promoter (CaMV35S). Bar genes and nptII gene were used as selectable markers. Presence of chitinase gene in trangenic lines was confirmed by PCR and southern blotting analysis. Effect of the extracted proteins from non-transgenic and transgenic lines was observed on the growth of Alternaria brassicicola, a common disease causing pathogen in brassica crop. In comparison to non-transgenic control lines, the leaf tissue extracts of the transgenic lines showed considerable resistance and antifungal activity against A. brassicicola. The antifungal activity in transgenic lines was observed as corresponding to the transgene copy number. (author)
Ana Paula Matoso Teixeira
Full Text Available Brazil produced 330,000 metric tons of melons in 2005, principally in the Northeast region where one of the most important melon pathogens is the powdery mildew fungus Podosphaera xanthii. The disease is controlled mainly by incorporating single dominant resistance genes into commercial hybrids. We report on linkage analysis of the Pm-1 resistance gene, introgressed from the AF125Pm-1 Cantalupensis Charentais-type breeding line into the yellow-fleshed melon (Group Inodorus breeding line AF426-S by backcrossing to produce the resistant line AF426-R, and the amplified fragment length polymorphism (AFLP marker M75/H35_155 reported to be polymorphic between AF426-S and AF426-R. Segregation analysis of M75/H35_155 using a backcross population of 143 plants derived from [AF426-R x AF426-S] x AF426-S and screened for resistance to P. xanthii race 1 produced a recombination frequency of 4.9%, indicating close linkage between M75/H35_155 and Pm-1. Using the same segregating population, the M75/H35_155 marker had previously been reported to be distantly linked to Prv¹, a gene conferring resistance to papaya ringspot virus-type W. Since M75/H35_155 is linked to Prv¹ at a distance of 40.9 cM it is possible that Pm-1 and Prv¹ are also linked.
Wang, Jun; Tian, Dongsheng; Gu, Keyu; Yang, Xiaobei; Wang, Lanlan; Zeng, Xuan; Yin, Zhongchao
Bacterial blight of rice, caused by Xanthomonas oryzae pv. oryzae, is one of the most destructive bacterial diseases throughout the major rice-growing regions in the world. The rice disease resistance (R) gene Xa10 confers race-specific disease resistance to X. oryzae pv. oryzae strains that deliver the corresponding transcription activator-like (TAL) effector AvrXa10. Upon bacterial infection, AvrXa10 binds specifically to the effector binding element in the promoter of the R gene and activates its expression. Xa10 encodes an executor R protein that triggers hypersensitive response and activates disease resistance. 'Nipponbare' rice carries two Xa10-like genes in its genome, of which one is the susceptible allele of the Xa23 gene, a Xa10-like TAL effector-dependent executor R gene isolated recently from 'CBB23' rice. However, the function of the two Xa10-like genes in disease resistance to X. oryzae pv. oryzae strains has not been investigated. Here, we designated the two Xa10-like genes as Xa10-Ni and Xa23-Ni and characterized their function for disease resistance to rice bacterial blight. Both Xa10-Ni and Xa23-Ni provided disease resistance to X. oryzae pv. oryzae strains that deliver the matching artificially designed TAL effectors (dTALE). Transgenic rice plants containing Xa10-Ni and Xa23-Ni under the Xa10 promoter provided specific disease resistance to X. oryzae pv. oryzae strains that deliver AvrXa10. Xa10-Ni and Xa23-Ni knock-out mutants abolished dTALE-dependent disease resistance to X. oryzae pv. oryzae. Heterologous expression of Xa10-Ni and Xa23-Ni in Nicotiana benthamiana triggered cell death. The 19-amino-acid residues at the N-terminal regions of XA10 or XA10-Ni are dispensable for their function in inducing cell death in N. benthamiana and the C-terminal regions of XA10, XA10-Ni, and XA23-Ni are interchangeable among each other without affecting their function. Like XA10, both XA10-Ni and XA23-Ni locate to the endoplasmic reticulum (ER) membrane
Chen, Honglin; Li, Chunrong; Liu, Liping; Zhao, Jiying; Cheng, Xuzhen; Jiang, Guanghuai; Zhai, Wenxue
Disease resistance is an important goal of crop improvement. The molecular mechanism of resistance requires further study. Here, we report the identification of a rice leaf color mutant, lc7, which is defective in chlorophyll synthesis and photosynthesis but confers resistance to Xanthomonas oryzae pv. Oryzae (Xoo). Map-based cloning revealed that lc7 encodes a mutant ferredoxin-dependent glutamate synthase1 (Fd-GOGAT1). Fd-GOGAT1 has been proposed to have great potential for improving nitrogen-use efficiency, but its function in bacterial resistance has not been reported. The lc7 mutant accumulates excessive levels of ROS (reactive oxygen species) in the leaves, causing the leaf color to become yellow after the four-leaf stage. Compared to the wild type, lc7 mutants have a broad-spectrum high resistance to seven Xoo strains. Differentially expressed genes (DEGs) and qRT-PCR analysis indicate that many defense pathways that are involved in this broad-spectrum resistance are activated in the lc7 mutant. These results suggest that Fd-GOGAT1 plays an important role in broad-spectrum bacterial blight resistance, in addition to modulating nitrogen assimilation and chloroplast development.
Background Adult plant rust resistance genes Lr67 and Lr34 confer race non-specific resistance to multiple fungal pathogens of wheat. Induced, susceptible mutants were characterised for both genes. Results Three categories of Lr34 mutants were identified that were either partial susceptible, fully susceptible or hyper-susceptible to stripe rust and leaf rust. The likely impact of the mutational change on the predicted Lr34 protein correlated with differences in response to rust infection. Four independent Lr67 mutants were recovered that were susceptible to stripe rust, leaf rust and stem rust pathogens, including one possible hyper-susceptible Lr67 mutant. Conclusions Detailed study of Lr34 mutants revealed that subtle changes in resistance response to multiple pathogens were correlated with mutational changes in the predicted protein. Recovery of independent Lr67 mutants indicates that as for Lr34, a single gene at the Lr67 locus is likely to confer resistance to multiple pathogens. The infection phenotypes of Lr67 mutants closely resembled that of Lr34 mutants. PMID:23819608
Hubert, Jan; Nesvorna, Marta; Kamler, Martin; Kopecky, Jan; Tyl, Jan; Titera, Dalibor; Stara, Jitka
Sodium channels (SCs) in mites and insects are target sites for pesticides, including pyrethroids. Point mutations in the SC gene have been reported to change the structural conformation of the protein and its sensitivity to pesticides. To find mutations in the SC gene of the mite Varroa destructor (VmNa), the authors analysed the VmNa gene sequences available in GenBank and prepared specific primers for the amplification of two fragments containing the regions coding for (i) the domain II S4-S6 region (bp 2805-3337) and (ii) the domain III S4-3' terminus region (bp 4737-6500), as determined according to the VmNa cDNA sequence AY259834. Sensitive and resistant mite populations did not differ in the amino acid sequences of the III S4-3' terminus VmNa region. However, differences were found in the IIS4-IIS6 fragment. In the resistant population, the mutation C(3004) → G resulted in the substitution L(1002) → V (codon ctg → gtg) at the position equivalent to that of the housefly L925 in the domain II S5 helix. Additionally, the mutation F(1052) → L (codon ttc → ctc) at the position equivalent to that of the housefly F975 in the domain II P-loop connecting segments S5 and S6 was detected in both the resistant and sensitive populations. All individuals that survived the tau-fluvalinate treatment in the bioassay harboured the L(1002) → V mutation combined with the F(1052), while dead individuals from both the sensitive and resistant populations harboured mostly the L(1002) residue and either of the two residues at position 1052. © 2013 Society of Chemical Industry.
Full Text Available An efficient method for constructing transgenic lettuce cultivars by Agrobacterium tumefaciens was described by Torres et al., 1993. In the present work, an improvement of the above procedure is described and applied to transform the cultivar Grand Rapids with a mutated P5CS gene. The major modifications were concerned with turning more practical the transformation and regeneration protocols. Also we tried to improve transformation steps by increasing injured area in explants and prolonging co-cultivation with Agrobacteria (in larger concentration. A more significant selective pressure was used against non-transformed plants and bacteria. In these work we were concerned to obtain T1 and T2 seeds. The P5CS gene codes for a delta¹-pyrroline-5-carboxylate synthetase, a bifunctional enzyme that catalyzes two steps of proline biosynthesis in plants (Zhang et al., 1995; Peng et al., 1996, while the mutated gene is insensitive to feedback inhibition by proline. The potential benefit of this gene is to confer water stress resistance (drought, salt, cold due to increased intracellular levels of proline that works like an osmoprotectant. In this work could obtain and characterize transgenic lettuce lineages which are resistant to freezing temperature.
Wang, Yi-Hong; Choi, Woobong; Thomas, Claude E; Dean, Ralph A
Disease resistance has not yet been characterized at the molecular level in cucurbits, a group of high-value, nutritious, horticultural plants. Previously, we genetically mapped the Fom-2 gene that confers resistance to Fusarium wilt races 0 and I of melon. In this paper, two cosegregating codominant markers (AM, AFLP marker; FM, Fusarium marker) were used to screen a melon bacterial artificial chromosome (BAC) library. Identified clones were fingerprinted and end sequenced. Fingerprinting analysis showed that clones identified by each marker assembled into two separate contigs at high stringency. GenBank searches produced matches to leucine-rich repeats (LRRs) of resistance genes (R genes); to retroelements and to cellulose synthase in clones identified by FM; and to nucleotide-binding sites (NBSs) of R genes, retroelements, and cytochrome P-450 in clones identified by AM. A 6.5-kb fragment containing both NBS and LRR sequences was found to share high homology to TIR (Toll-interleukin-1 receptor)-NBS-LRR R genes, such as N, with 42% identity and 58% similarity in the TIR-NBS and LRR regions. The sequence information may be useful for identifying NBS-LRR class of R genes in other cucurbits.
Jaime Maria DLA
Full Text Available Abstract Background Chitosan oligosaccharide (COS, a deacetylated derivative of chitin, is an abundant, and renewable natural polymer. COS has higher antimicrobial properties than chitosan and is presumed to act by disrupting/permeabilizing the cell membranes of bacteria, yeast and fungi. COS is relatively non-toxic to mammals. By identifying the molecular and genetic targets of COS, we hope to gain a better understanding of the antifungal mode of action of COS. Results Three different chemogenomic fitness assays, haploinsufficiency (HIP, homozygous deletion (HOP, and multicopy suppression (MSP profiling were combined with a transcriptomic analysis to gain insight in to the mode of action and mechanisms of resistance to chitosan oligosaccharides. The fitness assays identified 39 yeast deletion strains sensitive to COS and 21 suppressors of COS sensitivity. The genes identified are involved in processes such as RNA biology (transcription, translation and regulatory mechanisms, membrane functions (e.g. signalling, transport and targeting, membrane structural components, cell division, and proteasome processes. The transcriptomes of control wild type and 5 suppressor strains overexpressing ARL1, BCK2, ERG24, MSG5, or RBA50, were analyzed in the presence and absence of COS. Some of the up-regulated transcripts in the suppressor overexpressing strains exposed to COS included genes involved in transcription, cell cycle, stress response and the Ras signal transduction pathway. Down-regulated transcripts included those encoding protein folding components and respiratory chain proteins. The COS-induced transcriptional response is distinct from previously described environmental stress responses (i.e. thermal, salt, osmotic and oxidative stress and pre-treatment with these well characterized environmental stressors provided little or any resistance to COS. Conclusions Overexpression of the ARL1 gene, a member of the Ras superfamily that regulates membrane
Jaime, Maria D L A; Lopez-Llorca, Luis Vicente; Conesa, Ana; Lee, Anna Y; Proctor, Michael; Heisler, Lawrence E; Gebbia, Marinella; Giaever, Guri; Westwood, J Timothy; Nislow, Corey
Chitosan oligosaccharide (COS), a deacetylated derivative of chitin, is an abundant, and renewable natural polymer. COS has higher antimicrobial properties than chitosan and is presumed to act by disrupting/permeabilizing the cell membranes of bacteria, yeast and fungi. COS is relatively non-toxic to mammals. By identifying the molecular and genetic targets of COS, we hope to gain a better understanding of the antifungal mode of action of COS. Three different chemogenomic fitness assays, haploinsufficiency (HIP), homozygous deletion (HOP), and multicopy suppression (MSP) profiling were combined with a transcriptomic analysis to gain insight in to the mode of action and mechanisms of resistance to chitosan oligosaccharides. The fitness assays identified 39 yeast deletion strains sensitive to COS and 21 suppressors of COS sensitivity. The genes identified are involved in processes such as RNA biology (transcription, translation and regulatory mechanisms), membrane functions (e.g. signalling, transport and targeting), membrane structural components, cell division, and proteasome processes. The transcriptomes of control wild type and 5 suppressor strains overexpressing ARL1, BCK2, ERG24, MSG5, or RBA50, were analyzed in the presence and absence of COS. Some of the up-regulated transcripts in the suppressor overexpressing strains exposed to COS included genes involved in transcription, cell cycle, stress response and the Ras signal transduction pathway. Down-regulated transcripts included those encoding protein folding components and respiratory chain proteins. The COS-induced transcriptional response is distinct from previously described environmental stress responses (i.e. thermal, salt, osmotic and oxidative stress) and pre-treatment with these well characterized environmental stressors provided little or any resistance to COS. Overexpression of the ARL1 gene, a member of the Ras superfamily that regulates membrane trafficking, provides protection against COS
Mi, Xiaoxiao; Liu, Xue; Yan, Haolu; Liang, Lina; Zhou, Xiangyan; Yang, Jiangwei; Si, Huaijun; Zhang, Ning
Aphids, the largest group of sap-sucking pests, cause significant yield losses in agricultural crops worldwide every year. The massive use of pesticides to combat this pest causes severe damage to the environment, putting in risk the human health. In this study, transgenic potato plants expressing Galanthus nivalis agglutinin (GNA) gene were developed using CaMV 35S and ST-LS1 promoters generating six transgenic lines (35S1-35S3 and ST1-ST3 corresponding to the first and second promoter, respectively). Quantitative real-time polymerase chain reaction (qRT-PCR) analysis indicated that the GNA gene was expressed in leaves, stems and roots of transgenic plants under the control of the CaMV 35S promoter, while it was only expressed in leaves and stems under the control of the ST-LS1 promoter. The levels of aphid mortality after 5 days of the inoculation in the assessed transgenic lines ranged from 20 to 53.3%. The range of the aphid population in transgenic plants 15 days after inoculation was between 17.0±1.43 (ST2) and 36.6±0.99 (35S3) aphids per plant, which corresponds to 24.9-53.5% of the aphid population in non-transformed plants. The results of our study suggest that GNA expressed in transgenic potato plants confers a potential tolerance to aphid attack, which appears to be an alternative against the use of pesticides in the future. Copyright © 2016 Académie des sciences. Published by Elsevier SAS. All rights reserved.
Juliana Bernardi Ogliari
Full Text Available We used 125 microsatellite markers to genotype the maize (Zea mays L. near isogenic lines (NIL L30HtPHtPRtRt and L30htphtpRtRt and the L40htphtprtrt line which contrast regarding the presence of the recently described dominant HtP and the recessive rt genes that confer resistance to Exserohilum turcicum. Five microsatellite markers revealed polymorphisms between the NIL and were considered candidate linked markers for the HtP resistance gene. Linkage was confirmed by bulked segregant sample (BSS analysis of 32 susceptible and 34 resistant plants from a BC1F1 population derived from the cross (L30HtPHtPRtRt x L40htphtprtrt x L40htphtprtrt. The bnlg198 and dupssr25 markers, both located on maize chromosome 2L (bin 2.08, were polymorphic between bulks. Linkage distances were estimated based on co-segregation data of the 32 susceptible plants and indicated distances of 28.7 centimorgans (cM between HtP and bnlg198 and 23.5 cM between HtP and dupssr25. The same set of susceptible plants was also genotyped with markers polymorphic between L30HtPHtPRtRt and L40htphtprtrt in order to find markers linked to the rt gene. Marker bnlg197, from chromosome 3L (bin 3.06, was found linked to rt at a distance of 9.7 cM. This is the first report on the chromosomal locations of these newly described genes.
Hansen, Lykke H; Vester, Birte
The Cfr RNA methyltransferase causes multiple resistances to peptidyl transferase inhibitors by methylation of A2503 23S rRNA. Many cfr-like gene sequences in the databases code for unknown functions. This study confirms that a Cfr-like protein from a Peptoclostridium difficile (formerly Clostrid......The Cfr RNA methyltransferase causes multiple resistances to peptidyl transferase inhibitors by methylation of A2503 23S rRNA. Many cfr-like gene sequences in the databases code for unknown functions. This study confirms that a Cfr-like protein from a Peptoclostridium difficile (formerly...... Clostridium difficile) strain does function as a Cfr protein. The enzyme is expressed in Escherichia coli and shows elevated MICs for five classes of antibiotics. A primer extension stop indicates a modification at A2503 in 23S rRNA....
A horizontally gene transferred copper resistance locus confers hyper-resistance to antibacterial copper toxicity and enables survival of community acquired methicillin resistant Staphylococcus aureus USA300 in macrophages.
Purves, Joanne; Thomas, Jamie; Riboldi, Gustavo P; Zapotoczna, Marta; Tarrant, Emma; Andrew, Peter W; Londoño, Alejandra; Planet, Paul J; Geoghegan, Joan A; Waldron, Kevin J; Morrissey, Julie A
Excess copper is highly toxic and forms part of the host innate immune system's antibacterial arsenal, accumulating at sites of infection and acting within macrophages to kill engulfed pathogens. We show for the first time that a novel, horizontally gene transferred copper resistance locus (copXL), uniquely associated with the SCCmec elements of the highly virulent, epidemic, community acquired methicillin resistant Staphylococcus aureus (CA-MRSA) USA300, confers copper hyper-resistance. These genes are additional to existing core genome copper resistance mechanisms, and are not found in typical S. aureus lineages, but are increasingly identified in emerging pathogenic isolates. Our data show that CopX, a putative P 1B-3 -ATPase efflux transporter, and CopL, a novel lipoprotein, confer copper hyper-resistance compared to typical S. aureus strains. The copXL genes form an operon that is tightly repressed in low copper environments by the copper regulator CsoR. Significantly, CopX and CopL are important for S. aureus USA300 intracellular survival within macrophages. Therefore, the emergence of new S. aureus clones with the copXL locus has significant implications for public health because these genes confer increased resistance to antibacterial copper toxicity, enhancing bacterial fitness by altering S. aureus interaction with innate immunity. © 2018 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.
To research possible influences of the disease resistance conferred by different trans-resistance genes on the transgenic rice plants in their yields and grain quality, three transgenic rice lines, including two with the resistance genes Pi-d2 and Pi-d3, respectively, for rice blast, and one with the resistance gene Xa21 for rice ...
Mi, Xiaoxiao; Ji, Xiangzhuo; Yang, Jiangwei; Liang, Lina; Si, Huaijun; Wu, Jiahe; Zhang, Ning; Wang, Di
The Colorado potato beetle (Leptinotarsa decemlineata Say, CPB) is a fatal pest, which is a quarantine pest in China. The CPB has now invaded the Xinjiang Uygur Autonomous Region and is constantly spreading eastward in China. In this study, we developed transgenic potato plants expressing cry3A gene. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis indicated that the cry3A gene expressed in leaves, stems and roots of the transgenic plants under the control of CaMV 35S promoter, while they expressed only in leaves and stems under the control of potato leaf and stem-specific promoter ST-LS1. The mortality of the larvae was higher (28% and 36%) on the transgenic plant line 35S1 on the 3rd and 4th days, and on ST3 (48%) on the 5th day after inoculation with instar larvae. Insect biomass accumulation on the foliage of the transgenic plant lines 35S1, 35S2 and ST3 was significantly lower (0.42%, 0.43% and 0.42%). Foliage consumption was lowest on transgenic lines 35S8 and ST2 among all plant foliage (7.47 mg/larvae/day and 12.46 mg/larvae/day). The different transgenic plant foliages had varied inhibition to larval growth. The survivors on the transgenic lines obviously were smaller than their original size and extremely weak. The transgenic potato plants with CPB resistance could be used to develop germplasms or varieties for controlling CPB damage and halting its spread in China. Copyright © 2015 Académie des sciences. Published by Elsevier SAS. All rights reserved.
Identification of ABC transporter genes conferring combined pleuromutilin-lincosamide-streptogramin A resistance in bovine methicillin-resistant Staphylococcus aureus and coagulase-negative staphylococci.
Wendlandt, Sarah; Kadlec, Kristina; Feßler, Andrea T; Schwarz, Stefan
The aim of this study was to investigate the genetic basis of combined pleuromutilin-lincosamide-streptogramin A resistance in 26 unrelated methicillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative staphylococci (CoNS) from dairy cows suffering from mastitis. The 26 pleuromutilin-resistant staphylococcal isolates were screened for the presence of the genes vga(A), vga(B), vga(C), vga(E), vga(E) variant, sal(A), vmlR, cfr, lsa(A), lsa(B), lsa(C), and lsa(E) by PCR. None of the 26 isolates carried the genes vga(B), vga(C), vga(E), vga(E) variant, vmlR, cfr, lsa(A), lsa(B), or lsa(C). Two Staphylococcus haemolyticus and single Staphylococcus xylosus, Staphylococcus lentus, and Staphylococcus hominis were vga(A)-positive. Twelve S. aureus, two Staphylococcus warneri, as well as single S. lentus and S. xylosus carried the lsa(E) gene. Moreover, single S. aureus, S. haemolyticus, S. xylosus, and Staphylococcus epidermidis were positive for both genes, vga(A) and lsa(E). The sal(A) gene was found in a single Staphylococcus sciuri. All ABC transporter genes were located in the chromosomal DNA, except for a plasmid-borne vga(A) gene in the S. epidermidis isolate. The genetic environment of the lsa(E)-positive isolates was analyzed using previously described PCR assays. Except for the S. warneri and S. xylosus, all lsa(E)-positive isolates harbored a part of the previously described enterococcal multiresistance gene cluster. This is the first report of the novel lsa(E) gene in the aforementioned bovine CoNS species. This is also the first identification of the sal(A) gene in a S. sciuri from a case of bovine mastitis. Moreover, the sal(A) gene was shown to also confer pleuromutilin resistance. Copyright © 2015 Elsevier B.V. All rights reserved.
Guillén, P; Guis, M; Martínez-Reina, G; Colrat, S; Dalmayrac, S; Deswarte, C; Bouzayen, M; Roustan, J P; Fallot, J; Pech, J C; Latché, A
Eutypine, 4-hydroxy-3-(3-methyl-3-butene-1-ynyl) benzyl aldehyde, is a toxin produced by Eutypa lata, the causal agent of eutypa dieback of grapevines. It has previously been demonstrated that tolerance of some cultivars to this disease was correlated with their capacity to convert eutypine to the corresponding alcohol, eutypinol, which lacks phytotoxicity. We have thus purified to homogeneity a protein from Vigna radiata that exhibited eutypine-reducing activity and have isolated the corresponding cDNA. This encodes an NADPH-dependent reductase of 36 kDa that we have named Vigna radiata eutypine-reducing enzyme (VR-ERE), based on the capacity of a recombinant form of the protein to reduce eutypine into eutypinol. The strongest homologies (86.8%) of VR-ERE at the amino acid level were found with CPRD14, a drought-inducible gene of unknown function, isolated from Vigna unguiculata and with an aromatic alcohol dehydrogenase (71.7%) from Eucalyptus gunnii. Biochemical characterization of VR-ERE revealed that a variety of compounds containing an aldehyde group can act as substrates. However, the highest affinity was observed with 3-substituted benzaldehydes. Expression of a VR-ERE transgene in Vitis vinifera cells cultured in vitro conferred resistance to the toxin. This discovery opens up new biotechnological approaches for the generation of grapevines resistant to eutypa dieback.
Rivero, Mercedes; Furman, Nicolás; Mencacci, Nicolás; Picca, Pablo; Toum, Laila; Lentz, Ezequiel; Bravo-Almonacid, Fernando; Mentaberry, Alejandro
Solanum tuberosum plants were transformed with three genetic constructions expressing the Nicotiana tabacum AP24 osmotine, Phyllomedusa sauvagii dermaseptin and Gallus gallus lysozyme, and with a double-transgene construction expressing the AP24 and lysozyme sequences. Re-transformation of dermaseptin-transformed plants with the AP24/lysozyme construction allowed selection of plants simultaneously expressing the three transgenes. Potato lines expressing individual transgenes or double- and triple-transgene combinations were assayed for resistance to Erwinia carotovora using whole-plant and tuber infection assays. Resistance levels for both infection tests compared consistently for most potato lines and allowed selection of highly resistant phenotypes. Higher resistance levels were found in lines carrying the dermaseptin and lysozyme sequences, indicating that theses proteins are the major contributors to antibacterial activity. Similar results were obtained in tuber infection tests conducted with Streptomyces scabies. Plant lines showing the higher resistance to bacterial infections were challenged with Phytophthora infestans, Rhizoctonia solani and Fusarium solani. Considerable levels of resistance to each of these pathogens were evidenced employing semi-quantitative tests based in detached-leaf inoculation, fungal growth inhibition and in vitro plant inoculation. On the basis of these results, we propose that stacking of these transgenes is a promising approach to achieve resistance to both bacterial and fungal pathogens. Copyright © 2011 Elsevier B.V. All rights reserved.
Soybean cyst nematode (Heterodera glycines Ichinohe, SCN) is the most pervasive pest of soybean [Glycine max (L.) Merr.] in the USA and worldwide. SCN reduced soybean yields worldwide by an estimated billion dollars annually. These losses remained stable with the use of resistant cultivars but over ...
Full Text Available Abstract Background Thus far gene therapy strategies for HIV/AIDS have used either conventional retroviral vectors or lentiviral vectors for gene transfer. Although highly efficient, their use poses a certain degree of risk in terms of viral mediated oncogenesis. Sleeping Beauty (SB transposon system offers a non-viral method of gene transfer to avoid this possible risk. With respect to conferring HIV resistance, stable knock down of HIV-1 coreceptors CCR5 and CXCR4 by the use of lentiviral vector delivered siRNAs has proved to be a promising strategy to protect cells from HIV-1 infection. In the current studies our aim is to evaluate the utility of SB system for stable gene transfer of CCR5 and CXCR4 siRNA genes to derive HIV resistant cells as a first step towards using this system for gene therapy. Results Two well characterized siRNAs against the HIV-1 coreceptors CCR5 and CXCR4 were chosen based on their previous efficacy for the SB transposon gene delivery. The siRNA transgenes were incorporated individually into a modified SB transfer plasmid containing a FACS sortable red fluorescence protein (RFP reporter and a drug selectable neomycin resistance gene. Gene transfer was achieved by co-delivery with a construct expressing a hyperactive transposase (HSB5 into the GHOST-R3/X4/R5 cell line, which expresses the major HIV receptor CD4 and and the co-receptors CCR5 and CXCR4. SB constructs expressing CCR5 or CXCR4 siRNAs were also transfected into MAGI-CCR5 or MAGI-CXCR4 cell lines, respectively. Near complete downregulation of CCR5 and CXCR4 surface expression was observed in transfected cells. During viral challenge with X4-tropic (NL4.3 or R5-tropic (BaL HIV-1 strains, the respective transposed cells showed marked viral resistance. Conclusion SB transposon system can be used to deliver siRNA genes for stable gene transfer. The siRNA genes against HIV-1 coreceptors CCR5 and CXCR4 are able to downregulate the respective cell surface proteins
Salicylic acid plays a critical role in activating plant defence responses after pathogen attack. Salicylic acid methyltransferase (SAMT) modulates the level of salicylic acid by converting salicylic acid to methyl salicylate. Here, we report that a SAMT gene from soybean (GmSAMT1) plays a role in s...
Tomberg, Joshua; Unemo, Magnus; Ohnishi, Makoto; Davies, Christopher; Nicholas, Robert A
The recent identification of a high-level-ceftriaxone-resistant (MIC = 2 to 4 μg/ml) isolate of Neisseria gonorrhoeae from Japan (H041) portends the loss of ceftriaxone as an effective treatment for gonococcal infections. This is of grave concern because ceftriaxone is the last remaining option for first-line empirical antimicrobial monotherapy. The penA gene from H041 (penA41) is a mosaic penA allele similar to mosaic alleles conferring intermediate-level cephalosporin resistance (Ceph(i)) worldwide but has 13 additional mutations compared to the mosaic penA gene from the previously studied Ceph(i) strain 35/02 (penA35). When transformed into the wild-type strain FA19, the penA41 allele confers 300- and 570-fold increases in the MICs for ceftriaxone and cefixime, respectively. In order to understand the mechanisms involved in high-level ceftriaxone resistance and to improve surveillance and epidemiology during the potential emergence of ceftriaxone resistance, we sought to identify the minimum number of amino acid alterations above those in penA35 that confer high-level resistance to ceftriaxone. Using restriction fragment exchange and site-directed mutagenesis, we identified three mutations, A311V, T316P, and T483S, that, when incorporated into the mosaic penA35 allele, confer essentially all of the increased resistance of penA41. A311V and T316P are close to the active-site nucleophile Ser310 that forms the acyl-enzyme complex, while Thr483 is predicted to interact with the carboxylate of the β-lactam antibiotic. These three mutations have thus far been described only for penA41, but dissemination of these mutations in other mosaic alleles would spell the end of ceftriaxone as an effective treatment for gonococcal infections.
Valentini, Giseli; Gonçalves-Vidigal, Maria Celeste; Hurtado-Gonzales, Oscar P; de Lima Castro, Sandra Aparecida; Cregan, Perry B; Song, Qijian; Pastor-Corrales, Marcial A
Co-segregation analysis and high-throughput genotyping using SNP, SSR, and KASP markers demonstrated genetic linkage between Ur-14 and Co-3 4 /Phg-3 loci conferring resistance to the rust, anthracnose and angular leaf spot diseases of common bean. Rust, anthracnose, and angular leaf spot are major diseases of common bean in the Americas and Africa. The cultivar Ouro Negro has the Ur-14 gene that confers broad spectrum resistance to rust and the gene cluster Co-3 4 /Phg-3 containing two tightly linked genes conferring resistance to anthracnose and angular leaf spot, respectively. We used co-segregation analysis and high-throughput genotyping of 179 F 2:3 families from the Rudá (susceptible) × Ouro Negro (resistant) cross-phenotyped separately with races of the rust and anthracnose pathogens. The results confirmed that Ur-14 and Co-3 4 /Phg-3 cluster in Ouro Negro conferred resistance to rust and anthracnose, respectively, and that Ur-14 and the Co-3 4 /Phg-3 cluster were closely linked. Genotyping the F 2:3 families, first with 5398 SNPs on the Illumina BeadChip BARCBEAN6K_3 and with 15 SSR, and eight KASP markers, specifically designed for the candidate region containing Ur-14 and Co-3 4 /Phg-3, permitted the creation of a high-resolution genetic linkage map which revealed that Ur-14 was positioned at 2.2 cM from Co-3 4 /Phg-3 on the short arm of chromosome Pv04 of the common bean genome. Five flanking SSR markers were tightly linked at 0.1 and 0.2 cM from Ur-14, and two flanking KASP markers were tightly linked at 0.1 and 0.3 cM from Co-3 4 /Phg-3. Many other SSR, SNP, and KASP markers were also linked to these genes. These markers will be useful for the development of common bean cultivars combining the important Ur-14 and Co-3 4 /Phg-3 genes conferring resistance to three of the most destructive diseases of common bean.
Sun, Xueli; Guo, Juxin; Ye, Wenyun; Guo, Qin; Huang, Yun; Ma, Lei; Zhou, Dan; Shen, Bo; Sun, Yan; Zhu, Changliang
Cuticular proteins (CPs) are implicated in insecticide resistance in mosquito populations. Here, we investigated the role of cuticular genes in regulation of insecticide resistance in Culex pipiens pallens. We identified two CpCPRs (CpCPR63 and CpCPR47) that exhibited higher transcript levels in pyrethroid-resistant strains than in susceptible strains. Mosquito mortality was increased after knockdown of CpCPR genes by dsRNA injection. The RNA interference experiment suggested an interaction between CpCPR63 and CpCPR47, as silencing of one gene resulted in decreased expression of the other. These findings revealed that CpCPRs may regulate pyrethroid resistance and could be used as a potential genetic marker to monitor pyrethroid resistance in mosquitoes.
Full Text Available This study characterized isolates of P. capsici that had developed a novel mechanism of resistance to zoxamide, which altered the minimum inhibition concentration (MIC but not the EC50. Molecular analysis revealed that the β-tubulin gene of the resistant isolates contained no mutations and was expressed at the same level as in zoxamide-sensitive isolates. This suggested that P. capsici had developed a novel non-target-site-based resistance to zoxamide. Analysis of the segregation ratio of zoxamide-resistance in the sexual progeny of the sensitive isolates PCAS1 and PCAS2 indicated that the resistance to zoxamide was controlled by one or more recessive nuclear genes. Furthermore, the segregation of resistance in the F1, F2, and BC1 progeny was in accordance with the theoretical ratios of the χ(2 test (P>0.05, which suggested that the resistance to zoxamide was controlled by two recessive genes, and that resistance to zoxamide occurred when at least one pair of these alleles was homozygous. This implies that the risk of zoxamide-resistance in P. capsici is low to moderate. Nevertheless this potential for resistance should be monitored closely, especially if two compatible mating types co-exist in the same field.
Lyngkjær, M.F.; Carver, T.L.W.; Zeyen, R.J.
. Additional suppression of mlo5 penetration resistance against the avirulent E. graminis isolate was achieved by using DDG, mannose, or glucose in combination with the phenylalanine ammonia lyase inhibitor alpha-aminooxy-beta-phenylpropionic acid (AOPP). A mlo virulent isolate of E. graminis was also tested...
Henry V. Amerson
Full Text Available Nearly two decades of research on the host-pathogen interaction in fusiform rust of loblolly pine is detailed. Results clearly indicate that pathotype-specific genes in the host interacting with pathogen avirulence cause resistance as defined by the non-gall phenotype under favorable environmental conditions for disease development. In particular, nine fusiform rust resistance genes (Fr genes are described here including the specific methods to determine each and their localization on the reference genetic map of loblolly pine. Understanding how these and other apparent Fr genes in loblolly pine and other rust-susceptible pines impact resistance screening, parental and progeny selection, and family and clonal deployment is an important area in forest genetics research and operational tree breeding. The documentation of these Fr genes is a key piece of information towards gaining that understanding and ultimately improving breeding and deployment strategies.
Full Text Available A spontaneous fluoroquinolone-resistant mutant (STM1 was isolated from its parent Salmonella enterica serovar Typhi (S. Typhi clinical isolate. Unlike its parent isolate, this mutant has selective resistance to fluoroquinolones without any change in its sensitivity to various other antibiotics. DNA gyrase assays revealed that the fluoroquinolone resistance phenotype of the STM1 mutant did not result from alteration of the fluoroquinolone sensitivity of the DNA gyrase isolated from it. To study the mechanism of fluoroquinolone resistance, a genomic library from the STM1 mutant was constructed in Escherichia coli DH5α and two recombinant plasmids were obtained. Only one of these plasmids (STM1-A conferred the selective fluoroquinolone resistance phenotype to E. coli DH5α. The chromosomal insert from STM1-A, digested with EcoRI and HindIII restriction endonucleases, produced two DNA fragments and these were cloned separately into pUC19 thereby generating two new plasmids, STM1-A1 and STM1-A2. Only STM1-A1 conferred the selective fluoroquinolone resistance phenotype to E. coli DH5α. Sequence and subcloning analyses of STM1-A1 showed the presence of an intact RecA open reading frame. Unlike that of the wild-type E. coli DH5α, protein analysis of a crude STM1-A1 extract showed overexpression of a 40 kDa protein. Western blotting confirmed the 40 kDa protein band to be RecA. When a RecA PCR product was cloned into pGEM-T and introduced into E. coli DH5α, the STM1-A11 subclone retained fluoroquinolone resistance. These results suggest that overexpression of RecA causes selective fluoroquinolone resistance in E. coli DH5α.
Yassien, M A M; Elfaky, M A
A spontaneous fluoroquinolone-resistant mutant (STM1) was isolated from its parent Salmonella enterica serovar Typhi (S. Typhi) clinical isolate. Unlike its parent isolate, this mutant has selective resistance to fluoroquinolones without any change in its sensitivity to various other antibiotics. DNA gyrase assays revealed that the fluoroquinolone resistance phenotype of the STM1 mutant did not result from alteration of the fluoroquinolone sensitivity of the DNA gyrase isolated from it. To study the mechanism of fluoroquinolone resistance, a genomic library from the STM1 mutant was constructed in Escherichia coli DH5α and two recombinant plasmids were obtained. Only one of these plasmids (STM1-A) conferred the selective fluoroquinolone resistance phenotype to E. coli DH5α. The chromosomal insert from STM1-A, digested with EcoRI and HindIII restriction endonucleases, produced two DNA fragments and these were cloned separately into pUC19 thereby generating two new plasmids, STM1-A1 and STM1-A2. Only STM1-A1 conferred the selective fluoroquinolone resistance phenotype to E. coli DH5α. Sequence and subcloning analyses of STM1-A1 showed the presence of an intact RecA open reading frame. Unlike that of the wild-type E. coli DH5α, protein analysis of a crude STM1-A1 extract showed overexpression of a 40 kDa protein. Western blotting confirmed the 40 kDa protein band to be RecA. When a RecA PCR product was cloned into pGEM-T and introduced into E. coli DH5α, the STM1-A11 subclone retained fluoroquinolone resistance. These results suggest that overexpression of RecA causes selective fluoroquinolone resistance in E. coli DH5α.
Aug 2, 2004 ... had achieved full virological suppression (viral load. < 50 copies/ml). Thirty-two per cent of women had nevirapine-resistant virus. A novel strategy to avoid maternal exposure to nevirapine might be administering the drug to the newborn as post- exposure prophylaxis (PEP). Researchers from South Africa3.
Bulos, Mariano; Vergani, Pablo Nicolas; Altieri, Emiliano
Rust resistance in the sunflower line P386 is controlled by Pu 6 , a gene which was reported to segregate independently from other rust resistant genes, such as R 4 . The objectives of this work were to map Pu 6 , to provide and validate molecular tools for its identification, and to determine the linkage relationship of Pu 6 and R 4 . Genetic mapping of Pu 6 with six markers covered 24.8 cM of genetic distance on the lower end of linkage Group 13 of the sunflower consensus map. The marker most closely linked to Pu 6 was ORS316 at 2.5 cM in the distal position. ORS316 presented five alleles when was assayed with a representative set of resistant and susceptible lines. Allelism test between Pu 6 and R 4 indicated that both genes are linked at a genetic distance of 6.25 cM. This is the first confirmation based on an allelism test that at least two members of the R adv /R 4 /R 11 / R 13a /R 13b /Pu 6 cluster of genes are at different loci. A fine elucidation of the architecture of this complex locus will allow designing and constructing completely new genomic regions combining genes from different resistant sources and the elimination of the linkage drag around each resistant gene.
Chen, J; Fluharty, F L; St-Pierre, N; Morrison, M; Yu, Z
Development of antimicrobial resistance in food animals receiving antimicrobials has been well documented among bacterial isolates, especially pathogens, but information on development of antimicrobial resistance at the microbial community level during long-term feeding of antimicrobials is lacking. The objective of this study was to examine the association between inclusion of tylosin in feed and occurrence of resistance to macrolide-lincosamide-streptogramin B (MLS(B)) in the entire fecal microbial communities of beef cattle over a feeding study of 168 d. A completely randomized design included 6 pens housed together in 1 barn, with each pen housing 10 to 11 steers. The control and tylosin groups each had 3 pens, with the former receiving no antimicrobial whereas the latter received both tylosin and monensin (11 and 29.9 mg/ kg of feed, respectively, DM) in feed. The abundance of genes conferring resistance to MLS(B) (erm genes) and tetracyclines (tet genes) were quantified using class-specific, real-time PCR assays. The abundances of erm and tet genes were analyzed with pens as experimental units using the MIXED procedure of SAS. Correlations between abundance of different resistance genes were calculated using the CORR procedure of SAS. We identified 4 classes (B, F, T, and X) of erm genes in fresh fecal samples collected at wk 2, 17, and 21 of feeding. From wk 2 to 17, the abundance of erm(T) and erm(X) increased (P tylosin feeding. Such co-selection of multiresistance at community level by one antimicrobial drug used in animals has the important implication that future studies should examine resistance to not only the antimicrobials used in animals, but also other antimicrobials, especially those used in human medicine, to fully assess the potential risk associated with antimicrobial use in animals. Both the erm and tet genes appeared to be disseminated among the microbial populations in all steers housed together.
Full Text Available Clubroot, caused by the plasmodiophorid pathogen Plasmodiophora brassicae, is one of the most serious diseases on Brassica crops worldwide and a major threat to canola production in western Canada. Host resistance is the key strategy for clubroot management on canola. Several clubroot resistance (CR genes have been identified, but the mechanisms associated with these CR genes are poorly understood. In the current study, a label-free shotgun proteomic approach was used to profile and compare the proteomes of B. rapa carrying and not carrying the CR gene Rcr1 upon P. brassicae infection. A total of 527 differentially accumulated proteins (DAPs were identified between the resistant and susceptible samples, and functional annotation of these DAPs indicates that the perception of P. brassicae and activation of defense responses is triggered via an unique signaling pathway distinct from common modes of recognition receptors reported with many other plant-pathogen interactions; this pathway appears to act in a calcium-independent manner through a not-well defined cascade of mitogen-activated protein kinases and may require the ubiquitin-26S proteasome related to abiotic stresses, especially the cold-stress tolerance. Both up-regulation of defense-related and down-regulation of pathogenicity-related metabolism were observed in plants carrying Rcr1, and these functions may all contribute to the clubroot resistance mediated by this CR gene. These results, combined with those of transcriptomic analysis reported earlier, improved our understanding of molecular mechanisms associated with Rcr1 and clubroot resistance at large, and identified candidate metabolites or pathways for further confirmation of specific resistance mechanisms. Deploying CR genes with different modes of action may help improve the durability of clubroot resistance.
Xiao, Shunyuan; Charoenwattana, Piyavadee; Holcombe, Lucy; Turner, John G
Plant disease resistance (R) gene products recognize pathogen avirulence (Avr) gene products and induce defense responses. It is not known if an R gene can function in different plant families, however. The Arabidopsis thaliana R genes RPW8.1 and RPW8.2 confer resistance to the powdery mildew pathogens Erysiphe orontii, E. cichoracearum, and Oidium lycopersici, which also infect plants from other families. We produced transgenic Nicotiana tabacum, N. benthamiana, and Lycopersicon esculentum plants containing RPW8.1 and RPW8.2. Transgenic N. tabacum plants had increased resistance to E. orontii and O. lycopersici, transgenic N. benthamiana plants had increased resistance to E. cichoracearum, but transgenic L. esculentum plants remained susceptible to these pathogens. The defense responses induced in transgenic N. tabacum and N. benthamiana were similar to those mediated by RPW8.1 and RPW8.2 in Arabidopsis. Apparently, RPW8.1 and RPW8.2 could be used to control powdery mildew diseases of plants from other families.
Henry Amerson; C. Dana Nelson; Thomas L. Kubisiak; E.George Kuhlman; Saul Garcia
Nearly two decades of research on the host-pathogen interaction in fusiform rust of loblolly pine is detailed. Results clearly indicate that pathotype-specific genes in the host interacting with pathogen avirulence cause resistance as defined by the non-gall phenotype under favorable environmental conditions for disease development. In particular, nine fusiform rust...
Breuker, C.J.; Victoir, K.; Jong, de P.W.; Meijden, van der E.; Brakefield, P.M.; Vrieling, K.
A so-called R-gene renders the yellow-striped flea beetle Phyllotreta nemorum L. (Coleoptera: Chrysomelidae: Alticinae) resistant to the defenses of the yellow rocket Barbarea vulgaris R.Br. (Brassicacea) and enables it to use it as a host plant in Denmark. In this study, genetic markers for an
Coelho Adriano C.
Full Text Available Pentamidine (PEN is an alternative compound to treat antimony-resistant leishmaniasis patients, which cellular target remains unclear. One approach to the identification of prospective targets is to identify genes able to mediate PEN resistance following overexpression. Starting from a genomic library of transfected parasites bearing a multicopy episomal cosmid vector containing wild-type Leishmania major DNA, we isolated one locus capable to render PEN resistance to wild type cells after DNA transfection. In order to map this Leishmania locus, cosmid insert was deleted by two successive sets of partial digestion with restriction enzymes, followed by transfection into wild type cells, overexpression, induction and functional tests in the presence of PEN. To determine the Leishmania gene related to PEN resistance, nucleotide sequencing experiments were done through insertion of the transposon Mariner element of Drosophila melanogaster (mosK into the deleted insert to work as primer island. Using general molecular techniques, we described here this method that permits a quickly identification of a functional gene facilitating nucleotide sequence experiments from large DNA fragments. Followed experiments revealed the presence of a P-Glycoprotein gene in this locus which role in Leishmania metabolism has now been analyzed.
Valkovicova, Lenka; Vavrova, Silvia Minarikova; Mravec, Jozef; Grones, Jozef; Turna, Jan
Gene cluster "ter" conferring high tellurite resistance has been identified in various pathogenic bacteria including Escherichia coli O157:H7. However, the precise mechanism as well as the molecular function of the respective gene products is unclear. Here we describe protein-protein association and localization analyses of four essential Ter proteins encoded by minimal resistance-conferring fragment (terBCDE) by means of recombinant expression. By using a two-plasmid complementation system we show that the overproduced single Ter proteins are not able to mediate tellurite resistance, but all Ter members play an irreplaceable role within the cluster. We identified several types of homotypic and heterotypic protein-protein associations among the Ter proteins by in vitro and in vivo pull-down assays and determined their cellular localization by cytosol/membrane fractionation. Our results strongly suggest that Ter proteins function involves their mutual association, which probably happens at the interface of the inner plasma membrane and the cytosol.
Tran, Phu-Tri; Widyasari, Kristin; Seo, Jang-Kyun; Kim, Kook-Hyung
Soybean mosaic virus (SMV), a member of the genus Potyvirus, significantly reduces soybean production worldwide. Rsv3, which confers strain-specific resistance to SMV, was previously mapped between the markers A519F/R and M3Satt in chromosome 14 of the soybean [Glycine max (L.) Merr.] genotype L29. Analysis of the soybean genome database revealed that five different NBS-LRR sequences exist between the flanking markers. Among these candidate Rsv3 genes, the full-length cDNA of the Glyma.14g204700 was successfully cloned from L29. Over-expression of Glyma.14g204700 in leaves inoculated with SMV inhibited viral infection in a soybean genotype lacking Rsv3. In addition, the transient silencing of the candidate gene caused a high accumulation of an avirulent strain in L29 carrying Rsv3. Our results therefore provide additional line of evidence to support that Glyma.14g204700 is likely Rsv3 gene that confers strain-specific resistance to SMV. Copyright © 2017 Elsevier Inc. All rights reserved.
Sendín, Lorena Noelia; Orce, Ingrid Georgina; Gómez, Rocío Liliana; Enrique, Ramón; Grellet Bournonville, Carlos Froilán; Noguera, Aldo Sergio; Vojnov, Adrián Alberto; Marano, María Rosa; Castagnaro, Atilio Pedro; Filippone, María Paula
Transgenic expression of the pepper Bs2 gene confers resistance to Xanthomonas campestris pv. vesicatoria (Xcv) pathogenic strains which contain the avrBs2 avirulence gene in susceptible pepper and tomato varieties. The avrBs2 gene is highly conserved among members of the Xanthomonas genus, and the avrBs2 of Xcv shares 96% homology with the avrBs2 of Xanthomonas citri subsp. citri (Xcc), the causal agent of citrus canker disease. A previous study showed that the transient expression of pepper Bs2 in lemon leaves reduced canker formation and induced plant defence mechanisms. In this work, the effect of the stable expression of Bs2 gene on citrus canker resistance was evaluated in transgenic plants of Citrus sinensis cv. Pineapple. Interestingly, Agrobacterium-mediated transformation of epicotyls was unsuccessful when a constitutive promoter (2× CaMV 35S) was used in the plasmid construction, but seven transgenic lines were obtained with a genetic construction harbouring Bs2 under the control of a pathogen-inducible promoter, from glutathione S-transferase gene from potato. A reduction of disease symptoms of up to 70% was observed in transgenic lines expressing Bs2 with respect to non-transformed control plants. This reduction was directly dependent on the Xcc avrBs2 gene since no effect was observed when a mutant strain of Xcc with a disruption in avrBs2 gene was used for inoculations. Additionally, a canker symptom reduction was correlated with levels of the Bs2 expression in transgenic plants, as assessed by real-time qPCR, and accompanied by the production of reactive oxygen species. These results indicate that the pepper Bs2 resistance gene is also functional in a family other than the Solanaceae, and could be considered for canker control.
Full Text Available Abstract Background Nonhost resistance (NHR provides immunity to all members of a plant species against all isolates of a microorganism that is pathogenic to other plant species. Three Arabidopsis thaliana PEN (penetration deficient genes, PEN1, 2 and 3 have been shown to provide NHR against the barley pathogen Blumeria graminis f. sp. hordei at the prehaustorial level. Arabidopsis pen1-1 mutant lacking the PEN1 gene is penetrated by the hemibiotrophic oomycete pathogen Phytophthora sojae, the causal organism of the root and stem rot disease in soybean. We investigated if there is any novel nonhost resistance mechanism in Arabidopsis against the soybean pathogen, P. sojae. Results The P.sojaesusceptible (pss 1 mutant was identified by screening a mutant population created in the Arabidopsis pen1-1 mutant that lacks penetration resistance against the non adapted barley biotrophic fungal pathogen, Blumeria graminis f. sp. hordei. Segregation data suggested that PEN1 is not epistatic to PSS1. Responses of pss1 and pen1-1 to P. sojae invasion were distinct and suggest that PSS1 may act at both pre- and post-haustorial levels, while PEN1 acts at the pre-haustorial level against this soybean pathogen. Therefore, PSS1 encodes a new form of nonhost resistance. The pss1 mutant is also infected by the necrotrophic fungal pathogen, Fusarium virguliforme, which causes sudden death syndrome in soybean. Thus, a common NHR mechanism is operative in Arabidopsis against both hemibiotrophic oomycetes and necrotrophic fungal pathogens that are pathogenic to soybean. However, PSS1 does not play any role in immunity against the bacterial pathogen, Pseudomonas syringae pv. glycinea, that causes bacterial blight in soybean. We mapped PSS1 to a region very close to the southern telomere of chromosome 3 that carries no known disease resistance genes. Conclusions The study revealed that Arabidopsis PSS1 is a novel nonhost resistance gene that confers a new form of
Sumit, Rishi; Sahu, Binod B; Xu, Min; Sandhu, Devinder; Bhattacharyya, Madan K
Nonhost resistance (NHR) provides immunity to all members of a plant species against all isolates of a microorganism that is pathogenic to other plant species. Three Arabidopsis thaliana PEN (penetration deficient) genes, PEN1, 2 and 3 have been shown to provide NHR against the barley pathogen Blumeria graminis f. sp. hordei at the prehaustorial level. Arabidopsis pen1-1 mutant lacking the PEN1 gene is penetrated by the hemibiotrophic oomycete pathogen Phytophthora sojae, the causal organism of the root and stem rot disease in soybean. We investigated if there is any novel nonhost resistance mechanism in Arabidopsis against the soybean pathogen, P. sojae. The P.sojaesusceptible (pss) 1 mutant was identified by screening a mutant population created in the Arabidopsis pen1-1 mutant that lacks penetration resistance against the non adapted barley biotrophic fungal pathogen, Blumeria graminis f. sp. hordei. Segregation data suggested that PEN1 is not epistatic to PSS1. Responses of pss1 and pen1-1 to P. sojae invasion were distinct and suggest that PSS1 may act at both pre- and post-haustorial levels, while PEN1 acts at the pre-haustorial level against this soybean pathogen. Therefore, PSS1 encodes a new form of nonhost resistance. The pss1 mutant is also infected by the necrotrophic fungal pathogen, Fusarium virguliforme, which causes sudden death syndrome in soybean. Thus, a common NHR mechanism is operative in Arabidopsis against both hemibiotrophic oomycetes and necrotrophic fungal pathogens that are pathogenic to soybean. However, PSS1 does not play any role in immunity against the bacterial pathogen, Pseudomonas syringae pv. glycinea, that causes bacterial blight in soybean. We mapped PSS1 to a region very close to the southern telomere of chromosome 3 that carries no known disease resistance genes. The study revealed that Arabidopsis PSS1 is a novel nonhost resistance gene that confers a new form of nonhost resistance against both a hemibiotrophic oomycete
Wu, G; Shortt, B J; Lawrence, E B; Levine, E B; Fitzsimmons, K C; Shah, D M
Plant defense responses to pathogen infection involve the production of active oxygen species, including hydrogen peroxide (H2O2). We obtained transgenic potato plants expressing a fungal gene encoding glucose oxidase, which generates H2O2 when glucose is oxidized. H2O2 levels were elevated in both leaf and tuber tissues of these plants. Transgenic potato tubers exhibited strong resistance to a bacterial soft rot disease caused by Erwinia carotovora subsp carotovora, and disease resistance was sustained under both aerobic and anaerobic conditions of bacterial infection. This resistance to soft rot was apparently mediated by elevated levels of H2O2, because the resistance could be counteracted by exogenously added H2O2-degrading catalase. The transgenic plants with increased levels of H2O2 also exhibited enhanced resistance to potato late blight caused by Phytophthora infestans. The development of lesions resulting from infection by P. infestans was significantly delayed in leaves of these plants. Thus, the expression of an active oxygen species-generating enzyme in transgenic plants represents a novel approach for engineering broad-spectrum disease resistance in plants.
Zhang, Haiyan; Yu, Pengli; Zhao, Jiuhai; Jiang, Hongling; Wang, Haiyang; Zhu, Yingfang; Botella, Miguel A; Šamaj, Jozef; Li, Chuanyou; Lin, Jinxing
Systemin (SYS), an octadecapeptide hormone processed from a 200-amino-acid precursor (prosystemin, PS), plays a central role in the systemic activation of defense genes in tomato in response to herbivore and pathogen attacks. However, whether PS mRNA is transferable and its role in systemic defense responses remain unknown. We created the transgenic tomato PS gene tagged with the green fluorescent protein (PS-GFP) using a shoot- or root-specific promoter, and the constitutive 35S promoter in Arabidopsis. Subcellular localization of PS-/SYS-GFP was observed using confocal laser scanning microscopy and gene transcripts were determined using quantitative real-time PCR. In Arabidopsis, PS protein can be processed and SYS is secreted. Shoot-/root-specific expression of PS-GFP in Arabidopsis, and grafting experiments, revealed that the PS mRNA moves in a bi-directional manner. We also found that ectopic expression of PS improves Arabidopsis resistance to the necrotrophic fungus Botrytis cinerea, consistent with substantial upregulation of the transcript levels of specific pathogen-responsive genes. Our results provide novel insights into the multifaceted mechanism of SYS signaling transport and its potential application in genetic engineering for increasing pathogen resistance across diverse plant families. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.
Moon, Dong Chan; Seol, Sung Yong; Gurung, Mamata; Jin, Jong Sook; Choi, Chul Hee; Kim, Jungmin; Lee, Yoo Chul; Cho, Dong Taek; Lee, Je Chul
Mutations in DNA gyrase and topoisomerase IV genes are the main mechanisms of resistance to quinolones. In this study, we determined mutations in gyrA, gyrB, parC and parE among 57 ciprofloxacin-resistant Escherichia coli isolates from a South Korean hospital and analysed the relationship between the minimal inhibitory concentrations (MICs) of fluoroquinolones and mutations in the topoisomerase IV gene. All ciprofloxacin-resistant E. coli isolates carried double mutations in gyrA and at least a single mutation in parC; some isolates also carried a single mutation in parE. The most common mutations were S83L and D87N in gyrA, S80I in parC and S458A in parE, which accounted for 25% of isolates. Single mutations in parE at L445I, S458P and S458W were identified for the first time. Double mutations in parC and a combination of single mutations in parC and parE significantly increased the MIC values of fluoroquinolones. In vitro induction of resistance to ciprofloxacin showed that double mutations in gyrA were a prerequisite to conferring a resistant phenotype to fluoroquinolones, and an additional mutation in the topoisomerase IV gene increased the MIC values of ciprofloxacin. In conclusion, emergence of a new mutation in parC and parE and its accumulation induces high levels of resistance to fluoroquinolones in E. coli.
Huang, Li; Zhang, Songlin; Singer, Stacy D; Yin, Xiangjing; Yang, Jinhua; Wang, Yuejin; Wang, Xiping
Stilbene synthase ( STS ) is a key gene in the biosynthesis of various stilbenoids, including resveratrol and its derivative glucosides (such as piceid), that has been shown to contribute to disease resistance in plants. However, the mechanism behind such a role has yet to be elucidated. Furthermore, the function of STS genes in osmotic stress tolerance remains unclear. As such, we sought to elucidate the role of STS genes in the defense against biotic and abiotic stress in the model plant Arabidopsis thaliana . Expression profiling of 31 VqSTS genes from Vitis quinquangularis revealed that VqSTS21 was up-regulated in response to powdery mildew (PM) infection. To provide a deeper understanding of the function of this gene, we cloned the full-length coding sequence of VqSTS21 and overexpressed it in Arabidopsis thaliana via Agrobacterium -mediated transformation. The resulting VqSTS21 Arabidopsis lines produced trans -piceid rather than resveratrol as their main stilbenoid product and exhibited improved disease resistance to PM and Pseudomonas syringae pv. tomato DC3000, but displayed increased susceptibility to Botrytis cinerea . In addition, transgenic Arabidopsis lines were found to confer tolerance to salt and drought stress from seed germination through plant maturity. Intriguingly, qPCR assays of defense-related genes involved in salicylic acid, jasmonic acid, and abscisic acid-induced signaling pathways in these transgenic lines suggested that VqSTS21 plays a role in various phytohormone-related pathways, providing insight into the mechanism behind VqSTS21 -mediated resistance to biotic and abiotic stress.
Full Text Available Stilbene synthase (STS is a key gene in the biosynthesis of various stilbenoids, including resveratrol and its derivative glucosides (such as piceid, that has been shown to contribute to disease resistance in plants. However, the mechanism behind such a role has yet to be elucidated. Furthermore, the function of STS genes in osmotic stress tolerance remains unclear. As such, we sought to elucidate the role of STS genes in the defense against biotic and abiotic stress in the model plant Arabidopsis thaliana. Expression profiling of 31 VqSTS genes from Vitis quinquangularis revealed that VqSTS21 was up-regulated in response to powdery mildew (PM infection. To provide a deeper understanding of the function of this gene, we cloned the full-length coding sequence of VqSTS21 and overexpressed it in Arabidopsis thaliana via Agrobacterium-mediated transformation. The resulting VqSTS21 Arabidopsis lines produced trans-piceid rather than resveratrol as their main stilbenoid product and exhibited improved disease resistance to PM and Pseudomonas syringae pv. tomato DC3000, but displayed increased susceptibility to Botrytis cinerea. In addition, transgenic Arabidopsis lines were found to confer tolerance to salt and drought stress from seed germination through plant maturity. Intriguingly, qPCR assays of defense-related genes involved in salicylic acid, jasmonic acid, and abscisic acid-induced signaling pathways in these transgenic lines suggested that VqSTS21 plays a role in various phytohormone-related pathways, providing insight into the mechanism behind VqSTS21-mediated resistance to biotic and abiotic stress.
Palmeros-Suárez, Paola A; Massange-Sánchez, Julio A; Martínez-Gallardo, Norma A; Montero-Vargas, Josaphat M; Gómez-Leyva, Juan F; Délano-Frier, John P
Nuclear factor-Y (NF-Y), is a plant heterotrimeric transcription factor constituted by NF-YA, NF-YB and NF-YC subunits. The function of many NF-Y subunits, mostly of the A and B type, has been studied in plants, but knowledge regarding the C subunit remains fragmentary. Here, a water stress-induced NF-YC gene from Amaranthus hypochondriacus (AhNF-YC) was further characterized by its overexpression in transgenic Arabidospis thaliana plants. A role in development was inferred from modified growth rates in root, rosettes and inflorescences recorded in AhNF-YC overexpressing Arabidopsis plants, in addition to a delayed onset of flowering. Also, the overexpression of AhNF-YC caused increased seedling sensitivity to abscisic acid (ABA), and influenced the expression of several genes involved in secondary metabolism, development and ABA-related responses. An altered expression of the latter in water stressed and recovered transgenic plants, together with the observed increase in ABA sensitivity, suggested that their increased water stress resistance was partly ABA-dependent. An untargeted metabolomic analysis also revealed an altered metabolite pattern, both in normal and water stress/recovery conditions. These results suggest that AhNF-YC may play an important regulatory role in both development and stress, and represents a candidate gene for the engineering of abiotic stress resistance in commercial crops. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
Wienholtz, Nanna H; Ciechanowski, Aynur Barut; Nørskov-Lauritsen, Niels
I from clinical strains encoding four substitutions in the transpeptidase region of PBP3 conferred resistance to ampicillin, but not to cephalosporins. Introduction of ftsI from a clinical strain encoding eight substitutions conferred resistance to ampicillin, cefotaxime and ceftriaxone. MICs....../H/S in combination with V511A were resistant to ampicillin. Substitution S385T increased the MICs of third-generation cephalosporins if V511A was also present. Conclusions: Substitutions in PBP3 are sufficient to confer resistance to both ampicillin and third-generation cephalosporins in H. parainfluenzae...... . A combination of substitutions at positions Val-511 and Asn-526 confers resistance to ampicillin. Resistance to third-generation cephalosporins probably requires more than four substitutions in PBP3....
Mamta; Reddy, K R K; Rajam, M V
Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) is a devastating agricultural insect pest with broad spectrum of host range, causing million dollars crop loss annually. Limitations in the present conventional and transgenic approaches have made it crucial to develop sustainable and environmental friendly methods for crop improvement. In the present study, host-induced RNA interference (HI-RNAi) approach was used to develop H. armigera resistant tobacco and tomato plants. Chitinase (HaCHI) gene, critically required for insect molting and metamorphosis was selected as a potential target. Hair-pin RNAi construct was prepared from the conserved off-target free partial HaCHI gene sequence and was used to generate several HaCHI-RNAi tobacco and tomato plants. Northern hybridization confirmed the production of HaCHI gene-specific siRNAs in HaCHI-RNAi tobacco and tomato lines. Continuous feeding on leaves of RNAi lines drastically reduced the target gene transcripts and consequently, affected the overall growth and survival of H. armigera. Various developmental deformities were also manifested in H. armigera larvae after feeding on the leaves of RNAi lines. These results demonstrated the role of chitinase in insect development and potential of HI-RNAi for effective management of H. armigera.
Andrésen, Cecilia; Jalal, Shah; Aili, Daniel; Wang, Yi; Islam, Sohidul; Jarl, Anngelica; Liedberg, Bo; Wretlind, Bengt; Mårtensson, Lars-Göran; Sunnerhagen, Maria
The self-assembling MexA-MexB-OprM efflux pump system, encoded by the mexO operon, contributes to facile resistance of Pseudomonas aeruginosa by actively extruding multiple antimicrobials. MexR negatively regulates the mexO operon, comprising two adjacent MexR binding sites, and is as such highly targeted by mutations that confer multidrug resistance (MDR). To understand how MDR mutations impair MexR function, we studied MexR-wt as well as a selected set of MDR single mutants distant from the proposed DNA-binding helix. Although DNA affinity and MexA-MexB-OprM repression were both drastically impaired in the selected MexR-MDR mutants, MexR-wt bound its two binding sites in the mexO with high affinity as a dimer. In the MexR-MDR mutants, secondary structure content and oligomerization properties were very similar to MexR-wt despite their lack of DNA binding. Despite this, the MexR-MDR mutants showed highly varying stabilities compared with MexR-wt, suggesting disturbed critical interdomain contacts, because mutations in the DNA-binding domains affected the stability of the dimer region and vice versa. Furthermore, significant ANS binding to MexR-wt in both free and DNA-bound states, together with increased ANS binding in all studied mutants, suggest that a hydrophobic cavity in the dimer region already shown to be involved in regulatory binding is enlarged by MDR mutations. Taken together, we propose that the biophysical MexR properties that are targeted by MDR mutations-stability, domain interactions, and internal hydrophobic surfaces-are also critical for the regulation of MexR DNA binding.
Tanumihardja, J.; Bela, B.
Fusion inhibitors have potential for future use in HIV control programs in Indonesia, so the capacity to test resistance to such drugs needs to be developed. Resistance-detection with a genotypic assay began with amplification of the target gene, gp41. Based on the sequence of the two most common HIV subtypes in Indonesia, AE and B, a primer pair was designed. Plasma samples containing both subtypes were extracted to obtain HIV RNA. Using PCR, the primer pair was used to produce the amplification product, the identity of which was checked based on length under electrophoresis. Eleven plasma samples were included in this study. One-step PCR using the primer pair was able to amplify gp41 from 54.5% of the samples, and an unspecific amplification product was seen in 1.1% of the samples. Amplification failed in 36.4% of the samples, which may be due to an inappropriate primer sequence. It was also found that the optimal annealing temperature for producing the single expected band was 57.2 °C. With one-step PCR, the designed primer pair amplified the HIV-1 gp41 gene from subtypes AE and B. However, further research should be done to determine the conditions that will increase the sensitivity and specificity of the amplification process.
Jacobs Jeanne ME
Full Text Available Abstract Background The recovery of high performing transgenic lines in clonal crops is limited by the occurrence of somaclonal variation during the tissue culture phase of transformation. This is usually circumvented by developing large populations of transgenic lines, each derived from the first shoot to regenerate from each transformation event. This study investigates a new strategy of assessing multiple shoots independently regenerated from different transformed cell colonies of potato (Solanum tuberosum L.. Results A modified cry9Aa2 gene, under the transcriptional control of the CaMV 35S promoter, was transformed into four potato cultivars using Agrobacterium-mediated gene transfer using a nptII gene conferring kanamycin resistance as a selectable marker gene. Following gene transfer, 291 transgenic lines were grown in greenhouse experiments to assess somaclonal variation and resistance to potato tuber moth (PTM, Phthorimaea operculella (Zeller. Independently regenerated lines were recovered from many transformed cell colonies and Southern analysis confirmed whether they were derived from the same transformed cell. Multiple lines regenerated from the same transformed cell exhibited a similar response to PTM, but frequently exhibited a markedly different spectrum of somaclonal variation. Conclusions A new strategy for the genetic improvement of clonal crops involves the regeneration and evaluation of multiple shoots from each transformation event to facilitate the recovery of phenotypically normal transgenic lines. Most importantly, regenerated lines exhibiting the phenotypic appearance most similar to the parental cultivar are not necessarily derived from the first shoot regenerated from a transformed cell colony, but can frequently be a later regeneration event.
Han, Qiang; Wang, Zhenzhen; He, Yunxin; Xiong, Yehui; Lv, Shun; Li, Shupeng; Zhang, Zhigang; Qiu, Dewen; Zeng, Hongmei
RNA interference (RNAi) has been developed as an efficient technology. RNAi insect-resistant transgenic plants expressing double-stranded RNA (dsRNA) that is ingested into insects to silence target genes can affect the viability of these pests or even lead to their death. HaHR3 , a molt-regulating transcription factor gene, was previously selected as a target expressed in bacteria and tobacco plants to control Helicoverpa armigera by RNAi technology. In this work, we selected the dsRNA- HaHR3 fragment to silence HaHR3 in cotton bollworm for plant mediated-RNAi research. A total of 19 transgenic cotton lines expressing HaHR3 were successfully cultivated, and seven generated lines were used to perform feeding bioassays. Transgenic cotton plants expressing ds HaHR3 were shown to induce high larval mortality and deformities of pupation and adult eclosion when used to feed the newly hatched larvae, and 3rd and 5th instar larvae of H. armigera . Moreover, HaHR3 transgenic cotton also demonstrated an improved cotton yield when compared with controls.
Jeon, En Hee; Pak, Jung Hun; Kim, Mi Jin; Kim, Hye Jeong; Shin, Sang Hyun; Lee, Jai Heon; Kim, Doh Hoon; Oh, Ju Sung; Oh, Boung-Jun; Jung, Ho Won; Chung, Young Soo
Highlights: ► We isolated a novel E2 ubiquitin-conjugating enzyme from leaves of wild rice plants. ► The OgUBC1 was highly expressed in leaves treated with SA and UV-B radiation. ► The recombinant OgUBC1 has an enzymatic activity of E2 in vitro. ► The OgUBC1 could protect disruption of plant cells by UV-B radiation. ► OgUBC1 confers disease resistance and UV-B tolerance in transgenic Arabidopsis plants. -- Abstract: A previously unidentified gene encoding ubiquitin-conjugating enzyme was isolated from leaves of wild rice plant treated with wounding and microbe-associated molecular patterns. The OgUBC1 gene was composed of 148 amino acids and contained a typical active site and 21 ubiquitin thioester intermediate interaction residues and 4 E3 interaction residues. Both exogenous application of salicylic acid and UV-B irradiation triggered expression of OgUBC1 in leaves of wild rice. Recombinant OgUBC1 proteins bound to ubiquitins in vitro, proposing that the protein might act as E2 enzyme in planta. Heterologous expression of the OgUBC1 in Arabidopsis thaliana protected plants from cellular damage caused by an excess of UV-B radiation. A stable expression of chalcone synthase gene was detected in leaves of OgUBC1-expressing Arabidopsis, resulting in producing higher amounts of anthocyanin than those in wild-type Col-0 plants. Additionally, both pathogenesis-related gene1 and 5 were transcribed in the transgenic Arabidopsis in the absence of pathogen infection. The OgUBC1-expressing plants were resistant to the infection of Botrytis cinerea. Taken together, we suggested that the OgUBC1 is involved in ubiquitination process important for cellular response against biotic and abiotic stresses in plants.
Jeon, En Hee; Pak, Jung Hun; Kim, Mi Jin; Kim, Hye Jeong [Department of Genetic Engineering, Dong-A University, Busan 604-714 (Korea, Republic of); Shin, Sang Hyun [National Crop Experiment Station, Rural Development Administration, Suwon 441-100 (Korea, Republic of); Lee, Jai Heon; Kim, Doh Hoon; Oh, Ju Sung [Department of Genetic Engineering, Dong-A University, Busan 604-714 (Korea, Republic of); Oh, Boung-Jun [BioControl Center, Jeonnam 516-942 (Korea, Republic of); Jung, Ho Won, E-mail: email@example.com [Department of Genetic Engineering, Dong-A University, Busan 604-714 (Korea, Republic of); Chung, Young Soo, E-mail: firstname.lastname@example.org [Department of Genetic Engineering, Dong-A University, Busan 604-714 (Korea, Republic of)
Highlights: Black-Right-Pointing-Pointer We isolated a novel E2 ubiquitin-conjugating enzyme from leaves of wild rice plants. Black-Right-Pointing-Pointer The OgUBC1 was highly expressed in leaves treated with SA and UV-B radiation. Black-Right-Pointing-Pointer The recombinant OgUBC1 has an enzymatic activity of E2 in vitro. Black-Right-Pointing-Pointer The OgUBC1 could protect disruption of plant cells by UV-B radiation. Black-Right-Pointing-Pointer OgUBC1 confers disease resistance and UV-B tolerance in transgenic Arabidopsis plants. -- Abstract: A previously unidentified gene encoding ubiquitin-conjugating enzyme was isolated from leaves of wild rice plant treated with wounding and microbe-associated molecular patterns. The OgUBC1 gene was composed of 148 amino acids and contained a typical active site and 21 ubiquitin thioester intermediate interaction residues and 4 E3 interaction residues. Both exogenous application of salicylic acid and UV-B irradiation triggered expression of OgUBC1 in leaves of wild rice. Recombinant OgUBC1 proteins bound to ubiquitins in vitro, proposing that the protein might act as E2 enzyme in planta. Heterologous expression of the OgUBC1 in Arabidopsis thaliana protected plants from cellular damage caused by an excess of UV-B radiation. A stable expression of chalcone synthase gene was detected in leaves of OgUBC1-expressing Arabidopsis, resulting in producing higher amounts of anthocyanin than those in wild-type Col-0 plants. Additionally, both pathogenesis-related gene1 and 5 were transcribed in the transgenic Arabidopsis in the absence of pathogen infection. The OgUBC1-expressing plants were resistant to the infection of Botrytis cinerea. Taken together, we suggested that the OgUBC1 is involved in ubiquitination process important for cellular response against biotic and abiotic stresses in plants.
Cavaco, Lina; Hasman, Henrik; Xia, S.
In a previous study, four Salmonella isolates from humans in the Henan province of China showed reduced susceptibility to ciprofloxacin (MIC, 0.125 to 0.25 mu g/ml) but were susceptible to nalidixic acid ( MIC, 4 to 8 mu g/ml). All isolates were negative for known qnr genes ( A, B, and S), aac(6......')Ib-cr, and mutations in gyrA and parC. Plasmid DNA was extracted from all four isolates and transformed into Escherichia coli TG1 and DH10B cells by electroporation, and transformants were selected on 0.06 mu g/ml ciprofloxacin containing brain heart infusion agar plates. Resistance to ciprofloxacin...... qnrD, showed 48% similarity to qnrA1, 61% similarity to qnrB1, and 41% similarity to qnrS1. Further subcloning of the qnrD coding region into the constitutively expressed tetA gene of vector pBR322 showed that the gene conferred an increase in the MIC of ciprofloxacin by a factor of 32 ( from an MIC...
Rajasekaran, Kanniah; Cary, Jeffrey W; Jaynes, Jesse M; Cleveland, Thomas E
Fertile, transgenic cotton plants expressing the synthetic antimicrobial peptide, D4E1, were produced through Agrobacterium-mediated transformation. PCR products and Southern blots confirmed integration of the D4E1 gene, while RT-PCR of cotton RNA confirmed the presence of D4E1 transcripts. In vitro assays with crude leaf protein extracts from T0 and T1 plants confirmed that D4E1 was expressed at sufficient levels to inhibit the growth of Fusarium verticillioides and Verticillium dahliae compared to extracts from negative control plants transformed with pBI-d35S(Omega)-uidA-nos (CGUS). Although in vitro assays did not show control of pre-germinated spores of Aspergillus flavus, bioassays with cotton seeds in situ or in planta, inoculated with a GFP-expressing A. flavus, indicated that the transgenic cotton seeds inhibited extensive colonization and spread by the fungus in cotyledons and seed coats. In planta assays with the fungal pathogen, Thielaviopsis basicola, which causes black root rot in cotton, showed typical symptoms such as black discoloration and constriction on hypocotyls, reduced branching of roots in CGUS negative control T1 seedlings, while transgenic T1 seedlings showed a significant reduction in disease symptoms and increased seedling fresh weight, demonstrating tolerance to the fungal pathogen. Significant advantages of synthetic peptides in developing transgenic crop plants that are resistant to diseases and mycotoxin-causing fungal pathogens are highlighted in this report.
Konakalla, Naga Charan; Kaldis, Athanasios; Berbati, Margarita; Masarapu, Hema; Voloudakis, Andreas E
External application of dsRNA molecules from Tobacco mosaic virus (TMV) p126 and CP genes confers significant resistance against TMV infection. Exogenously applied dsRNA exhibits a rapid systemic trafficking in planta , and it is processed successfully by DICER-like proteins producing small interfering RNAs. RNA interference (RNAi) is a sequence-specific, post-transcriptional gene silencing mechanism, induced by double-stranded RNA (dsRNA), which protects eukaryotic cells against invasive nucleic acids like viruses and transposons. In the present study, we used a non-transgenic strategy to induce RNAi in Nicotiana tabacum cv. Xanthi plants against TMV. DsRNA molecules for the p126 (TMV silencing suppressor) and coat protein (CP) genes were produced by a two-step PCR approach followed by in vitro transcription. The application of TMV p126 dsRNA onto tobacco plants induced greater resistance against TMV infection as compared to CP dsRNA (65 vs. 50 %). This study also reported the fast systemic spread of TMV p126 dsRNA from the treated (local) to non-treated (systemic) leaves beginning from 1 h post-application, confirmed by both conventional and real-time RT-PCR. Furthermore, we employed a stem-loop RT-PCR and confirmed the presence of a putative viral siRNA for up to 9 days in local leaves and up to 6 days in systemic leaves post-application. The approach employed could represent a simple and environmentally safe way for the control of plant viruses in future agriculture.
Bidaud, Pauline; Hébert, Laurent; Barbey, Corinne; Appourchaux, Anne-Cécile; Torelli, Riccardo; Sanguinetti, Maurizio; Laugier, Claire; Petry, Sandrine
Rhodococcus equi is one of the most widespread causes of disease in foals aged from 1 to 6 months. R. equi possesses antioxidant defense mechanisms to protect it from reactive oxygen metabolites such as hydrogen peroxide (H(2)O(2)) generated during the respiratory burst of phagocytic cells. These defense mechanisms include enzymes such as catalase, which detoxify hydrogen peroxide. Recently, an analysis of the R. equi 103 genome sequence revealed the presence of four potential catalase genes. We first constructed ΔkatA-, ΔkatB-, ΔkatC-and ΔkatD-deficient mutants to study the ability of R. equi to survive exposure to H(2)O(2)in vitro and within mouse peritoneal macrophages. Results showed that ΔkatA and, to a lesser extent ΔkatC, were affected by 80 mM H(2)O(2). Moreover, katA deletion seems to significantly affect the ability of R. equi to survive within murine macrophages. We finally investigated the expression of the four catalases in response to H(2)O(2) assays with a real time PCR technique. Results showed that katA is overexpressed 367.9 times (± 122.6) in response to exposure to 50 mM of H(2)O(2) added in the stationary phase, and 3.11 times (± 0.59) when treatment was administered in the exponential phase. In untreated bacteria, katB, katC and katD were overexpressed from 4.3 to 17.5 times in the stationary compared to the exponential phase. Taken together, our results show that KatA is the major catalase involved in the extreme H(2)O(2) resistance capability of R. equi.
Full Text Available An abundant 17 kDa RNase, encoded by OsPR10a (also known as PBZ1, was purified from Pi-starved rice suspension-cultured cells. Biochemical analysis showed that the range of optimal temperature for its RNase activity was 40-70°C and the optimum pH was 5.0. Disulfide bond formation and divalent metal ion Mg2+ were required for the RNase activity. The expression of OsPR10a::GUS in transgenic rice was induced upon phosphate (Pi starvation, wounding, infection by the pathogen Xanthomonas oryzae pv. oryzae (Xoo, leaf senescence, anther, style, the style-ovary junction, germinating embryo and shoot. We also provide first evidence in whole-plant system, demonstrated that OsPR10a-overexpressing in rice and Arabidopsis conferred significant level of enhanced resistance to infection by the pathogen Xoo and Xanthomona campestris pv. campestris (Xcc, respectively. Transgenic rice and Arabidopsis overexpressing OsPR10a significantly increased the length of primary root under phosphate deficiency (-Pi condition. These results showed that OsPR10a might play multiple roles in phosphate recycling in phosphate-starved cells and senescing leaves, and could improve resistance to pathogen infection and/or against chewing insect pests. It is possible that Pi acquisition or homeostasis is associated with plant disease resistance. Our findings suggest that gene regulation of OsPR10a could act as a good model system to unravel the mechanisms behind the correlation between Pi starvation and plant-pathogen interactions, and also provides a potential application in crops disease resistance.
Yao, Hong; Liu, Dejun; Wang, Yang; Zhang, Qijing; Shen, Zhangqi
Campylobacter is a major foodborne pathogen, and previous studies revealed that Campylobacter isolates from food-producing animals are increasingly resistant to gentamicin in China. The molecular epidemiology and genetic mechanisms responsible for gentamicin resistance in China have not been well understood. In this study, 607 Campylobacter isolates of chicken and swine origins collected in 2014 were analyzed, revealing that 15.6% (25/160) of the Campylobacter jejuni isolates and 79.9% (357/4...
Cavaco, Lina; Hasman, Henrik; Stegger, Marc
determinant, czrC, by PCR. The cloning of czrC confirmed that the zinc chloride and cadmium acetate MICs for isogenic constructs carrying this gene were increased compared to those for S. aureus RN4220. No difference in susceptibility to sodium arsenate, copper sulfate, or silver nitrate was observed. Seventy...
Feng, Xue; Orellana, Gardenia; Myers, James; Karasev, Alexander V
Recessive resistance to Bean common mosaic virus (BCMV) in common bean (Phaseolus vulgaris L.) is governed by four genes that include one strain-nonspecific helper gene bc-u, and three strain-specific genes bc-1, bc-2, and bc-3. The bc-3 gene was identified as an eIF4E translation initiation factor gene mediating resistance through disruption of the interaction between this protein and the VPg protein of the virus. The mode of action of bc-1 and bc-2 in expression of BCMV resistance is unknown, although bc-1 gene was found to affect systemic spread of a related potyvirus, Bean common mosaic necrosis virus. To investigate the possible role of both bc-1 and bc-2 genes in replication, cell-to-cell, and long distance movement of BCMV in P. vulgaris, we tested virus spread of eight BCMV isolates representing pathogroups I, IV, VI, VII, and VIII, in a set of bean differentials expressing different combinations of six resistance alleles including bc-u, bc-1, bc-1 2 , bc-2, bc-2 2 , and bc-3. All studied BCMV isolates were able to replicate and spread in inoculated leaves of bean cultivars harboring bc-u, bc-1, bc-1 2 , bc-2, and bc-2 2 alleles and their combinations, while no BCMV replication was found in inoculated leaves of 'IVT7214' carrying the bc-u, bc-2 and bc-3 genes, except for isolate 1755a capable of overcoming the resistance conferred by bc-2 and bc-3. In contrast, the systemic spread of all BCMV isolates from pathogroups I, IV,VI, VII, and VIII was impaired in common bean cultivars carrying bc-1, bc-1 2 , bc-2, and bc-2 2 alleles. The data suggest that bc-1 and bc-2 recessive resistance genes have no effect on the replication and cell-to-cell movement of BCMV, but affect systemic spread of BCMV in common bean. The BCMV resistance conferred by bc-1 and bc-2 and affecting systemic spread was found only partially effective when these two genes were expressed singly. The efficiency of the restriction of the systemic spread of the virus was greatly enhanced when
Wang, Yan; Nsibo, D.L.; Juhar, H.M.; Govers, Francine; Bouwmeester, Klaas
Key message: TransgenicNicotiana benthamianalines with constitutive expression of an Arabidopsis lectin receptor kinase gene (LecRK-I.9orLecRK-IX.1) show enhanced resistance toPhytophthorapathogens, demonstrating conserved gene functionality after interfamily transfer.Abstract: In plants, cell
Huang, Li; Zhang, Songlin; Singer, Stacy D.; Yin, Xiangjing; Yang, Jinhua; Wang, Yuejin; Wang, Xiping
Stilbene synthase (STS) is a key gene in the biosynthesis of various stilbenoids, including resveratrol and its derivative glucosides (such as piceid), that has been shown to contribute to disease resistance in plants. However, the mechanism behind such a role has yet to be elucidated. Furthermore, the function of STS genes in osmotic stress tolerance remains unclear. As such, we sought to elucidate the role of STS genes in the defense against biotic and abiotic stress in the model plant Arab...
Identification of a novel transposon-associated phosphoethanolamine transferase gene, mcr-5, conferring colistin resistance in d-tartrate fermenting Salmonella enterica subsp. enterica serovar Paratyphi B
Borowiak, Maria; Fischer, Jennie; Hammerl, Jens A
. Our findings suggest that the transfer of colistin-resistance-mediating phosphoethanolamine transferase genes from bacterial chromosomes to mobile genetic elements has occurred in multiple independent events raising concern regarding their variety, prevalence and impact on public health....... phosphoethanolamine transferase genes involved in colistin resistance. Subsequently PCR screening, S1-PFGE and DNA-DNA hybridization were performed to analyse the prevalence and location of the identified mcr-5 gene. Cloning and transformation experiments in Escherichia coli DH5α and Salmonella Paratyphi B d Ta......Plasmid-mediated mobilized colistin resistance is currently known to be caused by phosphoethanolamine transferases termed MCR-1, MCR-2, MCR-3 and MCR-4. However, this study focuses on the dissection of a novel resistance mechanism in mcr-1 -, mcr-2 - and mcr-3 -negative d -tartrate fermenting...
The main objective of this study was to identify and isolate the genes conferring drought tolerance in cowpea. A cDNA library enriched for cowpea genes expressed specifically during responses to drought was constructed. A procedure called suppression subtractive hybridisation (SSH) was successfully employed to obtain ...
Yoshii, Atsushi; Moriyama, Hiromitsu; Fukuhara, Toshiyuki
Kasugamycin (KSM), a unique aminoglycoside antibiotic, has been used in agriculture for many years to control not only rice blast caused by the fungus Magnaporthe grisea but also rice bacterial grain and seedling rot or rice bacterial brown stripe caused by Burkholderia glumae or Acidovorax avenae subsp. avenae, respectively. Since both bacterial pathogens are seed-borne and cause serious injury to rice seedlings, the emergence of KSM-resistant B. glumae and A. avenae isolates highlights the urgent need to understand the mechanism of resistance to KSM. Here, we identified a novel gene, aac(2')-IIa, encoding a KSM 2'-N-acetyltransferase from both KSM-resistant pathogens but not from KSM-sensitive bacteria. AAC(2')-IIa inactivates KSM, although it reveals no cross-resistance to other aminoglycosides. The aac(2')-IIa gene from B. glumae strain 5091 was identified within the IncP genomic island inserted into the bacterial chromosome, indicating the acquisition of this gene by horizontal gene transfer. Although excision activity of the IncP island and conjugational gene transfer was not detected under the conditions tested, circular intermediates containing the aac(2')-IIa gene were detected. These results indicate that the aac(2')-IIa gene had been integrated into the IncP island of a donor bacterial species. Molecular detection of the aac(2')-IIa gene could distinguish whether isolates are resistant or susceptible to KSM. This may contribute to the production of uninfected rice seeds and lead to the effective control of these pathogens by KSM.
Strizhov, N.; Keller, M.; Mathur, J.; Koncz-Kaiman, Z.; Bosch, D.; Prudovksy, E.; Schell, J.; Sneh, B.; Koncz, C.; Zilberstein, A.
Spodoptera species, representing widespread polyphagous insect pests, are resistant to Bacillus thuringiensis δ-endotoxins used thus far as insecticides in transgenic plants. Here we describe the chemical synthesis of a cryIC gene by a novel template directed ligation–PCR method. This simple and
Zheng Sijun, S.J.; Henken, B.; Maagd, de R.A.; Purwito, A.; Krens, F.A.; Kik, C.
Agrobacterium-mediated genetic transformation was applied to produce beet armyworm (Spodoptera exigua Hübner) resistant tropical shallots (Allium cepa L. group Aggregatum). A cry1Ca or a H04 hybrid gene from Bacillus thuringiensis, driven by the chrysanthemum ribulose-1,5-bisphosphate
Lee, Hong Jo; Lee, Kyung Youn; Jung, Kyung Min; Park, Kyung Je; Lee, Ko On; Suh, Jeong-Yong; Yao, Yongxiu; Nair, Venugopal; Han, Jae Yong
Avian leukosis virus subgroup J (ALV-J), first isolated in the late 1980s, has caused economic losses to the poultry industry in many countries. As all chicken lines studied to date are susceptible to ALV infection, there is enormous interest in developing resistant chicken lines. The ALV-J receptor, chicken Na + /H + exchange 1 (chNHE1) and the critical amino acid sequences involved in viral attachment and entry have already been characterized. However, there are no reported attempts to induce resistance to the virus by targeted genome modification of the receptor sequences. In an attempt to induce resistance to ALV-J infection, we used clustered regularly interspaced short palindromic repeats (CRISPR)-associated (CRISPR/Cas9)-based genome editing approaches to modify critical residues of the chNHE1 receptor in chicken cells. The susceptibility of the modified cell lines to ALV-J infection was examined using enhanced green fluorescent protein (EGFP)-expressing marker viruses. We showed that modifying the chNHE1 receptor by artificially generating a premature stop codon induced absolute resistance to viral infection, with mutations of the tryptophan residue at position 38 (Trp38) being very critical. Single-stranded oligodeoxynucleotide (ssODN)-mediated targeted recombination of the Trp38 region revealed that deletions involving the Trp38 residue were most effective in conferring resistance to ALV-J. Moreover, protein structure analysis of the chNHE1 receptor sequence suggested that its intrinsically disordered region undergoes local conformational changes through genetic alteration. Collectively, these results demonstrate that targeted mutations on chNHE1 alter the susceptibility to ALV-J and the technique is expected to contribute to develop disease-resistant chicken lines. Copyright © 2017 Elsevier Ltd. All rights reserved.
Matthews, Benjamin F; Beard, Hunter; Brewer, Eric; Kabir, Sara; MacDonald, Margaret H; Youssef, Reham M
Extensive studies using the model system Arabidopsis thaliana to elucidate plant defense signaling and pathway networks indicate that salicylic acid (SA) is the key hormone triggering the plant defense response against biotrophic and hemi-biotrophic pathogens, while jasmonic acid (JA) and derivatives are critical to the defense response against necrotrophic pathogens. Several reports demonstrate that SA limits nematode reproduction. Here we translate knowledge gained from studies using Arabidopsis to soybean. The ability of thirty-one Arabidopsis genes encoding important components of SA and JA synthesis and signaling in conferring resistance to soybean cyst nematode (SCN: Heterodera glycines) are investigated. We demonstrate that overexpression of three of thirty-one Arabidoposis genes in transgenic soybean roots of composite plants decreased the number of cysts formed by SCN to less than 50% of those found on control roots, namely AtNPR1(33%), AtTGA2 (38%), and AtPR-5 (38%). Three additional Arabidopsis genes decreased the number of SCN cysts by 40% or more: AtACBP3 (53% of the control value), AtACD2 (55%), and AtCM-3 (57%). Other genes having less or no effect included AtEDS5 (77%), AtNDR1 (82%), AtEDS1 (107%), and AtPR-1 (80%), as compared to control. Overexpression of AtDND1 greatly increased susceptibility as indicated by a large increase in the number of SCN cysts (175% of control). Knowledge of the pathogen defense system gained from studies of the model system, Arabidopsis, can be directly translated to soybean through direct overexpression of Arabidopsis genes. When the genes, AtNPR1, AtGA2, and AtPR-5, encoding specific components involved in SA regulation, synthesis, and signaling, are overexpressed in soybean roots, resistance to SCN is enhanced. This demonstrates functional compatibility of some Arabidopsis genes with soybean and identifies genes that may be used to engineer resistance to nematodes.
Qi, L L; Seiler, G J; Vick, B A; Gulya, T J
Sunflower oil is one of the major sources of edible oil. As the second largest hybrid crop in the world, hybrid sunflowers are developed by using the PET1 cytoplasmic male sterility system that contributes to a 20 % yield advantage over the open-pollinated varieties. However, sunflower production in North America has recently been threatened by the evolution of new virulent pathotypes of sunflower rust caused by the fungus Puccinia helianthi Schwein. Rf ANN-1742, an 'HA 89' backcross restorer line derived from wild annual sunflower (Helianthus annuus L.), was identified as resistant to the newly emerged rust races. The aim of this study was to elucidate the inheritance of rust resistance and male fertility restoration and identify the chromosome location of the underlying genes in Rf ANN-1742. Chi-squared analysis of the segregation of rust response and male fertility in F(2) and F(3) populations revealed that both traits are controlled by single dominant genes, and that the rust resistance gene is closely linked to the restorer gene in the coupling phase. The two genes were designated as R ( 11 ) and Rf5, respectively. A set of 723 mapped SSR markers of sunflower was used to screen the polymorphism between HA 89 and the resistant plant. Bulked segregant analysis subsequently located R ( 11 ) on linkage group (LG) 13 of sunflower. Based on the SSR analyses of 192 F(2) individuals, R ( 11 ) and Rf5 both mapped to the lower end of LG13 at a genetic distance of 1.6 cM, and shared a common marker, ORS728, which was mapped 1.3 cM proximal to Rf5 and 0.3 cM distal to R ( 11 ) (Rf5/ORS728/R ( 11 )). Two additional SSRs were linked to Rf5 and R ( 11 ): ORS995 was 4.5 cM distal to Rf5 and ORS45 was 1.0 cM proximal to R ( 11 ). The advantage of such an introduced alien segment harboring two genes is its large phenotypic effect and simple inheritance, thereby facilitating their rapid deployment in sunflower breeding programs. Suppressed recombination was observed in LGs 2, 9
Momoi, Michiko; Tanoue, Daisuke; Sun, Yidi; Takematsu, Hiromu; Suzuki, Yusuke; Suzuki, Minoru; Suzuki, Akemi; Fujita, Tetsuro; Kozutsumi, Yasunori
ISP-1 (myriocin) is a potent inhibitor of serine palmitoyltransferase, the primary enzyme of sphingolipid biosynthesis, and is a useful tool for studying the biological functions of sphingolipids in both mammals and yeast (Saccharomyces cerevisiae). In a previous study, we cloned yeast multicopy suppressor genes for ISP-1, and one of these, YPK1/SLI2, was shown to encode a serine/threonine kinase which is a yeast homologue of mammalian SGK1 (serum/glucocorticoid-regulated kinase 1). In the present study, another gene, termed SLI1 (YGR212W; GenBank accession number CAA97239.1), was characterized. Sli1p has weak similarity to Atf1p and Atf2p, which are alcohol acetyltransferases. Although a sli1-null strain grew normally, the IC50 of ISP-1 for the growth of this strain was markedly decreased compared with that for the parental strain, indicating that Sli1p is a major contributor to ISP-1 resistance in yeast. On a sli1-null background, the increase in resistance to ISP-1 induced by YPK1 gene transfection was almost abolished. These data indicate that Sli1p co-operates with Ypk1p in mediating resistance to ISP-1 in yeast. Sli1p was found to convert ISP-1 into N-acetyl-ISP-1 in vitro. Furthermore, N-acetyl-ISP-1 did not share the ability of ISP-1 to inhibit the growth of yeast cells, and the serine palmitoyltransferase inhibitory activity of N-acetyl-ISP-1 was much lower than that of ISP-1. These data suggest that Sli1p inactivates ISP-1 due to its N-acetyltransferase activity towards ISP-1.
Lucotte, Gérard; Dieterlen, Florent
The chemokine receptor CCR5 constitutes the major coreceptor for the HIV-1, because a mutant allele of the CCR5 gene named delta32 was shown to provide to homozygotes a strong resistance against infection. In the present study the frequency of the delta32 allele was collected in 36 European populations and in Cyprus, and the highest allele frequencies were found in Nordic countries. We constructed an allele map of delta32 frequencies in Europe; the map is in accordance to the Vikings hypothesis of the origin of the mutation and his dissemination during the eighth to the tenth centuries.
Bowlin, Nicholas O.; Williams, John D.; Knoten, Claire A.; Torhan, Matthew C.; Tashjian, Tommy F.; Li, Bing; Aiello, Daniel; Mecsas, Joan; Hauser, Alan R.; Peet, Norton P.; Bowlin, Terry L.
The type III secretion system (T3SS) is a clinically important virulence mechanism in Pseudomonas aeruginosa that secretes and translocates effector toxins into host cells, impeding the host's rapid innate immune response to infection. Inhibitors of T3SS may be useful as prophylactic or adjunctive therapeutic agents to augment the activity of antibiotics in P. aeruginosa infections, such as pneumonia and bacteremia. One such inhibitor, the phenoxyacetamide MBX 1641, exhibits very responsive structure-activity relationships, including striking stereoselectivity, in its inhibition of P. aeruginosa T3SS. These features suggest interaction with a specific, but unknown, protein target. Here, we identify the apparent molecular target by isolating inhibitor-resistant mutants and mapping the mutation sites by deep sequencing. Selection and sequencing of four independent mutants resistant to the phenoxyacetamide inhibitor MBX 2359 identified the T3SS gene pscF, encoding the needle apparatus, as the only locus of mutations common to all four strains. Transfer of the wild-type and mutated alleles of pscF, together with its chaperone and cochaperone genes pscE and pscG, to a ΔpscF P. aeruginosa strain demonstrated that each of the single-codon mutations in pscF is necessary and sufficient to provide secretion and translocation that is resistant to a variety of phenoxyacetamide inhibitor analogs but not to T3SS inhibitors with different chemical scaffolds. These results implicate the PscF needle protein as an apparent new molecular target for T3SS inhibitor discovery and suggest that three other chemically distinct T3SS inhibitors interact with one or more different targets or a different region of PscF. PMID:24468789
Background Extensive studies using the model system Arabidopsis thaliana to elucidate plant defense signaling and pathway networks indicate that salicylic acid (SA) is the key hormone triggering the plant defense response against biotrophic and hemi-biotrophic pathogens, while jasmonic acid (JA) and derivatives are critical to the defense response against necrotrophic pathogens. Several reports demonstrate that SA limits nematode reproduction. Results Here we translate knowledge gained from studies using Arabidopsis to soybean. The ability of thirty-one Arabidopsis genes encoding important components of SA and JA synthesis and signaling in conferring resistance to soybean cyst nematode (SCN: Heterodera glycines) are investigated. We demonstrate that overexpression of three of thirty-one Arabidoposis genes in transgenic soybean roots of composite plants decreased the number of cysts formed by SCN to less than 50% of those found on control roots, namely AtNPR1(33%), AtTGA2 (38%), and AtPR-5 (38%). Three additional Arabidopsis genes decreased the number of SCN cysts by 40% or more: AtACBP3 (53% of the control value), AtACD2 (55%), and AtCM-3 (57%). Other genes having less or no effect included AtEDS5 (77%), AtNDR1 (82%), AtEDS1 (107%), and AtPR-1 (80%), as compared to control. Overexpression of AtDND1 greatly increased susceptibility as indicated by a large increase in the number of SCN cysts (175% of control). Conclusions Knowledge of the pathogen defense system gained from studies of the model system, Arabidopsis, can be directly translated to soybean through direct overexpression of Arabidopsis genes. When the genes, AtNPR1, AtGA2, and AtPR-5, encoding specific components involved in SA regulation, synthesis, and signaling, are overexpressed in soybean roots, resistance to SCN is enhanced. This demonstrates functional compatibility of some Arabidopsis genes with soybean and identifies genes that may be used to engineer resistance to nematodes. PMID:24739302
Frank, Kristi L.; Bundle, Sharyl F.; Kresge, Michele E.; Eggers, Christian H.; Samuels, D. Scott
To enhance genetic manipulation of the Lyme disease spirochete Borrelia burgdorferi, we assayed the aadA gene for the ability to confer resistance to the antibiotics spectinomycin and streptomycin. Using the previously described pBSV2 as a backbone, a shuttle vector, termed pKFSS1, which carries the aadA open reading frame fused to the B. burgdorferi flgB promoter was constructed. The hybrid flgB promoter-aadA cassette confers resistance to spectinomycin and streptomycin in both B. burgdorferi and Escherichia coli. pKFSS1 has a replication origin derived from the 9-kb circular plasmid and can be comaintained in B. burgdorferi with extant shuttle vector pCE320, which has a replication origin derived from a 32-kb circular plasmid, or pBSV2, despite the fact that pKFSS1 and pBSV2 have the same replication origin. Our results demonstrate the availability of a new selectable marker and shuttle vector for genetically dissecting B. burgdorferi at the molecular level. PMID:14594849
Brueggeman, Robert; Steffenson, Brian J; Kleinhofs, Andris
Two closely linked resistance genes, rpg4 and Rpg5, conferring resistance to several races of Puccinia graminis, were cloned and characterized. The Rpg5 gene confers resistance to an isolate of Puccinia graminis f. sp. secalis (Pgs), while rpg4 confers resistance to Puccinia graminis f. sp. tritici (Pgt). Rpg5 is a novel gene containing nucleotide binding site-leucine rich repeat domains in combination with a serine threonine protein kinase domain. High-resolution mapping plus allele and recombinant sequencing identified the rpg4 gene, which encodes an actin depolymerizing factor-like protein (ADF2). Resistance against the Pgt races QCCJ, MCCF, TTKSK (aka Ug99) and RCRS requires both Rpg5 and rpg4, while Rpg5 alone confers resistance to Pgs isolate 92-MN-90. The dependency on the actin modifying protein ADF2 indicates cytoskeleton reorganization or redirection plays a role in pathogen-host interactions. Rpg5 may interact with ADF2 to activate or deactivate its function in the resistance response. Alternatively, Rpg5 could initiate signal transduction leading to resistance in response to detecting ADF2 protein modification. Pgt may redirect the actin cytoskeleton by inducing modifications of ADF2. The redirection of actin could possibly enable the pathogen to develop a haustoria-plant cell cytoskeleton interface for acquisition of nutrients.
Full Text Available Rusts are biotrophic pathogens that attack many plant species but are particularly destructive on cereal crops. The stem rusts (caused by have historically caused severe crop losses and continue to threaten production today. Barley ( L. breeders have controlled major stem rust epidemics since the 1940s with a single durable resistance gene . As new epidemics have threatened, additional resistance genes were identified to counter new rust races, such as the complex locus against races QCCJ and TTKSK. To understand how these genes work, we initiated research to clone and characterize them. The gene encodes a unique protein kinase with dual kinase domains, an active kinase, and a pseudokinase. Function of both domains is essential to confer resistance. The and genes are closely linked and function coordinately to confer resistance to several wheat ( L. stem rust races, including the race TTKSK (also called Ug99 that threatens the world's barley and wheat crops. The gene encodes typical resistance gene domains NBS, LRR, and protein kinase but is unique in that all three domains reside in a single gene, a previously unknown structure among plant disease resistance genes. The gene encodes an actin depolymerizing factor that functions in cytoskeleton rearrangement.
The Ouro Negro common bean cultivar contains the Co-34/Phg-3 gene cluster that confers resistance to the anthracnose (ANT) and angular leaf spot (ALS) pathogens. These genes are tightly linked on chromosome 4. Ouro Negro also has the Ur-14 rust resistance gene, reportedly in the vicinity of Co- 34; ...
Rpp4 (Resistance to Phakopsora pachyrhizi 4) confers resistance to P. pachyrhizi, the causal agent of Asian soybean rust (ASR). By combining expression profiling and virus induced gene silencing (VIGS), we are developing a genetic framework for Rpp4-mediated resistance. We measured gene expression i...
Fukuoka, Shuichi; Saka, Norikuni; Mizukami, Yuko; Koga, Hironori; Yamanouchi, Utako; Yoshioka, Yosuke; Hayashi, Nagao; Ebana, Kaworu; Mizobuchi, Ritsuko; Yano, Masahiro
Effective control of blast, a devastating fungal disease of rice, would increase and stabilize worldwide food production. Resistance mediated by quantitative trait loci (QTLs), which usually have smaller individual effects than R-genes but confer broad-spectrum or non-race-specific resistance, is a promising alternative to less durable race-specific resistance for crop improvement, yet evidence that validates the impact of QTL combinations (pyramids) on the durability of plant disease resista...
Bossé, Janine T; Li, Yanwen; Walker, Stephanie; Atherton, Tom; Fernandez Crespo, Roberto; Williamson, Susanna M; Rogers, Jon; Chaudhuri, Roy R; Weinert, Lucy A; Oshota, Olusegun; Holden, Matt T G; Maskell, Duncan J; Tucker, Alexander W; Wren, Brendan W; Rycroft, Andrew N; Langford, Paul R
The objective of this study was to determine the distribution and genetic basis of trimethoprim resistance in Actinobacillus pleuropneumoniae isolates from pigs in England. Clinical isolates collected between 1998 and 2011 were tested for resistance to trimethoprim and sulphonamide. The genetic basis of trimethoprim resistance was determined by shotgun WGS analysis and the subsequent isolation and sequencing of plasmids. A total of 16 (out of 106) A. pleuropneumoniae isolates were resistant to both trimethoprim (MIC >32 mg/L) and sulfisoxazole (MIC ≥256 mg/L), and a further 32 were resistant only to sulfisoxazole (MIC ≥256 mg/L). Genome sequence data for the trimethoprim-resistant isolates revealed the presence of the dfrA14 dihydrofolate reductase gene. The distribution of plasmid sequences in multiple contigs suggested the presence of two distinct dfrA14-containing plasmids in different isolates, which was confirmed by plasmid isolation and sequencing. Both plasmids encoded mobilization genes, the sulphonamide resistance gene sul2, as well as dfrA14 inserted into strA, a streptomycin-resistance-associated gene, although the gene order differed between the two plasmids. One of the plasmids further encoded the strB streptomycin-resistance-associated gene. This is the first description of mobilizable plasmids conferring trimethoprim resistance in A. pleuropneumoniae and, to our knowledge, the first report of dfrA14 in any member of the Pasteurellaceae. The identification of dfrA14 conferring trimethoprim resistance in A. pleuropneumoniae isolates will facilitate PCR screens for resistance to this important antimicrobial. © The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy.
Ziebell, K.; Johnson, R. P.; Kropinski, A. M.; Reid-Smith, R.; Ahmed, R.; Gannon, V. P.; Gilmour, M.; Boerlin, P.
Multidrug resistance to streptomycin, sulfonamide, and tetracycline (AMR-SSuT) was identified in 156 of 171 isolates of Escherichia coli O157:H7 of phage types 23, 45, and 67. In 154 AMR-SSuT isolates, resistance was encoded by strA, strB, sul2, and tet(B), which in 59 of 63 tested isolates were found clustered together on the chromosome within the cdiA locus. PMID:21239555
Ziebell, K; Johnson, R P; Kropinski, A M; Reid-Smith, R; Ahmed, R; Gannon, V P; Gilmour, M; Boerlin, P
Multidrug resistance to streptomycin, sulfonamide, and tetracycline (AMR-SSuT) was identified in 156 of 171 isolates of Escherichia coli O157:H7 of phage types 23, 45, and 67. In 154 AMR-SSuT isolates, resistance was encoded by strA, strB, sul2, and tet(B), which in 59 of 63 tested isolates were found clustered together on the chromosome within the cdiA locus.
Novel Alleles of Two Tightly Linked Genes Encoding Polygalacturonase-Inhibiting Proteins (VrPGIP1 and VrPGIP2 Associated with the Br Locus That Confer Bruchid (Callosobruchus spp. Resistance to Mungbean (Vigna radiata Accession V2709
Full Text Available Nearly all mungbean cultivars are completely susceptible to seed bruchids (Callosobruchus chinensis and Callosobruchus maculatus. Breeding bruchid-resistant mungbean is a major goal in mungbean breeding programs. Recently, we demonstrated in mungbean (Vigna radiata accession V2802 that VrPGIP2, which encodes a polygalacturonase inhibiting protein (PGIP, is the Br locus responsible for resistance to C. chinensis and C. maculatus. In this study, mapping in mungbean accession V2709 using a BC11F2 population of 355 individuals revealed that a single major quantitative trait locus, which controlled resistance to both C. chinensis and C. maculatus, was located in a 237.35 Kb region of mungbean chromosome 5 that contained eight annotated genes, including VrPGIP1 (LOC106760236 and VrPGIP2 (LOC106760237. VrPGIP1 and VrPGIP2 are located next to each other and are only 27.56 Kb apart. Sequencing VrPGIP1 and VrPGIP2 in “V2709” revealed new alleles for both VrPGIP1 and VrPGIP2, named VrPGIP1-1 and VrPGIP2-2, respectively. VrPGIP2-2 has one single nucleotide polymorphism (SNP at position 554 of wild type VrPGIP2. This SNP is a guanine to cystine substitution and causes a proline to arginine change at residue 185 in the VrPGIP2 of “V2709”. VrPGIP1-1 has 43 SNPs compared with wild type and “V2802”, and 20 cause amino acid changes in VrPGIP1. One change is threonine to proline at residue 185 in VrPGIP1, which is the same as in VrPGIP2. Sequence alignments of VrPGIP2 and VrPGIP1 from “V2709” with common bean (Phaseolus vulgaris PGIP2 revealed that residue 185 in VrPGIP2 and VrPGIP1 contributes to the secondary structures of proteins that affect interactions between PGIP and polygalacturonase, and that some amino acid changes in VrPGIP1 also affect interactions between PGIP and polygalacturonase. Thus, tightly linked VrPGIP1 and VrPGIP2 are the likely genes at the Br locus that confer bruchid resistance in mungbean “V2709”.
Full Text Available Mutations in the Plasmodium falciparum cyclic amine resistance locus (PfCARL are associated with parasite resistance to the imidazolopiperazines, a potent class of novel antimalarial compounds that display both prophylactic and transmission-blocking activity, in addition to activity against blood-stage parasites. Here, we show that pfcarl encodes a protein, with a predicted molecular weight of 153 kDa, that localizes to the cis-Golgi apparatus of the parasite in both asexual and sexual blood stages. Utilizing clustered regularly interspaced short palindromic repeat (CRISPR-mediated gene introduction of 5 variants (L830V, S1076N/I, V1103L, and I1139K, we demonstrate that mutations in pfcarl are sufficient to generate resistance against the imidazolopiperazines in both asexual and sexual blood-stage parasites. We further determined that the mutant PfCARL protein confers resistance to several structurally unrelated compounds. These data suggest that PfCARL modulates the levels of small-molecule inhibitors that affect Golgi-related processes, such as protein sorting or membrane trafficking, and is therefore an important mechanism of resistance in malaria parasites.
Haroche, Julien; Allignet, Jeanine; Aubert, Sylvie; Van Den Bogaard, Anthony E.; El Solh, Névine
A gene almost identical to satG was isolated from an Enterococcus faecium strain. This gene was transferred to a Staphylococcus aureus recipient strain where it conferred resistance to streptogramin A. satG was found to be widely distributed among E. faecium strains but not detected among staphylococci. PMID:10602747
Oct 5, 2009 ... If the resistance in the transgenic rice plants with a disease resistance gene is similar to the RPM1 resis- tance in Arabidopsis, that is, negatively correlate with yield or grain quality in rice, we should not only consider the disease resistance of the transgenic rice plants but ignore their yields and grain quality, ...
The pyrethroid resistance of the diamondback moth Plutella xylostella (L.) is conferred by increased gene expression of cytochrome P450 to detoxify the insecticide and/or through gene mutation of the sodium channel, which makes the individual insensitive to pyrethroids. However, no information is available about the correlation between the increased metabolic detoxification and the target insensitivity in pyrethroid resistance. Frequencies of pyrethroid-resistant alleles (L1014F, T929I and M918I) and two resistance-related mutations (A1101T and P1879S) at the sodium channel and expression levels of the cytochrome P450 gene CYP6BG1 were examined individually using laboratory and field strains of P. xylostella. Real-time quantitative PCR analysis using the laboratory strains revealed that levels of larval expression of the resistant strain, homozygous for the pyrethroid-resistant alleles other than the M918I, are significantly higher than those of the susceptible strain. In the field strains, the expression levels in insects having the same resistant alleles as those of the resistant strains varied greatly among individuals. The expression levels were not significantly higher than those in the heterozygotes. Significant correlation between the target insensitivity and the increased metabolic detoxification in pyrethroid resistance of P. xylostella was observed in the laboratory but not in the field.
Belkina, Anna C; Denis, Gerald V
The exploding prevalence of insulin resistance and Type 2 diabetes (T2D) linked to obesity has become an alarming public health concern. Worldwide, approximately 171 million people suffer from obesity-induced diabetes and public health authorities expect this situation to deteriorate rapidly. An interesting clinical population of 'metabolically healthy but obese' (MHO) cases is relatively protected from T2D and its associated cardiovascular risk. The molecular basis for this protection is not well understood but is likely to involve reduced inflammatory responses. The inflammatory cells and pathways that respond to overnutrition are the primary subject matter for this review. The chance discovery of a genetic mutation in the Brd2 gene, which is located in the class II major histocompatibility complex and makes mice enormously fat but protects them from diabetes, offers revolutionary new insights into the cellular mechanisms that link obesity to insulin resistance and T2D. These Brd2-hypomorphic mice have reduced inflammation in fat that is normally associated with insulin resistance, and resemble MHO patients, suggesting novel therapeutic pathways for obese patients at risk for T2D. Deeper understanding of the functional links between genes that control inflammatory responses to diet-induced obesity is crucial to the development of therapies for obese, insulin-resistant patients.
Jiang, Xinglin; Ellabaan, Mostafa M Hashim; Charusanti, Pep
It has been hypothesized that some antibiotic resistance genes (ARGs) found in pathogenic bacteria derive from antibiotic-producing actinobacteria. Here we provide bioinformatic and experimental evidence supporting this hypothesis. We identify genes in proteobacteria, including some pathogens......, that appear to be closely related to actinobacterial ARGs known to confer resistance against clinically important antibiotics. Furthermore, we identify two potential examples of recent horizontal transfer of actinobacterial ARGs to proteobacterial pathogens. Based on this bioinformatic evidence, we propose...... results support the existence of ancient and, possibly, recent transfers of ARGs from antibiotic-producing actinobacteria to proteobacteria, and provide evidence for a defined mechanism....
Ullah, I; Jamil, S; Iqbal, M Z; Shaheen, H L; Hasni, S M; Jabeen, S; Mehmood, A; Akhter, M
Aromatic basmati rice is vulnerable to bacterial blight disease. Genes conferring resistance to bacterial blight have been identified in coarse rice; however, their incorporation into basmati varieties compromises the prized basmati aroma. We identified bacterial blight resistance genes Xa4, xa5, Xa7, and xa13 in 52 basmati landraces and five basmati cultivars using PCR markers. The Xa7 gene was found to be the most prevalent among the cultivars and landraces. The cultivars Basmati-385 and Basmati-2000 also contained the Xa4 gene; however, xa5 and xa13 were confined to landraces only. Ten landraces were found to have multiple resistance genes. Landraces Basmati-106, Basmati-189 and Basmati-208 contained Xa4 and Xa7 genes. Whereas, landraces Basmati-122, Basmati-427, Basmati-433 were observed to have xa5 and Xa7 genes. Landraces Basmati-48, Basmati-51A, Basmati-334, and Basmati-370A possessed Xa7 and xa13 genes. The use of landraces containing recessive genes xa5 and xa13 as donor parents in hybridization with cultivars Basmati-385 and Basmati-2000, which contain the genes Xa4 and Xa7, will expedite efforts to develop bacterial blight-resistant basmati rice cultivars through marker assisted selection, based on a pyramiding approach, without compromising aroma and grain quality.
Pandin, Caroline; Caroff, Martine; Condemine, Guy
Modification of teichoic acid through the incorporation of d-alanine confers resistance in Gram-positive bacteria to antimicrobial peptides (AMPs). This process involves the products of the dltXABCD genes. These genes are widespread in Gram-positive bacteria, and they are also found in a few Gram-negative bacteria. Notably, these genes are present in all soft-rot enterobacteria (Pectobacterium and Dickeya) whose dltDXBAC operons have been sequenced. We studied the function and regulation of these genes in Dickeya dadantii dltB expression was induced in the presence of the AMP polymyxin. It was not regulated by PhoP, which controls the expression of some genes involved in AMP resistance, but was regulated by ArcA, which has been identified as an activator of genes involved in AMP resistance. However, arcA was not the regulator responsible for polymyxin induction of these genes in this bacterium, which underlines the complexity of the mechanisms controlling AMP resistance in D. dadantii Two other genes involved in resistance to AMPs have also been characterized, phoS and phoH dltB, phoS, phoH, and arcA but not dltD mutants were more sensitive to polymyxin than the wild-type strain. Decreased fitness of the dltB, phoS, and phoH mutants in chicory leaves indicates that their products are important for resistance to plant AMPs. Gram-negative bacteria can modify their lipopolysaccharides (LPSs) to resist antimicrobial peptides (AMPs). Soft-rot enterobacteria (Dickeya and Pectobacterium spp.) possess homologues of the dlt genes in their genomes which, in Gram-positive bacteria, are involved in resistance to AMPs. In this study, we show that these genes confer resistance to AMPs, probably by modifying LPSs, and that they are required for the fitness of the bacteria during plant infection. Two other new genes involved in resistance were also analyzed. These results show that bacterial resistance to AMPs can occur in bacteria through many different mechanisms that need to be
Single amino acid substitution in the methyltransferase domain of Paprika mild mottle virus replicase proteins confers the ability to overcome the high temperature-dependent Hk gene-mediated resistance in Capsicum plants.
Matsumoto, Katsutoshi; Johnishi, Kousuke; Hamada, Hiroyuki; Sawada, Hiromasa; Takeuchi, Shigeharu; Kobayashi, Kappei; Suzuki, Kazumi; Kiba, Akinori; Hikichi, Yasufumi
Capsicum plants harboring the Hk gene (Hk) show resistance to Paprika mild mottle virus (PaMMV) at 32 degrees C but not 24 degrees C. To identify the viral elicitor that activates the Hk-mediated resistance, several chimeric viral genomes were constructed between PaMMV and Tobacco mosaic virus-L. Infection patterns of these chimeric viruses in Hk-harboring plants revealed responsibility of PaMMV replicase genes for activation of the Hk-mediated resistance. The comparison of nucleotide sequence of replicase genes between PaMMV and PaHk1, an Hk-resistance-breaking strain of PaMMV, revealed that the adenine-to-uracil substitution at the nucleotide position 721 causes an amino acid change from threonine to serine at the 241st residue in the methyltransferase domain. Introduction of the A721U mutation into the replicase genes of parental PaMMV overcame the Hk resistance at 32 degrees C. The results indicate that Hk-mediated resistance is induced by PaMMV replicase proteins and that methyltransferase domain has a role in this elicitation.
Moriyama, Hiromitsu; Fukuhara, Toshiyuki
Kasugamycin (KSM), a unique aminoglycoside antibiotic, has been used in agriculture for many years to control not only rice blast caused by the fungus Magnaporthe grisea but also rice bacterial grain and seedling rot or rice bacterial brown stripe caused by Burkholderia glumae or Acidovorax avenae subsp. avenae, respectively. Since both bacterial pathogens are seed-borne and cause serious injury to rice seedlings, the emergence of KSM-resistant B. glumae and A. avenae isolates highlights the urgent need to understand the mechanism of resistance to KSM. Here, we identified a novel gene, aac(2′)-IIa, encoding a KSM 2′-N-acetyltransferase from both KSM-resistant pathogens but not from KSM-sensitive bacteria. AAC(2′)-IIa inactivates KSM, although it reveals no cross-resistance to other aminoglycosides. The aac(2′)-IIa gene from B. glumae strain 5091 was identified within the IncP genomic island inserted into the bacterial chromosome, indicating the acquisition of this gene by horizontal gene transfer. Although excision activity of the IncP island and conjugational gene transfer was not detected under the conditions tested, circular intermediates containing the aac(2′)-IIa gene were detected. These results indicate that the aac(2′)-IIa gene had been integrated into the IncP island of a donor bacterial species. Molecular detection of the aac(2′)-IIa gene could distinguish whether isolates are resistant or susceptible to KSM. This may contribute to the production of uninfected rice seeds and lead to the effective control of these pathogens by KSM. PMID:22660700
Full Text Available The dinitroaniline herbicides (particularly trifluralin have been globally used in many crops for selective grass weed control. Consequently, trifluralin resistance has been documented in several important crop weed species and has recently reached a level of concern in Australian Lolium rigidum populations. Here, we report novel mutations in the L. rigidum α-tubulin gene which confer resistance to trifluralin and other dinitroaniline herbicides. Nucleotide mutations at the highly conserved codon Arg-243 resulted in amino acid substitutions of Met or Lys. Rice calli transformed with the mutant 243-Met or 243-Lys α-tubulin genes were 4- to 8-fold more resistant to trifluralin and other dinitroaniline herbicides (e.g., ethalfluralin and pendimethalin compared to calli transformed with the wild type α-tubulin gene from L. rigidum. Comprehensive modeling of molecular docking predicts that Arg-243 is close to the trifluralin binding site on the α-tubulin surface and that replacement of Arg-243 by Met/Lys-243 results in a spatial shift of the trifluralin binding domain, reduction of trifluralin-tubulin contacts, and unfavorable interactions. The major effect of these substitutions is a significant rise of free interaction energy between α-tubulin and trifluralin, as well as between trifluralin and its whole molecular environment. These results demonstrate that the Arg-243 residue in α-tubulin is a determinant for trifluralin sensitivity, and the novel Arg-243-Met/Lys mutations may confer trifluralin resistance in L. rigidum.
Yoshii, Atsushi; Omatsu, Tsutomu; Katayama, Yukie; Koyama, Satoshi; Mizutani, Tetsuya; Moriyama, Hiromitsu; Fukuhara, Toshiyuki
A unique aminoglycoside antibiotic, kasugamycin (KSM), has been used to control many plant bacterial and fungal diseases in several countries. The emergence of KSM-resistant Acidovorax avenae ssp. avenae and Burkholderia glumae, which cause rice bacterial brown stripe and rice bacterial grain and seedling rot, respectively, is a serious threat for the effective control of these diseases. Previously, we have identified the aac(2')-IIa gene, encoding a KSM 2'-N-acetyltransferase, from both KSM-resistant pathogens. Although all KSM-resistant isolates from both species possess the aac(2')-IIa gene, only A. avenae strain 83 showed higher resistance than other strains. In this research, kinetic analysis indicates that an amino acid substitution from serine to threonine at position 146 of AAC(2')-IIa in strain 83 is not involved in this increased resistance. Whole draft genome analysis of A. avenae 83 shows that the aac(2')-IIa gene is carried by the novel IncP-1β plasmid pAAA83, whereas the genetic carrier of other strains, the IncP genomic island, is inserted into their chromosomes. The difference in the nucleotides of the promoter region of aac(2')-IIa between strain 83 and other strains indicates an additional transcription start site and results in the increased transcription of aac(2')-IIa in strain 83. Moreover, biological characterization of pAAA83 demonstrates that it can be transferred by conjugation and maintained in the host cells. These results demonstrate that acquisition of the aac(2')-IIa gene takes place in at least two ways and that the gene module, which includes aac(2')-IIa and the downstream gene, may be an important unit for the dissemination of antibiotic resistance. © 2014 BSPP AND JOHN WILEY & SONS LTD.
Silva, Danielle C G; Yamanaka, Naoki; Brogin, Rodrigo L; Arias, Carlos A A; Nepomuceno, Alexandre L; Di Mauro, Antônio O; Pereira, Selma S; Nogueira, Livia M; Passianotto, André L L; Abdelnoor, Ricardo V
Asian soybean rust (ASR) is caused by the fungal pathogen Phakopsora pachyrhizi Sydow & Sydow. It was first identified in Brazil in 2001 and quickly infected soybean areas in several countries in South America. Primary efforts to combat this disease must involve the development of resistant cultivars. Four distinct genes that confer resistance against ASR have been reported: Rpp1, Rpp2, Rpp3, and Rpp4. However, no cultivar carrying any of those resistance loci has been released. The main objective of this study was to genetically map Rpp2 and Rpp4 resistance genes. Two F(2:3) populations, derived from the crosses between the resistant lines PI 230970 (Rpp2), PI 459025 (Rpp4) and the susceptible cultivar BRS 184, were used in this study. The mapping populations and parental lines were inoculated with a field isolate of P. pachyrhizi and evaluated for lesion type as resistant (RB lesions) or susceptible (TAN lesions). The mapping populations were screened with SSR markers, using the bulk segregant analysis (BSA) to expedite the identification of linked markers. Both resistance genes showed an expected segregation ratio for a dominant trait. This study allowed mapping Rpp2 and Rpp4 loci on the linkage groups J and G, respectively. The associated markers will be of great value on marker assisted selection for this trait.
Humphry, M.; Reinstädler, A.; Ivanov, S.; Bisseling, T.; Panstruga, R.
Loss-of-function alleles of plant-specific MLO (Mildew Resistance Locus O) genes confer broad-spectrum powdery mildew resistance in monocot (barley) and dicot (Arabidopsis thaliana, tomato) plants. Recessively inherited powdery mildew resistance in pea (Pisum sativum) er1 plants is, in many aspects,
Wong, Sharon Y; Lee, Jong Seok; Kwak, Hyun Kyung; Via, Laura E; Boshoff, Helena I M; Barry, Clifton E
The global threat posed by drug-resistant strains of Mycobacterium tuberculosis demands a greater understanding of the genetic basis and molecular mechanisms that govern how such strains develop resistance against various antituberculous drugs. In this report, we examine a new genetic basis for resistance to one of the oldest and most widely used second-line drugs employed in tuberculosis therapy, streptomycin (SM). This marker for SM resistance was first discovered on the basis of genomic data obtained from drug-resistant M. tuberculosis strains collected in Japan, wherein an association was observed between SM resistance and a mutation in gidB, a putative 16S rRNA methyltransferase. By evaluating an isogenic ΔgidB mutant strain constructed from strain H37Rv, we demonstrate the causal role of gidB in conferring a low-level SM-resistant phenotype in M. tuberculosis with a 16-fold increase in the MIC over the parent strain. Among clinical isolates, the modest increase in SM resistance conferred by a gidB mutation leads to an MIC distribution of gidB mutation-containing strains that spans the recommended SM breakpoint concentration currently used in drug susceptibility testing protocols. As such, some gidB mutation-containing isolates are found to be SM sensitive, while others are SM resistant. On the basis of a pharmacodynamic analysis and Monte Carlo simulation, those isolates that are found to be SM sensitive should still respond favorably to SM treatment, while nearly half of those found to be SM resistant will likely respond poorly. This report provides the first microbiological evidence for the contribution of gidB in streptomycin resistance and examines the clinical implications of mutations in the gidB gene.
Wong, Sharon Y.; Lee, Jong Seok; Kwak, Hyun Kyung; Via, Laura E.; Boshoff, Helena I. M.; Barry, Clifton E.
The global threat posed by drug-resistant strains of Mycobacterium tuberculosis demands a greater understanding of the genetic basis and molecular mechanisms that govern how such strains develop resistance against various antituberculous drugs. In this report, we examine a new genetic basis for resistance to one of the oldest and most widely used second-line drugs employed in tuberculosis therapy, streptomycin (SM). This marker for SM resistance was first discovered on the basis of genomic data obtained from drug-resistant M. tuberculosis strains collected in Japan, wherein an association was observed between SM resistance and a mutation in gidB, a putative 16S rRNA methyltransferase. By evaluating an isogenic ΔgidB mutant strain constructed from strain H37Rv, we demonstrate the causal role of gidB in conferring a low-level SM-resistant phenotype in M. tuberculosis with a 16-fold increase in the MIC over the parent strain. Among clinical isolates, the modest increase in SM resistance conferred by a gidB mutation leads to an MIC distribution of gidB mutation-containing strains that spans the recommended SM breakpoint concentration currently used in drug susceptibility testing protocols. As such, some gidB mutation-containing isolates are found to be SM sensitive, while others are SM resistant. On the basis of a pharmacodynamic analysis and Monte Carlo simulation, those isolates that are found to be SM sensitive should still respond favorably to SM treatment, while nearly half of those found to be SM resistant will likely respond poorly. This report provides the first microbiological evidence for the contribution of gidB in streptomycin resistance and examines the clinical implications of mutations in the gidB gene. PMID:21444711
Johnson, Timothy A; Stedtfeld, Robert D; Wang, Qiong; Cole, James R; Hashsham, Syed A; Looft, Torey; Zhu, Yong-Guan; Tiedje, James M
Antibiotic resistance is a worldwide health risk, but the influence of animal agriculture on the genetic context and enrichment of individual antibiotic resistance alleles remains unclear. Using quantitative PCR followed by amplicon sequencing, we quantified and sequenced 44 genes related to antibiotic resistance, mobile genetic elements, and bacterial phylogeny in microbiomes from U.S. laboratory swine and from swine farms from three Chinese regions. We identified highly abundant resistance clusters: groups of resistance and mobile genetic element alleles that cooccur. For example, the abundance of genes conferring resistance to six classes of antibiotics together with class 1 integrase and the abundance of IS6100-type transposons in three Chinese regions are directly correlated. These resistance cluster genes likely colocalize in microbial genomes in the farms. Resistance cluster alleles were dramatically enriched (up to 1 to 10% as abundant as 16S rRNA) and indicate that multidrug-resistant bacteria are likely the norm rather than an exception in these communities. This enrichment largely occurred independently of phylogenetic composition; thus, resistance clusters are likely present in many bacterial taxa. Furthermore, resistance clusters contain resistance genes that confer resistance to antibiotics independently of their particular use on the farms. Selection for these clusters is likely due to the use of only a subset of the broad range of chemicals to which the clusters confer resistance. The scale of animal agriculture and its wastes, the enrichment and horizontal gene transfer potential of the clusters, and the vicinity of large human populations suggest that managing this resistance reservoir is important for minimizing human risk. Agricultural antibiotic use results in clusters of cooccurring resistance genes that together confer resistance to multiple antibiotics. The use of a single antibiotic could select for an entire suite of resistance genes if
Olsen, Anders S; Warrass, Ralf; Douthwaite, Stephen Roger
OBJECTIVES: To determine how resistance to macrolides is conferred in field isolates of Pasteurella multocida and Mannheimia haemolytica that lack previously identified resistance determinants for rRNA methylation, efflux and macrolide-modifying enzymes. METHODS: Isolates of P. multocida and M...... by genome sequencing and primer extension on the rRNAs. RESULTS: Macrolide resistance in one M. haemolytica isolate was conferred by the 23S rRNA mutation A2058G; resistance in three P. multocida isolates were caused by mutations at the neighbouring nucleotide A2059G. In each strain, all six copies...... of the rrn operons encoded the respective mutations. There were no mutations in the ribosomal protein genes rplD or rplV, and no other macrolide resistance mechanism was evident. CONCLUSIONS: High-level macrolide resistance can arise from 23S rRNA mutations in P. multocida and M. haemolytica despite...
Rice blast disease is a significant threat to stable rice production in the USA and worldwide. The major resistance gene (Pi-ta) located within a cluster of resistance genes on rice chromosome 12 has been demonstrated to confer resistance to the rice blast disease. Katy, a rice cultivar released in ...
Ghio, Cecilia; Ramos, María Laura; Altieri, Emiliano; Bulos, Mariano; Sala, Carlos A
The AHAS gene family in soybean was characterized. The locus Als1 for sulfonylurea resistance was mapped and the resistant allele was characterized at the molecular level. Sulfonylurea (SU) resistance in soybean is controlled by Als1, a semi-dominant allele obtained by EMS mutagenesis over the cultivar Williams 82. The overall objective of this research was to map Als1 in the soybean genome and to determine the nucleotidic changes conferring resistance to SU. Four nucleotide sequences (GmAhas1-4) showing high homology with the Arabidopsis thaliana acetohydroxyacid synthase (AHAS, EC 184.108.40.206) gene sequence were identified by in silico analysis, PCR-amplified from the SU-resistant line BTK323STS and sequenced. Expression analysis showed that GmAhas1, located on chromosome 4 by in silico analysis, is the most expressed sequence in true leaves. F2:3 families derived from the cross between susceptible and resistant lines were evaluated for SU resistance. Mapping results indicate that the locus als1 is located on chromosome 4. Sequence comparison of GmAhas1 between BTK323STS and Williams 82 showed a single nucleotide change from cytosine to thymine at position 532. This transversion generates an amino acid change from proline to serine at position 197 (A. thaliana nomenclature) of the AHAS catalytic subunit. An allele-specific marker developed for the GmAhas1 mutant sequence cosegregated with SU resistance in the F2 population. Taking together, the mapping, expression and sequencing results indicate that the GmAhas1 sequence corresponds to the Als1 gene sequence controlling SU resistance in soybean. The molecular breeding tools described herein create the basis to speed up the identification of new mutations in soybean AHAS leading to enhanced levels of resistance to SU or to other families of AHAS inhibitor herbicides.
Ceasar, S Antony; Ignacimuthu, S
Fungal diseases damage crop plants and affect agricultural production. Transgenic plants have been produced by inserting antifungal genes to confer resistance against fungal pathogens. Genes of fungal cell wall-degrading enzymes, such as chitinase and glucanase, are frequently used to produce fungal-resistant transgenic crop plants. In this review, we summarize the details of various transformation studies to develop fungal resistance in crop plants.
Fukuoka, Shuichi; Saka, Norikuni; Mizukami, Yuko; Koga, Hironori; Yamanouchi, Utako; Yoshioka, Yosuke; Hayashi, Nagao; Ebana, Kaworu; Mizobuchi, Ritsuko; Yano, Masahiro
Effective control of blast, a devastating fungal disease of rice, would increase and stabilize worldwide food production. Resistance mediated by quantitative trait loci (QTLs), which usually have smaller individual effects than R-genes but confer broad-spectrum or non-race-specific resistance, is a promising alternative to less durable race-specific resistance for crop improvement, yet evidence that validates the impact of QTL combinations (pyramids) on the durability of plant disease resistance has been lacking. Here, we developed near-isogenic experimental lines representing all possible combinations of four QTL alleles from a durably resistant cultivar. These lines enabled us to evaluate the QTLs singly and in combination in a homogeneous genetic background. We present evidence that pyramiding QTL alleles, each controlling a different response to M. oryzae, confers strong, non-race-specific, environmentally stable resistance to blast disease. Our results suggest that this robust defence system provides durable resistance, thus avoiding an evolutionary "arms race" between a crop and its pathogen.
Achard, Adeline; Guérin-Faublée, Véronique; Pichereau, Vianney; Villers, Corinne; Leclercq, Roland
Streptococcus uberis UCN60 was resistant to spiramycin (MIC = 8 microg/ml) but susceptible to erythromycin (MIC = 0.06 microg/ml), azithromycin (MIC = 0.12 microg/ml), josamycin (MIC = 0.25 microg/ml), and tylosin (MIC = 0.5 microg/ml). A 2.5-kb HindIII fragment was cloned from S. uberis UCN60 DNA on plasmid pUC18 and introduced into Escherichia coli AG100A, where it conferred resistance to spiramycin by inactivation. The sequence analysis of the fragment showed the presence of an rdmC-like gene that putatively encoded a protein belonging to the alpha/beta hydrolase family and of the first 196 nucleotides of the mph(B) gene putatively encoding a phosphotransferase known to inactivate 14-, 15-, and 16-membered macrolides in E. coli. The entire mph(B) gene was then identified in S. uberis UCN60. The two genes were expressed alone or in combination in E. coli, Staphylococcus aureus, and Enterococcus faecalis. Analysis of MICs revealed that rdmC-like alone did not confer resistance to erythromycin, tylosin, and josamycin in those three hosts. It conferred resistance to spiramycin in E. coli and E. faecalis but not in S. aureus. mph(B) conferred resistance in E. coli to erythromycin, tylosin, josamycin, and spiramycin but only low levels of resistance in E. faecalis and S. aureus to spiramycin (MIC = 8 microg/ml). The combination of mph(B) and rdmC-like genes resulted in a resistance to spiramycin and tylosin in the three hosts that significantly exceeded the mere addition of the resistance levels conferred by each resistance mechanism alone.
H Deborah Chen
Full Text Available Horizontally acquired genes typically function as autonomous units conferring new abilities when introduced into different species. However, we reasoned that proteins preexisting in an organism might constrain the functionality of a horizontally acquired gene product if it operates on an ancestral pathway. Here, we determine how the horizontally acquired pmrD gene product activates the ancestral PmrA/PmrB two-component system in Salmonella enterica but not in the closely related bacterium Escherichia coli. The Salmonella PmrD protein binds to the phosphorylated PmrA protein (PmrA-P, protecting it from dephosphorylation by the PmrB protein. This results in transcription of PmrA-dependent genes, including those conferring polymyxin B resistance. We now report that the E. coli PmrD protein can activate the PmrA/PmrB system in Salmonella even though it cannot do it in E. coli, suggesting that these two species differ in an additional component controlling PmrA-P levels. We establish that the E. coli PmrB displays higher phosphatase activity towards PmrA-P than the Salmonella PmrB, and we identified a PmrB subdomain responsible for this property. Replacement of the E. coli pmrB gene with the Salmonella homolog was sufficient to render E. coli resistant to polymyxin B under PmrD-inducing conditions. Our findings provide a singular example whereby quantitative differences in the biochemical activities of orthologous ancestral proteins dictate the ability of a horizontally acquired gene product to confer species-specific traits. And they suggest that horizontally acquired genes can potentiate selection at ancestral loci.
Invasion of ocean surface waters by anthropogenic CO2 emitted to the atmosphere is expected to reduce surface seawater pH to 7.8 by the end of this century compromising marine calcifiers. A broad range of biological and mineralogical mechanisms allow marine calcifiers to cope with ocean acidification, however these mechanisms are energetically demanding which affect other biological processes (trade-offs) with important implications for the resilience of the organisms against stressful conditions. Hence, food availability may play a critical role in determining the resistance of calcifiers to OA. Here we show, based on a meta-analysis of existing experimental results assessing the role of food supply in the response of organisms to OA, that food supply consistently confers calcifiers resistance to ocean acidification.
Wang, Yong; Duan, Yabing; Wang, Jianxin; Zhou, Mingguo
Research has established that mutations in highly conserved amino acids of the succinate dehydrogenase (SDH) complex in various fungi confer SDH inhibitor (SDHI) resistance. For Sclerotinia sclerotiorum (Lib.) de Bary, a necrotrophic fungus with a broad host range and a worldwide distribution, boscalid resistance has been attributed to the mutation H132R in the highly conserved SdhD subunit protein of the SDH complex. In our previous study, however, only one point mutation, A11V in SdhB (GCA to GTA change in SdhB), was detected in S. sclerotiorum boscalid-resistant (BR) mutants. In the current study, replacement of the SdhB gene in a boscalid-sensitive (BS) S. sclerotiorum strain with the mutant SdhB gene conferred resistance. Compared with wild-type strains, BR and GSM (SdhB gene in the wild-type strain replaced by the mutant SdhB gene) mutants were more sensitive to osmotic stress, lacked the ability to produce sclerotia and exhibited lower expression of the pac1 gene. Importantly, the point mutation was not located in the highly conserved sequence of the iron-sulfur subunit of SDH. These results suggest that resistance based on non-conserved vs. conserved protein domains differs in mechanism. In addition to increasing our understanding of boscalid resistance in S. sclerotiorum, the new information will be useful for the development of alternative antifungal drugs. © 2014 BSPP AND JOHN WILEY & SONS LTD.
Full Text Available The ability of plant viruses to propagate their genomes in host cells depends on many host factors. In the absence of an agrochemical that specifically targets plant viral infection cycles, one of the most effective methods for controlling viral diseases in plants is taking advantage of the host plant’s resistance machinery. Recessive resistance is conferred by a recessive gene mutation that encodes a host factor critical for viral infection. It is a branch of the resistance machinery and, as an inherited characteristic, is very durable. Moreover, recessive resistance may be acquired by a deficiency in a negative regulator of plant defense responses, possibly due to the autoactivation of defense signaling. Eukaryotic translation initiation factor (eIF 4E and eIF4G and their isoforms are the most widely exploited recessive resistance genes in several crop species, and they are effective against a subset of viral species. However, the establishment of efficient, recessive resistance-type antiviral control strategies against a wider range of plant viral diseases requires genetic resources other than eIF4Es. In this review, we focus on recent advances related to antiviral recessive resistance genes evaluated in model plants and several crop species. We also address the roles of next-generation sequencing and genome editing technologies in improving plant genetic resources for recessive resistance-based antiviral breeding in various crop species.
Identificação e validação de marcadores microssatélites ligados ao gene Rpp5 de resistência à ferrugem-asiática-da-soja Identification and validation of microsatellite markers linked to the Rpp5 gene conferring resistance to Asian soybean rust
Thaiza Galhardo Silva Morceli
Full Text Available O objetivo deste trabalho foi identificar novos marcadores microssatélites, ligados ao gene Rpp5 de resistência à ferrugem-da-soja, e validar os marcadores previamente mapeados, para que possam ser utilizados em programas de seleção assistida por marcadores moleculares (SAM. Para tanto, uma população F2 com 100 indivíduos, derivada do cruzamento entre a PI 200526 e a cultivar Coodetec 208, suscetível à ferrugem, foi artificialmente infectada e avaliada quanto à sua reação de resistência à ferrugem. Marcadores microssatélites foram testados nos genitores e em dois "bulks" contrastantes, para a identificação de marcadores ligados. Dois novos marcadores, potencialmente associados à resistência, foram testados em plantas individuais, e se constatou que eles estão ligados ao gene Rpp5 e estão presentes no grupo de ligação N da soja. A eficiência de seleção foi determinada em relação a todos os marcadores ligados ao gene Rpp5, e a combinação entre os marcadores Sat_275+Sat_280 foi de 100%.The main objective of this work was to identify new microsatellite markers, linked to the Rpp5 resistance gene to Asian soybean rust, and to validate previously mapped markers for use in marker-assisted selection (MAS programs. To this end, a F2 population with 100 individuals, derived from crossing between PI 200526 and cultivar Coodetec 208, susceptible to rust, was artificially infected and evaluated for its reaction of resistance to rust. Microsatellite markers were tested on parents and in the two contrasting bulks to identifying linked markers. Two new markers, potentially associated with resistance, were tested in individual plants, and they were found to be linked to gene Rpp5 and to be present in the N linkage group of soybean. The selection efficiencies were determined for all markers linked to gene Rpp5, and the combination of the markers Sat_275+Sat_280 was 100%.
Jitwasinkul, Tossawan; Suriyaphol, Prapat; Tangphatsornruang, Sithichoke
Antibiotic resistance genes are rapidly spread between pathogens and the normal flora, with plasmids playing an important role in their circulation. This study aimed to investigate antibiotic resistance plasmids in the gut microbiome of hospitalised patients. Stool samples were collected from seven...... sequences (using >80% alignment length as the cut-off), and ResFinder was used to classify the antibiotic resistance gene pools. Plasmid replicon modules were used for plasmid typing. Forty-six genes conferring resistance to several classes of antibiotics were identified in the stool samples. Several...... antibiotic resistance genes were shared by the patients; interestingly, most were reported previously in food animals and healthy humans. Four antibiotic resistance genes were found in the healthy subject. One gene (aph3-III) was identified in the patients and the healthy subject and was related...
Sala, Carlos A; Bulos, Mariano; Echarte, Mariel; Whitt, Sherry R; Ascenzi, Robert
A partially dominant nuclear gene conferring resistance to the imidazolinone herbicides was previously identified in the cultivated sunflower (Helianthus annuus L.) line CLHA-Plus developed by seed mutagenesis. The objective of this study was to characterize this resistant gene at the phenotypic, biochemical and molecular levels. CLHA-Plus showed a complete susceptibility to sulfonylureas (metsulfuron, tribenuron and chlorsulfuron) but, on the other hand, it showed a complete resistance to imidazolinones (imazamox, imazapyr and imazapic) at two rates of herbicide application. This pattern was in close association with the AHAS-inhibition kinetics of protein extracts of CLHA-Plus challenged with different doses of imazamox and chlorsulfuron. Nucleotide and deduced amino acid sequence comparisons between resistant and susceptible lines indicated that the imidazolinone-resistant AHAS of CLHA-Plus has a threonine codon (ACG) at position 122 (relative to the Arabidopsis thaliana AHAS sequence), whereas the herbicide-susceptible enzyme from BTK47 has an alanine residue (GCG) at this position. Since the resistance genes to AHAS-inhibiting herbicides so far characterized in sunflower code for the catalytic (large) subunit of AHAS, we propose to redesignate the wild type allele as ahasl1 and the incomplete dominant resistant alleles as Ahasl1-1 (previously Imr1 or Ar ( pur )), Ahasl1-2 (previously Ar ( kan )) and Ahasl1-3 (for the allele present in CLHA-Plus). The higher tolerance level to imidazolinones and the lack of cross-resistance to other AHAS-inhibiting herbicides of Ahasl1-3 indicate that this induced mutation can be used to develop commercial hybrids with superior levels of tolerance and, at the same time, to assist weed management where control of weedy common sunflower is necessary.
Seifi, Alireza; Kaloshian, Isgouhi; Vossen, Jack; Che, Daidi; Bhattarai, Kishor K; Fan, Junmei; Naher, Zabun; Goverse, Aska; Tjallingii, W Freddy; Lindhout, Pim; Visser, Richard G F; Bai, Yuling
On the short arm of tomato chromosome 6, a cluster of disease resistance (R) genes have evolved harboring the Mi-1 and Cf genes. The Mi-1 gene confers resistance to root-knot nematodes, aphids, and whiteflies. Previously, we mapped two genes, Ol-4 and Ol-6, for resistance to tomato powdery mildew in this cluster. The aim of this study was to investigate whether Ol-4 and Ol-6 are homologues of the R genes located in this cluster. We show that near-isogenic lines (NIL) harboring Ol-4 (NIL-Ol-4) and Ol-6 (NIL-Ol-6) are also resistant to nematodes and aphids. Genetically, the resistance to nematodes cosegregates with Ol-4 and Ol-6, which are further fine-mapped to the Mi-1 cluster. We provide evidence that the composition of Mi-1 homologues in NIL-Ol-4 and NIL-Ol-6 is different from other nematode-resistant tomato lines, Motelle and VFNT, harboring the Mi-1 gene. Furthermore, we demonstrate that the resistance to both nematodes and tomato powdery mildew in these two NIL is governed by linked (if not the same) Mi-1 homologues in the Mi-1 gene cluster. Finally, we discuss how Solanum crops exploit Mi-1 homologues to defend themselves against distinct pathogens.
Cheng, Gong; Hu, Yongfei; Yin, Yeshi; Yang, Xi; Xiang, Chunsheng; Wang, Baohong; Chen, Yanfei; Yang, Fengling; Lei, Fang; Wu, Na; Lu, Na; Li, Jing; Chen, Quanze; Li, Lanjuan; Zhu, Baoli
The human gut microbiota has a high density of bacteria that are considered a reservoir for antibiotic resistance genes (ARGs). In this study, one fosmid metagenomic library generated from the gut microbiota of four healthy humans was used to screen for ARGs against seven antibiotics. Eight new ARGs were obtained: one against amoxicillin, six against d-cycloserine, and one against kanamycin. The new amoxicillin resistance gene encodes a protein with 53% identity to a class D β-lactamase from Riemerella anatipestifer RA-GD. The six new d-cycloserine resistance genes encode proteins with 73-81% identity to known d-alanine-d-alanine ligases. The new kanamycin resistance gene encodes a protein of 274 amino acids with an N-terminus (amino acids 1-189) that has 42% identity to the 6'-aminoglycoside acetyltransferase [AAC(6')] from Enterococcus hirae and a C-terminus (amino acids 190-274) with 35% identity to a hypothetical protein from Clostridiales sp. SSC/2. A functional study on the novel kanamycin resistance gene showed that only the N-terminus conferred kanamycin resistance. Our results showed that functional metagenomics is a useful tool for the identification of new ARGs. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.
Periyannan, Sambasivam; Moore, John; Ayliffe, Michael; Bansal, Urmil; Wang, Xiaojing; Huang, Li; Deal, Karin; Luo, Mingcheng; Kong, Xiuying; Bariana, Harbans; Mago, Rohit; McIntosh, Robert; Dodds, Peter; Dvorak, Jan; Lagudah, Evans
Wheat stem rust, caused by the fungus Puccinia graminis f. sp. tritici, afflicts bread wheat (Triticum aestivum). New virulent races collectively referred to as "Ug99" have emerged, which threaten global wheat production. The wheat gene Sr33, introgressed from the wild relative Aegilops tauschii into bread wheat, confers resistance to diverse stem rust races, including the Ug99 race group. We cloned Sr33, which encodes a coiled-coil, nucleotide-binding, leucine-rich repeat protein. Sr33 is orthologous to the barley (Hordeum vulgare) Mla mildew resistance genes that confer resistance to Blumeria graminis f. sp. hordei. The wheat Sr33 gene functions independently of RAR1, SGT1, and HSP90 chaperones. Haplotype analysis from diverse collections of Ae. tauschii placed the origin of Sr33 resistance near the southern coast of the Caspian Sea.
Mazodier, P; Cossart, P; Giraud, E; Gasser, F
The DNA sequence of the region located downstream from the kanamycin resistance gene of Tn5 up to the right inverted repeat IS50R has been determined. This completes the determination of the sequence of Tn5 which is 5818 bp long. The 2.7 Kb central region contains three resistance genes: the kanamycin-neomycin resistance gene, a gene coding for resistance to CL990 an antimitotic-antibiotic compound of the bleomycin family and a third gene that confers streptomycin resistance in some bacterial...
Yu, Long-Xi; Lorenz, Aaron; Rutkoski, Jessica; Singh, Ravi P; Bhavani, Sridhar; Huerta-Espino, Julio; Sorrells, Mark E
The recent emergence of wheat stem rust Ug99 and evolution of new races within the lineage threatens global wheat production because they overcome widely deployed stem rust resistance (Sr) genes that had been effective for many years. To identify loci conferring adult plant resistance to races of Ug99 in wheat, we employed an association mapping approach for 276 current spring wheat breeding lines from the International Maize and Wheat Improvement Center (CIMMYT). Breeding lines were genotyped with Diversity Array Technology (DArT) and microsatellite markers. Phenotypic data was collected on these lines for stem rust race Ug99 resistance at the adult plant stage in the stem rust resistance screening nursery in Njoro, Kenya in seasons 2008, 2009 and 2010. Fifteen marker loci were found to be significantly associated with stem rust resistance. Several markers appeared to be linked to known Sr genes, while other significant markers were located in chromosome regions where no Sr genes have been previously reported. Most of these new loci colocalized with QTLs identified recently in different biparental populations. Using the same data and Q + K covariate matrices, we investigated the interactions among marker loci using linear regression models to calculate P values for pairwise marker interactions. Resistance marker loci including the Sr2 locus on 3BS and the wPt1859 locus on 7DL had significant interaction effects with other loci in the same chromosome arm and with markers on chromosome 6B. Other resistance marker loci had significant pairwise interactions with markers on different chromosomes. Based on these results, we propose that a complex network of gene-gene interactions is, in part, responsible for resistance to Ug99. Further investigation may provide insight for understanding mechanisms that contribute to this resistance gene network.
Torres-Cortés, Gloria; Millán, Vicenta; Ramírez-Saad, Hugo C; Nisa-Martínez, Rafael; Toro, Nicolás; Martínez-Abarca, Francisco
The soil microbial community is highly complex and contains a high density of antibiotic-producing bacteria, making it a likely source of diverse antibiotic resistance determinants. We used functional metagenomics to search for antibiotic resistance genes in libraries generated from three different soil samples, containing 3.6 Gb of DNA in total. We identified 11 new antibiotic resistance genes: 3 conferring resistance to ampicillin, 2 to gentamicin, 2 to chloramphenicol and 4 to trimethoprim. One of the clones identified was a new trimethoprim resistance gene encoding a 26.8 kDa protein closely resembling unassigned reductases of the dihydrofolate reductase group. This protein, Tm8-3, conferred trimethoprim resistance in Escherichia coli and Sinorhizobium meliloti (γ- and α-proteobacteria respectively). We demonstrated that this gene encoded an enzyme with dihydrofolate reductase activity, with kinetic constants similar to other type I and II dihydrofolate reductases (K(m) of 8.9 µM for NADPH and 3.7 µM for dihydrofolate and IC(50) of 20 µM for trimethoprim). This is the first description of a new type of reductase conferring resistance to trimethoprim. Our results indicate that soil bacteria display a high level of genetic diversity and are a reservoir of antibiotic resistance genes, supporting the use of this approach for the discovery of novel enzymes with unexpected activities unpredictable from their amino acid sequences. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.
Jagielski, Tomasz; Ignatowska, Helena; Bakuła, Zofia; Dziewit, Łukasz; Napiórkowska, Agnieszka; Augustynowicz-Kopeć, Ewa; Zwolska, Zofia; Bielecki, Jacek
Currently, mutations in three genes, namely rrs, rpsL, and gidB, encoding 16S rRNA, ribosomal protein S12, and 16S rRNA-specific methyltransferase, respectively, are considered to be involved in conferring resistance to streptomycin (STR) in Mycobacterium tuberculosis. The aim of this study was to investigate the spectrum and frequency of these mutations in M. tuberculosis clinical isolates, both resistant and susceptible to STR. Sixty-four M. tuberculosis isolates recovered from as many TB patients from Poland in 2004 were included in the study. Within the sample were 50 multidrug-resistant (32 STR-resistant and 18 STR-susceptible) and 14 pan-susceptible isolates. Preliminary testing for STR resistance was performed with the 1% proportion method. The MICs of STR were determined by the Etest method. Mutation profiling was carried out by amplifying and sequencing the entire rrs, rpsL, and gidB genes. Non-synonymous mutations in either rrs or rpsL gene were detected in 23 (71.9%) of the STR-resistant and none of the STR-susceptible isolates. Mutations in the gidB gene were distributed among 12 (37.5%) STR-resistant and 13 (40.6%) STR-susceptible isolates. Four (12.5%) STR-resistant isolates were wild-type at all three loci examined. None of the rrs, rpsL or gidB mutations could be linked to low, intermediate or high level of STR resistance. In accordance with previous findings, the gidB 47T→G (L16R) mutation was associated with the Latin American-Mediterranean genotype family, whereas 276A→C (E92D) and 615A→G (A205A) mutations of the gidB gene were associated with the Beijing lineage. The study underlines the usefulness of rrs and rpsL mutations as molecular markers for STR resistance yet not indicative of its level. The gidB polymorphisms can serve as phylogenetic markers.
Gómez-Sanz, Elena; Kadlec, Kristina; Feßler, Andrea T.; Zarazaga, Myriam; Schwarz, Stefan
Transposon Tn558 integrated in the chromosomal radC gene was detected for the first time in Staphylococus pseudintermedius. It carried a novel fexA variant (fexAv) that confers only chloramphenicol resistance. The exporter FexAv exhibited two amino acid substitutions, Gly33Ala and Ala37Val, both of which seem to be important for substrate recognition. Site-directed mutagenesis that reverted the mutated base pairs to those present in the original fexA gene restored the chloramphenicol-plus-florfenicol resistance phenotype. PMID:23979755
Olsen, Anders S; Warrass, Ralf; Douthwaite, Stephen
To determine how resistance to macrolides is conferred in field isolates of Pasteurella multocida and Mannheimia haemolytica that lack previously identified resistance determinants for rRNA methylation, efflux and macrolide-modifying enzymes. Isolates of P. multocida and M. haemolytica identified as being highly resistant (MICs >64 mg/L) to the macrolides erythromycin, gamithromycin, tilmicosin, tildipirosin and tulathromycin were screened by multiplex PCR for the previously identified resistance genes erm(42), msr(E) and mph(E). Strains lacking these determinants were analysed by genome sequencing and primer extension on the rRNAs. Macrolide resistance in one M. haemolytica isolate was conferred by the 23S rRNA mutation A2058G; resistance in three P. multocida isolates were caused by mutations at the neighbouring nucleotide A2059G. In each strain, all six copies of the rrn operons encoded the respective mutations. There were no mutations in the ribosomal protein genes rplD or rplV, and no other macrolide resistance mechanism was evident. High-level macrolide resistance can arise from 23S rRNA mutations in P. multocida and M. haemolytica despite their multiple copies of rrn. Selective pressures from exposure to different macrolide or lincosamide drugs presumably resulted in consolidation of either the A2058G or the A2059G mutation. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: email@example.com.
Nakano, Shigeru; Fukaya, Masahiro
Acetic acid bacteria are used for industrial vinegar production because of their remarkable ability to oxidize ethanol and high resistance to acetic acid. Although several molecular machineries responsible for acetic acid resistance in acetic acid bacteria have been reported, the entire mechanism that confers acetic acid resistance has not been completely understood. One of the promising methods to elucidate the entire mechanism is global analysis of proteins responsive to acetic acid by two-dimensional gel electrophoresis. Recently, two proteins whose production was greatly enhanced by acetic acid in Acetobacter aceti were identified to be aconitase and a putative ABC-transporter, respectively; furthermore, overexpression or disruption of the genes encoding these proteins affected acetic acid resistance in A. aceti, indicating that these proteins are involved in acetic acid resistance. Overexpression of each gene increased acetic acid resistance in Acetobacter, which resulted in an improvement in the productivity of acetic acid fermentation. Taken together, the results of the proteomic analysis and those of previous studies indicate that acetic acid resistance in acetic acid bacteria is conferred by several mechanisms. These findings also provide a clue to breed a strain having high resistance to acetic acid for vinegar fermentation.
Hoorn, Van der R.A.L.; Roth, R.; Wit, De P.J.G.M.
The tomato resistance genes Cf-4 and Cf-9 confer specific, hypersensitive response-associated recognition of Cladosporium carrying the avirulence genes Avr4 and Avr9, respectively. Cf-4 and Cf-9 encode type I transmembrane proteins with extracellular leucine-rich repeats (LRRs). Compared with Cf-9,
Jiang, Shanshan; Jiang, Liangliang; Yang, Jian; Peng, Jiejun; Lu, Yuwen; Zheng, Hongying; Lin, Lin; Chen, Jianping; Yan, Fei
Plant Xrn4 is a cytoplasmic 5' to 3' exoribonuclease that is reported to play an antiviral role during viral infection as demonstrated by experiments using the Xrn4s of Nicotiana benthamiana and Arabidopsis thaliana. Meanwhile, little is known about the anti-viral activity of Xrn4 from other plants. Here, we cloned the cytoplasmic Xrn4 gene of Oryza sativa (OsXrn4), and demonstrated that its over-expression elevated the 5'-3' exoribonuclease activity in rice plants and conferred resistance to rice stripe virus, a negative-sense RNA virus causing serious losses in East Asia. The accumulation of viral RNAs was also decreased. Moreover, the ectopic expression of OsXrn4 in N. benthamiana also conferred plant resistance to tobacco mosaic virus infection. These results show that the monocotyledonous plant cytoplasmic Xrn4 also has an antiviral role and thus provides a strategy for producing transgenic plants resistant to viral infection. Copyright © 2017. Published by Elsevier B.V.
Herrera-Foessel, Sybil A; Singh, Ravi P; Lillemo, Morten; Huerta-Espino, Julio; Bhavani, Sridhar; Singh, Sukhwinder; Lan, Caixia; Calvo-Salazar, Violeta; Lagudah, Evans S
We demonstrate that Lr67/Yr46 has pleiotropic effect on stem rust and powdery mildew resistance and is associated with leaf tip necrosis. Genes are designated as Sr55, Pm46 and Ltn3 , respectively. Wheat (Triticum aestivum) accession RL6077, known to carry the pleiotropic slow rusting leaf and yellow rust resistance genes Lr67/Yr46 in Thatcher background, displayed significantly lower stem rust (P. graminis tritici; Pgt) and powdery mildew (Blumeria graminis tritici; Bgt) severities in Kenya and in Norway, respectively, compared to its recurrent parent Thatcher. We investigated the resistance of RL6077 to stem rust and powdery mildew using Avocet × RL6077 F6 recombinant inbred lines (RILs) derived from two photoperiod-insensitive F3 families segregating for Lr67/Yr46. Greenhouse seedling tests were conducted with Mexican Pgt race RTR. Field evaluations were conducted under artificially initiated stem rust epidemics with Pgt races RTR and TTKST (Ug99 + Sr24) at Ciudad Obregon (Mexico) and Njoro (Kenya) during 2010-2011; and under natural powdery mildew epiphytotic in Norway at Ås and Hamar during 2011 and 2012. In Mexico, a mean reduction of 41 % on stem rust severity was obtained for RILs carrying Lr67/Yr46, compared to RILs that lacked the gene, whereas in Kenya the difference was smaller (16 %) but significant. In Norway, leaf tip necrosis was associated with Lr67/Yr46 and RILs carrying Lr67/Yr46 showed a 20 % reduction in mean powdery mildew severity at both sites across the 2 years of evaluation. Our study demonstrates that Lr67/Yr46 confers partial resistance to stem rust and powdery mildew and is associated with leaf tip necrosis. The corresponding pleiotropic, or tightly linked, genes, designated as Sr55, Pm46, and Ltn3, can be utilized to provide broad-spectrum durable disease resistance in wheat.
Achard-Joris, M; van Saparoea, HBV; Driessen, AJM; Bourdineaud, JP; Bourdineaud, Jean-Paul
The human MDR1 gene is induced by cadmium exposure although no resistance to this metal is observed in human cells overexpressing hMDR1. To access the role of MDR proteins in cadmium resistance, human MDR1, Lactococcus lactis lmrA, and Oenococcus oeni omrA were expressed in an Escherichia coli tolC
Weedy red rice (Oryza sativa) competes aggressively with rice, reducing yields and grain quality. Clearfield™ rice, a nontransgenic, herbicide-resistant (HR) rice introduced in 2002 to control weedy rice, has resulted in some ALS-resistant weedy rice apparently due to gene flow. Studies were conduct...
Nakai, Yusuke; Fujiwara, Sumire; Kubo, Yasuyuki; Sato, Masa H
VOZ (vascular plant one zinc-finger protein) is a plant specific one-zinc finger type transcriptional activator, which is highly conserved through land plant evolution. We have previously shown that loss-of-function mutations in VOZ1 and VOZ2 showed increased cold and drought stress tolerances whereas decreased biotic stress resistance in Arabidopsis. Here, we demonstrate that transgenic plants overexpressing VOZ2 impairs freezing and drought stress tolerances but increases resistance to a fungal pathogen, Colletoricum higginsianum. Consistent with changes in the tolerance to biotic and abiotic stresses, the expression of marker genes for these stresses is significantly altered compared with those of the wild-type plant. These results indicate that a overexpression of VOZ2 confers biotic stress tolerance but impairs abiotic stress tolerances in Arabidopsis.
Hitch, Thomas C A; Thomas, Ben J; Friedersdorff, Jessica C A; Ougham, Helen; Creevey, Christopher J
Antibiotic resistance is an increasingly important environmental pollutant with direct consequences for human health. Identification of environmental sources of antibiotic resistance genes (ARGs) makes it possible to follow their evolution and prevent their entry into the clinical setting. ARGs have been found in environmental sources exogenous to the original source and previous studies have shown that these genes are capable of being transferred from livestock to humans. Due to the nature of farming and the slaughter of ruminants for food, humans interact with these animals in close proximity, and for this reason it is important to consider the risks to human health. In this study, we characterised the ARG populations in the ovine rumen, termed the resistome. This was done using the Comprehensive Antibiotic Resistance Database (CARD) to identify the presence of genes conferring resistance to antibiotics within the rumen. Genes were successfully mapped to those that confer resistance to a total of 30 different antibiotics. Daptomycin was identified as the most common antibiotic for which resistance is present, suggesting that ruminants may be a source of daptomycin ARGs. Colistin resistance, conferred by the gene pmrE, was also found to be present within all samples, with an average abundance of 800 counts. Due to the high abundance of some ARGs (against daptomycin) and the presence of rare ARGs (against colistin), we suggest further study and monitoring of the rumen resistome as a possible source of clinically relevant ARGs. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.
Seifi Abdolabad, A.R.; Visser, R.G.F.; Bai, Y.
Transport inhibitor 1 (TIR1) is an auxin receptor that plays a pivotal role in auxin signaling. It has been reported that TIR-like genes are present in a gene cluster carrying the Mi-1 gene which confers resistance to nematodes, aphids and whiteflies. Since auxin is involved in the pathogenicity of
Rozwandowicz, M.; Brouwer, M.S.M.; Fischer, J.; Wagenaar, J.A.; Gonzalez-Zorn, B.; Guerra, B.; Mevius, D.J.; Hordijk, J.
Bacterial antimicrobial resistance (AMR) is constantly evolving and horizontal gene transfer through plasmids plays a major role. The identification of plasmid characteristics and their association with different bacterial hosts provides crucial knowledge that is essential to understand the
Yang, Yongqing; Zheng, Guijie; Han, Lu; Dagang, Wang; Yang, Xiaofeng; Yuan, Yuan; Huang, Saihua; Zhi, Haijian
Soybean mosaic virus (SMV) is one of the most broadly distributed soybean (Glycine max (L.) Merr.) diseases and causes severe yield loss and seed quality deficiency. Multiple studies have proved that a single dominant gene can confer resistance to several SMV strains. Plant introduction (PI) 96983 has been reported to contain SMV resistance genes (e.g., Rsv1 and Rsc14) on chromosome 13. The objective of this study was to delineate the genetics of resistance to SMV in PI 96983 and determine whether one gene can control resistance to more than one Chinese SMV strain. In this study, PI 96983 was identified as resistant and Nannong 1138-2 was identified as susceptible to four SMV strains SC3, SC6, SC7, and SC17. Genetic maps based on 783 F2 individuals from the cross of PI 96983 × Nannong 1138-2 showed that the gene(s) conferring resistance to SC3, SC6, and SC17 were between SSR markers BARCSOYSSR_13_1114 and BARCSOYSSR_13_1136, whereas SC7 was between markers BARCSOYSSR_13_1140 and BARCSOYSSR_13_1185. The physical map based on 58 recombinant lines confirmed these results. The resistance gene for SC7 was positioned between BARCSOYSSR_13_1140 and BARCSOYSSR_13_1155, while the resistance gene(s) for SC3, SC6, and SC17 were between BARCSOYSSR_13_1128 and BARCSOYSSR_13_1136. We concluded that, there were two dominant resistance genes flanking Rsv1 or one of them at the reported genomic location of Rsv1. One of them (designated as "Rsc-pm") conditions resistance for SC3, SC6, and SC17 and another (designated as "Rsc-ps") confers resistance for SC7. The two tightly linked genes identified in this study would be helpful to cloning of resistance genes and breeding of multiple resistances soybean cultivars to SMV through marker-assisted selection (MAS).
The chicken’s major histocompatibility complex (MHC) haplotype has a profound influence on the resistance or susceptibility to certain pathogens such as B21 MHC haplotype confers resistance to Marek’s disease (MD). However, non-MHC genes are also important in disease resistance. For example, both li...
Song, Xiaozhao; Kain, Wendy; Cassidy, Douglas
The resistance to the Bacillus thuringiensis (Bt) toxin Cry2Ab in a greenhouse-originated Trichoplusia ni strain resistant to both Bt toxins Cry1Ac and Cry2Ab was characterized. Biological assays determined that the Cry2Ab resistance in the T. ni strain was a monogenic recessive trait independent of Cry1Ac resistance, and there existed no significant cross-resistance between Cry1Ac and Cry2Ab in T. ni. From the dual-toxin-resistant T. ni strain, a strain resistant to Cry2Ab only was isolated, and the Cry2Ab resistance trait was introgressed into a susceptible laboratory strain to facilitate comparative analysis of the Cry2Ab resistance with the susceptible T. ni strain. Results from biochemical analysis showed no significant difference between the Cry2Ab-resistant and -susceptible T. ni larvae in midgut proteases, including caseinolytic proteolytic activity and zymogram profile and serine protease activities, in midgut aminopeptidase and alkaline phosphatase activity, and in midgut esterases and hemolymph plasma melanization activity. For analysis of genetic linkage of Cry2Ab resistance with potential Cry toxin receptor genes, molecular markers for the midgut cadherin, alkaline phosphatase (ALP), and aminopeptidase N (APN) genes were identified between the original greenhouse-derived dual-toxin-resistant and the susceptible laboratory T. ni strains. Genetic linkage analysis showed that the Cry2Ab resistance in T. ni was not genetically associated with the midgut genes coding for the cadherin, ALP, and 6 APNs (APN1 to APN6) nor associated with the ABC transporter gene ABCC2. Therefore, the Cry2Ab resistance in T. ni is conferred by a novel but unknown genetic mechanism. PMID:26025894
Mohamed H. Al-Agamy
Full Text Available Background. This study described various molecular and epidemiological characters determining antibiotic resistance patterns in Pseudomonas aeruginosa isolates. Methods. A total of 34 carbapenem-resistant P. aeruginosa clinical isolates were isolated from samples collected at a tertiary hospital in Riyadh, Saudi Arabia, from January to December 2011. Susceptibility testing, serotyping, molecular characterization of carbapenem resistance, and pulsed-field gel electrophoresis (PFGE were performed. Results. All isolates were resistant to ceftazidime, and more than half were highly resistant (minimum inhibitory concentration (MIC > 256 mg/L. Fifteen isolates had MIC values ≥64 mg/L for any of the carbapenems examined. Vietnamese extended-spectrum β-lactamase (VEB-1 (n=16/34 and oxacillinase (OXA-10 (n=14/34 were the most prevalent extended-spectrum β-lactamase and penicillinase, respectively. Verona imipenemase (VIM-1, VIM-2, VIM-4, VIM-11, and VIM-28 and imipenemase (IMP-7 variants were found in metallo-β-lactamase producers. A decrease in outer membrane porin gene (oprD expression was seen in nine isolates, and an increase in efflux pump gene (MexAB expression was detected in five isolates. Six serotypes (O:1, O:4, O:7, O:10, O:11, and O:15 were found among the 34 isolates. The predominant serotype was O:11 (16 isolates, followed by O:15 (nine isolates. PFGE analysis of the 34 carbapenem-resistant P. aeruginosa isolates revealed 14 different pulsotypes. Conclusions. These results revealed diverse mechanisms conferring carbapenem resistance to P. aeruginosa isolates from Saudi Arabia.
Daniela M Cirillo
A user-friendly interface designed for nonexpert or expert operability.A standardized and validated analysis pipeline for variant analyses of M. tuberculosis next-generation sequencing (NGS data.Access to data beyond the published literature with dynamic and iterative updates of new data generated by global surveillance and clinical trials.A well-developed legal structure to ensure intellectual property rights and data ownership remain with contributors.A structured data-sharing architecture to restrict access to sensitive or unpublished data sets.Metadata standardization using CDISC: supports global, platform-independent data standards that enable information system interoperability.An emphasis on data quality and rigorous, expert curation with multiple quality control checks for whole-genome sequencing and other metadata.Validation of NGS analysis output by an expert committee with grading of resistance conferring mutations based on rigorous statistical standards.Regulatory-compliant analysis pipeline and database architecture. Successful execution of such an extensive database platform requires substantial collaboration from scientists investigating the genetic basis for drug resistance worldwide, and from developers with expertise in database design and implementation.
Zankari, Ea; Hasman, Henrik; Cosentino, Salvatore
ObjectivesIdentification of antimicrobial resistance genes is important for understanding the underlying mechanisms and the epidemiology of antimicrobial resistance. As the costs of whole-genome sequencing (WGS) continue to decline, it becomes increasingly available in routine diagnostic laborato......ObjectivesIdentification of antimicrobial resistance genes is important for understanding the underlying mechanisms and the epidemiology of antimicrobial resistance. As the costs of whole-genome sequencing (WGS) continue to decline, it becomes increasingly available in routine diagnostic...... laboratories and is anticipated to substitute traditional methods for resistance gene identification. Thus, the current challenge is to extract the relevant information from the large amount of generated data.MethodsWe developed a web-based method, ResFinder that uses BLAST for identification of acquired...... antimicrobial resistance genes in whole-genome data. As input, the method can use both pre-assembled, complete or partial genomes, and short sequence reads from four different sequencing platforms. The method was evaluated on 1862 GenBank files containing 1411 different resistance genes, as well as on 23 de...
Full Text Available Plasmids operate as independent genetic elements in microorganism communities. Through horizontal gene transfer, they can provide their host microorganisms with important functions such as antibiotic resistance and heavy metal resistance. In this study, six metagenomic libraries were constructed with plasmid DNA extracted from influent, activated sludge and digested sludge of two wastewater treatment plants. Compared with the metagenomes of the total DNA extracted from the same sectors of the wastewater treatment plant, the plasmid metagenomes had significantly higher annotation rates, indicating that the functional genes on plasmids are commonly shared by those studied microorganisms. Meanwhile, the plasmid metagenomes also encoded many more genes related to defense mechanisms, including ARGs. Searching against an antibiotic resistance genes (ARGs database and a metal resistance genes (MRGs database revealed a broad-spectrum of antibiotic (323 out of a total 618 subtypes and metal resistance genes (23 out of a total 23 types on these plasmid metagenomes. The influent plasmid metagenomes contained many more resistance genes (both ARGs and MRGs than the activated sludge and the digested sludge metagenomes. Sixteen novel plasmids with a complete circular structure that carried these resistance genes were assembled from the plasmid metagenomes. The results of this study demonstrated that the plasmids in wastewater treatment plants could be important reservoirs for resistance genes, and may play a significant role in the horizontal transfer of these genes.
Dheilly, Alexandra; Le Devendec, Laëtitia; Mourand, Gwenaëlle; Bouder, Axelle; Jouy, Eric; Kempf, Isabelle
An experiment was conducted in animal facilities to compare the impacts of four avian colibacillosis treatments-oxytetracycline (OTC), trimethoprim-sulfadimethoxine (SXT), amoxicillin (AMX), or enrofloxacin (ENR)-on the susceptibility of Escherichia coli in broiler intestinal tracts. Birds were first orally inoculated with rifampin-resistant E. coli strains bearing plasmid genes conferring resistance to fluoroquinolones (qnr), cephalosporins (bla(CTX-M) or bla(FOX)), trimethoprim-sulfonamides, aminoglycosides, or tetracyclines. Feces samples were collected before, during, and after antimicrobial treatments. The susceptibilities of E. coli strains were studied, and resistance gene transfer was analyzed. An increase in the tetracycline-resistant E. coli population was observed only in OTC-treated birds, whereas multiresistant E. coli was detected in the dominant E. coli populations of SXT-, AMX-, or ENR-treated birds. Most multiresistant E. coli strains were susceptible to rifampin and exhibited various pulsed-field gel electrophoresis profiles, suggesting the transfer of one of the multiresistance plasmids from the inoculated strains to other E. coli strains in the intestinal tract. In conclusion, this study clearly illustrates how, in E. coli, "old" antimicrobials may coselect antimicrobial resistance to recent and critical molecules.
Garrett, K A; Andersen, K F; Asche, F; Bowden, R L; Forbes, G A; Kulakow, P A; Zhou, B
Resistance genes are a major tool for managing crop diseases. The networks of crop breeders who exchange resistance genes and deploy them in varieties help to determine the global landscape of resistance and epidemics, an important system for maintaining food security. These networks function as a complex adaptive system, with associated strengths and vulnerabilities, and implications for policies to support resistance gene deployment strategies. Extensions of epidemic network analysis can be used to evaluate the multilayer agricultural networks that support and influence crop breeding networks. Here, we evaluate the general structure of crop breeding networks for cassava, potato, rice, and wheat. All four are clustered due to phytosanitary and intellectual property regulations, and linked through CGIAR hubs. Cassava networks primarily include public breeding groups, whereas others are more mixed. These systems must adapt to global change in climate and land use, the emergence of new diseases, and disruptive breeding technologies. Research priorities to support policy include how best to maintain both diversity and redundancy in the roles played by individual crop breeding groups (public versus private and global versus local), and how best to manage connectivity to optimize resistance gene deployment while avoiding risks to the useful life of resistance genes. [Formula: see text] Copyright © 2017 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .
Quintavalle, Cristina; Burmeister, Katharina; Piscuoglio, Salvatore; Quagliata, Luca; Karamitopoulou, Eva; Sepe, Romina; Fusco, Alfredo; Terracciano, Luigi M; Andersen, Jesper B; Pallante, Pierlorenzo; Matter, Matthias S
High mobility group A1 (HMGA1) protein has been described to play an important role in numerous types of human carcinoma. By the modulation of several target genes HMGA1 promotes proliferation and epithelial-mesenchymal transition of tumor cells. However, its role in cholangiocarcinoma (CCA) has not been addressed yet. Therefore, we determined HMGA1 mRNA expression in CCA samples in a transcriptome array (n = 104) and a smaller cohort (n = 13) by qRT-PCR. Protein expression was evaluated by immunohistochemistry in a tissue microarray (n = 67). In addition, we analyzed changes in cell proliferation, colony formation, response to gemcitabine treatment, and target gene expression after modulation of HMGA1 expression in CCA cell lines. mRNA levels of HMGA1 were found to be upregulated in 15-62% depending on the cohort analyzed. Immunohistochemistry showed HMGA1 overexpression in 51% of CCA specimens. Integration with clinico-pathological data revealed that high HMGA1 expression was associated with reduced time to recurrence and a positive lymph node status in extrahepatic cholangiocellular carcinoma. In vitro experiments showed that overexpression of HMGA1 in CCA cell lines promoted cell proliferation, whereas its suppression reduced growth rate. HMGA1 further promoted colony formation in an anchorage independent growth and conferred resistance to gemcitabine treatment. Finally, HMGA1 modulated the expression of two genes involved in CCA carcinogenesis, iNOS and ERBB2. In conclusion, our findings indicate that HMGA1 expression is increased in a substantial number of CCA specimens. HMGA1 further promotes CCA tumorigenicity and confers resistance to chemotherapy. © 2017 Wiley Periodicals, Inc.
Brosnan, James T; Vargas, Jose J; Breeden, Gregory K; Grier, Logan; Aponte, Raphael A; Tresch, Stefan; Laforest, Martin
This is a first report of an Ala-205-Phe substitution in acetolactate synthase conferring resistance to imidazolinone, sulfonylurea, triazolopyrimidines, sulfonylamino-carbonyl-triazolinones, and pyrimidinyl (thio) benzoate herbicides. Resistance to acetolactate synthase (ALS) and photosystem II inhibiting herbicides was confirmed in a population of allotetraploid annual bluegrass (Poa annua L.; POAAN-R3) selected from golf course turf in Tennessee. Genetic sequencing revealed that seven of eight POAAN-R3 plants had a point mutation in the psbA gene resulting in a known Ser-264-Gly substitution on the D1 protein. Whole plant testing confirmed that this substitution conferred resistance to simazine in POAAN-R3. Two homeologous forms of the ALS gene (ALSa and ALSb) were detected and expressed in all POAAN-R3 plants sequenced. The seven plants possessing the Ser-264-Gly mutation conferring resistance to simazine also had a homozygous Ala-205-Phe substitution on ALSb, caused by two nucleic acid substitutions in one codon. In vitro ALS activity assays with recombinant protein and whole plant testing confirmed that this Ala-205-Phe substitution conferred resistance to imidazolinone, sulfonylurea, triazolopyrimidines, sulfonylamino-carbonyl- triazolinones, and pyrimidinyl (thio) benzoate herbicides. This is the first report of Ala-205-Phe mutation conferring wide spectrum resistance to ALS inhibiting herbicides.
Full Text Available Blast disease caused by Pyricularia oryzae is one of the limiting factors for rice production world wide. The use of resistant varieties for managing blast disease is considered as the most eco-friendly approaches. However, their resistances may be broken down within a few years due to the appearance of new virulent blast races in the field. The objective of the present study was to identify the quantitative trait locus (QTL conferring resistance to blast disease using 126 recombinant inbred (RI lines originated from a crossing of a durably resistant upland rice genotype (Laka and a highly susceptible rice accession cultivar (Kencana Bali. The RI population was developed through a single seed descent method from 1997 to 2004. Resistance of the RI lines was evaluated for blast in an endemic area of Sukabumi, West Java, in 2005. Disease intensity of the blast was examined following the standard evaluation system developed by the International Rice Research Institute (IRRI. At the same year the RI lines were analyzed with 134 DNA markers. Results of the study showed that one major QTL was found to be associated with blast resistance, and this QTL was located near RM2136 marker on the long arm of chromosome 11. This QTL explained 87% of the phenotypic variation with 37% additive effect. The map position of this QTL differed from that of a partial resistant gene, Pi34, identified previously on chromosome 11 in the Japanese durably resistant variety, Chubu 32. The QTL, however, was almost at the same position as that of the multiple allele-resistant gene, Pik. Therefore, an allelic test should be conducted to clarify the allelic relationship between QTL identified in this study and the Pik. The RI lines are the permanent segregating population that could be very useful for analysing phenotypic variations of important agronomic traits possibly owned by the RI lines. The major QTL identified in this study could be used as a genetic resource in
Land application of manure from tylosin-treated swine introduces tylosin-resistant enterococci, erm genes, which confer resistance to tylosin, and tylosin. This study documents the occurrence and transport of tylosin-resistant enterococci, erm genes, and tylosin in tile-drained chisel plow and no-ti...
Dogimont, Catherine; Chovelon, Veronique; Pauquet, Jerome; Boualem, Adnane; Bendahmane, Abdelhafid
Aphis gossypii is a polyphagous sucking aphid and a vector for many viruses. In Cucumis melo, a dominant locus, Vat, confers a high level of resistance to Aphis gossypii infestation and to viruses transmitted by this vector. To investigate the mechanism underlying this double resistance, we first genetically dissected the Vat locus. We delimited the double resistance to a single gene that encodes for a coiled-coil-nucleotide-binding-site-leucine-rich repeat (CC-NBS-LRR) protein type. To validate the genetic data, transgenic lines expressing the Vat gene were generated and assessed for the double resistance. In this analysis, Vat-transgenic plants were resistant to A. gossypii infestation as well as A. gossypii-mediated virus transmission. When the plants were infected mechanically, virus infection occurred on both transgenic and non-transgenic control plants. These results confirmed that the cloned CC-NBS-LRR gene mediates both resistance to aphid infestation and virus infection using A. gossypii as a vector. This resistance also invokes a separate recognition and response phases in which the recognition phase involves the interaction of an elicitor molecule from the aphid and Vat from the plant. The response phase is not specific and blocks both aphid infestation and virus infection. Sequence analysis of Vat alleles suggests a major role of an unusual conserved LRR repeat in the recognition of A. gossypii. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.
Fenny M. Dwivany
Full Text Available Banana is one of the world's most important trade commodities. However, infection of banana pathogenic fungi (Fusarium oxysporum race 4 is one of the major causes of decreasing production in Indonesia. Genetic engineering has become an alternative way to control this problem by isolating genes that involved in plant defense mechanism against pathogens. Two of the important genes are API5 and ChiI1, each gene encodes apoptosis inhibitory protein and chitinase enzymes. The purpose of this study was to study the expression of API5 and ChiI1 genes as candidate pathogenic resistance genes. The amplified fragments were then cloned, sequenced, and confirmed with in silico studies. Based on sequence analysis, it is showed that partial API5 gene has putative transactivation domain and ChiI1 has 9 chitinase family GH19 protein motifs. Data obtained from this study will contribute in banana genetic improvement.
Donato, Justin J.; Moe, Luke A.; Converse, Brandon J.; Smart, Keith D.; Berklein, Flora C.; McManus, Patricia S.; Handelsman, Jo
To gain insight into the diversity and origins of antibiotic resistance genes, we identified resistance genes in the soil in an apple orchard using functional metagenomics, which involves inserting large fragments of foreign DNA into Escherichia coli and assaying the resulting clones for expressed functions. Among 13 antibiotic-resistant clones, we found two genes that encode bifunctional proteins. One predicted bifunctional protein confers resistance to ceftazidime and contains a natural fusion between a predicted transcriptional regulator and a β-lactamase. Sequence analysis of the entire metagenomic clone encoding the predicted bifunctional β-lactamase revealed a gene potentially involved in chloramphenicol resistance as well as a predicted transposase. A second clone that encodes a predicted bifunctional protein confers resistance to kanamycin and contains an aminoglycoside acetyltransferase domain fused to a second acetyltransferase domain that, based on nucleotide sequence, was predicted not to be involved in antibiotic resistance. This is the first report of a transcriptional regulator fused to a β-lactamase and of an aminoglycoside acetyltransferase fused to an acetyltransferase not involved in antibiotic resistance. PMID:20453147
Yu, Q; Ahmad-Hamdani, M S; Han, H; Christoffers, M J; Powles, S B
Many herbicide-resistant weed species are polyploids, but far too little about the evolution of resistance mutations in polyploids is understood. Hexaploid wild oat (Avena fatua) is a global crop weed and many populations have evolved herbicide resistance. We studied plastidic acetyl-coenzyme A carboxylase (ACCase)-inhibiting herbicide resistance in hexaploid wild oat and revealed that resistant individuals can express one, two or three different plastidic ACCase gene resistance mutations (Ile-1781-Leu, Asp-2078-Gly and Cys-2088-Arg). Using ACCase resistance mutations as molecular markers, combined with genetic, molecular and biochemical approaches, we found in individual resistant wild-oat plants that (1) up to three unlinked ACCase gene loci assort independently following Mendelian laws for disomic inheritance, (2) all three of these homoeologous ACCase genes were transcribed, with each able to carry its own mutation and (3) in a hexaploid background, each individual ACCase resistance mutation confers relatively low-level herbicide resistance, in contrast to high-level resistance conferred by the same mutations in unrelated diploid weed species of the Poaceae (grass) family. Low resistance conferred by individual ACCase resistance mutations is likely due to a dilution effect by susceptible ACCase expressed by homoeologs in hexaploid wild oat and/or differential expression of homoeologous ACCase gene copies. Thus, polyploidy in hexaploid wild oat may slow resistance evolution. Evidence of coexisting non-target-site resistance mechanisms among wild-oat populations was also revealed. In all, these results demonstrate that herbicide resistance and its evolution can be more complex in hexaploid wild oat than in unrelated diploid grass weeds. Our data provide a starting point for the daunting task of understanding resistance evolution in polyploids. PMID:23047200
Yu, Q; Ahmad-Hamdani, M S; Han, H; Christoffers, M J; Powles, S B
Many herbicide-resistant weed species are polyploids, but far too little about the evolution of resistance mutations in polyploids is understood. Hexaploid wild oat (Avena fatua) is a global crop weed and many populations have evolved herbicide resistance. We studied plastidic acetyl-coenzyme A carboxylase (ACCase)-inhibiting herbicide resistance in hexaploid wild oat and revealed that resistant individuals can express one, two or three different plastidic ACCase gene resistance mutations (Ile-1781-Leu, Asp-2078-Gly and Cys-2088-Arg). Using ACCase resistance mutations as molecular markers, combined with genetic, molecular and biochemical approaches, we found in individual resistant wild-oat plants that (1) up to three unlinked ACCase gene loci assort independently following Mendelian laws for disomic inheritance, (2) all three of these homoeologous ACCase genes were transcribed, with each able to carry its own mutation and (3) in a hexaploid background, each individual ACCase resistance mutation confers relatively low-level herbicide resistance, in contrast to high-level resistance conferred by the same mutations in unrelated diploid weed species of the Poaceae (grass) family. Low resistance conferred by individual ACCase resistance mutations is likely due to a dilution effect by susceptible ACCase expressed by homoeologs in hexaploid wild oat and/or differential expression of homoeologous ACCase gene copies. Thus, polyploidy in hexaploid wild oat may slow resistance evolution. Evidence of coexisting non-target-site resistance mechanisms among wild-oat populations was also revealed. In all, these results demonstrate that herbicide resistance and its evolution can be more complex in hexaploid wild oat than in unrelated diploid grass weeds. Our data provide a starting point for the daunting task of understanding resistance evolution in polyploids.
Hansen, Lykke H.; Planellas, Mercè H.; Long, Katherine S.
The cfr gene encodes the Cfr methyltransferase that methylates a single adenine in the peptidyl transferase region of bacterial ribosomes. The methylation provides resistance to several classes of antibiotics that include drugs of clinical and veterinary importance. This paper describes a first...... coli, and MICs for selected antibiotics indicate that the cfr-like genes confer resistance to PhLOPSa (phenicol, lincosamide, oxazolidinone, pleuromutilin, and streptogramin A) antibiotics in the same way as the cfr gene. In addition, modification at A2503 on 23S rRNA was confirmed by primer extension...
Straimer, Judith; Gnädig, Nina F; Witkowski, Benoit; Amaratunga, Chanaki; Duru, Valentine; Ramadani, Arba Pramundita; Dacheux, Mélanie; Khim, Nimol; Zhang, Lei; Lam, Stephen; Gregory, Philip D; Urnov, Fyodor D; Mercereau-Puijalon, Odile; Benoit-Vical, Françoise; Fairhurst, Rick M; Ménard, Didier; Fidock, David A
The emergence of artemisinin resistance in Southeast Asia imperils efforts to reduce the global malaria burden. We genetically modified the Plasmodium falciparum K13 locus using zinc-finger nucleases and measured ring-stage survival rates after drug exposure in vitro; these rates correlate with parasite clearance half-lives in artemisinin-treated patients. With isolates from Cambodia, where resistance first emerged, survival rates decreased from 13 to 49% to 0.3 to 2.4% after the removal of K13 mutations. Conversely, survival rates in wild-type parasites increased from ≤0.6% to 2 to 29% after the insertion of K13 mutations. These mutations conferred elevated resistance to recent Cambodian isolates compared with that of reference lines, suggesting a contemporary contribution of additional genetic factors. Our data provide a conclusive rationale for worldwide K13-propeller sequencing to identify and eliminate artemisinin-resistant parasites. Copyright © 2015, American Association for the Advancement of Science.
... rust resistance depicted a single major gene conditioning adult plant resistance (APR) with stripe rust reaction varying from TR-20MS in resistant RILs signifying the presence of some minor genes as well. Genetic association with leaf rust resistance revealed that two genes are located at a recombination distance of 13%.
Karkman, Antti; Do, Thi Thuy; Walsh, Fiona; Virta, Marko P J
Waste water and waste water treatment plants can act as reservoirs and environmental suppliers of antibiotic resistance. They have also been proposed to be hotspots for horizontal gene transfer, enabling the spread of antibiotic resistance genes between different bacterial species. Waste water contains antibiotics, disinfectants, and metals which can form a selection pressure for antibiotic resistance, even in low concentrations. Our knowledge of antibiotic resistance in waste water has increased tremendously in the past few years with advances in the molecular methods available. However, there are still some gaps in our knowledge on the subject, such as how active is horizontal gene transfer in waste water and what is the role of the waste water treatment plant in the environmental resistome? The purpose of this review is to briefly describe some of the main methods for studying antibiotic resistance in waste waters and the latest research and main knowledge gaps on the issue. In addition, some future research directions are proposed. Copyright © 2017 Elsevier Ltd. All rights reserved.
Shi, Haitao; Liu, Wen; Yao, Yue; Wei, Yunxie; Chan, Zhulong
Although the transcriptional regulation and upstream transcription factors of AtADH1 in response to abiotic stress are widely revealed, the in vivo roles of AtADH1 remain unknown. In this study, we found that the expression of AtADH1 was largely induced after salt, drought, cold and pathogen infection. Further studies found that AtADH1 overexpressing plants were more sensitive to abscisic acid (ABA) in comparison to wide type (WT), while AtADH1 knockout mutants showed no significant difference compared with WT in ABA sensitivity. Consistently, AtADH1 overexpressing plants showed improved stress resistance to salt, drought, cold and pathogen infection than WT, but the AtADH1 knockout mutants had no significant difference in abiotic and biotic stress resistance. Moreover, overexpression of AtADH1 expression increased the transcript levels of multiple stress-related genes, accumulation of soluble sugars and callose depositions. All these results indicate that AtADH1 confers enhanced resistance to both abiotic and biotic stresses. Copyright © 2017 Elsevier B.V. All rights reserved.
Pavli, R.; Panopoulos, N.J.; Goldbach, R.W.; Skaracis, G.N.
Agrobacterium rhizogenes-transformed sugar beet hairy roots, expressing dsRNA from the Beet necrotic yellow vein virus replicase gene, were used as a novel approach to assess the efficacy of three intron-hairpin constructs at conferring resistance to rhizomania disease. Genetically engineered roots
Kruse, T.; Levisson, M.; Vos, de W.M.; Smidt, H.
The glycopeptide vancomycin was until recently considered a drug of last resort against Gram-positive bacteria. Increasing numbers of bacteria, however, are found to carry genes that confer resistance to this antibiotic. So far, 10 different vancomycin resistance clusters have been described. A
Markussen, Mette Drude Kjær; Heiberg, Ann-Charlotte; Fredholm, Merete
Background: Anticoagulant resistance in Norway rats, Rattus norvegicus (Berk.), has been suggested to be conferred by mutations in the VKORC1 gene, encoding the target protein of anticoagulant rodenticides. Other factors, e.g. pharmacokinetics, may also contribute to resistance, however. To examine...
Li, Jian; Li, Mei; Gao, Xingxiang; Fang, Feng
Crabgrass (Digitaria sanguinalis) is an annual monocotyledonous weed. In recent years, field applications of nicosulfuron have been ineffective in controlling crabgrass populations in Shandong Province, China. To investigate the mechanisms of resistance to nicosulfuron in crabgrass populations, the acetolactate synthase (ALS) gene fragment covering known resistance-confering mutation sites was amplified and sequenced. Dose-response experiments suggested that the resistant population SD13 (R) was highly resistant to nicosulfuron (resistance index R/S = 43.7) compared with the sensitive population SD22 (S). ALS gene sequencing revealed a Trp574Arg substitution in the SD13 population, and no other known resistance-conferring mutations were found. In vitro ALS enzyme assays further confirmed that the SD13 population was resistant to all tested ALS-inhibiting herbicides. The resistance pattern experiments revealed that, compared with SD22, the SD13 population exhibited broad-spectrum resistance to nicosulfuron (43.7-fold), imazethapyr (11.4-fold) and flumetsulam (16.1-fold); however, it did not develop resistance to atrazine, mesotrione and topramezone. This study demonstrated that Trp574Arg substitution was the main reason for crabgrass resistance to ALS-inhibiting herbicides. To our knowledge, this is the first report of Trp574Arg substitution in a weed species, and is the first report of target-site mechanisms of herbicide resistance for crabgrass. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.
Pradhan, Sharat Kumar; Nayak, Deepak Kumar; Pandit, Elssa; Behera, Lambodar; Anandan, Annamalai; Mukherjee, Arup Kumar; Lenka, Srikanta; Barik, Durga Prasad
Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv. oryzae is a major disease of rice in many rice growing countries. Pyramided lines carrying two BB resistance gene combinations (Xa21+xa13 and Xa21+xa5) were developed in a lowland cultivar Jalmagna background through backcross breeding by integrating molecular markers. In each backcross generation, markers closely linked to the disease resistance genes were used to select plants possessing the target genes. Background selection was continued in those plants carrying resistant genes until BC(3) generation. Plants having the maximum contribution from the recurrent parent genome were selected in each generation and hybridized with the recipient parent. The BB-pyramided line having the maximum recipient parent genome recovery of 95% was selected among BC3F1 plants and selfed to isolate homozygous BC(3)F(2) plants with different combinations of BB resistance genes. Twenty pyramided lines with two resistance gene combinations exhibited high levels of tolerance against the BB pathogen. In order to confirm the resistance, the pyramided lines were inoculated with different X. oryzae pv. oryzae strains of Odisha for bioassay. The genotypes with combination of two BB resistance genes conferred high levels of resistance to the predominant X. oryzae pv. oryzae isolates prevalent in the region. The pyramided lines showed similarity with the recipient parent with respect to major agro-morphologic traits.
Zhao, Li-Li; Liu, Hai-Can; Sun, Qing; Xiao, Tong-Yang; Zhao, Xiu-Qin; Li, Gui-Lian; Zeng, Chun-Yan; Wan, Kang-Lin
We investigated the spectrum and frequency of mutations in rpsL, rrs, and gidB among 140 multidrug-resistant tuberculosis (MDR-TB) clinical isolates from China. The association between mutations and different genotypes was also analyzed. Our data revealed that 65.7% of MDR-TB were resistant to streptomycin (STR), and 90.2% of STR-resistant isolates were Beijing strains. STR resistance was correlated with Beijing family (P=0.00). Compared with phenotypic data, detection of mutations for the combination of these 3 genes exhibited 94.6% sensitivity, 91.7% specificity, and 93.6% accuracy. The most common mutations in STR-resistant isolates were rpsL128, 262, and rrs514, of which rpsL128 showed association with Beijing lineage (P=0.00). A combination of these 3 mutations can serve as the reliable predictors for STR resistance, showing the sensitivity, specificity, and accuracy of 85.9%, 97.9%, and 90.0%, respectively. Furthermore, gidBA276C, not A615G, was Beijing lineage specific. These findings are useful to develop rapid molecular diagnostic methods for STR resistance in China. Copyright © 2015 Elsevier Inc. All rights reserved.
Wee Tek Tay
Full Text Available The use of conventional chemical insecticides and bacterial toxins to control lepidopteran pests of global agriculture has imposed significant selection pressure leading to the rapid evolution of insecticide resistance. Transgenic crops (e.g., cotton expressing the Bt Cry toxins are now used world wide to control these pests, including the highly polyphagous and invasive cotton bollworm Helicoverpa armigera. Since 2004, the Cry2Ab toxin has become widely used for controlling H. armigera, often used in combination with Cry1Ac to delay resistance evolution. Isolation of H. armigera and H. punctigera individuals heterozygous for Cry2Ab resistance in 2002 and 2004, respectively, allowed aspects of Cry2Ab resistance (level, fitness costs, genetic dominance, complementation tests to be characterised in both species. However, the gene identity and genetic changes conferring this resistance were unknown, as was the detailed Cry2Ab mode of action. No cross-resistance to Cry1Ac was observed in mutant lines. Biphasic linkage analysis of a Cry2Ab-resistant H. armigera family followed by exon-primed intron-crossing (EPIC marker mapping and candidate gene sequencing identified three independent resistance-associated INDEL mutations in an ATP-Binding Cassette (ABC transporter gene we named HaABCA2. A deletion mutation was also identified in the H. punctigera homolog from the resistant line. All mutations truncate the ABCA2 protein. Isolation of further Cry2Ab resistance alleles in the same gene from field H. armigera populations indicates unequal resistance allele frequencies and the potential for Bt resistance evolution. Identification of the gene involved in resistance as an ABC transporter of the A subfamily adds to the body of evidence on the crucial role this gene family plays in the mode of action of the Bt Cry toxins. The structural differences between the ABCA2, and that of the C subfamily required for Cry1Ac toxicity, indicate differences in the
Carter Tamar E
Full Text Available Abstract Background Malaria caused by Plasmodium falciparum infects roughly 30,000 individuals in Haiti each year. Haiti has used chloroquine (CQ as a first-line treatment for malaria for many years and as a result there are concerns that malaria parasites may develop resistance to CQ over time. Therefore it is important to prepare for alternative malaria treatment options should CQ resistance develop. In many other malaria-endemic regions, antifolates, particularly pyrimethamine (PYR and sulphadoxine (SDX treatment combination (SP, have been used as an alternative when CQ resistance has developed. This study evaluated mutations in the dihydrofolate reductase (dhfr and dihydropteroate synthetase (dhps genes that confer PYR and SDX resistance, respectively, in P. falciparum to provide baseline data in Haiti. This study is the first comprehensive study to examine PYR and SDX resistance genotypes in P. falciparum in Haiti. Methods DNA was extracted from dried blood spots and genotyped for PYR and SDX resistance mutations in P. falciparum using PCR and DNA sequencing methods. Sixty-one samples were genotyped for PYR resistance in codons 51, 59, 108 and 164 of the dhfr gene and 58 samples were genotyped for SDX resistance codons 436, 437, 540 of the dhps gene in P. falciparum. Results Thirty-three percent (20/61 of the samples carried a mutation at codon 108 (S108N of the dhfr gene. No mutations in dhfr at codons 51, 59, 164 were observed in any of the samples. In addition, no mutations were observed in dhps at the three codons (436, 437, 540 examined. No significant difference was observed between samples collected in urban vs rural sites (Welch’s T-test p-value = 0.53 and permutations p-value = 0.59. Conclusion This study has shown the presence of the S108N mutation in P. falciparum that confers low-level PYR resistance in Haiti. However, the absence of SDX resistance mutations suggests that SP resistance may not be present in Haiti. These
Carter, Tamar E; Warner, Megan; Mulligan, Connie J; Existe, Alexander; Victor, Yves S; Memnon, Gladys; Boncy, Jacques; Oscar, Roland; Fukuda, Mark M; Okech, Bernard A
Malaria caused by Plasmodium falciparum infects roughly 30,000 individuals in Haiti each year. Haiti has used chloroquine (CQ) as a first-line treatment for malaria for many years and as a result there are concerns that malaria parasites may develop resistance to CQ over time. Therefore it is important to prepare for alternative malaria treatment options should CQ resistance develop. In many other malaria-endemic regions, antifolates, particularly pyrimethamine (PYR) and sulphadoxine (SDX) treatment combination (SP), have been used as an alternative when CQ resistance has developed. This study evaluated mutations in the dihydrofolate reductase (dhfr) and dihydropteroate synthetase (dhps) genes that confer PYR and SDX resistance, respectively, in P. falciparum to provide baseline data in Haiti. This study is the first comprehensive study to examine PYR and SDX resistance genotypes in P. falciparum in Haiti. DNA was extracted from dried blood spots and genotyped for PYR and SDX resistance mutations in P. falciparum using PCR and DNA sequencing methods. Sixty-one samples were genotyped for PYR resistance in codons 51, 59, 108 and 164 of the dhfr gene and 58 samples were genotyped for SDX resistance codons 436, 437, 540 of the dhps gene in P. falciparum. Thirty-three percent (20/61) of the samples carried a mutation at codon 108 (S108N) of the dhfr gene. No mutations in dhfr at codons 51, 59, 164 were observed in any of the samples. In addition, no mutations were observed in dhps at the three codons (436, 437, 540) examined. No significant difference was observed between samples collected in urban vs rural sites (Welch's T-test p-value = 0.53 and permutations p-value = 0.59). This study has shown the presence of the S108N mutation in P. falciparum that confers low-level PYR resistance in Haiti. However, the absence of SDX resistance mutations suggests that SP resistance may not be present in Haiti. These results have important implications for ongoing discussions on
Warburton, Philip J; Ciric, Lena; Lerner, Avigdor; Seville, Lorna A; Roberts, Adam P; Mullany, Peter; Allan, Elaine
To identify the genes responsible for tetracycline resistance in a strain of Streptococcus australis isolated from pooled saliva from healthy volunteers in France. S. australis is a viridans Streptococcus, originally isolated from the oral cavity of children in Australia, and subsequently reported in the lungs of cystic fibrosis patients and as a cause of invasive disease in an elderly patient. Agar containing 2 mg/L tetracycline was used for the isolation of tetracycline-resistant organisms. A genomic library in Escherichia coli was used to isolate the tetracycline resistance determinant. In-frame deletions and chromosomal repair were used to confirm function. Antibiotic susceptibility was determined by agar dilution and disc diffusion assay. The tetracycline resistance determinant from S. australis FRStet12 was isolated from a genomic library in E. coli and DNA sequencing showed two open reading frames predicted to encode proteins with similarity to multidrug resistance-type ABC transporters. Both genes were required for tetracycline resistance (to both the naturally occurring and semi-synthetic tetracyclines) and they were designated tetAB(46). This is the first report of a predicted ABC transporter conferring tetracycline resistance in a member of the oral microbiota.
A single recessive gene conferring short leaves in romaine x Latin type lettuce (Lactuca sativa L.) crosses, and its effect on plant morphology and resistance to lettuce drop caused by Sclerotinia minor Jagger.
Understanding the relationship between plant morphology and disease resistance is crucial to successful breeding, particularly resistance to lettuce drop caused by Sclerotinia minor. Latin type lettuce cultivars are small plants with upright leaves longer than they are wide, similar to romaine type...
Panozzo, Silvia; Scarabel, Laura; Rosan, Valentina; Sattin, Maurizio
Gene mutations conferring herbicide resistance may cause pleiotropic effects on plant fitness. Knowledge of these effects is important for managing the evolution of herbicide-resistant weeds. An Echinochloa crus-galli population resistant to acetolactate synthase (ALS) herbicides was collected in a maize field in north-eastern Italy and the cross-resistance pattern, resistance mechanism and fitness costs associated to mutant-resistant plants under field conditions in the presence or absence of intra-specific competition were determined. The study reports for the first time the Ala-122-Asn amino-acid change in the ALS gene that confers high levels of cross-resistance to all ALS inhibitors tested. Results of 3-year growth analysis showed that mutant resistant E. crus-galli plants had a delayed development in comparison with susceptible plants and this was registered in both competitive (3, 7, and 20 plants m -2 ) and non-competitive (spaced plants) situations. The number of panicles produced by resistant plants was also lower (about 40% fewer panicles) than susceptible plants under no-intraspecific competition. Instead, with the increasing competition level, the difference in panicle production at harvest time decreased until it became negligible at 20 plants m -2 . Evaluation of total dry biomass as well as biomass allocation in vegetative parts did not highlight any difference between resistant and susceptible plants. Instead, panicle dry weight was higher in susceptible plants indicating that they allocated more biomass than resistant ones to the reproductive organs, especially in no-competition and in competition situations at lower plant densities. The different fitness between resistant and susceptible phenotypes suggests that keeping the infestation density as low as possible can increase the reproduction success of the susceptible phenotype and therefore contribute to lowering the ratio between resistant and susceptible alleles. If adequately embedded in a
Full Text Available Gene mutations conferring herbicide resistance may cause pleiotropic effects on plant fitness. Knowledge of these effects is important for managing the evolution of herbicide-resistant weeds. An Echinochloa crus-galli population resistant to acetolactate synthase (ALS herbicides was collected in a maize field in north-eastern Italy and the cross-resistance pattern, resistance mechanism and fitness costs associated to mutant-resistant plants under field conditions in the presence or absence of intra-specific competition were determined. The study reports for the first time the Ala-122-Asn amino-acid change in the ALS gene that confers high levels of cross-resistance to all ALS inhibitors tested. Results of 3-year growth analysis showed that mutant resistant E. crus-galli plants had a delayed development in comparison with susceptible plants and this was registered in both competitive (3, 7, and 20 plants m-2 and non-competitive (spaced plants situations. The number of panicles produced by resistant plants was also lower (about 40% fewer panicles than susceptible plants under no-intraspecific competition. Instead, with the increasing competition level, the difference in panicle production at harvest time decreased until it became negligible at 20 plants m-2. Evaluation of total dry biomass as well as biomass allocation in vegetative parts did not highlight any difference between resistant and susceptible plants. Instead, panicle dry weight was higher in susceptible plants indicating that they allocated more biomass than resistant ones to the reproductive organs, especially in no-competition and in competition situations at lower plant densities. The different fitness between resistant and susceptible phenotypes suggests that keeping the infestation density as low as possible can increase the reproduction success of the susceptible phenotype and therefore contribute to lowering the ratio between resistant and susceptible alleles. If adequately
Chen, Haifeng; Zhao, Sheng; Yang, Zhonglu; Sha, Aihua; Wan, Qiao; Zhang, Chanjuan; Chen, Limiao; Yuan, Songli; Qiu, Dezhen; Chen, Shuilian; Shan, Zhihui; Zhou, Xin-an
In this study, Rpp6907, a novel resistance gene/allele to Phakopsora pachyrhizi in soybean, was mapped in a 111.9-kb region, including three NBS-LRR type predicted genes, on chromosome 18. Soybean rust caused by Phakopsora pachyrhizi Sydow has been reported in numerous soybean-growing regions worldwide. The development of rust-resistant varieties is the most economical and environmentally safe method to control the disease. The Chinese soybean germplasm SX6907 is resistant to P. pachyrhizi and exhibits immune reaction compared with the known Rpp genes. These characteristics suggest that SX6907 may carry at least one novel Rpp gene/allele. Three F2 populations from the crosses of SX6907 (resistant) and Tianlong 1, Zhongdou40, and Pudou11 (susceptible) were used to map the Rpp gene. Three resistance responses (immune, red-brown, and tan-colored lesion) were observed from the F2 individuals. The segregation follows a ratio of 1(resistance):2(heterozygous):1(susceptible), indicating that the resistance in SX6907 is controlled by a single incomplete dominant gene (designated as Rpp6907). Results showed that Rpp6907 was mapped on soybean chromosome 18 (molecular linkage group G, MLG G) flanked by simple sequence repeat (SSR) markers SSR24 and SSR40 at a distance of 111.9 kb. Among the ten genes marked within this 111.9-kb region between the two markers, three genes (Glyma18g51930, Glyma18g51950, and Glyma18g51960) are nucleotide-binding site and leucine-rich repeat-type genes. These genes may be involved in recognizing the presence of pathogens and ultimately conferring resistance. Based on resistance spectrum analysis and mapping results, we inferred that Rpp6907 is a novel gene different from Rpp1 in PI 200492, PI 561356, PI 587880A, PI 587886, and PI 594538A, or a new Rpp1-b allele.
Lin, Y. F.; Yannarell, A. C.; Mackie, R. I.; Krapac, I. G.; Chee-Sanford, J. S.; Koike, S.
The use of antibiotics at concentrated animal feeding operations (CAFOs) for disease prevention, disease treatment, and growth promotion can contribute to the spread of antibiotic compounds, their breakdown products, and antibiotic resistant bacteria and/or the genes that confer resistance. In addition, constitutive use of antibiotics at sub-therapeutic levels can select for antibiotic resistance among the bacteria that inhabit animal intestinal tracts, onsite manure treatment facilities, and any environments receiving significant inputs of manure (e.g. through waste lagoon leakage or fertilizer amendments to farm soils). If the antibiotic resistant organisms persist in these new environments, or if they participate in genetic exchanges with the native microflora, then CAFOs may constitute a significant reservoir for the spread of antibiotic resistance to the environment at large. Our results have demonstrated that leakage from waste treatment lagoons can influence the presence and persistence of tetracycline resistance genes in the shallow aquifer adjacent to swine CAFOs, and molecular phylogeny allowed us to distinguish "native" tetracycline resistance genes in control groundwater wells from manure-associated genes introduced from the lagoon. We have also been able to detect the presence of erythromycin resistance genes in CAFO surface and groundwater even though erythromycin is strictly reserved for use in humans and thus is not utilized at any of these sites. Ongoing research, including modeling of particle transport in groundwater, will help to determine the potential spatial and temporal extent of CAFO-derived antibiotic resistance.
Ghosh, Tarini Shankar; Gupta, Sourav Sen; Nair, Gopinath Balakrish; Mande, Sharmila S.
The spread of antibiotic resistance, originating from the rampant and unrestrictive use of antibiotics in humans and livestock over the past few decades has emerged as a global health problem. This problem has been further compounded by recent reports implicating the gut microbial communities to act as reservoirs of antibiotic resistance. We have profiled the presence of probable antibiotic resistance genes in the gut flora of 275 individuals from eight different nationalities. For this purpose, available metagenomic data sets corresponding to 275 gut microbiomes were analyzed. Sequence similarity searches of the genomic fragments constituting each of these metagenomes were performed against genes conferring resistance to around 240 antibiotics. Potential antibiotic resistance genes conferring resistance against 53 different antibiotics were detected in the human gut microflora analysed in this study. In addition to several geography/country-specific patterns, four distinct clusters of gut microbiomes, referred to as ‘Resistotypes’, exhibiting similarities in their antibiotic resistance profiles, were identified. Groups of antibiotics having similarities in their resistance patterns within each of these clusters were also detected. Apart from this, mobile multi-drug resistance gene operons were detected in certain gut microbiomes. The study highlighted an alarmingly high abundance of antibiotic resistance genes in two infant gut microbiomes. The results obtained in the present study presents a holistic ‘big picture’ on the spectra of antibiotic resistance within our gut microbiota across different geographies. Such insights may help in implementation of new regulations and stringency on the existing ones. PMID:24391833
Jang, Hyun Min; Lee, Jangwoo; Kim, Young Beom; Jeon, Jong Hun; Shin, Jingyeong; Park, Mee-Rye; Kim, Young Mo
This study examines the fate of twenty-three representative antibiotic resistance genes (ARGs) encoding tetracyclines, sulfonamides, quinolones, β-lactam antibiotics, macrolides, florfenicol and multidrug resistance during thermophilic aerobic digestion (TAD) of sewage sludge. The bacterial community, class 1 integrons (intI1) and four metal resistance genes (MRGs) were also quantified to determine the key drivers of changes in ARGs during TAD. At the end of digestion, significant decreases in the quantities of ARGs, MRGs and intI1 as well as 16S rRNA genes were observed. Partial redundancy analysis (RDA) showed that shifts in temperature were the key factors affecting a decrease in ARGs. Shifts in temperature led to decreased amounts of ARGs by reducing resistome and bacterial diversity, rather than by lowering horizontal transfer potential via intI1 or co-resistance via MRGs. Copyright © 2017 Elsevier Ltd. All rights reserved.
Hossain, Md Kamal; Jena, Kshirod; Bhuiyan, Md Atiqur Rahman; Ratnam, Wickneswari
Sheath blight is an emerging threat in rice cultivation. It is animportant disease caused by the soil-borne necrotrophic pathogenic fungus, Rhizoctonia solani Kühn. However, to date neither known major genes for quantitative resistance, nor any rice lines immune to this disease has been identified. The disease resistance is quantitative in nature. Numerous genes are involved in this resistance process. There are few quantitative trait loci (QTLs) detected conferring improved resistance against the disease. Teqing and Tetepshowimproved resistance having QTLs, qSB-9 and qSBR11-1, respectively. Since, these QTLs demonstrates additive effects, pyramiding of these QTLs might be an option to increase the sheath blight resistance in rice. Nine rice cultivars were screened at greenhouse conditions. Results showed that Tetep and Teqing had the lowest disease ratings. UKMRC2a new high yielding cultivar was as recipient parent. Crosses between UKMRC2 and Teqing, and UKMRC2 and Tetep were made and confirmed. Subsequently 4-way crosses between the two F1s were performed to develop pyramidal lines.
Umemura, Kenji; Tanino, Shigeki; Nagatsuka, Tadako; Koga, Jinichiro; Iwata, Michiaki; Nagashima, Kenji; Amemiya, Yoshimiki
ABSTRACT In the rice blast fungus pathosystem, cerebroside, a compound categorized as a sphingolipid, was found in our previous study to be a non-racespecific elicitor, which elicits defense responses in rice. Here we describe that cerebroside C is produced in diverse strains of Fusarium oxysporum, a common soilborne agent of wilt disease affecting a wide range of plant species. In addition, some type of cerebroside elicitor involving cerebroside A, B, or C was detected in other soilborne phytopathogens, such as Pythium and Botrytis. Treatment of lettuce (Lactuca sativa), tomato (Lycopersicon esculentum), melon (Cucumis melo), and sweet potato (Ipomoea batatas) with cerebroside B resulted in resistance to infection by each pathogenic strain of F. oxysporum. Induction of pathogenesis-related genes and H(2)O(2) production by treatment with cerebroside B were observed in tomato root tissues. The cerebroside elicitor showed no antifungal activity against F. oxysporum in vitro, indicating that the cerebroside elicitor activates defense mechanisms to confer resistance to Fusarium disease. These results suggest that cerebroside functions as a non-race-specific elicitor in a wide range of plant-phytopathogenic fungus interactions. Additionally, cerebroside elicitor serves as a potential biologically derived control agent.
Takken, F.L.W.; Joosten, M.H.A.J.
Plants have developed efficient mechanisms to avoid infection or to mount responses that render them resistant upon attack by a pathogen. One of the best-studied defence mechanisms is based on gene-for-gene resistance through which plants, harbouring specific resistance (R) genes, specifically
Achard, Adeline; Guérin-Faublée, Véronique; Pichereau, Vianney; Villers, Corinne; Leclercq, Roland
Streptococcus uberis UCN60 was resistant to spiramycin (MIC = 8 μg/ml) but susceptible to erythromycin (MIC = 0.06 μg/ml), azithromycin (MIC = 0.12 μg/ml), josamycin (MIC = 0.25 μg/ml), and tylosin (MIC = 0.5 μg/ml). A 2.5-kb HindIII fragment was cloned from S. uberis UCN60 DNA on plasmid pUC18 and introduced into Escherichia coli AG100A, where it conferred resistance to spiramycin by inactivation. The sequence analysis of the fragment showed the presence of an rdmC-like gene that putatively encoded a protein belonging to the alpha/beta hydrolase family and of the first 196 nucleotides of the mph(B) gene putatively encoding a phosphotransferase known to inactivate 14-, 15-, and 16-membered macrolides in E. coli. The entire mph(B) gene was then identified in S. uberis UCN60. The two genes were expressed alone or in combination in E. coli, Staphylococcus aureus, and Enterococcus faecalis. Analysis of MICs revealed that rdmC-like alone did not confer resistance to erythromycin, tylosin, and josamycin in those three hosts. It conferred resistance to spiramycin in E. coli and E. faecalis but not in S. aureus. mph(B) conferred resistance in E. coli to erythromycin, tylosin, josamycin, and spiramycin but only low levels of resistance in E. faecalis and S. aureus to spiramycin (MIC = 8 μg/ml). The combination of mph(B) and rdmC-like genes resulted in a resistance to spiramycin and tylosin in the three hosts that significantly exceeded the mere addition of the resistance levels conferred by each resistance mechanism alone. PMID:18519724
Markussen, Mette Drude; Heiberg, Ann-Charlotte; Alsbo, Carsten
To examine the role of xenobiotic relevant genes in bromadiolone resistance in wild Norway rats (Rattus norvegicus) we compared the constitutive liver gene expression and expression upon bromadiolone administration in bromadiolone resistant and anticoagulant susceptible female rats using a LNA...... expressed in resistant than susceptible rats upon bromadiolone exposure. To establish how bromadiolone affected xenobiotic gene expression in the two strains we compared bromadiolone expression profiles to saline profiles of both strains. Bromadiolone mediated significant up-regulation of Cyp2e1 and Cyp3a3...... expression in the resistant rats whereas the rodenticide conferred down-regulation of Cyp2e1, Cyp3a3 and Gpox1 and induction of Cyp2c12 expression in susceptible rats. Cyp2c13 and Cyp3a2 expression were markedly suppressed in both strains upon treatment. This suggests that xenobiotic relevant enzymes play...
Li, Lili; Heidemann Olsen, Rikke; Ye, Lei; Yan, He; Nie, Qing; Meng, Hecheng; Shi, Lei
The aim of this study was to investigate the phenotypic and genotypic antimicrobial resistance, integrons, and transferability of resistance markers in 243 aerobic bacteria recovered from pork at slaughter in the People's Republic of China. The organisms belonged to 22 genera of gram-negative bacteria (92.2%) and gram-positive bacteria (7.8%). High levels of resistance were detected to tetracycline, trimethoprim-sulfamethoxazole, and ampicillin (36.2 to 54.3%), and lower levels were detected to nitrofurantoin, cefotaxime, gentamicin, ciprofloxacin, and chloramphenicol (7.8 to 29.2%). Across species, genes conferring antimicrobial resistance were observed with the following frequencies: blaTEM, 40.7%; blaCMY-2, 15.2%; blaCTX-M, 11.5%; sul2, 27.2%; sul1, 14.4%; tet(A), 5.4%; tet(L), 5.4%; tet(M), 5.0%; tet(E), 3.7%; tet(C), 3.3%; tet(S), 2.5%; and tet(K), 0.8%. Various antimicrobial resistance genes were found in new carriers: blaTEM in Lactococcus garvieae, Myroides odoratimimus, Aeromonas hydrophila, Staphylococcus sciuri, Raoultella terrigena, Macrococcus caseolyticus, Acinetobacter ursingii, Sphingobacterium sp., and Oceanobacillus sp.; blaCMY-2 in Lactococcus lactis, Klebsiella oxytoca, Serratia marcescens, Acinetobacter baumannii, and Myroides phaeus; tet(L) in M. caseolyticus; sul1 in Vibrio cincinnatiensis; sul2 in Acinetobacter bereziniae, Acinetobacter johnsonii, and V. cincinnatiensis; and the class 1 integron and gene cassette aadA2 in V. cincinnatiensis. Approximately 6.6% of isolates contained class 1 integrons, and one isolate harbored class 2 integrons. Plasmid associated intI1 and androgen receptor- encoding genes were transferred into Escherichia coli J53 and E. coli DH5α by conjugation and transformation experiments, respectively. Our study highlights the importance of aerobic bacteria from pork as reservoirs for antimicrobial resistance genes and mobile genetic elements that can readily be transferred intra- and interspecies.
Li, Lili; Olsen, Rikke Heidemann; Ye, Lei
The aim of this study was to investigate the phenotypic and genotypic antimicrobial resistance, integrons, and transferability of resistance markers in 243 aerobic bacteria recovered from pork at slaughter in the People's Republic of China. The organisms belonged to 22 genera of gram......-negative bacteria (92.2%) and gram-positive bacteria (7.8%). High levels of resistance were detected to tetracycline, trimethoprim-sulfamethoxazole, and ampicillin (36.2 to 54.3%), and lower levels were detected to nitrofurantoin, cefotaxime, gentamicin, ciprofloxacin, and chloramphenicol (7.8 to 29.2%). Across...... species, genes conferring antimicrobial resistance were observed with the following frequencies: bla TEM, 40.7%; bla CMY-2, 15.2%; bla CTX-M, 11.5%; sul2, 27.2%; sul1, 14.4%; tet(A), 5.4%;tet(L), 5.4%; tet(M), 5.0%; tet(E), 3.7%; tet(C), 3.3%; tet(S), 2.5%; and tet(K), 0.8%. Various antimicrobial...
Riveron, Jacob M; Yunta, Cristina; Ibrahim, Sulaiman S; Djouaka, Rousseau; Irving, Helen; Menze, Benjamin D; Ismail, Hanafy M; Hemingway, Janet; Ranson, Hilary; Albert, Armando; Wondji, Charles S
Metabolic resistance to insecticides is the biggest threat to the continued effectiveness of malaria vector control. However, its underlying molecular basis, crucial for successful resistance management, remains poorly characterized. Here, we demonstrate that the single amino acid change L119F in an upregulated glutathione S-transferase gene, GSTe2, confers high levels of metabolic resistance to DDT in the malaria vector Anopheles funestus. Genome-wide transcription analysis revealed that GSTe2 was the most over-expressed detoxification gene in DDT and permethrin-resistant mosquitoes from Benin. Transgenic expression of GSTe2 in Drosophila melanogaster demonstrated that over-transcription of this gene alone confers DDT resistance and cross-resistance to pyrethroids. Analysis of GSTe2 polymorphism established that the point mutation is tightly associated with metabolic resistance to DDT and its geographical distribution strongly correlates with DDT resistance patterns across Africa. Functional characterization of recombinant GSTe2 further supports the role of the L119F mutation, with the resistant allele being more efficient at metabolizing DDT than the susceptible one. Importantly, we also show that GSTe2 directly metabolizes the pyrethroid permethrin. Structural analysis reveals that the mutation confers resistance by enlarging the GSTe2 DDT-binding cavity, leading to increased DDT access and metabolism. Furthermore, we show that GSTe2 is under strong directional selection in resistant populations, and a restriction of gene flow is observed between African regions, enabling the prediction of the future spread of this resistance. This first DNA-based metabolic resistance marker in mosquitoes provides an essential tool to track the evolution of resistance and to design suitable resistance management strategies.
Background Metabolic resistance to insecticides is the biggest threat to the continued effectiveness of malaria vector control. However, its underlying molecular basis, crucial for successful resistance management, remains poorly characterized. Results Here, we demonstrate that the single amino acid change L119F in an upregulated glutathione S-transferase gene, GSTe2, confers high levels of metabolic resistance to DDT in the malaria vector Anopheles funestus. Genome-wide transcription analysis revealed that GSTe2 was the most over-expressed detoxification gene in DDT and permethrin-resistant mosquitoes from Benin. Transgenic expression of GSTe2 in Drosophila melanogaster demonstrated that over-transcription of this gene alone confers DDT resistance and cross-resistance to pyrethroids. Analysis of GSTe2 polymorphism established that the point mutation is tightly associated with metabolic resistance to DDT and its geographical distribution strongly correlates with DDT resistance patterns across Africa. Functional characterization of recombinant GSTe2 further supports the role of the L119F mutation, with the resistant allele being more efficient at metabolizing DDT than the susceptible one. Importantly, we also show that GSTe2 directly metabolizes the pyrethroid permethrin. Structural analysis reveals that the mutation confers resistance by enlarging the GSTe2 DDT-binding cavity, leading to increased DDT access and metabolism. Furthermore, we show that GSTe2 is under strong directional selection in resistant populations, and a restriction of gene flow is observed between African regions, enabling the prediction of the future spread of this resistance. Conclusions This first DNA-based metabolic resistance marker in mosquitoes provides an essential tool to track the evolution of resistance and to design suitable resistance management strategies. PMID:24565444
Zaanan, Aziz; Okamoto, Koichi; Kawakami, Hisato; Khazaie, Khashayarsha; Huang, Shengbing; Sinicrope, Frank A
In colorectal cancers with oncogenic GTPase Kras (KRAS) mutations, inhibition of downstream MEK/ERK signaling has shown limited efficacy, in part because of failure to induce a robust apoptotic response. We studied the mechanism of apoptosis resistance in mutant KRAS cells and sought to enhance the efficacy of a KRAS-specific MEK/ERK inhibitor, GDC-0623. GDC-0623 was shown to potently up-regulate BIM expression to a greater extent versus other MEK inhibitors in isogenic KRAS HCT116 and mutant KRAS SW620 colon cancer cells. ERK silencing enhanced BIM up-regulation by GDC-0623 that was due to its loss of phosphorylation at Ser(69), confirmed by a BIM-EL phosphorylation-defective mutant (S69G) that increased protein stability and blocked BIM induction. Despite BIM and BIK induction, the isogenic KRAS mutant versus wild-type cells remained resistant to GDC-0623-induced apoptosis, in part because of up-regulation of BCL-XL. KRAS knockdown by a doxycycline-inducible shRNA attenuated BCL-XL expression. BCL-XL knockdown sensitized KRAS mutant cells to GDC-0623-mediated apoptosis, as did the BH3 mimetic ABT-263. GDC-0623 plus ABT-263 induced a synergistic apoptosis by a mechanism that includes release of BIM from its sequestration by BCL-XL. Furthermore, mutant KRAS activated p-STAT3 (Tyr(705)) in the absence of IL-6 secretion, and STAT3 knockdown reduced BCL-XL mRNA and protein expression. These data suggest that BCL-XL up-regulation by STAT3 contributes to mutant KRAS-mediated apoptosis resistance. Such resistance can be overcome by potent BIM induction and concurrent BCL-XL antagonism to enable a synergistic apoptotic response. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.
Yoshii, Atsushi; Moriyama, Hiromitsu; Fukuhara, Toshiyuki
Kasugamycin (KSM), a unique aminoglycoside antibiotic, has been used in agriculture for many years to control not only rice blast caused by the fungus Magnaporthe grisea but also rice bacterial grain and seedling rot or rice bacterial brown stripe caused by Burkholderia glumae or Acidovorax avenae subsp. avenae, respectively. Since both bacterial pathogens are seed-borne and cause serious injury to rice seedlings, the emergence of KSM-resistant B. glumae and A. avenae isolates highlights the ...
Root-knot nematodes (RKN; Meloidogyne spp.) are among the most destructive of the plant parasitic nematodes, infecting almost all cultivated plants and resulting in yield losses of billions of dollars annually. NPR1 (nonexpresser of pathogenesis related genes 1, AtNPR1) plays a positive role in the ...
Expression of a Chimeric Gene Encoding Insecticidal Crystal Protein Cry1Aabc of Bacillus thuringiensis in Chickpea (Cicer arietinum L.) Confers Resistance to Gram Pod Borer (Helicoverpa armigera Hubner.).
Das, Alok; Datta, Subhojit; Thakur, Shallu; Shukla, Alok; Ansari, Jamal; Sujayanand, G K; Chaturvedi, Sushil K; Kumar, P A; Singh, N P
Domain swapping and generation of chimeric insecticidal crystal protein is an emerging area of insect pest management. The lepidopteran insect pest, gram pod borer ( Helicoverpa armigera H.) wreaks havoc to chickpea crop affecting production. Lepidopteran insects were reported to be controlled by Bt ( cryI ) genes. We designed a plant codon optimized chimeric Bt gene ( cry1Aabc ) using three domains from three different cry1A genes (domains I, II, and III from cry1Aa , cry1Ab , and cry1Ac , respectively) and expressed it under the control of a constitutive promoter in chickpea ( cv . DCP92-3) to assess its effect on gram pod borer. A total of six transgenic chickpea shoots were established by grafting into mature fertile plants. The in vitro regenerated (organogenetic) shoots were selected based on antibiotic kanamycin monosulfate (100 mg/L) with transformation efficiency of 0.076%. Three transgenic events were extensively studied based on gene expression pattern and insect mortality across generations. Protein expression in pod walls, immature seeds and leaves (pre- and post-flowering) were estimated and expression in pre-flowering stage was found higher than that of post-flowering. Analysis for the stable integration, expression and insect mortality (detached leaf and whole plant bioassay) led to identification of efficacious transgenic chickpea lines. The chimeric cry1Aabc expressed in chickpea is effective against gram pod borer and generated events can be utilized in transgenic breeding program.
Expression of a Chimeric Gene Encoding Insecticidal Crystal Protein Cry1Aabc of Bacillus thuringiensis in Chickpea (Cicer arietinum L. Confers Resistance to Gram Pod Borer (Helicoverpa armigera Hubner.
Full Text Available Domain swapping and generation of chimeric insecticidal crystal protein is an emerging area of insect pest management. The lepidopteran insect pest, gram pod borer (Helicoverpa armigera H. wreaks havoc to chickpea crop affecting production. Lepidopteran insects were reported to be controlled by Bt (cryI genes. We designed a plant codon optimized chimeric Bt gene (cry1Aabc using three domains from three different cry1A genes (domains I, II, and III from cry1Aa, cry1Ab, and cry1Ac, respectively and expressed it under the control of a constitutive promoter in chickpea (cv. DCP92-3 to assess its effect on gram pod borer. A total of six transgenic chickpea shoots were established by grafting into mature fertile plants. The in vitro regenerated (organogenetic shoots were selected based on antibiotic kanamycin monosulfate (100 mg/L with transformation efficiency of 0.076%. Three transgenic events were extensively studied based on gene expression pattern and insect mortality across generations. Protein expression in pod walls, immature seeds and leaves (pre- and post-flowering were estimated and expression in pre-flowering stage was found higher than that of post-flowering. Analysis for the stable integration, expression and insect mortality (detached leaf and whole plant bioassay led to identification of efficacious transgenic chickpea lines. The chimeric cry1Aabc expressed in chickpea is effective against gram pod borer and generated events can be utilized in transgenic breeding program.
Lau, Calvin Ho-Fung; Li, Bing; Zhang, Tong; Tien, Yuan-Ching; Scott, Andrew; Murray, Roger; Sabourin, Lyne; Lapen, David R; Duenk, Peter; Topp, Edward
In many jurisdictions sludge recovered from the sewage treatment process is a valued fertilizer for crop production. Pre-treatment of sewage sludge prior to land application offers the potential to abate enteric microorganisms that carry genes conferring resistance to antibiotics. Pre-treatment practices that accomplish this should have the desirable effect of reducing the risk of contamination of crops or adjacent water with antibiotic resistance genes carried in these materials. In the present study, we obtained municipal sludge that had been subjected to one of five treatments. There were, anaerobic-digestion or aerobic-digestion, in both instances with and without dewatering; and heat-treatment and pelletization. Each of the five types of biosolids was applied to an agricultural field at commercial rates, following which lettuce, carrots and radishes were planted. Based on qPCR, the estimated antibiotic gene loading rates were comparable with each of the five biosolids. However, the gene abundance in soil following application of the pelletized biosolids was anomalously lower than expected. Following application, the abundance of antibiotic resistance genes decreased in a generally coherent fashion, except sul1 which increased in abundance during the growing season in the soil fertilized with pelletized biosolids. Based on qPCR and high throughput sequencing evidence for transfer of antibiotic resistance genes from the biosolids to the vegetables at harvest was weak. Clostridia were more abundant in soils receiving any of the biosolids except the pelletized. Overall, the behavior of antibiotic resistance genes in soils receiving aerobically or anaerobically-digested biosolids was consistent and coherent with previous studies. However, dynamics of antibiotic resistance genes in soils receiving the heat treated pelletized biosolids were very different, and the underlying mechanisms merit investigation. Crown Copyright © 2017. Published by Elsevier B.V. All
Karthikeyan, Adhimoolam; Li, Kai; Jiang, Hua; Ren, Rui; Li, Cui; Zhi, Haijian; Chen, Shouyi; Gai, Junyi
Soybean mosaic virus (SMV) is one of the most devastating pathogens for soybeans in China. Among the country-wide 22 strains, SC5 dominates in Huang-Huai and Changjiang valleys. For controlling its damage, the resistance gene was searched through Mendelian inheritance study, gene fine-mapping, and candidate gene analysis combined with qRT-PCR (quantitative real-time polymerase chain reaction) analysis. The parents F 1 , F 2 , and RILs (recombinant inbred lines) of the cross Kefeng-1 (Resistance, R) × NN1138-2 (Susceptible, S) were used to examine the inheritance of SC5-resistance. The F 1 was resistant and the F 2 and RILs segregated in a 3R:1S and 1R:1S ratio, respectively, indicating a single dominant gene conferring the Kefeng-1 resistance. Subsequently, the genomic region conferring the resistance was found in "Bin 352-Bin353 with 500 kb" on Chromosome 2 using the phenotyping data of the 427 RILs and a high-density genetic map with 4703 bin markers. In the 500 kb genomic region, 38 putative genes are contained. The association analysis between the SNPs in a putative gene and the resistance phenotype for the 427 RILs prioritized 11 candidate genes using Chi-square criterion. The expression levels of these genes were tested by qRT-PCR. On infection with SC5, 7 out of the 11 genes had differential expression in Kefeng-1 and NN1138-2. Furthermore, integrating SNP-phenotype association analysis with qRT-PCR expression profiling analysis, Glyma02g13495 was found the most possible candidate gene for SC5-resistance. This finding can facilitate the breeding for SC5-resistance through marker-assisted selection and provide a platform to gain a better understanding of SMV-resistance gene system in soybean.
Cui, J.J.; Luo, J.Y.; Werf, van der, W.; Ma, Y.; Xia, J.Y.
Transgenic cotton (Gossypium hirsutum L.) varieties, adapted to China, have been bred that express two genes for resistance to insects. the Cry1Ac gene from Bacillus thuringiensis (Berliner) (Bt), and a trypsin inhibitor gene from cowpea (CpTI). Effectiveness of the double gene modification in conferring resistance to cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), was studied in laboratory and field experiments. In each experiment, performance of Bt+CpTI cotton was c...
Wipf, Juliette R K; Schwendener, Sybille; Nielsen, Jesper Boye
Genome alignment of a macrolide, lincosamide, and streptogramin B (MLSB)-resistant Staphylococcus fleurettii strain with an MLSB-susceptible S. fleurettii strain revealed a novel 11,513-bp genomic island carrying the new erythromycin resistance methylase gene erm(45). This gene was shown to confer...... inducible MLSB resistance when cloned into Staphylococcus aureus. The erm(45)-containing island was integrated into the housekeeping gene guaA in S. fleurettii and was able to form a circular intermediate but was not transmissible to S. aureus....
Kendrick, Mandy D; Harris, Donna K; Ha, Bo-Keun; Hyten, David L; Cregan, Perry B; Frederick, Reid D; Boerma, H Roger; Pedley, Kerry F
ABSTRACT Asian soybean rust (ASR) is an economically significant disease caused by the fungus Phakopsora pachyrhizi. The soybean genes Rpp3 and Rpp?(Hyuuga) confer resistance to specific isolates of the pathogen. Both genes map to chromosome 6 (Gm06) (linkage group [LG] C2). We recently identified 12 additional soybean accessions that harbor ASR resistance mapping to Gm06, within 5 centimorgans of Rpp3 and Rpp?(Hyuuga). To further characterize genotypes with resistance on Gm06, we used a set of eight P. pachyrhizi isolates collected from geographically diverse areas to inoculate plants and evaluate them for differential phenotypic responses. Three isolates elicited different responses from soybean accessions PI 462312 (Ankur) (Rpp3) and PI 506764 (Hyuuga) (Rpp?[Hyuuga]). In all, 11 of the new accessions yielded responses identical to either PI 462312 or Hyuuga and 1 of the new accessions, PI 417089B (Kuro daizu), differed from all others. Additional screening of Hyuuga-derived recombinant inbred lines indicated that Hyuuga carries two resistance genes, one at the Rpp3 locus on Gm06 and a second, unlinked ASR resistance gene mapping to Gm03 (LG-N) near Rpp5. These findings reveal a natural case of gene pyramiding for ASR resistance in Hyuuga and underscore the importance of utilizing multiple isolates of P. pachyrhizi when screening for ASR resistance.
Li, An-Dong; Li, Li-Guan; Zhang, Tong
Plasmids operate as independent genetic elements in microorganism communities. Through horizontal gene transfer, they can provide their host microorganisms with important functions such as antibiotic resistance and heavy metal resistance. In this study, six metagenomic libraries were constructed with plasmid DNA extracted from influent, activated sludge and digested sludge of two wastewater treatment plants. Compared with the metagenomes of the total DNA extracted from the same sectors of the...
Full Text Available Three quantitative trait loci (QTL conferring broad spectrum resistance to powdery mildew, caused by the fungus Blumeria graminis f. sp. hordei, were previously identified on chromosomes 7HS, 7HL and 6HL in the Spanish barley landrace-derived lines SBCC097 and SBCC145. In the present work, a genome-wide putative linear gene index of barley (Genome Zipper and the first draft of the physical, genetic and functional sequence of the barley genome were used to go one step further in the shortening and explicit demarcation on the barley genome of these regions conferring resistance to powdery mildew as well as in the identification of candidate genes. First, a comparative analysis of the target regions to the barley Genome Zippers of chromosomes 7H and 6H allowed the development of 25 new gene-based molecular markers, which slightly better delimit the QTL intervals. These new markers provided the framework for anchoring of genetic and physical maps, figuring out the outline of the barley genome at the target regions in SBCC097 and SBCC145. The outermost flanking markers of QTLs on 7HS, 7HL and 6HL defined a physical area of 4 Mb, 3.7 Mb and 3.2 Mb, respectively. In total, 21, 10 and 16 genes on 7HS, 7HL and 6HL, respectively, could be interpreted as potential candidates to explain the resistance to powdery mildew, as they encode proteins of related functions with respect to the known pathogen defense-related processes. The majority of these were annotated as belonging to the NBS-LRR class or protein kinase family.
N. R. Redekar
Full Text Available is one of three genetic loci conferring strain-specific resistance to (SMV. The locus has been mapped to a 154-kb region on chromosome 14, containing a cluster of five nucleotide-binding leucine-rich repeat (NB-LRR resistance genes. High sequence similarity between the candidate genes challenges fine mapping of the locus. Among the five, Glyma14g38533 showed the highest transcript abundance in 1 to 3 h of SMV-G7 inoculation. Comparative sequence analyses were conducted with the five candidate NB-LRR genes from susceptible (-type soybean [ (L. Merr.] cultivar Williams 82, resistant (-type cultivar Hwangkeum, and resistant lines L29 and RRR. Sequence comparisons revealed that Glyma14g38533 had far more polymorphisms than the other candidate genes. Interestingly, Glyma14g38533 gene from -type lines exhibited 150 single-nucleotide polymorphism (SNP and six insertion–deletion (InDel markers relative to -type line, Furthermore, the polymorphisms identified in three -type lines were highly conserved. Several polymorphisms were validated in 18 -type resistant and six -type susceptible lines and were found associated with their disease response. The majority of the polymorphisms were located in LRR domain encoding region, which is involved in pathogen recognition via protein–protein interactions. These findings associating Glyma14g38533 with -type resistance to SMV suggest it is the most likely candidate gene for .
Full Text Available Klebsiella pneumoniae (K. pneumoniae, is an opportunistic pathogen raising significant public health concerns owing to its multi-drug resistance. Hfq, one of the main RNA-binding proteins, is a key post-transcriptional regulator. This protein is closely related to virulence and resistance in various pathogenic bacteria. Although the role of hfq in K pneumoniae virulence has been explored, its influence on resistance remains largely unknown. The aim of this study was to investigate the role of hfq in the resistance of K. pneumoniae to cephalosporins. An hfq mutant was constructed, and its resistance to cephalosporins was investigated. The hfq mutant exhibited over 16-fold higher cephalosporin resistance than that exhibited by the wild type. Time-kill curve analysis showed that the hfq mutant could survive under higher concentrations of cephalosporins than the wild-type strain could. Quantitative RT-PCR showed that expression levels for 8 out of the 9 penicillin-binding proteins, which are the targets of cephalosporins, were downregulated in the hfq mutant. Taken together, contrary to its role in many other bacteria, hfq is involved in a negative regulation of K. pneumoniae resistance to cephalosporins by downregulating the expression of penicillin-binding proteins.
Margaret M. Briehl
Full Text Available Acquired resistance to drugs commonly used for lymphoma treatment poses a significant barrier to improving lymphoma patient survival. Previous work with a lymphoma tissue culture model indicates that selection for resistance to oxidative stress confers resistance to chemotherapy-induced apoptosis. This suggests that adaptation to chronic oxidative stress can contribute to chemoresistance seen in lymphoma patients. Oxidative stress-resistant WEHI7.2 cell variants in a lymphoma tissue culture model exhibit a range of apoptosis sensitivities. We exploited this phenotype to test for mitochondrial changes affecting sensitivity to apoptosis in cells made resistant to oxidative stress. We identified impaired release of cytochrome c, and the intermembrane proteins adenylate kinase 2 and Smac/DIABLO, indicating inhibition of the pathway leading to permeabilization of the outer mitochondrial membrane. Blunting of a glucocorticoid-induced signal and intrinsic mitochondrial resistance to cytochrome c release contributed to both points of resistance. The level of Bcl-2 family members or a difference in Bim induction were not contributing factors. The extent of cardiolipin oxidation following dexamethasone treatment, however, did correlate with apoptosis resistance. The differences found in the variants were all proportionate to the degree of resistance to glucocorticoid treatment. We conclude that tolerance to oxidative stress leads to mitochondrial changes that confer resistance to apoptosis.
Chee-Sanford, J. C.; Aminov, R.I.; Krapac, I.J.; Garrigues-Jeanjean, N.; Mackie, R.I.
In this study, we used PCR typing methods to assess the presence of tetracycline resistance determinants conferring ribosomal protection in waste lagoons and in groundwater underlying two swine farms. All eight classes of genes encoding this mechanism of resistance [tet(O), tet(Q), tet(W), tet(M), tetB(P), tet(S), tet(T), and otrA] were found in total DNA extracted from water of two lagoons. These determinants were found to be seeping into the underlying groundwater and could be detected as far as 250 m downstream from the lagoons. The identities and origin of these genes in groundwater were confirmed by PCR-denaturing gradient gel electrophoresis and sequence analyses. Tetracycline-resistant bacterial isolates from groundwater harbored the tet(M) gene, which was not predominant in the environmental samples and was identical to tet(M) from the lagoons. The presence of this gene in some typical soil inhabitants suggests that the vector of antibiotic resistance gene dissemination is not limited to strains of gastrointestinal origin carrying the gene but can be mobilized into the indigenous soil microbiota. This study demonstrated that tet genes occur in the environment as a direct result of agriculture and suggested that groundwater may be a potential source of antibiotic resistance in the food chain.
Risk, Joanna M; Selter, Liselotte L; Chauhan, Harsh; Krattinger, Simon G; Kumlehn, Jochen; Hensel, Goetz; Viccars, Libby A; Richardson, Terese M; Buesing, Gabriele; Troller, Anna; Lagudah, Evans S; Keller, Beat
The Lr34 gene encodes an ABC transporter and has provided wheat with durable, broad-spectrum resistance against multiple fungal pathogens for over 100 years. Because barley does not have an Lr34 ortholog, we expressed Lr34 in barley to investigate its potential as a broad-spectrum resistance resource in another grass species. We found that introduction of the genomic Lr34 sequence confers resistance against barley leaf rust and barley powdery mildew, two pathogens specific for barley but not virulent on wheat. In addition, the barley lines showed enhanced resistance against wheat stem rust. Transformation with the Lr34 cDNA or the genomic susceptible Lr34 allele did not result in increased resistance. Unlike wheat, where Lr34-conferred resistance is associated with adult plants, the genomic Lr34 transgenic barley lines exhibited multipathogen resistance in seedlings. These transgenic barley lines also developed leaf tip necrosis (LTN) in young seedlings, which correlated with an up-regulation of senescence marker genes and several pathogenesis-related (PR) genes. In wheat, transcriptional expression of Lr34 is highest in adult plants and correlates with increased resistance and LTN affecting the last emerging leaf. The severe phenotype of transgenic Lr34 barley resulted in reduced plant growth and total grain weight. These results demonstrate that Lr34 provides enhanced multipathogen resistance early in barley plant development and implies the conservation of the substrate and mechanism of the LR34 transporter and its molecular action between wheat and barley. With controlled gene expression, the use of Lr34 may be valuable for many cereal breeding programmes, particularly given its proven durability. © 2013 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.
Liu, Qin-Mei; Li, Chun-Xiao; Wu, Qun; Shi, Qing-Ming; Sun, Ai-Juan; Zhang, Heng-Duan; Guo, Xiao-Xia; Dong, Yan-De; Xing, Dan; Zhang, Ying-Mei; Han, Qian; Diao, Xiao-Ping; Zhao, Tong-Yan
Culex quinquefasciatus is one of China's major house-dwelling mosquito species and an important vector of filariasis and encephalitis. Chemical treatments represent one of the most successful approaches for comprehensive mosquito prevention and control. However, the widespread use of chemical pesticides has led to the occurrence and development of insecticide resistance. Therefore, in-depth studies of resistance to insecticides are of vital importance. In this study, we performed a gene expression analysis to investigate genes from Cx. quinquefasciatus that may confer pyrethroid resistance. We aimed to understand the mechanisms of Cx. quinquefasciatus resistance to pyrethroid insecticides and provide insights into insect resistance management. Using a resistance bioassay, we determined the deltamethrin LC 50 values (lethal concentration required to kill 50% of the population) for Cx. quinquefasciatus larvae in the F 21 , F 23 , F 24 , F 26 , F 27 , and F 30 generations. The 7 tested strains exhibited pesticide resistance that was 25.25 to 87.83 times higher than that of the SanYa strain. Moreover, the expression of the OBPjj7a (odorant-binding protein OBPjj7a), OBP28 (odorant-binding protein OBP28), and E2 (ubiquitin-conjugating enzyme) genes was positively correlated with deltamethrin resistance ( R 2 = 0.836, P = 0.011; R 2 = 0.788, P = 0.018; and R 2 = 0.850, P = 0.009, respectively) in Cx. quinquefasciatus. The expression of 4 additional genes, H/ACA, S19, SAR2, and PGRP, was not correlated with deltamethrin resistance. In summary, this study identified 3 Cx. quinquefasciatus genes with potential involvement in deltamethrin resistance, and these results may provide a theoretical basis for the control of mosquito resistance and insights into resistance detection.
Full Text Available BACKGROUND: The small brown planthopper (SBPH, Laodelphax striatellus (Fallén, is one of the major rice pests in Asia and has developed resistance to multiple classes of insecticides. Understanding resistance mechanisms is essential to the management of this pest. Biochemical and molecular assays were performed in this study to systematically characterize deltamethrin resistance mechanisms with laboratory-selected resistant and susceptible strains of SBPH. METHODOLOGY/PRINCIPAL FINDINGS: Deltamethrin resistant strains of SBPH (JH-del were derived from a field population by continuously selections (up to 30 generations in the laboratory, while a susceptible strain (JHS was obtained from the same population by removing insecticide pressure for 30 generations. The role of detoxification enzymes in the resistance was investigated using synergism and enzyme activity assays with strains of different resistant levels. Furthermore, 71 cytochrome P450, 93 esterases and 12 glutathione-S-transferases cDNAs were cloned based on transcriptome data of a field collected population. Semi-quantitative RT-PCR screening analysis of 176 identified detoxification genes demonstrated that multiple P450 and esterase genes were overexpressed (>2-fold in JH-del strains (G4 and G30 when compared to that in JHS, and the results of quantitative PCR coincided with the semi-quantitative RT-PCR results. Target mutation at IIS3-IIS6 regions encoded by the voltage-gated sodium channel gene was ruled out for conferring the observed resistance. CONCLUSION/SIGNIFICANCE: As the first attempt to discover genes potentially involved in SBPH pyrethroid resistance, this study putatively identified several candidate genes of detoxification enzymes that were significantly overexpressed in the resistant strain, which matched the synergism and enzyme activity testing. The biochemical and molecular evidences suggest that the high level pyrethroid resistance in L. striatellus could be due to
Full Text Available Potato Genebank of the Universidad Austral de Chile (UACh is an important gene bank in Chile. The accessions collected all over the country possess high genetic diversity, present interesting agronomic and cooking traits, and show resistance to biotic and abiotic stress. A particularly interesting subgroup of the gene bank includes the accessions collected in the South of Chile, the Chilota Potato Genebank. The focus of this study is the identification of virus and nematode resistant genes in potatoes (Solatium tuberosum L., using the RYSC3 and YES3-3B molecular markers. The Potato virus Y(PVY resistance genes Ry adg and Ry sto were identified. Furthermore, the CP60 marker was used to assess the Rx resistance gene that confers resistance to Potato virus X (PVX. In addition, the HC and GRO1-4 markers were utilized to identify the GpaVvrn_QTL and Gro1-4, resistance genes of Globodera pallida and Globodera rostochiensis, respectively. Both G. pallida and G. rostochiensis are Potato Cyst Nematodes (PCN. The plant material used in this study included leaves from 271 accessions of the gene bank. These samples were collected in the field where natural pathogen pressure of potential viruses and diseases exists. ELISA assays were run for field detection of PVY and PVX. However, there have been no previous reports of nematode presence in the plant material. The results herein presented indicate presence of virus and nematode resistance genes in accessions of the Chilota Potato Genebank. In terms of virus resistance, 99 accessions out of the 271 tested possess the Ry adg resistance gene and 17 accessions of these 271 tested have the Ry sto resistance gene. Also, 10 accessions showed positive amplification of the Rxl resistant gene marker. As to nematode resistance, 99 accessions have possible resistance to G. pallida and 54 accessions show potential resistance to G. rostochiensis as detected using the available molecular markers.
Nakaoku, Takashi; Kohno, Takashi; Araki, Mitsugu; Niho, Seiji; Chauhan, Rakhee; Knowles, Phillip P; Tsuchihara, Katsuya; Matsumoto, Shingo; Shimada, Yoko; Mimaki, Sachiyo; Ishii, Genichiro; Ichikawa, Hitoshi; Nagatoishi, Satoru; Tsumoto, Kouhei; Okuno, Yasushi; Yoh, Kiyotaka; McDonald, Neil Q; Goto, Koichi
Resistance to vandetanib, a type I RET kinase inhibitor, developed in a patient with metastatic lung adenocarcinoma harboring a CCDC6-RET fusion that initially exhibited a response to treatment. The resistant tumor acquired a secondary mutation resulting in a serine-to-phenylalanine substitution at codon 904 in the activation loop of the RET kinase domain. The S904F mutation confers resistance to vandetanib by increasing the ATP affinity and autophosphorylation activity of RET kinase. A reduced interaction with the drug is also observed in vitro for the S904F mutant by thermal shift assay. A crystal structure of the S904F mutant reveals a small hydrophobic core around F904 likely to enhance basal kinase activity by stabilizing an active conformer. Our findings indicate that missense mutations in the activation loop of the kinase domain are able to increase kinase activity and confer drug resistance through allosteric effects.
Rezzonico, Fabio; Stockwell, Virginia O; Duffy, Brion
Streptomycin is used in plant agriculture for bacterial disease control, particularly against fire blight in pome fruit orchards. Concerns that this may increase environmental antibiotic resistance have led to bans or restrictions on use. Experience with antibiotic use in animal feeds raises the possible influence of formulation-delivered resistance genes. We demonstrate that agricultural streptomycin formulations do not carry producer organism resistance genes. By using an optimized extraction procedure, Streptomyces 16S rRNA genes and the streptomycin resistance gene strA were not detected in agricultural streptomycin formulations. This diminishes the likelihood for one potential factor in resistance development due to streptomycin use.
Mansvelt, E.L.; Glyn-Woods, T.; Watts, L.; Rabie, A.; Appel, M.; Bellstedt, D.U.
Long breeding cycles make cultivar development a lengthy process in deciduous fruit species. Gene transfer is, accordingly, a goal with significant commercial value. In many plant species, especially in woody plants, a prerequisite for genetic engineering is the ability to regenerate plants from transformed cells. Development of single cell regeneration is the first step towards exploration of gene transfer techniques. In this investigation media for plum and apple leaf disk regeneration were developed. Transformation experiments were performed. The vector EHA105 containing the gus-intron gene was found to be effective for gene transfer. Induction of the virG genes with aceto-syringone did not enhance transformation. Cefotaxime that was supplemented in the plum selection medium to suppress the Agrobacterium vector seriously inhibited leaf disk regeneration. However, in applies it was not detrimental. With further apple transformation experiments, factors such as preculturing, age of leaves, sucrose and cefotaxime concentrations did not increase the transformation efficiency of the marker gene. The harpin protein, essential for the pathogenicity of Pseudomonas syringae pv. syringae which incites bacterial canker of stone fruit, ws amplified and cloned into an expression vector. The fusion protein was purified. This will be used in future studies to elucidate the host-pathogen interaction, and to identify antibacterial genes. (author)
The invention provides novel molecular genetic markers in soybean, where the markers are useful, for example, in the marker-assisted selection of gene alleles that impart disease-resistance, thereby allowing the identification and selection of a disease-resistant plant. The markers also find use in positional cloning of disease-resistance genes.
Rezaei, Faranak; Haeili, Mehri; Imani Fooladi, Abbasali; Azari Garmjan, Gholam Ali; Feizabadi, Mohammad Mehdi
Point mutations in the rpsL and rrs genes can lead to development of streptomycin (STR) resistance in Mycobacterium tuberculosis. The aims of this study were to determine the frequency of mutations in STR resistant M. tuberculosis isolates in Iran and to analyze the possible relationship between bacterial genotype and STR resistance. Twenty-three M. tuberculosis samples comprising 9 multidrug-resistant (MDR) and 14 non-MDR isolates, recovered from TB patients in four regions: Tehran (n = 14), Isfahan (n = 2), Zahedan (n = 2), and Khorasan (n = 5), were analysed. Mutational profiling was performed by sequencing of the rrs and rpsL genes and spoligotyping method was used for genotyping. Nineteen isolates were resistant to STR, among them 7 exhibited mutations in the rpsL gene and 7 had mutations in the rrs gene. The remaining 5 STR resistant as well as all susceptible isolates lacked any mutation in both genes. Beijing genotype was associated with both MDR and STR resistance in which all mutations occurred at codon 43 of the rpsL gene. There was an association between mutations in the rpsL and rrs genes and STR resistance. We also found a correlation between Beijing genotype and STR resistance.
Yu, Guotai; Champouret, Nicolas; Steuernagel, Burkhard; Olivera, Pablo D; Simmons, Jamie; Williams, Cole; Johnson, Ryan; Moscou, Matthew J; Hernández-Pinzón, Inmaculada; Green, Phon; Sela, Hanan; Millet, Eitan; Jones, Jonathan D G; Ward, Eric R; Steffenson, Brian J; Wulff, Brande B H
We identified two novel wheat stem rust resistance genes, Sr-1644-1Sh and Sr-1644-5Sh in Aegilops sharonensis that are effective against widely virulent African races of the wheat stem rust pathogen. Stem rust is one of the most important diseases of wheat in the world. When single stem rust resistance (Sr) genes are deployed in wheat, they are often rapidly overcome by the pathogen. To this end, we initiated a search for novel sources of resistance in diverse wheat relatives and identified the wild goatgrass species Aegilops sharonesis (Sharon goatgrass) as a rich reservoir of resistance to wheat stem rust. The objectives of this study were to discover and map novel Sr genes in Ae. sharonensis and to explore the possibility of identifying new Sr genes by genome-wide association study (GWAS). We developed two biparental populations between resistant and susceptible accessions of Ae. sharonensis and performed QTL and linkage analysis. In an F 6 recombinant inbred line and an F 2 population, two genes were identified that mapped to the short arm of chromosome 1S sh , designated as Sr-1644-1Sh, and the long arm of chromosome 5S sh , designated as Sr-1644-5Sh. The gene Sr-1644-1Sh confers a high level of resistance to race TTKSK (a member of the Ug99 race group), while the gene Sr-1644-5Sh conditions strong resistance to TRTTF, another widely virulent race found in Yemen. Additionally, GWAS was conducted on 125 diverse Ae. sharonensis accessions for stem rust resistance. The gene Sr-1644-1Sh was detected by GWAS, while Sr-1644-5Sh was not detected, indicating that the effectiveness of GWAS might be affected by marker density, population structure, low allele frequency and other factors.
Full Text Available The polycomb-group (PcG proteins function as general regulators of stem cells. We previously reported that retrovirus-mediated overexpression of Bmi1, a gene encoding a core component of polycomb repressive complex (PRC 1, maintained self-renewing hematopoietic stem cells (HSCs during long-term culture. However, the effects of overexpression of Bmi1 on HSCs in vivo remained to be precisely addressed.In this study, we generated a mouse line where Bmi1 can be conditionally overexpressed under the control of the endogenous Rosa26 promoter in a hematopoietic cell-specific fashion (Tie2-Cre;R26Stop(FLBmi1. Although overexpression of Bmi1 did not significantly affect steady state hematopoiesis, it promoted expansion of functional HSCs during ex vivo culture and efficiently protected HSCs against loss of self-renewal capacity during serial transplantation. Overexpression of Bmi1 had no effect on DNA damage response triggered by ionizing radiation. In contrast, Tie2-Cre;R26Stop(FLBmi1 HSCs under oxidative stress maintained a multipotent state and generally tolerated oxidative stress better than the control. Unexpectedly, overexpression of Bmi1 had no impact on the level of intracellular reactive oxygen species (ROS.Our findings demonstrate that overexpression of Bmi1 confers resistance to stresses, particularly oxidative stress, onto HSCs. This thereby enhances their regenerative capacity and suggests that Bmi1 is located downstream of ROS signaling and negatively regulated by it.
Hong, Myoung-Ki; Lee, Jae Jin; Wu, Xing; Kim, Jin-Kwang; Jeong, Byeong Chul; Pham, Tan-Viet; Kim, Seung-Hwan; Lee, Sang Hee; Kang, Lin-Woo
The SFC-1 gene from S. fonticola was cloned and SFC-1 was expressed, purified and crystallized. X-ray diffraction data were collected from an SFC-1 crystal to 1.6 Å resolution. SFC-1, a class A carbapenemase that confers antibiotic resistance, hydrolyzes the β-lactam rings of β-lactam antibiotics (carbapenems, cephalosporins, penicillins and aztreonam). SFC-1 presents an enormous challenge to infection control, particularly in the eradication of Gram-negative pathogens. As SFC-1 exhibits a remarkably broad substrate range, including β-lactams of all classes, the enzyme is a potential target for the development of antimicrobial agents against pathogens producing carbapenemases. In this study, SFC-1 was cloned, overexpressed, purified and crystallized. The SFC-1 crystal diffracted to 1.6 Å resolution and belonged to the orthorhombic space group P2 1 2 1 2 1 , with unit-cell parameters a = 65.8, b = 68.3, c = 88.8 Å. Two molecules are present in the asymmetric unit, with a corresponding V M of 1.99 Å 3 Da −1 and a solvent content of 38.1%
Hereward, James P; Werth, Jeff A; Thornby, David F; Keenan, Michelle; Chauhan, Bhagirath Singh; Walter, Gimme H
This study takes a whole-transcriptome approach to assess gene expression changes in response to glyphosate treatment in glyphosate-resistant fleabane. We assessed gene expression changes in both susceptible and resistant lines so that the glyphosate death response could be quantified, and constitutively expressed candidate resistance genes identified. There are three copies of the glyphosate target site (5-enolpyruvylshikimate-3-phosphate; EPSPS) gene in Conyza and because Conyza bonariensis is allohexaploid, there is a baseline nine copies of the gene in any individual. Many genes were differentially expressed in response to glyphosate treatment. Known resistance mutations are present in EPSPS2 but they are present in a glyphosate-susceptible line as well as resistant lines and therefore not sufficient to confer resistance. EPSPS1 is expressed four times more than EPSPS2, further reducing the overall contribution of these mutations. We demonstrate that glyphosate resistance in C. bonariensis is not the result of EPSPS mutations or overexpression, but due to a non-target-site mechanism. A large number of genes are affected by glyphosate treatment. We present a list of candidate non-target-site-resistance (NTSR) genes in fleabane for future studies into these mechanisms. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.
Ciric, Lena; Mullany, Peter; Roberts, Adam P.
Objectives Tn916-like elements are one of the most common types of integrative and conjugative element (ICE). In this study we aimed to determine whether novel accessory genes, i.e. genes whose products are not involved in mobility or regulation, were present on a Tn916-like element (Tn6087) isolated from Streptococcus oralis from the human oral cavity. Methods A minocycline-resistant isolate was analysed using restriction fragment length polymorphism (RFLP) analysis on amplicons derived from Tn916 and DNA sequencing to determine whether there were genetic differences in Tn6087 compared with Tn916. Mutational analysis was used to determine whether the novel accessory gene found was responsible for an observed extra phenotype. Results A novel Tn916-like element, Tn6087, is described that encodes both antibiotic and antiseptic resistance. The antiseptic resistance protein is encoded by a novel small multidrug resistance gene, designated qrg, that was shown to encode resistance to cetyltrimethylammonium bromide (CTAB), also known as cetrimide bromide. Conclusions This is the first Tn916-like element described that confers both antibiotic and antiseptic resistance, suggesting that selection of either antibiotic or antiseptic resistance will also select for the other and further highlights the need for prudent use of both types of compound. PMID:21816764
This conference was attended by power industry decision makers who face continuing challenges regarding changes in electricity market mechanisms, pricing options, and power generation and transmission alternatives. It provided an opportunity to review energy markets in North American with particular reference to supply and demand and opportunities for traditional or new generation technologies based on renewable energy sources including wind powered generation. The presentations focused on transmission issues, market design and capacity issues as well as market power and pricing. The integration of wind energy into the power grid as a measure to diversity the power generation portfolio in North America was also discussed along with hydrothermal synergies and interconnections. The role of wind, coal and nuclear power in future North American energy markets was also discussed along with their environmental consequences. tabs., figs
2Department of Genetics, Owaisi Medical and Research Centre, Deccan College of Medical Sciences and ... data, are comparable to those from Africa and Southeast Asia, where AIDS is known to be widespread. ... HIV-1 resistance polymorphism; chemokine receptor; stromal-derived factor-1; Andhra Pradesh; AIDS.
Guardabassi, L.; Agersø, Yvonne
The occurrence of D-Ala : D-Lac ligase genes homologous to glycopeptide resistance vanA was studied in samples of agricultural (n=9) and garden (n=3) soil by culture-independent methods. Cloning and sequencing of nested degenerate PCR products obtained from soil DNA revealed the occurrence of D......A in enterococci. Such sequences were recovered from all agricultural samples as well as from two garden samples with no history of organic fertilization. The results indicated that soil is a rich and assorted reservoir of genes closely related to those conferring glycopeptide resistance in clinical bacteria.......-Ala : D-Ala ligase genes unrelated to vanA. In order to enhance detection of vanA-homologous genes, a third PCR step was added using primers targeting vanA in soil Paenibacillus. Sequencing of 25 clones obtained by this method allowed recovery of 23 novel sequences having 86-100% identity with van...
Zhang, L; Fetch, T; Nirmala, J; Schmierer, D; Brueggeman, R; Steffenson, B; Kleinhofs, A
Rpg1 is a stem rust resistance gene that has protected barley from severe losses for over 60 years in the US and Canada. It confers resistance to many, but not all, pathotypes of the stem rust fungus Puccinia graminis f. sp. tritici. A fast neutron induced deletion mutant, showing susceptibility to stem rust pathotype Pgt-MCC, was identified in barley cv. Morex, which carries Rpg1. Genetic and Rpg1 mRNA and protein expression level analyses showed that the mutation was a suppressor of Rpg1 and was designated Rpr1 (Required for P. graminis resistance). Genome-wide expression profiling, using the Affymetrix Barley1 GeneChip containing approximately 22,840 probe sets, was conducted with Morex and the rpr1 mutant. Of the genes represented on the Barley1 microarray, 20 were up-regulated and 33 were down-regulated by greater than twofold in the mutant, while the Rpg1 mRNA level remained constant. Among the highly down-regulated genes (greater than fourfold), genomic PCR, RT-PCR and Southern analyses identified that three genes (Contig4901_s_at, HU03D17U_s_at, and Contig7061_s_at), were deleted in the rpr1 mutant. These three genes mapped to chromosome 4(4H) bin 5 and co-segregated with the rpr1-mediated susceptible phenotype. The loss of resistance was presumed to be due to a mutation in one or more of these genes. However, the possibility exists that there are other genes within the deletions, which are not represented on the Barley1 GeneChip. The Rpr1 gene was not required for Rpg5- and rpg4-mediated stem rust resistance, indicating that it shows specificity to the Rpg1-mediated resistance pathway.
Muller, Michael; Merrett, Neil D
Silver in its ionic form (Ag+), but not the bulk metal (Ag0), is toxic to microbial life forms and has been used for many years in the treatment of wound infections. The prevalence of bacterial resistance to silver is considered low due to the nonspecific nature of its toxicity. However, the recent increased use of silver as an antimicrobial agent for medical, consumer, and industrial products has raised concern that widespread silver resistance may emerge. Pseudomonas aeruginosa is a common pathogen that produces pyocyanin, a redox toxin and a reductant for molecular oxygen and ferric (Fe3+) ions. The objective of this study was to determine whether pyocyanin reduces Ag+ to Ag0, which may contribute to silver resistance due to lower bioavailability of the cation. Using surface plasmon resonance spectroscopy and scanning electron microscopy, pyocyanin was confirmed to be a reductant for Ag+, forming Ag0 nanoparticles and reducing the bioavailability of free Ag+ by >95% within minutes. Similarly, a pyocyanin-producing strain of P. aeruginosa (PA14) reduced Ag+ but not a pyocyanin-deficient (ΔphzM) strain of the bacterium. Challenge of each strain with Ag+ (as AgNO3) gave MICs of 20 and 5 μg/ml for the PA14 and ΔphzM strains, respectively. Removal of pyocyanin from the medium strain PA14 was grown in or its addition to the medium that ΔphzM mutant was grown in gave MICs of 5 and 20 μg/ml, respectively. Clinical isolates demonstrated similar pyocyanin-dependent resistance to Ag+. We conclude that pseudomonal silver resistance exists independently of previously recognized intracellular mechanisms and may be more prevalent than previously considered. Copyright © 2014, American Society for Microbiology. All Rights Reserved.
ABSTRACT The hospital environment is a potential reservoir of bacteria with plasmids conferring carbapenem resistance. Our Hospital Epidemiology Service routinely performs extensive sampling of high-touch surfaces, sinks, and other locations in the hospital. Over a 2-year period, additional sampling was conducted at a broader range of locations, including housekeeping closets, wastewater from hospital internal pipes, and external manholes. We compared these data with previously collected information from 5 years of patient clinical and surveillance isolates. Whole-genome sequencing and analysis of 108 isolates provided comprehensive characterization of blaKPC/blaNDM-positive isolates, enabling an in-depth genetic comparison. Strikingly, despite a very low prevalence of patient infections with blaKPC-positive organisms, all samples from the intensive care unit pipe wastewater and external manholes contained carbapenemase-producing organisms (CPOs), suggesting a vast, resilient reservoir. We observed a diverse set of species and plasmids, and we noted species and susceptibility profile differences between environmental and patient populations of CPOs. However, there were plasmid backbones common to both populations, highlighting a potential environmental reservoir of mobile elements that may contribute to the spread of resistance genes. Clear associations between patient and environmental isolates were uncommon based on sequence analysis and epidemiology, suggesting reasonable infection control compliance at our institution. Nonetheless, a probable nosocomial transmission of Leclercia sp. from the housekeeping environment to a patient was detected by this extensive surveillance. These data and analyses further our understanding of CPOs in the hospital environment and are broadly relevant to the design of infection control strategies in many infrastructure settings. PMID:29437920
Rebecca A. Weingarten
Full Text Available The hospital environment is a potential reservoir of bacteria with plasmids conferring carbapenem resistance. Our Hospital Epidemiology Service routinely performs extensive sampling of high-touch surfaces, sinks, and other locations in the hospital. Over a 2-year period, additional sampling was conducted at a broader range of locations, including housekeeping closets, wastewater from hospital internal pipes, and external manholes. We compared these data with previously collected information from 5 years of patient clinical and surveillance isolates. Whole-genome sequencing and analysis of 108 isolates provided comprehensive characterization of blaKPC/blaNDM-positive isolates, enabling an in-depth genetic comparison. Strikingly, despite a very low prevalence of patient infections with blaKPC-positive organisms, all samples from the intensive care unit pipe wastewater and external manholes contained carbapenemase-producing organisms (CPOs, suggesting a vast, resilient reservoir. We observed a diverse set of species and plasmids, and we noted species and susceptibility profile differences between environmental and patient populations of CPOs. However, there were plasmid backbones common to both populations, highlighting a potential environmental reservoir of mobile elements that may contribute to the spread of resistance genes. Clear associations between patient and environmental isolates were uncommon based on sequence analysis and epidemiology, suggesting reasonable infection control compliance at our institution. Nonetheless, a probable nosocomial transmission of Leclercia sp. from the housekeeping environment to a patient was detected by this extensive surveillance. These data and analyses further our understanding of CPOs in the hospital environment and are broadly relevant to the design of infection control strategies in many infrastructure settings.
Zhu, Xiao Fang; Lei, Gui Jie; Wang, Zhi Wei; Shi, Yuan Zhi; Braam, Janet; Li, Gui Xin; Zheng, Shao Jian
Whether aluminum toxicity is an apoplastic or symplastic phenomenon is still a matter of debate. Here, we found that three auxin overproducing mutants, yucca, the recessive mutant superroot2, and superroot1 had increased aluminum sensitivity, while a transfer DNA insertion mutant, xyloglucan endotransglucosylase/hydrolases15 (xth15), showed enhanced aluminum resistance, accompanied by low endogenous indole-3-acetic acid levels, implying that auxin may be involved in plant responses to aluminum stress. We used yucca and xth15 mutants for further study. The two mutants accumulated similar total aluminum in roots and had significantly reduced cell wall aluminum and increased symplastic aluminum content relative to the wild-type ecotype Columbia, indicating that altered aluminum levels in the symplast or cell wall cannot fully explain the differential aluminum resistance of these two mutants. The expression of Al sensitive1 (ALS1), a gene that functions in aluminum redistribution between the cytoplasm and vacuole and contributes to symplastic aluminum detoxification, was less abundant in yucca and more abundant in xth15 than the wild type, consistent with possible ALS1 function conferring altered aluminum sensitivity in the two mutants. Consistent with the idea that xth15 can tolerate more symplastic aluminum because of possible ALS1 targeting to the vacuole, morin staining of yucca root tip sections showed more aluminum accumulation in the cytosol than in the wild type, and xth15 showed reduced morin staining of cytosolic aluminum, even though yucca and xth15 had similar overall symplastic aluminum content. Exogenous application of an active auxin analog, naphthylacetic acid, to the wild type mimicked the aluminum sensitivity and distribution phenotypes of yucca, verifying that auxin may regulate aluminum distribution in cells. Together, these data demonstrate that auxin negatively regulates aluminum tolerance through altering ALS1 expression and aluminum distribution
Roeske-Nielsen, A.; Buschard, K.; Manson, J.E.
, the homozygous CC individuals displayed lower insulin resistance measured by HOMA-IR (P = .05) than the C/T or TT persons; this was particularly prevalent in individuals who exercise (P = .03). CONCLUSION: Heterozygosity at SNP rs2267161 in the gene encoding the CST enzyme confers increased risk of T2D. Females...
Ayliffe, Michael A; Steinau, Martin; Park, Robert F; Rooke, Lee; Pacheco, Maria G; Hulbert, Scot H; Trick, Harold N; Pryor, Anthony J
The maize Rp1-D gene confers race-specific resistance against Puccinia sorghi (common leaf rust) isolates containing a corresponding avrRp1-D avirulence gene. An Rp1-D genomic clone and a similar Rp1-D transgene regulated by the maize ubiquitin promoter were transformed independently into susceptible maize lines and shown to confer Rp1-D resistance, demonstrating that this resistance can be transferred as a single gene. Transfer of these functional transgenes into wheat and barley did not result in novel resistances when these plants were challenged with isolates of wheat stem rust (P. graminis), wheat leaf rust (P. triticina), or barley leaf rust (P. hordei). Regardless of the promoter employed, low levels of gene expression were observed. When constitutive promoters were used for transgene expression, a majority of Rp1-D transcripts were truncated in the nucleotide binding site-encoding region by premature polyadenylation. This aberrant mRNA processing was unrelated to gene function because an inactive version of the gene also generated such transcripts. These data demonstrate that resistance gene transfer between species may not be limited only by divergence of signaling effector molecules and pathogen avirulence ligands, but potentially also by more fundamental gene expression and transcript processing limitations.
Ribeiro, Thuanne Pires; Arraes, Fabricio Barbosa Monteiro; Lourenço-Tessutti, Isabela Tristan; Silva, Marilia Santos; Lisei-de-Sá, Maria Eugênia; Lucena, Wagner Alexandre; Macedo, Leonardo Lima Pepino; Lima, Janaina Nascimento; Santos Amorim, Regina Maria; Artico, Sinara; Alves-Ferreira, Márcio; Mattar Silva, Maria Cristina; Grossi-de-Sa, Maria Fatima
Genetically modified (GM) cotton plants that effectively control cotton boll weevil (CBW), which is the most destructive cotton insect pest in South America, are reported here for the first time. This work presents the successful development of a new GM cotton with high resistance to CBW conferred by Cry10Aa toxin, a protein encoded by entomopathogenic Bacillus thuringiensis (Bt) gene. The plant transformation vector harbouring cry10Aa gene driven by the cotton ubiquitination-related promoter uceA1.7 was introduced into a Brazilian cotton cultivar by biolistic transformation. Quantitative PCR (qPCR) assays revealed high transcription levels of cry10Aa in both T 0 GM cotton leaf and flower bud tissues. Southern blot and qPCR-based 2 -ΔΔCt analyses revealed that T 0 GM plants had either one or two transgene copies. Quantitative and qualitative analyses of Cry10Aa protein expression showed variable protein expression levels in both flower buds and leaves tissues of T 0 GM cotton plants, ranging from approximately 3.0 to 14.0 μg g -1 fresh tissue. CBW susceptibility bioassays, performed by feeding adults and larvae with T 0 GM cotton leaves and flower buds, respectively, demonstrated a significant entomotoxic effect and a high level of CBW mortality (up to 100%). Molecular analysis revealed that transgene stability and entomotoxic effect to CBW were maintained in T 1 generation as the Cry10Aa toxin expression levels remained high in both tissues, ranging from 4.05 to 19.57 μg g -1 fresh tissue, and the CBW mortality rate remained around 100%. In conclusion, these Cry10Aa GM cotton plants represent a great advance in the control of the devastating CBW insect pest and can substantially impact cotton agribusiness. © 2017 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.
Weingarten, Rebecca A; Johnson, Ryan C; Conlan, Sean; Ramsburg, Amanda M; Dekker, John P; Lau, Anna F; Khil, Pavel; Odom, Robin T; Deming, Clay; Park, Morgan; Thomas, Pamela J; Henderson, David K; Palmore, Tara N; Segre, Julia A; Frank, Karen M
The hospital environment is a potential reservoir of bacteria with plasmids conferring carbapenem resistance. Our Hospital Epidemiology Service routinely performs extensive sampling of high-touch surfaces, sinks, and other locations in the hospital. Over a 2-year period, additional sampling was conducted at a broader range of locations, including housekeeping closets, wastewater from hospital internal pipes, and external manholes. We compared these data with previously collected information from 5 years of patient clinical and surveillance isolates. Whole-genome sequencing and analysis of 108 isolates provided comprehensive characterization of bla KPC / bla NDM -positive isolates, enabling an in-depth genetic comparison. Strikingly, despite a very low prevalence of patient infections with bla KPC -positive organisms, all samples from the intensive care unit pipe wastewater and external manholes contained carbapenemase-producing organisms (CPOs), suggesting a vast, resilient reservoir. We observed a diverse set of species and plasmids, and we noted species and susceptibility profile differences between environmental and patient populations of CPOs. However, there were plasmid backbones common to both populations, highlighting a potential environmental reservoir of mobile elements that may contribute to the spread of resistance genes. Clear associations between patient and environmental isolates were uncommon based on sequence analysis and epidemiology, suggesting reasonable infection control compliance at our institution. Nonetheless, a probable nosocomial transmission of Leclercia sp. from the housekeeping environment to a patient was detected by this extensive surveillance. These data and analyses further our understanding of CPOs in the hospital environment and are broadly relevant to the design of infection control strategies in many infrastructure settings. IMPORTANCE Carbapenemase-producing organisms (CPOs) are a global concern because of the morbidity and
Douthwaite, S; Powers, T; Lee, J Y
The helix spanning nucleotides 1198 to 1247 (helix 1200-1250) in Escherichia coli 23 S ribosomal RNA (rRNA) is functionally important in protein synthesis, and deletions in this region confer erythromycin resistance. In order to define the structural requirements for resistance, we have dissected....... However, removal of either these or non-conserved nucleotides from helix 1200-1250 measurably reduces the efficiency of 23 S RNA in forming functional ribosomes. We have used chemical probing and a modified primer extension method to investigate erythromycin binding to wild-type and resistant ribosomes...
Winkworth-Lawrence, Cynthia; Lange, Katharina
Antibiotic resistance is a major public health concern with growing evidence of environmental gene reservoirs, especially in freshwater. However, the presence of antibiotic resistance genes in freshwater, in addition to the wide spectrum of land use contaminants like nitrogen and phosphate, that waterways are subjected to is inconclusive. Using molecular analyses, freshwater benthic rock biofilms were screened for genes conferring resistance to antibiotics used in both humans and farmed animals (aacA-aphD to aminoglycosides; mecA to ß-lactams; ermA and ermB to macrolides; tetA, tetB, tetK, and tetM to tetracyclines; vanA and vanB to glycopeptides). We detected widespread low levels of antibiotic resistance genes from 20 waterways across southern New Zealand throughout the year (1.3 % overall detection rate; 480 samples from three rocks per site, 20 sites, eight occasions; July 2010-May 2011). Three of the ten genes, ermB, tetK, and tetM, were detected in 62 of the 4800 individual screens; representatives confirmed using Sanger sequencing. No distinction could be made between human and agricultural land use contamination sources based on gene presence distribution alone. However, land use pressures are suggested by moderate correlations between antibiotic resistance genes and high-intensity farming in winter. The detection of antibiotic resistance genes at several sites not subject to known agricultural pressures suggests human sources of resistance, like waterway contamination resulting from unsatisfactory toilet facilities at recreational sites.
Uzarowska, Anna; Dionisio, Giuseppe; Sarholz, Barbara; Piepho, Hans-Peter; Xu, Mingliang; Ingvardsen, Christina Rønn; Wenzel, Gerhard; Lübberstedt, Thomas
The potyviruses sugarcane mosaic virus (SCMV) and maize dwarf mosaic virus (MDMV) are major pathogens of maize worldwide. Two loci, Scmv1 and Scmv2, have ealier been shown to confer complete resistance to SCMV. Custom-made microarrays containing previously identified SCMV resistance candidate genes and resistance gene analogs were utilised to investigate and validate gene expression and expression patterns of isogenic lines under pathogen infection in order to obtain information about the molecular mechanisms involved in maize-potyvirus interactions. By employing time course microarray experiments we identified 68 significantly differentially expressed sequences within the different time points. The majority of differentially expressed genes differed between the near-isogenic line carrying Scmv1 resistance locus at chromosome 6 and the other isogenic lines. Most differentially expressed genes in the SCMV experiment (75%) were identified one hour after virus inoculation, and about one quarter at multiple time points. Furthermore, most of the identified mapped genes were localised outside the Scmv QTL regions. Annotation revealed differential expression of promising pathogenesis-related candidate genes, validated by qRT-PCR, coding for metallothionein-like protein, S-adenosylmethionine synthetase, germin-like protein or 26S ribosomal RNA. Our study identified putative candidate genes and gene expression patterns related to resistance to SCMV. Moreover, our findings support the effectiveness and reliability of the combination of different expression profiling approaches for the identification and validation of candidate genes. Genes identified in this study represent possible future targets for manipulation of SCMV resistance in maize.
Okamoto, Susumu; Tamaru, Aki; Nakajima, Chie; Nishimura, Kenji; Tanaka, Yukinori; Tokuyama, Shinji; Suzuki, Yasuhiko; Ochi, Kozo
Streptomycin has been an important drug for the treatment of tuberculosis since its discovery in 1944. But numerous strains of Mycobacterium tuberculosis, the bacterial pathogen that causes tuberculosis, are now streptomycin resistant. Although such resistance is often mediated by mutations within rrs, a 16S rRNA gene or rpsL, which encodes the ribosomal protein S12, these mutations are found in a limited proportion of clinically isolated streptomycin-resistant M. tuberculosis strains. Here we have succeeded in identifying a mutation that confers low-level streptomycin resistance to bacteria, including M. tuberculosis. We found that mutations within the gene gidB confer low-level streptomycin resistance and are an important cause of resistance found in 33% of resistant M. tuberculosis isolates. We further clarified that the gidB gene encodes a conserved 7-methylguanosine (m(7)G) methyltransferase specific for the 16S rRNA, apparently at position G527 located in the so-called 530 loop. Thus, we have identified gidB as a new streptomycin-resistance locus and uncovered a resistance mechanism that is mediated by loss of a conserved m(7)G modification in 16S rRNA. The clinical significance of M. tuberculosis gidB mutation also is noteworthy, as gidB mutations emerge spontaneously at a high frequency of 10(-6) and, once emerged, result in vigorous emergence of high-level streptomycin-resistant mutants at a frequency more than 2000 times greater than that seen in wild-type strains. Further studies on the precise function of GidB may provide a basis for developing strategies to suppress pathogenic bacteria, including M. tuberculosis.
Steuernagel, Burkhard; Periyannan, Sambasivam K; Hernández-Pinzón, Inmaculada; Witek, Kamil; Rouse, Matthew N; Yu, Guotai; Hatta, Asyraf; Ayliffe, Mick; Bariana, Harbans; Jones, Jonathan D G; Lagudah, Evans S; Wulff, Brande B H
Wild relatives of domesticated crop species harbor multiple, diverse, disease resistance (R) genes that could be used to engineer sustainable disease control. However, breeding R genes into crop lines often requires long breeding timelines of 5-15 years to break linkage between R genes and deleterious alleles (linkage drag). Further, when R genes are bred one at a time into crop lines, the protection that they confer is often overcome within a few seasons by pathogen evolution. If several cloned R genes were available, it would be possible to pyramid R genes in a crop, which might provide more durable resistance. We describe a three-step method (MutRenSeq)-that combines chemical mutagenesis with exome capture and sequencing for rapid R gene cloning. We applied MutRenSeq to clone stem rust resistance genes Sr22 and Sr45 from hexaploid bread wheat. MutRenSeq can be applied to other commercially relevant crops and their relatives, including, for example, pea, bean, barley, oat, rye, rice and maize.
Full Text Available Fosfomycin is a decades-old antibiotic which is being revisited because of its perceived activity against many extensively drug-resistant Gram-negative pathogens. FosA proteins are Mn2+ and K+-dependent glutathione S-transferases which confer fosfomycin resistance in Gram-negative bacteria by conjugation of glutathione to the antibiotic. Plasmid-borne fosA variants have been reported in fosfomycin-resistant Escherichia coli strains. However, the prevalence and distribution of fosA in other Gram-negative bacteria are not known. We systematically surveyed the presence of fosA in Gram-negative bacteria in over 18,000 published genomes from 18 Gram-negative species and investigated their contribution to fosfomycin resistance. We show that FosA homologues are present in the majority of genomes in some species (e.g., Klebsiella spp., Enterobacter spp., Serratia marcescens, and Pseudomonas aeruginosa, whereas they are largely absent in others (e.g., E. coli, Acinetobacter baumannii, and Burkholderia cepacia. FosA proteins in different bacterial pathogens are highly divergent, but key amino acid residues in the active site are conserved. Chromosomal fosA genes conferred high-level fosfomycin resistance when expressed in E. coli, and deletion of chromosomal fosA in S. marcescens eliminated fosfomycin resistance. Our results indicate that FosA is encoded by clinically relevant Gram-negative species and contributes to intrinsic fosfomycin resistance.
Fukaya, M; Takemura, H; Okumura, H; Kawamura, Y; Horinouchi, S; Beppu, T
Five acetic acid-sensitive mutants of Acetobacter aceti subsp. aceti no. 1023 were isolated by mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. Three recombinant plasmids that complemented the mutations were isolated from a gene bank of the chromosome DNA of the parental strain constructed in Escherichia coli by using cosmid vector pMVC1. One of these plasmids (pAR1611), carrying about a 30-kilobase-pair (kb) fragment that conferred acetic acid resistance to all five mutants, was further analyzed. Subcloning experiments indicated that a 8.3-kb fragment was sufficient to complement all five mutations. To identify the mutation loci and genes involved in acetic acid resistance, insertional inactivation was performed by insertion of the kanamycin resistance gene derived from E. coli plasmid pACYC177 into the cloned 8.3-kb fragment and successive integration into the chromosome of the parental strain. The results suggested that three genes, designated aarA, aarB, and aarC, were responsible for expression of acetic acid resistance. Gene products of these genes were detected by means of overproduction in E. coli by use of the lac promoter. The amino acid sequence of the aarA gene product deduced from the nucleotide sequence was significantly similar to those of the citrate synthases (CSs) of E. coli and other bacteria. The A. aceti mutants defective in the aarA gene were found to lack CS activity, which was restored by introduction of a plasmid containing the aarA gene. A mutation in the CS gene of E. coli was also complemented by the aarA gene. These results indicate that aarA is the CS gene.
Pan, Cuili; Yao, Miaomiao; Zhang, Jinpeng; Yang, Xinming; Liu, Weihua; Li, Xiuquan; Xi, Yajun; Li, Lihui
Creation of wheat-alien disomic addition lines and localization of desirable genes on alien chromosomes are important for utilization of these genes in genetic improvement of common wheat. In this study, wheat-Agropyron cristatum derivative line 5113 was characterized by genomic in situ hybridization (GISH) and specific-locus amplified fragment sequencing (SLAF-seq), and was demonstrated to be a novel wheat-A. cristatum disomic 6P addition line. Compared with its parent Fukuhokomugi (Fukuho), 5113 displayed multiple elite agronomic traits, including higher uppermost internode/plant height ratio, larger flag leaf, longer spike length, elevated grain number per spike and spikelet number per spike, more kernel number in the middle spikelet, more fertile tiller number per plant, and enhanced resistance to powdery mildew and leaf rust. Genes conferring these elite traits were localized on the A. cristatum 6P chromosome by using SLAF-seq markers and biparental populations (F1, BC1F1 and BC1F2 populations) produced from the crosses between Fukuho and 5113. Taken together, chromosomal localization of these desirable genes will facilitate transferring of high-yield and high-resistance genes from A. cristatum into common wheat, and serve as the foundation for the utilization of 5113 in wheat breeding. PMID:27824906
Yuan, Cuiling; Wu, Jingzheng; Yan, Baiqiang; Hao, Qunqun; Zhang, Chaozhong; Lyu, Bo; Ni, Fei; Caplan, Allan; Wu, Jiajie; Fu, Daolin
Yr10 is an important gene to control wheat stripe rust, and the search for Yr10 needs to be continued. Wheat stripe rust or yellow rust is a devastating fungal disease caused by Puccinia striiformis f. sp. tritici (Pst). Host disease resistance offers a primary source for controlling wheat stripe rust. The stripe rust resistance gene Yr10 confers the race-specific resistance to most tested Pst races in China including CYR29. Early studies proposed that Yr10 was a nucleotide-binding site, leucine-rich repeat gene archived as GenBank accession AF149112 (hereafter designated the Yr10 candidate gene or Yr10 CG ). In this study, we revealed that 15 Chinese wheat cultivars positive for Yr10 CG are susceptible to CYR29. We then expressed the Yr10 CG cDNA in the common wheat 'Bobwhite'. The Yr10 CG -cDNA positive transgenic plants were also susceptible to CYR29. Thus, it is highly unlikely that Yr10 CG corresponds to the Yr10 resistance gene. Using the Yr10 donor 'Moro' and the Pst-susceptible wheat 'Huixianhong', we generated two F 3 populations that displayed a single Mendelian segregation on the Yr10 gene, and used them to remap the Yr10 gene. Six markers were placed in the Yr10 region, with the Yr10 CG gene now mapping about 1.2-cM proximal to the Yr10 locus and the Xsdauw79 marker is completely linked to the Yr10 locus. Apparently, the Yr10 gene has not yet been identified. Fine mapping and positional cloning of Yr10 is important for gene pyramiding for stripe rust resistance in wheat.
Divya, Dhanasekar; Singh, Y Tunginba; Nair, Suresh; Bentur, J S
The Asian rice gall midge, Orseolia oryzae, is a serious insect pest causing extensive yield loss. Interaction between the gall midge and rice genotypes is known to be on a gene-for-gene basis. Here, we report molecular basis of HR- (hypersensitive reaction-negative) type of resistance in Aganni (an indica rice variety possessing gall midge resistance gene Gm8) through the construction and analysis of a suppressive subtraction hybridization (SSH) cDNA library. In all, 2,800 positive clones were sequenced and analyzed. The high-quality ESTs were assembled into 448 non-redundant gene sequences. Homology search with the NCBI databases, using BlastX and BlastN, revealed that 73% of the clones showed homology to genes with known function and majority of ESTs belonged to the gene ontology category 'biological process'. Validation of 27 putative candidate gall midge resistance genes through real-time PCR, following gall midge infestation, in contrasting parents and their derived pre-NILs (near isogenic lines) revealed induction of specific genes related to defense and metabolism. Interestingly, four genes, belonging to families of leucine-rich repeat (LRR), heat shock protein (HSP), pathogenesis related protein (PR), and NAC domain-containing protein, implicated in conferring HR+ type of resistance, were found to be up-regulated in Aganni. Two of the reactive oxygen intermediates (ROI)-scavenging-enzyme-coding genes Cytosolic Ascorbate Peroxidase1, 2 (OsAPx1 and OsAPx2) were found up-regulated in Aganni in incompatible interaction possibly suppressing HR. We suggest that Aganni has a deviant form of inducible, salicylic acid (SA)-mediated resistance but without HR.
Full Text Available Abstract Background Genome scans are becoming an increasingly popular approach to study the genetic basis of adaptation and speciation, but on their own, they are often helpless at identifying the specific gene(s or mutation(s targeted by selection. This shortcoming is hopefully bound to disappear in the near future, thanks to the wealth of new genomic resources that are currently being developed for many species. In this article, we provide a foretaste of this exciting new era by conducting a genome scan in the mosquito Aedes aegypti with the aim to look for candidate genes involved in resistance to Bacillus thuringiensis subsp. israelensis (Bti insecticidal toxins. Results The genome of a Bti-resistant and a Bti-susceptible strains was surveyed using about 500 MITE-based molecular markers, and the loci showing the highest inter-strain genetic differentiation were sequenced and mapped on the Aedes aegypti genome sequence. Several good candidate genes for Bti-resistance were identified in the vicinity of these highly differentiated markers. Two of them, coding for a cadherin and a leucine aminopeptidase, were further examined at the sequence and gene expression levels. In the resistant strain, the cadherin gene displayed patterns of nucleotide polymorphisms consistent with the action of positive selection (e.g. an excess of high compared to intermediate frequency mutations, as well as a significant under-expression compared to the susceptible strain. Conclusion Both sequence and gene expression analyses agree to suggest a role for positive selection in the evolution of this cadherin gene in the resistant strain. However, it is unlikely that resistance to Bti is conferred by this gene alone, and further investigation will be needed to characterize other genes significantly associated with Bti resistance in Ae. aegypti. Beyond these results, this article illustrates how genome scans can build on the body of new genomic information (here, full
Roychowdhury, M; Jia, Y; Jia, M H; Fjellstrom, R; Cartwright, R D
The Pib gene in rice confers resistance to a wide range of races of the rice blast pathogen, Magnaporthe oryzae, including race IE1k that overcomes Pita, another broad-spectrum resistance gene. In this study, the presence of Pib was determined in 164 rice germplasm accessions from a core subset of the National Small Grains Collection utilizing DNA markers and pathogenicity assays. The presence of Pib was evaluated with two simple sequence repeat (SSR) markers and a dominant marker (Pib-dom) derived from the Pib gene sequence. Pathogenicity assays using two avirulent races (IE1k and IB1) and a virulent race (IB54) were performed to verify the resistance responses of accessions. Of the 164 accessions evaluated, 109 contained the Pib gene as determined using both SSR markers and pathogenicity assays, albeit different haplotypes were detected. The remaining 52 germplasm accessions were different in their responses to the blast races IB54, IE1k, and IB1, thus indicating the presence of R gene(s) other than Pib. The accessions characterized in this study could be used for marker-assisted breeding to improve blast resistance in indica and japonica cultivars worldwide.
Blair, Jessica M A; Bavro, Vassiliy N; Ricci, Vito; Modi, Niraj; Cacciotto, Pierpaolo; Kleinekathӧfer, Ulrich; Ruggerone, Paolo; Vargiu, Attilio V; Baylay, Alison J; Smith, Helen E; Brandon, Yvonne; Galloway, David; Piddock, Laura J V
The incidence of multidrug-resistant bacterial infections is increasing globally and the need to understand the underlying mechanisms is paramount to discover new therapeutics. The efflux pumps of Gram-negative bacteria have a broad substrate range and transport antibiotics out of the bacterium, conferring intrinsic multidrug resistance (MDR). The genomes of pre- and posttherapy MDR clinical isolates of Salmonella Typhimurium from a patient that failed antibacterial therapy and died were sequenced. In the posttherapy isolate we identified a novel G288D substitution in AcrB, the resistance-nodulation division transporter in the AcrAB-TolC tripartite MDR efflux pump system. Computational structural analysis suggested that G288D in AcrB heavily affects the structure, dynamics, and hydration properties of the distal binding pocket altering specificity for antibacterial drugs. Consistent with this hypothesis, recreation of the mutation in standard Escherichia coli and Salmonella strains showed that G288D AcrB altered substrate specificity, conferring decreased susceptibility to the fluoroquinolone antibiotic ciprofloxacin by increased efflux. At the same time, the substitution increased susceptibility to other drugs by decreased efflux. Information about drug transport is vital for the discovery of new antibacterials; the finding that one amino acid change can cause resistance to some drugs, while conferring increased susceptibility to others, could provide a basis for new drug development and treatment strategies.
Yosep S Mau
Full Text Available The lesser grain borer Rhyzopertha dominica (F. is one of the most destructive insect pests of stored grain. This pest has been controlled successfully by fumigation with phosphine for the last several decades, though strong resistance to phosphine in many countries has raised concern about the long term usefulness of this control method. Previous genetic analysis of strongly resistant (SR R. dominica from three widely geographically dispersed regions of Australia, Queensland (SR(QLD, New South Wales (SR(NSW and South Australia (SR(SA, revealed a resistance allele in the rph1 gene in all three strains. The present study confirms that the rph1 gene contributes to resistance in a fourth strongly resistant strain, SR2(QLD, also from Queensland. The previously described rph2 gene, which interacts synergistically with rph1 gene, confers strong resistance on SR(QLD and SR(NSW. We now provide strong circumstantial evidence that weak alleles of rph2, together with rph1, contribute to the strong resistance phenotypes of SR(SA and SR2(QLD. To test the notion that rph1 and rph2 are solely responsible for the strong resistance phenotype of all resistant R. dominica, we created a strain derived by hybridising the four strongly resistant lines. Following repeated selection for survival at extreme rates of phosphine exposure, we found only slightly enhanced resistance. This suggests that a single sequence of genetic changes was responsible for the development of resistance in these insects.
Elvis Terci Valera
Full Text Available CONTEXT: Despite the advances in the cure rate for acute lymphoblastic leukemia, approximately 25% of affected children suffer relapses. Expression of genes for the multiple drug resistance protein (MDR-1, multidrug resistance-related protein (MRP, and lung resistance protein (LRP may confer the phenotype of resistance to the treatment of neoplasias. OBJECTIVE: To analyze the expression of the MDR-1, MRP and LRP genes in children with a diagnosis of acute lymphoblastic leukemia via the semiquantitative reverse transcription polymerase chain reaction (RT-PCR, and to determine the correlation between expression and event-free survival and clinical and laboratory variables. DESIGN: A retrospective clinical study. SETTING: Laboratory of Pediatric Oncology, Department of Pediatrics, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Brazil. METHODS: Bone marrow aspirates from 30 children with a diagnosis of acute lymphoblastic leukemia were assessed for the expression of messenger RNA for the MDR-1, MRP and LRP genes by semi-quantitative RT-PCR. RESULTS: In the three groups studied, only the increased expression of LRP was related to worsened event-free survival (p = 0.005. The presence of the common acute lymphoblastic leukemia antigen (CALLA was correlated with increased LRP expression (p = 0.009 and increased risk of relapse or death (p = 0.05. The relative risk of relapse or death was six times higher among children with high LRP expression upon diagnosis (p = 0.05, as confirmed by multivariate analysis of the three genes studied (p = 0.035. DISCUSSION: Cell resistance to drugs is a determinant of the response to chemotherapy and its detection via RT-PCR may be of clinical importance. CONCLUSIONS: Evaluation of the expression of genes for resistance to antineoplastic drugs in childhood acute lymphoblastic leukemia upon diagnosis, and particularly the expression of the LRP gene, may be of clinical relevance, and should be the
Engl, Tobias; Eberl, Nadia; Gorse, Carla; Krüger, Theresa; Schmidt, Thorsten H P; Plarre, Rudy; Adler, Cornel; Kaltenpoth, Martin
Microbial symbionts of insects provide a range of ecological traits to their hosts that are beneficial in the context of biotic interactions. However, little is known about insect symbiont-mediated adaptation to the abiotic environment, for example, temperature and humidity. Here, we report on an ancient clade of intracellular, bacteriome-located Bacteroidetes symbionts that are associated with grain and wood pest beetles of the phylogenetically distant families Silvanidae and Bostrichidae. In the saw-toothed grain beetle Oryzaephilus surinamensis, we demonstrate that the symbionts affect cuticle thickness, melanization and hydrocarbon profile, enhancing desiccation resistance and thereby strongly improving fitness under dry conditions. Together with earlier observations on symbiont contributions to cuticle biosynthesis in weevils, our findings indicate that convergent acquisitions of bacterial mutualists represented key adaptations enabling diverse pest beetle groups to survive and proliferate under the low ambient humidity that characterizes dry grain storage facilities. © 2017 John Wiley & Sons Ltd.
Zhang, Zhi; Song, Liqiang; Han, Haiming; Zhou, Shenghui; Zhang, Jinpeng; Yang, Xinming; Li, Xiuquan; Liu, Weihua; Li, Lihui
Stripe rust, caused by Puccinia striiformis f. sp. tritici ( Pst ), is one of the most destructive diseases of wheat ( Triticum aestivum L.) worldwide. Agropyron cristatum (L.) Gaertn. (2 n = 28, PPPP), one of the wild relatives of wheat, exhibits resistance to stripe rust. In this study, wheat- A . cristatum 6P disomic addition line 4844-12 also exhibited resistance to stripe rust. To identify the stripe rust resistance locus from A . cristatum 6P, ten translocation lines, five deletion lines and the BC₂F₂ and BC₃F₂ populations of two wheat- A . cristatum 6P whole-arm translocation lines were tested with a mixture of two races of Pst in two sites during 2015-2016 and 2016-2017, being genotyped with genomic in situ hybridization (GISH) and molecular markers. The result indicated that the locus conferring stripe rust resistance was located on the terminal 20% of 6P short arm's length. Twenty-nine 6P-specific sequence-tagged-site (STS) markers mapped on the resistance locus have been acquired, which will be helpful for the fine mapping of the stripe rust resistance locus. The stripe rust-resistant translocation lines were found to carry some favorable agronomic traits, which could facilitate their use in wheat improvement. Collectively, the stripe rust resistance locus from A . cristatum 6P could be a novel resistance source and the screened stripe rust-resistant materials will be valuable for wheat disease breeding.
Luan, Ying-zi; Li, Li; Li, Dang-rong; Zhang, Wei; Tang, Bu-jian
To investigate expression difference of several drug resistance related genes between sensitive and resistant ovarian carcinoma cells. Cell lines resistant to cisplatin, carboplatin and taxol were established from ovarian carcinoma cell lines of SKOV3 and A2780, and their biological features were detected. The expressions of several genes related to drug resistance were measured by RT-PCR method. (1) The values of resistance index (RI) of resistant cells to relevant drugs were elevated 3 times or more, with different degrees of cross-resistance to several other drugs (RI 2 approximately 20). They grew more slowly than primary cells (Td elongated 1.4 approximately 2.4 times, P 0.05). Intracellular concentrations of relevant drugs were reduced 2.0 approximately 8.5 times in resistant cells (P p53, lung resistance protein-1 (LRP-1), multiple drug resistance related protein-1 (MRP-1) genes were expressed at lower levels in resistant cells than in sensitive cells; while protein kinase C (PKC), topoisomerase (topo) I, and topo II beta were expressed higher, no obvious alterations were found concerning glutathione S transferase-pi (GST-pi), and topo II alpha. Expression of multiple drug resistance-1 (MDR-1) gene was either elevated or reduced in different cells. The expressions of resistance related genes were widely different in different kinds of resistant cells, suggesting more than one pathway leading to resistance transformation. This adds more difficulties for clinical management.
Jackson, C R; Davis, J A; Frye, J G; Barrett, J B; Hiott, L M
The presence and transfer of antimicrobial resistance genes from commensal bacteria in companion animals to more pathogenic bacteria may contribute to dissemination of antimicrobial resistance. The purpose of this study was to determine antimicrobial resistance gene content and the presence of genetic elements in antimicrobial resistant Escherichia coli from healthy companion animals. In our previous study, from May to August, 2007, healthy companion animals (155 dogs and 121 cats) from three veterinary clinics in the Athens, GA, USA area were sampled and multidrug-resistant E. coli (n = 36; MDR, resistance to ≥ 2 antimicrobial classes) were obtained. Of the 25 different plasmid replicon types tested by PCR, at least one plasmid replicon type was detected in 94% (34/36) of the MDR E. coli; four isolates contained as many as five different plasmid replicons. Nine replicon types (FIA, FIB, FII, I2, A/C, U, P, I1 and HI2) were identified with FIB, FII, I2 as the most common pattern. The presence of class I integrons (intI) was detected in 61% (22/36) of the isolates with eight isolates containing aminoglycoside- and/or trimethoprim-resistance genes in the variable cassette region of intI. Microarray analysis of a subset of the MDR E. coli (n = 9) identified the presence of genes conferring resistance to aminoglycosides (aac, aad, aph and strA/B), β-lactams (ampC, cmy, tem and vim), chloramphenicol (cat), sulfonamides (sulI and sulII), tetracycline [tet(A), tet(B), tet(C), tet(D) and regulator, tetR] and trimethoprim (dfrA). Antimicrobial resistance to eight antimicrobials (ampicillin, cefoxitin, ceftiofur, amoxicillin/clavulanic acid, streptomycin, gentamicin, sulfisoxazole and trimethoprim-sulfamethoxazole) and five plasmid replicons (FIA, FIB, FII, I1 and I2) were transferred via conjugation. The presence of antimicrobial resistance genes, intI and transferable plasmid replicons indicate that E. coli from companion animals may play an important role in the
Haymes, K.M.; Weg, van de W.E.; Arens, P.; Vosman, B.; Nijs, den A.P.M.
The commercial strawberry (Fragaria x ananassa) resistance gene Rpfl conferring resistance to various isolates of Phytophthora fragariae, was mapped using 7 RAPD markers. A DNA fragment representing a RAPD marker linked to susceptibility was cloned, sequenced and converted into a sequence
Haymes, K.M.; Weg, van de W.E.; Arens, P.; Vosman, B.; Nijs, den A.P.M.
The commercial strawberry (Fragaria x ananassa) resistance gene Rpfl conferring resistance to various isolates of Phytophthora fragariae, was mapped using 7 RAPD markers. A DNA fragment representing a RAPD marker linked to susceptibility was cloned, sequenced and converted into a sequence
Microorganisms are capable of producing advanced biofuels that can be used as 'drop-in' alternatives to conventional liquid fuels. However, vital physiological processes and membrane properties are often disrupted by the presence of biofuel and limit the production yields. In order to make microbial biofuels a competitive fuel source, finding mechanisms for improving resistance to the toxic effects of biofuel production is vital. This investigation aims to identify resistance mechanisms from microorganisms that have evolved to withstand hydrocarbon-rich environments, such as those that thrive near natural oil seeps and in oil-polluted waters. First, using genomic DNA from Marinobacter aquaeolei, we constructed a transgenic library that we expressed in Escherichia coli. We exposed cells to inhibitory levels of pinene, a monoterpene that can serve as a jet fuel precursor with chemical properties similar to existing tactical fuels. Using a sequential strategy of a fosmid library followed by a plasmid library, we were able to isolate a region of DNA from the M. aquaeolei genome that conferred pinene tolerance when expressed in E. coli. We determined that a single gene, yceI, was responsible for the tolerance improvements. Overexpression of this gene placed no additional burden on the host. We also tested tolerance to other monoterpenes and showed that yceI selectively improves tolerance. Additionally, we used genomic DNA from Pseudomonas putida KT2440, which has innate solvent-tolerance properties, to create transgenic libraries in an E. coli host. We exposed cells containing the library to pinene, selecting for genes that improved tolerance. Importantly, we found that expressing the sigma factor RpoD from P. putida greatly expanded the diversity of tolerance genes recovered. With low expression of rpoDP. putida, we isolated a single pinene tolerance gene; with increased expression of the sigma factor our selection experiments returned multiple distinct tolerance
Das, Gitishree; Rao, G. J. N.
Severe yield loss due to various biotic stresses like bacterial blight (BB), gall midge (insect) and Blast (disease) and abiotic stresses like submergence and salinity are a serious constraint to the rice productivity throughout the world. The most effective and reliable method of management of the stresses is the enhancement of host resistance, through an economical and environmentally friendly approach. Through the application of marker assisted selection (MAS) technique, the present study reports a successful pyramidization of genes/QTLs to confer resistance/tolerance to blast (Pi2, Pi9), gall Midge (Gm1, Gm4), submergence (Sub1), and salinity (Saltol) in a released rice variety CRMAS2621-7-1 as Improved Lalat which had already incorporated with three BB resistance genes xa5, xa13, and Xa21 to supplement the Xa4 gene present in Improved Lalat. The molecular analysis revealed clear polymorphism between the donor and recipient parents for all the markers that are tagged to the target traits. The conventional backcross breeding approach was followed till BC3F1 generation and starting from BC1F1 onwards, marker assisted selection was employed at each step to monitor the transfer of the target alleles with molecular markers. The different BC3F1s having the target genes/QTLs were inter crossed to generate hybrids with all 10 stress resistance/tolerance genes/QTLs into a single plant/line. Homozygous plants for resistance/tolerance genes in different combinations were recovered. The BC3F3 lines were characterized for their agronomic and quality traits and promising progeny lines were selected. The SSR based background selection was done. Most of the gene pyramid lines showed a high degree of similarity to the recurrent parent for both morphological, grain quality traits and in SSR based background selection. Out of all the gene pyramids tested, two lines had all the 10 resistance/tolerance genes and showed adequate levels of resistance/tolerance against the five target
Hoek, van A.H.A.M.; Aarts, H.J.M.
In the presented study, 143 Salmonella isolates belonging to 26 different serovars were screened for the presence of antibiotic resistance genes by microarray analysis. The microarray contained a total of 223 oligonucleotides representing genes encoding for resistance to the following antibiotic
Oryza sativa L.) ... four blast resistance genes Pi1, Pi2, Pi33 and Pi54 in combination were used to study the nature and magnitude of gene action for disease resistance and yield attributes. ... Please take note of this change.
A study was conducted to detect the presence of disease resistance genes to infection of wheat powdery mildew (Blumeria graminis f. sp. tritici) in selected wheat cultivars from China using molecular markers. Genomic DNA of sixty cultivars was extracted and tested for the presence of selected prominent resistance genes to ...
Success rate of transient transformation and cell growth in selective culture were significantly increased by use of fgmR instead of a native gentamicin resistance gene, suggesting that codon optimization improved translation efficiency of the marker gene and increased antibiotic resistance. Our result shows that similarity in ...
Genetic mapping indicated the introgression of stripe rust resistance gene on wheat chromosome. 5DS in the region carrying leaf rust resistance gene LrAc, but as an independent introgression. Simple sequence repeat (SSR) and sequence-tagged site (STS) markers designed from the survey sequence data of 5DS ...
Disease resistance in plants is a desirable economic trait. Many disease resistance genes from various plants have been cloned so far. The gene products of some of these can be distinguished by the presence of an N terminal nucleotide binding site and a C-terminal stretch of leucine-rich repeats. Oligonucleotides already ...
Li, Ming; Reid, William R; Zhang, Lee
Background Studies suggest that not only is insecticide resistance conferred via multiple gene up-regulation, but it is mediated through the interaction of regulatory factors. However, no regulatory factors in insecticide resistance have yet been identified, and there has been no examination...... of the regulatory interaction of resistance genes. Our current study generated the first reference transcriptome from the adult house fly and conducted a whole transcriptome analysis for the multiple insecticide resistant strain ALHF (wild-type) and two insecticide susceptible strains: aabys (with morphological...... recessive markers) and CS (wild type) to gain valuable insights into the gene interaction and complex regulation in insecticide resistance of house flies, Musca domestica. Results Over 56 million reads were used to assemble the adult female M. domestica transcriptome reference and 14488 contigs were...
Juliana Bernardi Ogliari
Full Text Available The use of monogenic race-specific resistance is widespread for the control of maize (Zea mays L. helminthosporiosis caused by Exserohilum turcicum. Inoculation of 18 Brazilian isolates of E. turcicum onto elite maize lines containing previously identified resistance genes and onto differential near-isogenic lines allowed the identification of new qualitative resistance genes. The inoculation of one selected isolate on differential near-isogenic lines, F1 generations and a BC1F1 population from the referred elite lines enabled the characterization of the resistance spectrum of three new genes, one dominant (HtP, one recessive (rt and a third with non-identified genetic action. Three physiological races of the pathogen were also identified including two with new virulence factors capable of overcoming the resistance of one of the resistance genes identified here (rt.
Peirano, G.; Agersø, Yvonne; Aarestrup, Frank Møller
Objectives: To determine the occurrence of class 1 and 2 integrons and antimicrobial resistance genes among sulphonamide-resistant Shigella strains isolated in Brazil during 1999-2003. Methods: Sixty-two Shigella (Shigella flexneri, n = 47 and Shigella sonnei, n = 15) were tested against 21....... Conclusions: The detection of class 1 and 2 integrons and additional antimicrobial resistance genes allowed us to identify the most frequent antimicrobial resistance patterns of Shigella spp. isolated in Brazil....
Antimicrobial susceptibility testing among the isolates showed resistance to amoxicillin (92%), amoxicillin-clavulanic acid (84.4%), tetracycline (71.4%), gentamycin (43.5%), nalidixic acid (38.3%) and nitrofurantoin (7.9%). E. coli showed the highest resistance to most of the antibiotics. Tetracycline resistance gene was ...
Galvez, H.F.; Narciso, J.O.; Opina, N.L.; Canama, A.O.; Colle, M.G.; Latiza, M.A.; Caspillo, C.L.; Bituin, J.L.; Frankie, R.B.; Hautea, D.M.
Tomato (Lycopersicon esculentum Mill.) is the most important vegetable commodity of the Philippines. Bacterial wilt caused by Ralstonia solanacearum is one serious constraint in tomato production particularly during off-season planting. A major locus derived from H7996 that confers resistance to bacterial wilt has been mapped in the tomato genome. To validate the biological function of the resistance locus and generate multiple allele -mimics-, targeted mutation was induced in tomato using gamma ray and ethyl methane sulfonate (EMS) mutagens. Suitable mutagen treatment was established by evaluating a wide range of mutagen doses/concentrations for a) percent seed germination, b) reduction in plant height, and c) loss of resistance. Six hundred Gy and 1.0% EMS were identified to generate large M1 families of H7996. From 10,000 initial seeds treated with either gamma ray or EMS, a total of 3,663 M1 plants were generated. M2 seeds were harvested from all surviving M1 plants. Several DNA markers have been resourced and are being developed specific to the bacterial wilt resistant gene. In the large M2 population, of H7996, both the phenotypic manifestation of bacterial wilt susceptibility and nucleotide changes in the resistance locus will be evaluated. Large M3 families for the different allele series of the bacterial wilt resistance gene will be established for future high throughput TILLING (Targeting Induced Local Lesions in Genomes) analysis in the gene region
Fierros-Romero, Grisel; Gómez-Ramírez, Marlenne; Arenas-Isaac, Ginesa E; Pless, Reynaldo C; Rojas-Avelizapa, Norma G
Bacillus megaterium MNSH1-9K-1 and Microbacterium liquefaciens MNSH2-PHGII-2, 2 nickel- and vanadium-resistant bacteria from mine tailings located in Guanajuato, Mexico, are shown to have the ability to remove 33.1% and 17.8% of Ni, respectively, and 50.8% and 14.0% of V, respectively, from spent petrochemical catalysts containing 428 ± 30 mg·kg(-1) Ni and 2165 ± 77 mg·kg(-1) V. In these strains, several Ni resistance determinants were detected by conventional PCR. The nccA (nickel-cobalt-cadmium resistance) was found for the first time in B. megaterium. In M. liquefaciens, the above gene as well as the czcD gene (cobalt-zinc-cadmium resistance) and a high-affinity nickel transporter were detected for the first time. This study characterizes the resistance of M. liquefaciens and B. megaterium to Ni through the expression of genes conferring metal resistance.
Full Text Available During infection, pathogens secrete an arsenal of molecules, collectively called effectors, key elements of pathogenesis which modulate innate immunity of the plant and facilitate infection. Some of these effectors can be recognized directly or indirectly by resistance (R proteins from the plant and are then called avirulence (AVR proteins. This recognition usually triggers defense responses including the hypersensitive response and results in resistance of the plant. R—AVR gene interactions are frequently exploited in the field to control diseases. Recently, the availability of fungal genomes has accelerated the identification of AVR genes in plant pathogenic fungi, including in fungi infecting agronomically important crops. While single AVR genes recognized by their corresponding R gene were identified, more and more complex interactions between AVR and R genes are reported (e.g., AVR genes recognized by several R genes, R genes recognizing several AVR genes in distinct organisms, one AVR gene suppressing recognition of another AVR gene by its corresponding R gene, two cooperating R genes both necessary to recognize an AVR gene. These complex interactions were particularly reported in pathosystems showing a long co-evolution with their host plant but could also result from the way agronomic crops were obtained and improved (e.g., through interspecific hybridization or introgression of resistance genes from wild related species into cultivated crops. In this review, we describe some complex R—AVR interactions between plants and fungi that were recently reported and discuss their implications for AVR gene evolution and R gene management.
Conde, M F; Boynton, J E; Gillham, N W; Harris, E H; Tingle, C L; Wang, W L
Six chloroplast gene mutants of Chlamydomonas reinhardtii resistant to spectinomycin, erythromycin, or streptomycin have been assessed for antibiotic resistance of their chloroplast ribosomes. Four of these mutations clearly confer high levels of antibiotic resistance on the chloroplast ribosomes both in vivo. Although one mutant resistant to streptomycin and one resistant to spectinomycin have chloroplast ribosomes as sensitive to antibiotics as those of wild type in vivo, these mutations can be shown to alter the wildtype sensitivity of chloroplast ribosomes in polynucleotide-directed amino acid incorporation in vitro. Genetic analysis of these six chloroplast mutants and three similar mutants (Sager, 1972), two of which have been shown to affect chloroplast ribosomes (Mets and Bogorad, 1972; Schlanger and Sager, 1974), indicates that in Chlamydomonas at least three chloroplast gene loci can affect streptomycin resistance of chloroplast ribosomes and that two can affect erythromycin resistance. The three spectinomycin-resistant mutants examined appear to be alleles at a single chloroplast gene locus, but may represent mutations at two different sites within the same gene. Unlike wild type, the streptomycin and spectinomycin resistant mutants which have chloroplast ribosomes sensitive to antibiotics in vivo, grow well in the presence of antibiotic by respiring exogenously supplied acetate as a carbon source, and have normal levels of cytochrome oxidase activity and cyanide-sensitive respiration. We conclude that mitochondrial protein synthesis in these mutants is resistant to these antibiotics, whereas in wild type it is sensitive. To explain the behavior of these two chloroplast gene mutants as well as other one-step mutants which are resistant both photosynthetically and when respiring acetate in the dark, we have postulated that a mutation in a single chloroplast gene may result in alteration of both chloroplast and mitochondrial ribosomes. Mitochondrial
PUNEET INDER TOOR
end of 5DS linked with a group of four colocated SSRs and two resistance gene analogue (RGA)-STS markers at a distance of 5.3 cM. ... and LrAc appear to be the candidate genes for marker-assisted enrichment of the wheat gene pool for rust resistance. [Toor P. I., Kaur S., Bansal ..... stocks with reduced alien chromatin.
Yan, Qiang; Cui, Xiaoxia; Su, Liming; Xu, Na; Guo, Na; Xing, Han; Dou, Daolong
Using RNAi approach, we demonstrate that GmSGT1 is an essential component in soybean against Phytophthora sojae, but not required for Rps 2 or Rps 3a-mediated resistance. Utilization of disease resistance in soybean is a major approach to combat root and stem rot disease, which is caused by Phytophthora sojae and poses a growing threat to soybean safety production. The SGT1 protein is essential for disease resistance in many plant species. Here, we analyzed and characterized functions of GmSGT1 gene family in R protein-mediated resistance and basal defense in this important crop. Five candidate genes of GmSGT1 were identified and they were grouped into three clades. Transcriptional levels of all the tested genes were highly induced upon P. sojae infection in four soybean cultivars that confer different resistant levels. Using a gene silencing system in soybean cotyledons, we demonstrated that silencing GmSGT1 genes comprised race-specific resistance in soybean lines carrying genes at the following loci for race-specific resistance to P. sojae: Rps1a, Rps1c, Rps1d, Rps1k, and Rps8. In contrast, the resistance mediated by Rps2 or Rps3a was not affected. Silencing GmSGT1 genes in cotyledons also reduced resistance to this pathogen in a moderately partial resistant cultivar. We further showed that transient overexpression of GmSGT1-1 in Nicotiana benthamiana could enhance the resistance to P. capsici. These results suggest that GmSGT1 is an essential component for soybean in resisting the pathogen and pathways of Rps-mediated disease resistance are diverse in soybean.
Rowe, Will P M; Baker-Austin, Craig; Verner-Jeffreys, David W; Ryan, Jim J; Micallef, Christianne; Maskell, Duncan J; Pearce, Gareth P
Effluents contain a diverse abundance of antibiotic resistance genes that augment the resistome of receiving aquatic environments. However, uncertainty remains regarding their temporal persistence, transcription and response to anthropogenic factors, such as antibiotic usage. We present a spatiotemporal study within a river catchment (River Cam, UK) that aims to determine the contribution of antibiotic resistance gene-containing effluents originating from sites of varying antibiotic usage to the receiving environment. Gene abundance in effluents (municipal hospital and dairy farm) was compared against background samples of the receiving aquatic environment (i.e. the catchment source) to determine the resistome contribution of effluents. We used metagenomics and metatranscriptomics to correlate DNA and RNA abundance and identified differentially regulated gene transcripts. We found that mean antibiotic resistance gene and transcript abundances were correlated for both hospital ( ρ = 0.9, two-tailed P resistance genes ( bla GES and bla OXA ) were overexpressed in all hospital effluent samples. High β-lactam resistance gene transcript abundance was related to hospital antibiotic usage over time and hospital effluents contained antibiotic residues. We conclude that effluents contribute high levels of antibiotic resistance genes to the aquatic environment; these genes are expressed at significant levels and are possibly related to the level of antibiotic usage at the effluent source. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy.
Classical breeding for virus resistance is a lengthy process and is restricted by the availability of resistance genes. Precise genome editing is a "dream technology" to improve plants for virus resistance and these tools have opened new and very promising ways to generate virus resistant plants by ...
Cubero José I
Full Text Available Abstract Background Ascochyta blight, caused by Mycosphaerella pinodes is one of the most important pea pathogens. However, little is known about the genes and mechanisms of resistance acting against M. pinodes in pea. Resistance identified so far to this pathogen is incomplete, polygenic and scarce in pea, being most common in Pisum relatives. The identification of the genes underlying resistance would increase our knowledge about M. pinodes-pea interaction and would facilitate the introgression of resistance into pea varieties. In the present study differentially expressed genes in the resistant P. sativum ssp. syriacum accession P665 comparing to the susceptible pea cv. Messire after inoculation with M. pinodes have been identified using a M. truncatula microarray. Results Of the 16,470 sequences analysed, 346 were differentially regulated. Differentially regulated genes belonged to almost all functional categories and included genes involved in defense such as genes involved in cell wall reinforcement, phenylpropanoid and phytoalexins metabolism, pathogenesis- related (PR proteins and detoxification processes. Genes associated with jasmonic acid (JA and ethylene signal transduction pathways were induced suggesting that the response to M. pinodes in pea is regulated via JA and ET pathways. Expression levels of ten differentially regulated genes were validated in inoculated and control plants using qRT-PCR showing that the P665 accession shows constitutively an increased expression of the defense related genes as peroxidases, disease resistance response protein 39 (DRR230-b, glutathione S-transferase (GST and 6a-hydroxymaackiain methyltransferase. Conclusions Through this study a global view of genes expressed during resistance to M. pinodes has been obtained, giving relevant information about the mechanisms and pathways conferring resistance to this important disease. In addition, the M. truncatula microarray represents an efficient tool to
Fondevilla, Sara; Küster, Helge; Krajinski, Franziska; Cubero, José I; Rubiales, Diego
Ascochyta blight, caused by Mycosphaerella pinodes is one of the most important pea pathogens. However, little is known about the genes and mechanisms of resistance acting against M. pinodes in pea. Resistance identified so far to this pathogen is incomplete, polygenic and scarce in pea, being most common in Pisum relatives. The identification of the genes underlying resistance would increase our knowledge about M. pinodes-pea interaction and would facilitate the introgression of resistance into pea varieties. In the present study differentially expressed genes in the resistant P. sativum ssp. syriacum accession P665 comparing to the susceptible pea cv. Messire after inoculation with M. pinodes have been identified using a M. truncatula microarray. Of the 16,470 sequences analysed, 346 were differentially regulated. Differentially regulated genes belonged to almost all functional categories and included genes involved in defense such as genes involved in cell wall reinforcement, phenylpropanoid and phytoalexins metabolism, pathogenesis- related (PR) proteins and detoxification processes. Genes associated with jasmonic acid (JA) and ethylene signal transduction pathways were induced suggesting that the response to M. pinodes in pea is regulated via JA and ET pathways. Expression levels of ten differentially regulated genes were validated in inoculated and control plants using qRT-PCR showing that the P665 accession shows constitutively an increased expression of the defense related genes as peroxidases, disease resistance response protein 39 (DRR230-b), glutathione S-transferase (GST) and 6a-hydroxymaackiain methyltransferase. Through this study a global view of genes expressed during resistance to M. pinodes has been obtained, giving relevant information about the mechanisms and pathways conferring resistance to this important disease. In addition, the M. truncatula microarray represents an efficient tool to identify candidate genes controlling resistance to M
Rosengren, Leigh B.; Waldner, Cheryl L.; Reid-Smith, Richard J.
Escherichia coli often carries linked antimicrobial resistance genes on transmissible genetic elements. Through coselection, antimicrobial use may select for unrelated but linked resistance or virulence genes. This study used unconditional statistical associations to investigate the relationships between antimicrobial resistance phenotypes and antimicrobial resistance genes in 151 E. coli isolates from healthy pigs. Phenotypic resistance to each drug was significantly associated with phenotyp...
Abril, Carlos; Brodard, Isabelle; Perreten, Vincent
New tetracycline and streptomycin resistance genes, tet(44) and ant(6)-Ib, were identified in Campylobacter fetus subsp. fetus within a transferable pathogenicity island that is typically unique to Campylobacter fetus subsp. venerealis. The 640-amino-acid tetracycline resistance determinant, Tet 44, belongs to a class of proteins that confers resistance to tetracycline and minocycline by ribosomal protection. The 286-amino-acid streptomycin resistance determinant, ANT(6)-Ib, belongs to a family of aminoglycoside nucleotidyltransferases. The resistance phenotypes were demonstrated by gene inactivation and expression. PMID:20479200
Oct 1, 2013 ... native gentamicin resistance gene, suggesting that codon optimization improved translation efficiency of the marker gene and ... to be taken into account when exogenous transgenes are expressed in Frankia cells. [Kucho K, Kakoi K, ..... gene coding for the green fluorescent protein (GFP) is a versatile ...
. The cfr gene is found in various bacteria in many geographical locations and placed on plasmids or associated with transposons. Cfr-related genes providing similar resistance have been identified in Bacillales, and now also in the pathogens Clostridium difficile and Enterococcus faecium. In addition......, the presence of the cfr gene has been detected in harbours and food markets....
There is widespread interest in monitoring the development of antibiotic resistant bacteria and antibiotic resistance genes in agriculturally impacted environments, however little is known about the relationships between bacterial community structure, and antibiotic resistance gene profiles. Cattl...
Full Text Available In recent years, more and more antibiotics have become ineffective in the treatment of bacterial nfections. The acquisition of antibiotic resistance by bacteria is associated with circulation of genes in the environment. Determinants of antibiotic resistance may be transferred to pathogenic bacteria. It has been shown that conjugation is one of the key mechanisms responsible for spread of antibiotic resistance genes, which is highly efficient and allows the barrier to restrictions and modifications to be avoided. Some conjugative modules enable the transfer of plasmids even between phylogenetically distant bacterial species. Many scientific reports indicate that food is one of the main reservoirs of these genes. Antibiotic resistance genes have been identified in meat products, milk, fruits and vegetables. The reason for such a wide spread of antibiotic resistance genes is the overuse of antibiotics by breeders of plants and animals, as well as by horizontal gene transfer. It was shown, that resistance determinants located on mobile genetic elements, which are isolated from food products, can easily be transferred to another niche. The antibiotic resistance genes have been in the environment for 30 000 years. Their removal from food products is not possible, but the risks associated with the emergence of multiresistant pathogenic strains are very large. The only option is to control the emergence, selection and spread of these genes. Therefore measures are sought to prevent horizontal transfer of genes. Promising concepts involve the combination of developmental biology, evolution and ecology in the fight against the spread of antibiotic resistance.
Godziszewska, Jolanta; Guzek, Dominika; Głąbski, Krzysztof; Wierzbicka, Agnieszka
In recent years, more and more antibiotics have become ineffective in the treatment of bacterial nfections. The acquisition of antibiotic resistance by bacteria is associated with circulation of genes in the environment. Determinants of antibiotic resistance may be transferred to pathogenic bacteria. It has been shown that conjugation is one of the key mechanisms responsible for spread of antibiotic resistance genes, which is highly efficient and allows the barrier to restrictions and modifications to be avoided. Some conjugative modules enable the transfer of plasmids even between phylogenetically distant bacterial species. Many scientific reports indicate that food is one of the main reservoirs of these genes. Antibiotic resistance genes have been identified in meat products, milk, fruits and vegetables. The reason for such a wide spread of antibiotic resistance genes is the overuse of antibiotics by breeders of plants and animals, as well as by horizontal gene transfer. It was shown, that resistance determinants located on mobile genetic elements, which are isolated from food products, can easily be transferred to another niche. The antibiotic resistance genes have been in the environment for 30 000 years. Their removal from food products is not possible, but the risks associated with the emergence of multiresistant pathogenic strains are very large. The only option is to control the emergence, selection and spread of these genes. Therefore measures are sought to prevent horizontal transfer of genes. Promising concepts involve the combination of developmental biology, evolution and ecology in the fight against the spread of antibiotic resistance.
Locke, Jeffrey B; Zuill, Douglas E; Scharn, Caitlyn R; Deane, Jennifer; Sahm, Daniel F; Denys, Gerald A; Goering, Richard V; Shaw, Karen J
The Cfr methyltransferase confers resistance to six classes of drugs which target the peptidyl transferase center of the 50S ribosomal subunit, including some oxazolidinones, such as linezolid (LZD). The mobile cfr gene was identified in European veterinary isolates from the late 1990s, although the earliest report of a clinical cfr-positive strain was the 2005 Colombian methicillin-resistant Staphylococcus aureus (MRSA) isolate CM05. Here, through retrospective analysis of LZD(r) clinical strains from a U.S. surveillance program, we identified a cfr-positive MRSA isolate, 1128105, from January 2005, predating CM05 by 5 months. Molecular typing of 1128105 revealed a unique pulsed-field gel electrophoresis (PFGE) profile most similar to that of USA100, spa type t002, and multilocus sequence type 5 (ST5). In addition to cfr, LZD resistance in 1128105 is partially attributed to the presence of a single copy of the 23S rRNA gene mutation T2500A. Transformation of the ∼37-kb conjugative p1128105 cfr-bearing plasmid from 1128105 into S. aureus ATCC 29213 background strains was successful in recapitulating the Cfr antibiogram, as well as resistance to aminoglycosides and trimethoprim. A 7-kb cfr-containing region of p1128105 possessed sequence nearly identical to that found in the Chinese veterinary Proteus vulgaris isolate PV-01 and in U.S. clinical S. aureus isolate 1900, although the presence of IS431-like sequences is unique to p1128105. The cfr gene environment in this early clinical cfr-positive isolate has now been identified in Gram-positive and Gram-negative strains of clinical and veterinary origin and has been associated with multiple mobile elements, highlighting the versatility of this multidrug resistance gene and its potential for further dissemination. Copyright © 2014, American Society for Microbiology. All Rights Reserved.
Burt, Andrew J.; William, H. Manilal; Perry, Gregory; Khanal, Raja; Pauls, K. Peter; Kelly, James D.; Navabi, Alireza
Anthracnose, caused by Colletotrichum lindemuthianum, is an important fungal disease of common bean (Phaseolus vulgaris). Alleles at the Co–4 locus confer resistance to a number of races of C. lindemuthianum. A population of 94 F4:5 recombinant inbred lines of a cross between resistant black bean genotype B09197 and susceptible navy bean cultivar Nautica was used to identify markers associated with resistance in bean chromosome 8 (Pv08) where Co–4 is localized. Three SCAR markers with known linkage to Co–4 and a panel of single nucleotide markers were used for genotyping. A refined physical region on Pv08 with significant association with anthracnose resistance identified by markers was used in BLAST searches with the genomic sequence of common bean accession G19833. Thirty two unique annotated candidate genes were identified that spanned a physical region of 936.46 kb. A majority of the annotated genes identified had functional similarity to leucine rich repeats/receptor like kinase domains. Three annotated genes had similarity to 1, 3-β-glucanase domains. There were sequence similarities between some of the annotated genes found in the study and the genes associated with phosphoinositide-specific phosphilipases C associated with Co-x and the COK–4 loci found in previous studies. It is possible that the Co–4 locus is structured as a group of genes with functional domains dominated by protein tyrosine kinase along with leucine rich repeats/nucleotide binding site, phosphilipases C as well as β-glucanases. PMID:26431031
Gong, L; Hulke, B S; Gulya, T J; Markell, S G; Qi, L L
Sunflower production in North America has recently suffered economic losses in yield and seed quality from sunflower rust (Puccinia helianthi Schwein.) because of the increasing incidence and lack of resistance to new rust races. RHA 464, a newly released sunflower male fertility restorer line, is resistant to both of the most predominant and most virulent rust races identified in the Northern Great Plains of the USA. The gene conditioning rust resistance in RHA 464 originated from wild Helianthus annuus L., but has not been molecularly marked or determined to be independent from other rust loci. The objectives of this study are to identify molecular markers linked to the rust resistance gene and to investigate the allelism of this gene with the unmapped rust resistance genes present in HA-R6, HA-R8 and RHA 397. Virulence phenotypes of seedlings for the F(2) population and F(2:3) families suggested that a single dominant gene confers rust resistance in RHA 464, and this gene was designated as R(12). Bulked segregant analysis identified ten markers polymorphic between resistant and susceptible bulks. In subsequent genetic mapping, the ten markers covered 33.4 cM of genetic distance on linkage group 11 of sunflower. A co-dominant marker CRT275-11 is the closest marker distal to R(12) with a genetic distance of 1.0 cM, while ZVG53, a dominant marker linked in the repulsion phase, is proximal to R(12) with a genetic distance of 9.6 cM. The allelism test demonstrated that R(12) is not allelic to the rust resistance genes in HA-R6, HA-R8 and RHA 397, and it is also not linked to any previously mapped rust resistance genes. Discovery of the R(12) novel rust resistance locus in sunflower and associated markers will potentially support the molecular marker-assisted introgression and pyramiding of R(12) into sunflower breeding lines.
Qamar, M.; Ahmad, S.D.; Rabbani, M.A.; Shinwari, Z.K.
Stripe and leaf rusts are the major constraints to bread wheat production in Pakistan. Molecular markers were used to investigate the presence of leaf rust and stripe rust resistance gene cluster Lr34/Yr18 and stem rust resistance gene Sr2 in 52 Pakistani bread wheat cultivars/lines. PCR amplification of DNA fragments using DNA marker csLV-34 showed that 13 of the studied cultivars/lines, namely 03FJ26, NR 337, NR 339, NR 347, NR 350, Manthar, Margalla 99, Iqbal 2000, Saleem 2000, Wafaq 2001, Marwat 2001, Pirsabak 2004 and Fareed 2006 carry leaf rust and stripe rust resistance genes Lr34/Yr18. Stem rust resistance gene Sr2 was observed in 36 Pakistani spring wheat cultivars/lines using stm560.3tgag marker. The slow rusting gene Sr2 needs to be combined with additional stem rust resistance genes to establish durable resistance against Ug99 in modern wheat cultivars. Low frequency of Lr34/Yr18 was found in Pakistani wheats. This gene cluster needs to be incorporated into Pakistani wheats for durable rust resistance. (author)
Xu, Lei; Yang, Huan; Gao, Yang; Chen, Zeyu; Xie, Liangfu; Liu, Yulin; Liu, Ying; Wang, Xiaobao; Li, Hanwei; Lai, Weifeng; He, Yuan; Yao, Anzhi; Ma, Liying; Shao, Yiming; Zhang, Bin; Wang, Chengyan; Chen, Hu; Deng, Hongkui
Transplantation of hematopoietic stem cells (HSCs) with a naturally occurring CCR5 mutation confers a loss of detectable HIV-1 in the patient, making ablation of the CCR5 gene in HSCs an ideal therapy for an HIV-1 cure. Although CCR5 disruption has been attempted in CD4 + T cells and hematopoietic stem/progenitor cells (HSPCs), efficient gene editing with high specificity and long-term therapeutic potential remains a major challenge for clinical translation. Here, we established a CRISPR/Cas9 gene editing system in human CD34 + HSPCs and achieved efficient CCR5 ablation evaluated in long-term reconstituted NOD/Prkdc scid /IL-2Rγ null mice. The CCR5 disruption efficiency in our system remained robust in secondary transplanted repopulating hematopoietic cells. More importantly, an HIV-1 resistance effect was observed as indicated by significant reduction of virus titration and enrichment of human CD4 + T cells. Hence, we successfully established a CRISPR/Cas9 mediated CCR5 ablating system in long-term HSCs, which confers HIV-1 resistance in vivo. Our study provides evidence for translating CCR5 gene-edited HSC transplantation for an HIV cure to the clinic. Copyright © 2017 The American Society of Gene and Cell Therapy. Published by Elsevier Inc. All rights reserved.
Wang, Ruibai; Liu, Haican; Zhao, Xiuqin; Li, Jie; Wan, Kanglin
Azithromycin (AZM) is a clinically important antibiotic against Vibrio cholerae, especially for inhibiting V. cholerae colonisation of the intestine and for the treatment of severe cholera in children and pregnant women. An IncA/C plasmid was isolated from two high minimum inhibitory concentration (MIC) AZM-resistant V. cholerae strains of the two mainly pathogenic serogroups (O1 and O139) isolated in China. In the 172 predicted open reading frames (ORFs), 16 genes were related to antibiotic resistance, of which 5 were well-defined genes associated with macrolide resistance. The five macrolide resistance genes distributed in two clusters, mphR-mrx-mph(K) and mel-mph2, flanked by insertion sequence elements and involving two kinds of resistance mechanism. Deletion of the complete region of the two clusters deceased the AZM MIC from ≥64 µg/mL to ≤0.5 µg/mL. This IncA/C plasmid shows great ability to accumulate antibiotic resistance genes. In addition to 11 resistance genes to other antibiotics, 5 macrolide resistance genes with different function were gathered repeatedly through transposition on one plasmid. This genotype could not be simply explained by antibiotic stress applied on the host from the environment or treatment. These phosphorylases and transmembrane transporters might be involved in the transport and metabolism of other non-antibiotic substances, enabling this kind of plasmid to propagate better in the host. Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.
Nakipoğlu, Mustafa; Yilmaz, Fadime; Icgen, Bulent
Untreated wastewaters and treated effluents even after final disinfection contain antibiotic resistant bacteria and resistance genes before they are released into surface waters. A correlation between resistant bacteria and antibiotics in surface waters has been found, as have antibiotic resistance genes. Of particular interest are vancomycin-resistant enterococci harboring vanA gene that confers high level of resistance to glycopeptide antibiotics including teicoplanin. Therefore, in this study, river water samples were analysed to investigate vancomycin- and teicoplanin-resistant bacterial isolates harboring vanA gene. Out of 290, 15 surface water isolates displayed resistance to both antibiotics. These glycopeptide resistant enterococcal and non-enterococcal isolates, identified by 16S rRNA sequencing, were found to harbor vanA gene with sequence similarities of 50 % to 100 %. The presence of D-alanine-D-lactate ligase encoded by vanA gene was also shown for all vancomycin- and teicoplanin-resistant isolates through western blot analysis. Due to reuse of treated wastewater and release of untreated wastewaters to water bodies, antibiotic resistant bacteria and resistance genes are being introduced into surface waters and present human health risks. Therefore, surface waters are not only hot spots for vanA harboring enterococcal isolates but also non-enterococcal isolates due to gene dissemination and require special scientific consideration.
Rimbara, Emiko; Noguchi, Norihisa; Kawai, Takashi; Sasatsu, Masanori
Fluoroquinolone-containing regimens have been suggested as an alternate to standard triple therapy for the treatment of Helicobacter pylori infections. To determine the relationship between fluoroquinolone resistance and mutations of GyrA and GyrB in H. pylori, we exchanged the mutations at positions 87 and 91 of GyrA among fluoroquinolone-resistant clinical isolates. GyrB of a strain with no mutations in GyrA was also analyzed to identify mechanisms of resistance to norfloxacin. Natural transformation was performed using the amplified fragment of the gyrA and gyrB gene as donor DNA. The amino acid sequences of GyrA and GyrB were determined by DNA sequencing of the gyrA and gyrB genes. Norfloxacin-resistant strains which had mutations at position 87 and 91 became susceptible when the mutations were converted to the wild type. When the mutation from Asp to Asn at position 91 was exchanged to the mutation from Asn to Lys at position 87, the MIC to levofloxacin, gatifloxacin, and sitafloxacin increased. Norfloxacin-resistant strain TS132 with no mutations in GyrA but had a mutation at position 463 in GyrB. Transformants obtained by natural transformation using gyrB DNA of TS132 had a mutation at position 463 of GyrB and revealed resistant to norfloxacin and levofloxacin. Mutation from Asn to Lys at position 87 of GyrA confers higher resistance to levofloxacin and gatifloxacin than does mutation from Asp to Asn at position 91. We propose that mutation at position 463 in GyrB as a novel mechanism of fluoroquinolone resistance in H. pylori. © 2011 Blackwell Publishing Ltd.
Quintavalle, Cristina; Hindupur, Sravanth Kumar; Quagliata, Luca; Pallante, Pierlorenzo; Nigro, Cecilia; Condorelli, Gerolama; Andersen, Jesper Bøje; Tagscherer, Katrin Elisabeth; Roth, Wilfried; Beguinot, Francesco; Heim, Markus Hermann; Ng, Charlotte Kiu Yan; Piscuoglio, Salvatore; Matter, Matthias Sebastian
Hepatocellular carcinoma (HCC) is the third-leading cause of cancer-related death with limited treatment options and frequent resistance to sorafenib, the only drug currently approved for first-line therapy. Therefore, better understanding of HCC tumor biology and its resistance to treatment is urgently needed. Here, we analyzed the role of phosphoprotein enriched in diabetes (PED) in HCC. PED has been shown to regulate cell proliferation, apoptosis and migration in several types of cancer. However, its function in HCC has not been addressed yet. Our study revealed that both transcript and protein levels of PED were significantly high in HCC compared with non-tumoral tissue. Clinico-pathological correlation revealed that PED high HCCs showed an enrichment of gene signatures associated with metastasis and poor prognosis. Further, we observed that PED overexpression elevated the migration potential and PED silencing the decreased migration potential in liver cancer cell lines without effecting cell proliferation. Interestingly, we found that PED expression was regulated by a hepatocyte specific nuclear factor, HNF4α. A reduction of HNF4α induced an increase in PED expression and consequently, promoted cell migration in vitro. Finally, PED reduced the antitumoral effect of sorafenib by inhibiting caspase-3/7 activity. In conclusion, our data suggest that PED has a prominent role in HCC biology. It acts particularly on promoting cell migration and confers resistance to sorafenib treatment. PED may be a novel target for HCC therapy and serve as a predictive marker for treatment response against sorafenib.
Full Text Available This study investigated fates of nine antibiotic-resistant bacteria as well as two series of antibiotic resistance genes in wastewater treated by various doses of chlorine (0, 15, 30, 60, 150 and 300 mg Cl2 min/L. The results indicated that chlorination was effective in inactivating antibiotic-resistant bacteria. Most bacteria were inactivated completely at the lowest dose (15 mg Cl2 min/L. By comparison, sulfadiazine- and erythromycin-resistant bacteria exhibited tolerance to low chlorine dose (up to 60 mg Cl2 min/L. However, quantitative real-time PCRs revealed that chlorination decreased limited erythromycin or tetracycline resistance genes, with the removal levels of overall erythromycin and tetracycline resistance genes at 0.42 ± 0.12 log and 0.10 ± 0.02 log, respectively. About 40% of erythromycin-resistance genes and 80% of tetracycline resistance genes could not be removed by chlorination. Chlorination was considered not effective in controlling antimicrobial resistance. More concern needs to be paid to the potential risk of antibiotic resistance genes in the wastewater after chlorination.
Yuan, Qing-Bin; Guo, Mei-Ting; Yang, Jian
This study investigated fates of nine antibiotic-resistant bacteria as well as two series of antibiotic resistance genes in wastewater treated by various doses of chlorine (0, 15, 30, 60, 150 and 300 mg Cl2 min/L). The results indicated that chlorination was effective in inactivating antibiotic-resistant bacteria. Most bacteria were inactivated completely at the lowest dose (15 mg Cl2 min/L). By comparison, sulfadiazine- and erythromycin-resistant bacteria exhibited tolerance to low chlorine dose (up to 60 mg Cl2 min/L). However, quantitative real-time PCRs revealed that chlorination decreased limited erythromycin or tetracycline resistance genes, with the removal levels of overall erythromycin and tetracycline resistance genes at 0.42 ± 0.12 log and 0.10 ± 0.02 log, respectively. About 40% of erythromycin-resistance genes and 80% of tetracycline resistance genes could not be removed by chlorination. Chlorination was considered not effective in controlling antimicrobial resistance. More concern needs to be paid to the potential risk of antibiotic resistance genes in the wastewater after chlorination.
Miller, Jennifer H.; Novak, John T.; Knocke, William R.; Pruden, Amy
Understanding fate of antibiotic resistant bacteria (ARB) versus their antibiotic resistance genes (ARGs) during wastewater sludge treatment is critical in order to reduce the spread of antibiotic resistance through process optimization. Here, we spiked high concentrations of tetracycline-resistant bacteria, isolated from mesophilic (Iso M1-1- a Pseudomonas sp.) and thermophilic (Iso T10- a Bacillus sp.) anaerobic digested sludge, into batch digesters and monitored their fate by plate counts ...
Fierros-Romero, Grisel; Wrosek-Cabrera, José A; Gómez-Ramírez, Marlenne; Pless, Reynaldo C; Rivas-Castillo, A M; Rojas-Avelizapa, Norma G
Microbacterium liquefaciens MNSH2-PHGII-2 is a nickel-vanadium-resistant bacterium isolated from mine tailings located in Guanajuato, Mexico. In PHGII liquid media, M. liquefaciens has the ability to remove 29.5 ppm of Ni and 168.3 ppm of V. The present study reports, for the first time in M. liquefaciens, the presence of the genes nccA (Ni-Co-Cd resistance), hant (high-affinity nickel transporter), smtA, a metal-binding protein gene, and VAN2 (V resistance), which showed an increased expression under exposure to 200 ppm of Ni and 200 ppm of V during the logarithmic growth phase of the microorganism in PHGII liquid media. Data about the expression profile of genes conferring metal resistance to M. liquefaciens can improve the knowledge of those mechanisms involved in the processes of Ni-V resistance and probably in Ni-V removal processes. Based on our data, we can suggest that M. liquefaciens has the potential to be used in the biological treatment of toxic wastes with high Ni and V content.
Tao, Bo; Shao, Bai-Hui; Qiao, Yu-Xin; Wang, Xiao-Qin; Chang, Shu-Jun; Qiu, Li-Juan
Glyphosate is a widely used broad spectrum herbicide; however, this limits its use once crops are planted. If glyphosate-resistant crops are grown, glyphosate can be used for weed control in crops. While several glyphosate resistance genes are used in commercial glyphosate tolerant crops, there is interest in identifying additional genes for glyphosate tolerance. This research constructed a high-quality cDNA library form the glyphosate-resistant fungus Aspergillus oryzae RIB40 to identify genes that may confer resistance to glyphosate. Using a medium containing glyphosate (120mM), we screened several clones from the library. Based on a nucleotide sequence analysis, we identified a gene of unknown function (GenBank accession number: XM_001826835.2) that encoded a hypothetical 344-amino acid protein. The gene was named MFS40. Its ORF was amplified to construct an expression vector, pGEX-4T-1-MFS40, to express the protein in Escherichia coli BL21. The gene conferred glyphosate tolerance to E. coli ER2799 cells. Copyright © 2017 Elsevier B.V. All rights reserved.
Versluis, Dennis; de Evgrafov, Mari Cristina Rodriguez; Sommer, Morten Otto Alexander
Wide application of antibiotics has contributed to the evolution of multi-drug resistant human pathogens, resulting in poorer treatment outcomes for infections. In the marine environment, seawater samples have been investigated as a resistance reservoir; however, no studies have methodically...... examined sponges as a reservoir of antibiotic resistance. Sponges could be important in this respect because they often contain diverse microbial communities that have the capacity to produce bioactive metabolites. Here, we applied functional metagenomics to study the presence and diversity of functional......). Fifteen of 37 inserts harbored resistance genes that shared resistance gene could be identified with high confidence, in which case we predicted resistance to be mainly mediated by antibiotic efflux. One marine-specific ampicillin-resistance...
Schwaiger, Karin; Bauer, Johann; Hörmansdorfer, Stefan; Mölle, Gabriele; Preikschat, Petra; Kämpf, Peter; Bauer-Unkauf, Ilse; Bischoff, Meike; Hölzel, Christina
Ampicillin and vancomycin are important antibiotics for the therapy of Enterococcus faecalis infections. The ampicillin resistance gene pbp5 is intrinsic in Enterococcus faecium. The vanC1 gene confers resistance to vancomycin and serves as a species marker for Enterococcus gallinarum. Both genes are chromosomally located. Resistance to ampicillin and vancomycin was determined in 484 E. faecalis of human and porcine origin by microdilution. Since E. faecalis are highly skilled to acquire resistance genes, all strains were investigated for the presence of pbp5 (and, in positive strains, for the penicillin-binding protein synthesis repressor gene psr) and vanC1 (and, in positive strains, for vanXYc and vanT) by using polymerase chain reaction (PCR). One porcine and one human isolate were phenotypically resistant to ampicillin; no strain was vancomycin resistant. Four E. faecalis (3/1 of porcine/human origin) carried pbp5 (MIC=1 mg/L), and four porcine strains were vanC1 positive (minimum inhibitory concentration [MIC]=1 mg/L). Real-time reverse transcriptase (RT)-PCR revealed that the genes were not expressed. The psr gene was absent in the four pbp5-positive strains; the vanXYc gene was absent in the four vanC1-positive strains. However, vanT of the vanC gene cluster was detected in two vanC1-positive strains. To our knowledge, this is the first report on the presence of pbp5, identical with the "E. faecium pbp5 gene," and of vanC1/vanT in E. faecalis. Even if resistance is not expressed in these strains, this study shows that E. faecalis have a strong ability to acquire resistance genes-and potentially to spread them to other bacteria. Therefore, close monitoring of this species should be continued.
Yu, Guotai; Zhang, Qijun; Friesen, Timothy L; Rouse, Matthew N; Jin, Yue; Zhong, Shaobin; Rasmussen, Jack B; Lagudah, Evans S; Xu, Steven S
Mapping studies confirm that resistance to Ug99 race of stem rust pathogen in Aegilops tauschii accession Clae 25 is conditioned by Sr46 and markers linked to the gene were developed for marker-assisted selection. The race TTKSK (Ug99) of Puccinia graminis f. sp. tritici, the causal pathogen for wheat stem rust, is considered as a major threat to global wheat production. To address this threat, researchers across the world have been devoted to identifying TTKSK-resistant genes. Here, we report the identification and mapping of a stem rust resistance gene in Aegilops tauschii accession CIae 25 that confers resistance to TTKSK and the development of molecular markers for the gene. An F2 population of 710 plants from an Ae. tauschii cross CIae 25 × AL8/78 were first evaluated against race TPMKC. A set of 14 resistant and 116 susceptible F2:3 families from the F2 plants were then evaluated for their reactions to TTKSK. Based on the tests, 179 homozygous susceptible F2 plants were selected as the mapping population to identify the simple sequence repeat (SSR) and sequence tagged site (STS) markers linked to the gene by bulk segregant analysis. A dominant stem rust resistance gene was identified and mapped with 16 SSR and five new STS markers to the deletion bin 2DS5-0.47-1.00 of chromosome arm 2DS in which Sr46 was located. Molecular marker and stem rust tests on CIae 25 and two Ae. tauschii accessions carrying Sr46 confirmed that the gene in CIae 25 is Sr46. This study also demonstrated that Sr46 is temperature-sensitive being less effective at low temperatures. The marker validation indicated that two closely linked markers Xgwm210 and Xwmc111 can be used for marker-assisted selection of Sr46 in wheat breeding programs.
Barbary, Arnaud; Djian-Caporalino, Caroline; Palloix, Alain; Castagnone-Sereno, Philippe
Root-knot nematodes (RKNs) heavily damage most solanaceous crops worldwide. Fortunately, major resistance genes are available in a number of plant species, and their use provides a safe and economically relevant strategy for RKN control. From a structural point of view, these genes often harbour NBS-LRR motifs (i.e. a nucleotide binding site and a leucine rich repeat region near the carboxy terminus) and are organised in syntenic clusters in solanaceous genomes. Their introgression from wild to cultivated plants remains a challenge for breeders, although facilitated by marker-assisted selection. As shown with other pathosystems, the genetic background into which the resistance genes are introgressed is of prime importance to both the expression of the resistance and its durability, as exemplified by the recent discovery of quantitative trait loci conferring quantitative resistance to RKNs in pepper. The deployment of resistance genes at a large scale may result in the emergence and spread of virulent nematode populations able to overcome them, as already reported in tomato and pepper. Therefore, careful management of the resistance genes available in solanaceous crops is crucial to avoid significant reduction in the duration of RKN genetic control in the field. From that perspective, only rational management combining breeding and cultivation practices will allow the design and implementation of innovative, sustainable crop production systems that protect the resistance genes and maintain their durability. © 2015 Society of Chemical Industry.
Mercer, Ryan; Nguyen, Oanh; Ou, Qixing; McMullen, Lynn; Gänzle, Michael G
The locus of heat resistance (LHR) is a 15- to 19-kb genomic island conferring exceptional heat resistance to organisms in the family Enterobacteriaceae , including pathogenic strains of Salmonella enterica and Escherichia coli The complement of LHR-comprising genes that is necessary for heat resistance and the stress-induced or growth-phase-induced expression of LHR-comprising genes are unknown. This study determined the contribution of the seven LHR-comprising genes yfdX1 GI , yfdX2 , hdeD GI , orf11 , trx GI , kefB , and psiE GI by comparing the heat resistances of E. coli strains harboring plasmid-encoded derivatives of the different LHRs in these genes. (Genes carry a subscript "GI" [genomic island] if an ortholog of the same gene is present in genomes of E. coli ) LHR-encoded heat shock proteins sHSP20, ClpK GI , and sHSP GI are not sufficient for the heat resistance phenotype; YfdX1, YfdX2, and HdeD are necessary to complement the LHR heat shock proteins and to impart a high level of resistance. Deletion of trx GI , kefB , and psiE GI from plasmid-encoded copies of the LHR did not significantly affect heat resistance. The effect of the growth phase and the NaCl concentration on expression from the putative LHR promoter p2 was determined by quantitative reverse transcription-PCR and by a plasmid-encoded p2:GFP promoter fusion. The expression levels of exponential- and stationary-phase E. coli cells were not significantly different, but the addition of 1% NaCl significantly increased LHR expression. Remarkably, LHR expression in E. coli was dependent on a chromosomal copy of evgA In conclusion, this study improved our understanding of the genes required for exceptional heat resistance in E. coli and factors that increase their expression in food. IMPORTANCE The locus of heat resistance (LHR) is a genomic island conferring exceptional heat resistance to several foodborne pathogens. The exceptional level of heat resistance provided by the LHR questions the
Teixeira, Bertinellys; Rodulfo, Hectorina; Carreño, Numirin; Guzmán, Militza; Salazar, Elsa; De Donato, Marcos
The enzymatic modification of aminoglycosides by aminoglycoside-acetyltransferases (AAC), aminoglycoside-adenyltransferases (AAD), and aminoglycoside-phosphotransferases (APH), is the most common resistance mechanism in P. aeruginosa and these enzymes can be coded on mobile genetic elements that contribute to their dispersion. One hundred and thirty seven P. aeruginosa isolates from the University Hospital, Cumana, Venezuela (HUAPA) were evaluated. Antimicrobial susceptibility was determined by the disk diffusion method and theaac, aadB and aph genes were detected by PCR. Most of the P. aeruginosa isolates (33/137) were identified from the Intensive Care Unit (ICU), mainly from discharges (96/137). The frequency of resistant P. aeruginosaisolates was found to be higher for the aminoglycosides tobramycin and amikacin (30.7 and 29.9%, respectively). Phenotype VI, resistant to these antibiotics, was the most frequent (14/49), followed by phenotype I, resistant to all the aminoglycosides tested (12/49). The aac(6´)-Ib,aphA1 and aadB genes were the most frequently detected, and the simultaneous presence of several resistance genes in the same isolate was demonstrated. Aminoglycoside resistance in isolates ofP. aeruginosa at the HUAPA is partly due to the presence of the aac(6´)-Ib, aphA1 andaadB genes, but the high rates of antimicrobial resistance suggest the existence of several mechanisms acting together. This is the first report of aminoglycoside resistance genes in Venezuela and one of the few in Latin America.
Marathe, Nachiket P; Pal, Chandan; Gaikwad, Swapnil S; Jonsson, Viktor; Kristiansson, Erik; Larsson, D G Joakim
Efficient sewage treatment is critical for limiting environmental transmission of antibiotic-resistant bacteria. In many low and middle income countries, however, large proportions of sewage are still released untreated into receiving water bodies. In-depth knowledge of how such discharges of untreated urban waste influences the environmental resistome is largely lacking. Here, we highlight the impact of uncontrolled discharge of partially treated and/or untreated wastewater on the structure of bacterial communities and resistome of sediments collected from Mutha river flowing through Pune city in India. Using shotgun metagenomics, we found a wide array (n = 175) of horizontally transferable antibiotic resistance genes (ARGs) including carbapenemases such as NDM, VIM, KPC, OXA-48 and IMP types. The relative abundance of total ARGs was 30-fold higher in river sediments within the city compared to upstream sites. Forty four ARGs, including the tet(X) gene conferring resistance to tigecycline, OXA-58 and GES type carbapenemases, were significantly more abundant in city sediments, while two ARGs were more common at upstream sites. The recently identified mobile colistin resistance gene mcr-1 was detected only in one of the upstream samples, but not in city samples. In addition to ARGs, higher abundances of various mobile genetic elements were found in city samples, including integron-associated integrases and ISCR transposases, as well as some biocide/metal resistance genes. Virulence toxin genes as well as bacterial genera comprising many pathogens were more abundant here; the genus Acinetobacter, which is often associated with multidrug resistance and nosocomial infections, comprised up to 29% of the 16S rRNA reads, which to our best knowledge is unmatched in any other deeply sequenced metagenome. There was a strong correlation between the abundance of Acinetobacter and the OXA-58 carbapenemase gene. Our study shows that uncontrolled discharge of untreated urban
Full Text Available Plant genetic engineering is a powerful tool for producing crops resistant to pests, diseases and abiotic stress or crops with improved nutritional value or better quality products. Currently over 70 genetically modified (GM crops have been approved for use in different countries. These cover a wide range of plant species with significant number of different modified traits. However, beside the technology used for their improvement, the common component of most GM crops is the neomycin phosphotransferase II gene (nptII, which confers resistance to the antibiotics kanamycin and neomycin. The nptII gene is present in GM crops as a marker gene to select transformed plant cells during the first steps of the transformation process. The use of antibiotic-resistance genes is subject to controversy and intense debate, because of the likelihood that clinical therapy could be compromised due to inactivation of the oral dose of the antibiotic from consumption of food derived from the transgenic plant, and because of the risk of gene transfer from plants to gut and soil microorganisms or to consumer’s cells. The present article discusses these possibilities in the light of current scientific knowledge.
Su, Jian Qiang; Wei, Bei; Xu, Chun Yan; Qiao, Min; Zhu, Yong Guan
Soil has been regarded as a rich source of antibiotic resistance genes (ARGs) due to the complex microbial community and diverse antibiotic-producing microbes in soil, however, little is known about the ARGs in unculturable bacteria. To investigate the diversity and distribution of ARGs in soil and assess the impact of agricultural practice on the ARGs, we screened soil metagenomic library constructed using DNA from four different agricultural soil for ARGs. We identified 45 clones conferring resistance to minocycline, tetracycline, streptomycin, gentamicin, kanamycin, amikacin, chloramphenicol and rifampicin. The similarity of identified ARGs with the closest protein in GenBank ranged from 26% to 92%, with more than 60% of identified ARGs had low similarity less than 60% at amino acid level. The identified ARGs include aminoglycoside acetyltransferase, aminoglycoside 6-adenyltransferase, ADP-ribosyl transferase, ribosome protection protein, transporters and other antibiotic resistant determinants. The identified ARGs from the soil with manure application account for approximately 70% of the total ARGs in this study, implying that manure amendment may increase the diversity of antibiotic resistance genes in soil bacteria. These results suggest that antibiotic resistance in soil remains unexplored and functional metagenomic approach is powerful in discovering novel ARGs and resistant mechanisms. Copyright © 2013 Elsevier Ltd. All rights reserved.
Zacharia, Vineetha M; Manzanillo, Paolo S; Nair, Vidhya R; Marciano, Denise K; Kinch, Lisa N; Grishin, Nick V; Cox, Jeffery S; Shiloh, Michael U
Tuberculosis, caused by Mycobacterium tuberculosis, remains a devastating human infectious disease, causing two million deaths annually. We previously demonstrated that M. tuberculosis induces an enzyme, heme oxygenase (HO1), that produces carbon monoxide (CO) gas and that M. tuberculosis adapts its transcriptome during CO exposure. We now demonstrate that M. tuberculosis carries a novel resistance gene to combat CO toxicity. We screened an M. tuberculosis transposon library for CO-susceptible mutants and found that disruption of Rv1829 (carbon monoxide resistance, Cor) leads to marked CO sensitivity. Heterologous expression of Cor in Escherichia coli rescued it from CO toxicity. Importantly, the virulence of the cor mutant is attenuated in a mouse model of tuberculosis. Thus, Cor is necessary and sufficient to protect bacteria from host-derived CO. Taken together, this represents the first report of a role for HO1-derived CO in controlling infection of an intracellular pathogen and the first identification of a CO resistance gene in a pathogenic organism. Macrophages produce a variety of antimicrobial molecules, including nitric oxide (NO), hydrogen peroxide (H2O2), and acid (H+), that serve to kill engulfed bacteria. In addition to these molecules, human and mouse macrophages also produce carbon monoxide (CO) gas by the heme oxygenase (HO1) enzyme. We observed that, in contrast to other bacteria, mycobacteria are resistant to CO, suggesting that this might be an evolutionary adaptation of mycobacteria for survival within macrophages. We screened a panel of ~2,500 M. tuberculosis mutants to determine which genes are required for survival of M. tuberculosis in the presence of CO. Within this panel, we identified one such gene, cor, that specifically confers CO resistance. Importantly, we found that the ability of M. tuberculosis cells carrying a mutated copy of this gene to cause tuberculosis in a mouse disease model is significantly attenuated. This indicates that
Liu, M; Kirpekar, F; Van Wezel, G P
tlrB is one of four resistance genes encoded in the operon for biosynthesis of the macrolide tylosin in antibiotic-producing strains of Streptomyces fradiae. Introduction of tlrB into Streptomyces lividans similarly confers tylosin resistance. Biochemical analysis of the rRNA from the two......, indicating that TlrB is the first member to be described in a new subclass of rRNA methyltransferases that are implicated in macrolide drug resistance....
Kilian, A; Steffenson, B J; Saghai Maroof, M A; Kleinhofs, A
The gene, Rpg1, conferring stable resistance in barley to the wheat stem rust pathogen (Puccinia graminis f. sp. tritici) was mapped using two doubled haploid populations. Rpg1 mapped to the extreme subteleomeric region of barley chromosome 1P 0.3 and 1.1 cM proximal from the molecular markers ABG704 and plastocyanin (Plc), respectively, and 2.2 cM distal from MWG036B. The closest marker, ABG704, was sequenced and PCR-based markers were developed.
Tripathi, Jaindra N; Lorenzen, Jim; Bahar, Ofir; Ronald, Pamela; Tripathi, Leena
Banana Xanthomonas wilt (BXW), caused by the bacterium Xanthomonas campestris pv. musacearum (Xcm), is the most devastating disease of banana in east and central Africa. The spread of BXW threatens the livelihood of millions of African farmers who depend on banana for food security and income. There are no commercial chemicals, biocontrol agents or resistant cultivars available to control BXW. Here, we take advantage of the robust resistance conferred by the rice pattern-recognition receptor (PRR), XA21, to the rice pathogen Xanthomonas oryzae pv. oryzae (Xoo). We identified a set of genes required for activation of Xa21-mediated immunity (rax) that were conserved in both Xoo and Xcm. Based on the conservation, we hypothesized that intergeneric transfer of Xa21 would confer resistance to Xcm. We evaluated 25 transgenic lines of the banana cultivar 'Gonja manjaya' (AAB) using a rapid bioassay and 12 transgenic lines in the glasshouse for resistance against Xcm. About 50% of the transgenic lines showed complete resistance to Xcm in both assays. In contrast, all of the nontransgenic control plants showed severe symptoms that progressed to complete wilting. These results indicate that the constitutive expression of the rice Xa21 gene in banana results in enhanced resistance against Xcm. Furthermore, this work demonstrates the feasibility of PRR gene transfer between monocotyledonous species and provides a valuable new tool for controlling the BXW pandemic of banana, a staple food for 100 million people in east Africa. © 2014 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.
Background: Classical and quantitative linkage analyses of genetic crosses have traditionally been used to map genes of interest, such as those conferring chloroquine or quinine resistance in malaria parasites. Next-generation sequencing technologies now present the possibility of determining genome-wide genetic variation at single base-pair resolution. Here, we combine in vivo experimental evolution, a rapid genetic strategy and whole genome re-sequencing to identify the precise genetic basis of artemisinin resistance in a lineage of the rodent malaria parasite, Plasmodium chabaudi. Such genetic markers will further the investigation of resistance and its control in natural infections of the human malaria, P. falciparum.Results: A lineage of isogenic in vivo drug-selected mutant P. chabaudi parasites was investigated. By measuring the artemisinin responses of these clones, the appearance of an in vivo artemisinin resistance phenotype within the lineage was defined. The underlying genetic locus was mapped to a region of chromosome 2 by Linkage Group Selection in two different genetic crosses. Whole-genome deep coverage short-read re-sequencing (IlluminaSolexa) defined the point mutations, insertions, deletions and copy-number variations arising in the lineage. Eight point mutations arise within the mutant lineage, only one of which appears on chromosome 2. This missense mutation arises contemporaneously with artemisinin resistance and maps to a gene encoding a de-ubiquitinating enzyme.Conclusions: This integrated approach facilitates the rapid identification of mutations conferring selectable phenotypes, without prior knowledge of biological and molecular mechanisms. For malaria, this model can identify candidate genes before resistant parasites are commonly observed in natural human malaria populations. 2010 Hunt et al; licensee BioMed Central Ltd.
Full Text Available Abstract Background Classical and quantitative linkage analyses of genetic crosses have traditionally been used to map genes of interest, such as those conferring chloroquine or quinine resistance in malaria parasites. Next-generation sequencing technologies now present the possibility of determining genome-wide genetic variation at single base-pair resolution. Here, we combine in vivo experimental evolution, a rapid genetic strategy and whole genome re-sequencing to identify the precise genetic basis of artemisinin resistance in a lineage of the rodent malaria parasite, Plasmodium chabaudi. Such genetic markers will further the investigation of resistance and its control in natural infections of the human malaria, P. falciparum. Results A lineage of isogenic in vivo drug-selected mutant P. chabaudi parasites was investigated. By measuring the artemisinin responses of these clones, the appearance of an in vivo artemisinin resistance phenotype within the lineage was defined. The underlying genetic locus was mapped to a region of chromosome 2 by Linkage Group Selection in two different genetic crosses. Whole-genome deep coverage short-read re-sequencing (Illumina® Solexa defined the point mutations, insertions, deletions and copy-number variations arising in the lineage. Eight point mutations arise within the mutant lineage, only one of which appears on chromosome 2. This missense mutation arises contemporaneously with artemisinin resistance and maps to a gene encoding a de-ubiquitinating enzyme. Conclusions This integrated approach facilitates the rapid identification of mutations conferring selectable phenotypes, without prior knowledge of biological and molecular mechanisms. For malaria, this model can identify candidate genes before resistant parasites are commonly observed in natural human malaria populations.
Christopher C. Mundt
There is now a very long history of genetics/breeding for disease resistance in annual crops. These efforts have resulted in conceptual advances and frustrations, as well as practical successes and failures. This talk will review this history and its relevance to the genetics of resistance in forest species. All plant breeders and pathologists are familiar with boom-...
Szmolka, Ama; Lestár, Barbara; Pászti, Judit; Fekete, Péter; Nagy, Béla
Enterotoxigenic E. coli (ETEC) bacteria frequently cause watery diarrhoea in newborn and weaned pigs. Plasmids carrying genes of different enterotoxins and fimbrial adhesins, as well as plasmids conferring antimicrobial resistance are of prime importance in the epidemiology and pathogenesis of ETEC. Recent studies have revealed the significance of the porcine ETEC plasmid pTC, carrying tetracycline resistance gene tet(B) with enterotoxin genes. In contrast, the role of tet(A) plasmids in transferring resistance of porcine ETEC is less understood. The objective of the present study was to provide a comparative analysis of antimicrobial resistance and virulence gene profiles of porcine post-weaning ETEC strains representing pork-producing areas in Central Europe and in the USA, with special attention to plasmids carrying the tet(A) gene. Antimicrobial resistance phenotypes and genotypes of 87 porcine ETEC strains isolated from cases of post-weaning diarrhoea in Austria, the Czech Republic, Hungary and the Midwest USA was determined by disk diffusion and by PCR. Central European strains carrying tet(A) or tet(B) were further subjected to molecular characterisation of their tet plasmids. Results indicated that > 90% of the ETEC strains shared a common multidrug resistant (MDR) pattern of sulphamethoxazole (91%), tetracycline (84%) and streptomycin (80%) resistance. Tetracycline resistance was most frequently determined by the tet(B) gene (38%), while tet(A) was identified in 26% of all isolates with wide ranges for both tet gene types between some countries and with class 1 integrons and resistance genes co-transferred by conjugation. The virulence gene profiles included enterotoxin genes (lt, sta and/or stb), as well as adhesin genes (k88/f4, f18). Characterisation of two representative tet(A) plasmids of porcine F18(+) ETEC from Central Europe revealed that the IncF plasmid (pES11732) of the Czech strain (~120 kb) carried tet(A) in association with catA1 for
Background Generally drug resistant bacteria carry antibiotic resistance genes and heavy metal and biocide resistance genes on large conjugative plasmids. The presence of these metal and biocide resistance genes in susceptible bacteria are not assessed comprehensively. Hence, WGS data of susceptib...
Antimicrobial resistance (AMR) is an acknowledged crisis for humanity. Its genetic origins and dire potential outcomes are increasingly well understood. However, diagnostic techniques for monitoring the crisis are currently largely limited to enumerating the increasing incidence of resistant pathogens. Being the end-stage of the evolutionary process that produces antimicrobial resistant pathogens, these measurements, while diagnostic, are not prognostic, and so are not optimal in managing this crisis. A better test is required. Here, using insights from an understanding of evolutionary processes ruling the changing abundance of genes under selective pressure, we suggest a predictive framework for the AMR crisis. We then discuss the likely progression of resistance for both existing and prospective antimicrobial therapies. Finally, we suggest that by the environmental monitoring of resistance gene frequency, resistance may be detected and tracked presumptively, and how this tool may be used to guide decision-making in the local and global use of antimicrobials. PMID:27831476
Mohamed K. Fakhr
Full Text Available Studies that investigate arsenic resistance in the foodborne bacterium Campylobacter are limited. A total of 552 Campylobacter isolates (281 Campylobacter jejuni and 271 Campylobacter coli isolated from retail meat samples were subjected to arsenic resistance profiling using the following arsenic compounds: arsanilic acid (4–2,048 μg/mL, roxarsone (4–2048 μg/mL, arsenate (16–8,192 μg/mL and arsenite (4–2,048 μg/mL. A total of 223 of these isolates (114 Campylobacter jejuni and 109 Campylobacter coli were further analyzed for the presence of five arsenic resistance genes (arsP, arsR, arsC, acr3, and arsB by PCR. Most of the 552 Campylobacter isolates were able to survive at higher concentrations of arsanilic acid (512–2,048 μg/mL, roxarsone (512–2,048 μg/mL, and arsenate (128–1,024 μg/mL, but at lower concentrations for arsenite (4–16 μg/mL. Ninety seven percent of the isolates tested by PCR showed the presence of arsP and arsR genes. While 95% of the Campylobacter coli isolates contained a larger arsenic resistance operon that has all of the four genes (arsP, arsR, arsC and acr3, 85% of the Campylobacter jejuni isolates carried the short operon (arsP, and arsR. The presence of arsC and acr3 did not significantly increase arsenic resistance with the exception of conferring resistance to higher concentrations of arsenate to some Campylobacter isolates. arsB was prevalent in 98% of the tested Campylobacter jejuni isolates, regardless of the presence or absence of arsC and acr3, but was completely absent in Campylobacter coli. To our knowledge, this is the first study to determine arsenic resistance and the prevalence of arsenic resistance genes in such a large number of Campylobacter isolates.
Khanna, Apurva; Sharma, Vinay; Ellur, Ranjith K; Shikari, Asif B; Gopala Krishnan, S; Singh, U D; Prakash, G; Sharma, T R; Rathour, Rajeev; Variar, Mukund; Prashanthi, S K; Nagarajan, M; Vinod, K K; Bhowmick, Prolay K; Singh, N K; Prabhu, K V; Singh, B D; Singh, Ashok K
A set of NILs carrying major blast resistance genes in a Basmati rice variety has been developed. Also, the efficacy of pyramids over monogenic NILs against rice blast pathogen Magnaporthe oryzae has been demonstrated. Productivity and quality of Basmati rice is severely affected by rice blast disease. Major genes and QTLs conferring resistance to blast have been reported only in non-Basmati rice germplasm. Here, we report incorporation of seven blast resistance genes from the donor lines DHMASQ164-2a (Pi54, Pi1, Pita), IRBLz5-CA (Pi2), IRBLb-B (Pib), IRBL5-M (Pi5) and IRBL9-W (Pi9) into the genetic background of an elite Basmati rice variety Pusa Basmati 1 (PB1). A total of 36 near-isogenic lines (NILs) comprising of 14 monogenic, 16 two-gene pyramids and six three-gene pyramids were developed through marker-assisted backcross breeding (MABB). Foreground, recombinant and background selection was used to identify the plants with target gene(s), minimize the linkage drag and increase the recurrent parent genome (RPG) recovery (93.5-98.6 %), respectively, in the NILs. Comparative analysis performed using 50,051 SNPs and 500 SSR markers revealed that the SNPs provided better insight into the RPG recovery. Most of the monogenic NILs showed comparable performance in yield and quality, concomitantly, Pusa1637-18-7-6-20 (Pi9), was significantly superior in yield and stable across four different environments as compared to recurrent parent (RP) PB1. Further, among the pyramids, Pusa1930-12-6 (Pi2+Pi5) showed significantly higher yield and Pusa1633-7-8-53-6-8 (Pi54+Pi1+Pita) was superior in cooking quality as compared to RP PB1. The NILs carrying gene Pi9 were found to be the most effective against the concoction of virulent races predominant in the hotspot locations for blast disease. Conversely, when analyzed under artificial inoculation, three-gene pyramids expressed enhanced resistance as compared to the two-gene and monogenic NILs.
Full Text Available Based on the sequence of a resistance gene analog FZ14 derived from Zizania latifolia (Griseb., a pair of specific PCR primers FZ14P1/FZ14P2 was designed to isolate candidate disease resistance gene. The pooled-PCR approach was adopted using the primer pair to screen a genomic transformation-competent artificial chromosome (TAC library derived from Z. latifolia. A positive TAC clone (ZR1 was obtained and confirmed by sequence analysis. The results indicated that ZR1 consisted of conserved motifs similar to P-loop (kinase 1a, kinase 2, kinase 3a and GLPL (Gly-Leu-Pro-Leu, suggesting that it could be a portion of NBS-LRR type of resistance gene. Using Agrobacterium-mediated transformation of Nipponbare mature embryo, a total of 48 independent transgenic T0 plants were obtained. Among them, 36 plants were highly resistant to the virulent bacterial blight strain PXO71. The results indicate that ZR1 contains at least one functional bacterial blight resistance gene.
Ten crosses were made between resistant (R), susceptible (S), RxS susceptible and Intermediate (I), SxI and RxR bean lines to common bacterial blight. The F1 were advanced to F2 and in each cross over 250 F2 plants were used to evaluate for the number of genes controlling resistance using Mendelian genetics and ...
Prevalence, antibiotic-resistance properties and enterotoxin gene profile of Bacillus cereus strains isolated from milk-based baby foods. ... Conclusion: Considerable prevalence of resistant and toxigenic B. cereus and high consumption of milk-based infant foods in Iran, represent an important public health issue which ...
Seveno, N.; Kallifidas, D.; Smalla, K.; Elsas, van J.D.; Collard, J.M.; Karagouni, A.; Wellington, E.M.H.
Antibiotic resistance genes have become highly mobile since the development of antibiotic chemotherapy. A considerable body of evidence exists proving the link between antibiotic use and the significant increase in drug-resistant human bacterial pathogens. The application of molecular detection and
Identification of bacterial blight resistance genes Xa4 in Pakistani rice germplasm using PCR. M Arif, M Jaffar, M Babar, MA Sheikh, S Kousar, A Arif, Y Zafar. Abstract. Bacterial blight (BB) caused by Xanthomonas oryzae pv oryzae (Xoo) is a major biotic constraint in the irrigated rice belts. Genetic resistance is the most ...
Kyselková, Martina; Jirout, Jiří; Vrchotová, Naděžda; Schmitt, Heike; Elhottová, Dana
The use of antibiotics in animal husbandry contributes to the worldwide problem of increasing antibiotic resistance in animal and human pathogens. Intensive animal production is considered an important source of antibiotic resistance genes released to the environment, while the contribution of
Feb 25, 2016 ... Opposite and significant signs of dominance [d] and dominance × dominance [l] components indicated the importance of duplicate epitasis in the latter crosses in the control of GRD resistance, which revealed a complex nature of inheritance of GRD resistance. Key Words: Arachis hypogaea, gene effects, ...
Sunflower rust (Puccinia helianthi) emerged as a serious disease in the last few years. Confection sunflower is particularly vulnerable to the disease due to the lack of resistance sources. The objectives of this project are to transfer rust resistance genes from oil sunflower to confectionery sunfl...
ARC) domain, and a leucine-rich repeat (LRR) domain, all of which are typical characteristics of resistance genes. We proposed the resistance mechanism of CreV8 based on functional analysis and predictions from its conserved domains and ...
Kehrenberg, Corinna; Schwarz, Stefan
A total of 302 chloramphenicol-resistant Staphylococcus isolates were screened for the presence of the florfenicol/chloramphenicol resistance genes fexA and cfr and their localization on mobile genetic elements. Of the 114 isolates from humans, only a single Staphylococcus aureus isolate showed an elevated MIC to florfenicol, but did not carry either of the known resistance genes, cfr or fexA. In contrast, 11 of the 188 staphylococci from animal sources were considered florfenicol resistant and carried either cfr (one isolate), fexA (five isolates), or both resistance genes (five isolates). In nine cases we confirmed that these genes were carried on a plasmid. Five different types of plasmids could be differentiated on the basis of their sizes, restriction patterns, and resistance genes. The gene fexA, which has previously been shown to be part of the nonconjugative transposon Tn558, was identified in 10 of the 11 resistant isolates from animals. PCR assays were developed to detect different parts of this transposon as well as their physical linkage. Complete copies of Tn558 were found in five different isolates and shown by inverse PCR to be functionally active. Truncated copies of Tn558, in which the tnpA-tnpB area was in part deleted by the integration of a 4,674-bp segment including the gene cfr and a novel 2,446-bp IS21-like insertion sequence, were seen in a plasmid present in three staphylococcal isolates. PMID:16569824
Bossé, Janine T; Li, Yanwen; Atherton, Tom G; Walker, Stephanie; Williamson, Susanna M; Rogers, Jon; Chaudhuri, Roy R; Weinert, Lucy A; Holden, Matthew TG; Maskell, Duncan J; Tucker, Alexander W; Wren, Brendan W; Rycroft, Andrew N; Langford, Paul R
The complete nucleotide sequence of a 7.7 kb mobilisable plasmid (pM3446F), isolated from a florfenicol resistant isolate of Actinobacillus pleuropneumoniae, showed extended similarity to plasmids found in other members of the Pasteurellaceae containing the floR gene as well as replication and mobilisation genes. Mobilisation into other Pasteurellaceae species confirmed that this plasmid can be transferred horizontally. PMID:26049592
Imran, Muhammad; Asad, Shaheen; Barboza, Andre Luiz; Galeano, Esteban; Carrer, Helaine; Mukhtar, Zahid
Glyphosate quashes the synthesis of 5-enolpyruvylshikimate-3- phosphate synthase (EPSPS) enzyme which intercedes the functioning of shikimate pathway for the production of aromatic amino acids. Herbicide resistant crops are developed using glyphosate insensitive EPSPS gene isolated from Agrobacterium sp. strain CP4, which give farmers a sustainable weed control option. Intentions behind this study were to design and characterize the synthetic herbicide resistant CP4 - EPSPS gene in a model plant system and check the effectiveness of transformed tobacco against application of glyphosate. Putative transgenic plants were obtained from independent transformation events, and stable plant transformation, transgene expression and integration were demonstrated respectively by PCR, qRT-PCR and Southern hybridization. Gene transcript level and gene copy number (1-4) varied among the tested transgenic tobacco lines. Herbicide assays showed that transgenic plants were resistant to glyphosate after 12 days of spraying with glyphosate, and EPSPS activity remained at sufficient level to withstand the spray at 1000 ppm of the chemical. T 1 plants analyzed through immunoblot strips and PCR showed that the gene was being translated into protein and transmitted to the next generation successfully. This codon optimized synthetic CP4 - EPSPS gene is functionally equivalent to the gene for glyphosate resistance available in the commercial crops and hence we recommend this gene for transformation into commercial crops.
Klima, Cassidy L; Zaheer, Rahat; Cook, Shaun R; Booker, Calvin W; Hendrick, Steve; Alexander, Trevor W; McAllister, Tim A
In this study, we determined the prevalence of bovine respiratory disease (BRD)-associated viral and bacterial pathogens in cattle and characterized the genetic profiles, antimicrobial susceptibilities, and nature of antimicrobial resistance determinants in collected bacteria. Nasopharyngeal swab and lung tissue samples from 68 BRD mortalities in Alberta, Canada (n = 42), Texas (n = 6), and Nebraska (n = 20) were screened using PCR for bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus, bovine herpesvirus 1, parainfluenza type 3 virus, Mycoplasma bovis, Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni. Excepting bovine herpesvirus 1, all agents were detected. M. haemolytica (91%) and BVDV (69%) were the most prevalent, with cooccurrence in 63% of the cattle. Isolates of M. haemolytica (n = 55), P. multocida (n = 8), and H. somni (n = 10) from lungs were also collected. Among M. haemolytica isolates, a clonal subpopulation (n = 8) was obtained from a Nebraskan feedlot. All three bacterial pathogens exhibited a high rate of antimicrobial resistance, with 45% exhibiting resistance to three or more antimicrobials. M. haemolytica (n = 18), P. multocida (n = 3), and H. somni (n = 3) from Texas and Nebraska possessed integrative conjugative elements (ICE) that conferred resistance for up to seven different antimicrobial classes. ICE were shown to be transferred via conjugation from P. multocida to Escherichia coli and from M. haemolytica and H. somni to P. multocida. ICE-mediated multidrug-resistant profiles of bacterial BRD pathogens could be a major detriment to many of the therapeutic antimicrobial strategies currently used to control BRD.
Simko, Ivan; Atallah, Amy J.; Ochoa, Oswaldo E.; Antonise, Rudie; Galeano, Carlos H.; Truco, Maria Jose; Michelmore, Richard W.
Many cultivars of lettuce (Lactuca sativa L.), the most popular leafy vegetable, are susceptible to downy mildew disease caused by Bremia lactucae. Cultivars Iceberg and Grand Rapids that were released in the 18th and 19th centuries, respectively, have high levels of quantitative resistance to downy mildew. We developed a population of recombinant inbred lines (RILs) originating from a cross between these two legacy cultivars, constructed a linkage map, and identified two QTLs for resistance on linkage groups 2 (qDM2.1) and 5 (qDM5.1) that determined resistance under field conditions in California and the Netherlands. The same QTLs determined delayed sporulation at the seedling stage in laboratory experiments. Alleles conferring elevated resistance at both QTLs originate from cultivar Iceberg. An additional QTL on linkage group 9 (qDM9.1) was detected through simultaneous analysis of all experiments with mixed-model approach. Alleles for elevated resistance at this locus originate from cultivar Grand Rapids. PMID:24096732
Induced mutations are being used as a tool to study genes for resistance in wheat. It was found that Pm1 can be separated from Lr20 and Sr15, but these two react like a single pleiotropic gene. Mutants were further examined in crosses and backmutations have been attempted. (author)
Characterization of genomic sequence of a drought-resistant gene. TaSnRK2.7 in wheat species. HONG YING ZHANG1,2, WEI LI3, XIN GUO MAO1 and RUI LIAN JING1∗. 1The National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science,. Chinese Academy of Agricultural Sciences, ...
Transformation of pokeweed antiviral protein gene (PAP) into plants was shown to improve plant resistance to several viruses or fungi pathogens with no much negative effect on plant growth. The non-virulent defective PAP inhibits only the virus but does not interfere with the host. A non-virulent defective PAP gene ...
May 17, 2012 ... Cereal cyst nematode (CCN) (Heterodera avenae Woll.) is one of the most economically damaging endoparasite pests of wheat worldwide. We isolated and characterized a novel cereal CCN resistance candidate gene, CreV8, from Aegilops variabilis (2n = 28, UUSvSv). The gene was 3,568 bp long and.
Full Text Available The objective of this research was to characterize the high level of resistance to stripe that has been observed in the released wheat cultivar, Chuanmai45. A combination of classic genetic analysis, molecular and cytogenetic methods were used to characterize resistance in an F2 population derived from Chuanmai45 and the susceptible Chuanmai42. Inheritance of resistance was shown to be conferred by two genes in Chuanmai45. Fluorescence in situ hybridization (FISH was used along with segregation studies to show that one gene was located on a 1RS.1BL translocation. Molecular markers were employed to show that the other locus was located on chromosome 4B. The defeated gene, Yr24/26, on chromosome 1BL was present in the susceptible parent and lines that recombined this gene with the 1RS.1BL translocation were identified. The germplasm, loci, and associated markers identified in this study will be useful for application in breeding programs utilizing marker-assisted selection.
Mago, R; Simkova, H; Brown-Guedira, G; Dreisigacker, S; Breen, J; Jin, Y; Singh, R; Appels, R; Lagudah, E S; Ellis, J; Dolezel, J; Spielmeyer, W
The stem rust resistance gene Sr2 has provided broad-spectrum protection against stem rust (Puccinia graminis Pers. f. sp. tritici) since its wide spread deployment in wheat from the 1940s. Because Sr2 confers partial resistance which is difficult to select under field conditions, a DNA marker is desirable that accurately predicts Sr2 in diverse wheat germplasm. Using DNA sequence derived from the vicinity of the Sr2 locus, we developed a cleaved amplified polymorphic sequence (CAPS) marker that is associated with the presence or absence of the gene in 115 of 122 (95%) diverse wheat lines. The marker genotype predicted the absence of the gene in 100% of lines which were considered to lack Sr2. Discrepancies were observed in lines that were predicted to carry Sr2 but failed to show the CAPS marker. Given the high level of accuracy observed, the marker provides breeders with a selection tool for one of the most important disease resistance genes of wheat.
Bulos, Mariano; Ramos, María L; Altieri, Emiliano; Sala, Carlos A
Sunflower rust, caused by Puccinia helianthi Schw., can result in significant yield losses in cultivated sunflower (Helianthus annuus L. var. macrocarpus Ckll.). HAR6 is a germplasm population resistant to most predominant rust races. The objectives of this study were to map the resistance factor present in HAR6 (R HAR6 ), and to provide and validate molecular tools for the identification of this gene for marker assisted selection purposes. Virulence reaction of seedlings for the F2 population and F2:3 families suggested that a single dominant gene confers rust resistance in HAR6-1, a selected rust resistance line from the original population. Genetic mapping with eight markers covered 97.4 cM of genetic distance on linkage group 13 of the sunflower consensus map. A co-dominant marker ZVG61 is the closest marker distal to R HAR6 at a genetic distance of 0.7 cM, while ORS581, a dominant marker linked in the coupling phase, is proximal to R HAR6 at a genetic distance of 1.5 cM. Validation of these markers was assessed by converting a susceptible line into a rust resistant isoline by means of marker assisted backcrossing. The application of these results to assist the breeding process and to design new strategies for rust control in sunflower is discussed.
Bajgain, P; Rouse, M N; Bulli, P; Bhavani, S; Gordon, T; Wanyera, R; Njau, P N; Legesse, W; Anderson, J A; Pumphrey, M O
The recently identified Puccinia graminis f. sp. tritici (Pgt) race TTKSK (Ug99) poses a severe threat to global wheat production because of its broad virulence on several widely deployed resistance genes. Additional virulences have been detected in the Ug99 group of races, and the spread of this race group has been documented across wheat growing regions in Africa, the Middle East (Yemen), and West Asia (Iran). Other broadly virulent Pgt races, such as TRTTF and TKTTF, present further difficulties in maintaining abundant genetic resistance for their effective use in wheat breeding against this destructive fungal disease of wheat. In an effort to identify loci conferring resistance to these races, a genome-wide association study was carried out on a panel of 250 spring wheat breeding lines from the International Maize and Wheat Improvement Center (CIMMYT), six wheat breeding programs in the United States and three wheat breeding programs in Canada. The lines included in this study were grouped into two major clusters, based on the results of principal component analysis using 23,976 SNP markers. Upon screening for adult plant resistance (APR) to Ug99 during 2013 and 2014 in artificial stem rust screening nurseries at Njoro, Kenya and at Debre Zeit, Ethiopia, several wheat lines were found to exhibit APR. The lines were also screened for resistance at the seedling stage against races TTKSK, TRTTF, and TKTTF at USDA-ARS Cereal Disease Laboratory in St. Paul, Minnesota; and only 9 of the 250 lines displayed seedling resistance to all the races. Using a mixed linear model, 27 SNP markers associated with APR against Ug99 were detected, including markers linked with the known APR gene Sr2. Using the same model, 23, 86, and 111 SNP markers associated with seedling resistance against races TTKSK, TRTTF, and TKTTF were identified, respectively. These included markers linked to the genes Sr8a and Sr11 providing seedling resistance to races TRTTF and TKTTF, respectively. We
O'Neil Michael T
Full Text Available Abstract Background In order to maximize the useful therapeutic life of antimalarial drugs, it is crucial to understand the mechanisms by which parasites resistant to antimalarial drugs are selected and spread in natural populations. Recent work has demonstrated that pyrimethamine-resistance conferring mutations in Plasmodium falciparum dihydrofolate reductase (dhfr have arisen rarely de novo, but spread widely in Asia and Africa. The origin and spread of mutations in Plasmodium vivax dhfr were assessed by constructing haplotypes based on sequencing dhfr and its flanking regions. Methods The P. vivax dhfr coding region, 792 bp upstream and 683 bp downstream were amplified and sequenced from 137 contemporary patient isolates from Colombia, India, Indonesia, Papua New Guinea, Sri Lanka, Thailand, and Vanuatu. A repeat motif located 2.6 kb upstream of dhfr was also sequenced from 75 of 137 patient isolates, and mutational relationships among the haplotypes were visualized using the programme Network. Results Synonymous and non-synonymous single nucleotide polymorphisms (SNPs within the dhfr coding region were identified, as was the well-documented in-frame insertion/deletion (indel. SNPs were also identified upstream and downstream of dhfr, with an indel and a highly polymorphic repeat region identified upstream of dhfr. The regions flanking dhfr were highly variable. The double mutant (58R/117N dhfr allele has evolved from several origins, because the 58R is encoded by at least 3 different codons. The triple (58R/61M/117T and quadruple (57L/61M/117T/173F, 57I/58R/61M/117T and 57L/58R/61M/117T mutant alleles had at least three independent origins in Thailand, Indonesia, and Papua New Guinea/Vanuatu. Conclusion It was found that the P. vivax dhfr coding region and its flanking intergenic regions are highly polymorphic and that mutations in P. vivax dhfr that confer antifolate resistance have arisen several times in the Asian region. This contrasts
Full Text Available Antibiotic-resistant bacteria and genes enter the environment in different ways. The release of these factors into the environment has increased concerns related to public health. The aim of the study was to evaluate the antibiotic resistance genes (ARGs in the environmental resources. In this systematic review, the data were extracted from valid sources of information including ScienceDirect, PubMed, Google Scholar and SID. Evaluation and selection of articles were conducted on the basis of the PRISMA checklist. A total of 39 articles were included in the study, which were chosen from a total of 1249 papers. The inclusion criterion was the identification of genes encoding antibiotic resistance against the eight important groups of antibiotics determined by using the PCR technique in the environmental sources including municipal and hospital wastewater treatment plants, animal and agricultural wastes, effluents from treatment plants, natural waters, sediments, and drinking waters. In this study, 113 genes encoding antibiotic resistance to eight groups of antibiotics (beta-lactams, aminoglycosides, tetracyclines, macrolides, sulfonamides, chloramphenicol, glycopeptides and quinolones were identified in various environments. Antibiotic resistance genes were found in all the investigated environments. The investigation of microorganisms carrying these genes shows that most of the bacteria especially gram-negative bacteria are effective in the acquisition and the dissemination of these pollutants in the environment. Discharging the raw wastewaters and effluents from wastewater treatments acts as major routes in the dissemination of ARGs into environment sources and can pose hazards to public health.
Rinaldo, Amy; Gilbert, Brian; Boni, Rainer; Krattinger, Simon G; Singh, Davinder; Park, Robert F; Lagudah, Evans; Ayliffe, Michael
The hexaploid wheat (Triticum aestivum) adult plant resistance gene, Lr34/Yr18/Sr57/Pm38/Ltn1, provides broad-spectrum resistance to wheat leaf rust (Lr34), stripe rust (Yr18), stem rust (Sr57) and powdery mildew (Pm38) pathogens, and has remained effective in wheat crops for many decades. The partial resistance provided by this gene is only apparent in adult plants and not effective in field-grown seedlings. Lr34 also causes leaf tip necrosis (Ltn1) in mature adult plant leaves when grown under field conditions. This D genome-encoded bread wheat gene was transferred to tetraploid durum wheat (T. turgidum) cultivar Stewart by transformation. Transgenic durum lines were produced with elevated gene expression levels when compared with the endogenous hexaploid gene. Unlike nontransgenic hexaploid and durum control lines, these transgenic plants showed robust seedling resistance to pathogens causing wheat leaf rust, stripe rust and powdery mildew disease. The effectiveness of seedling resistance against each pathogen correlated with the level of transgene expression. No evidence of accelerated leaf necrosis or up-regulation of senescence gene markers was apparent in these seedlings, suggesting senescence is not required for Lr34 resistance, although leaf tip necrosis occurred in mature plant flag leaves. Several abiotic stress-response genes were up-regulated in these seedlings in the absence of rust infection as previously observed in adult plant flag leaves of hexaploid wheat. Increasing day length significantly increased Lr34 seedling resistance. These data demonstrate that expression of a highly durable, broad-spectrum adult plant resistance gene can be modified to provide seedling resistance in durum wheat. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.
Full Text Available Verticillium wilt caused by Verticillium dahliae results in severe losses in cotton, and is economically the most destructive disease of this crop. Improving genetic resistance is the cleanest and least expensive option to manage Verticillium wilt. Previously, we identified the island cotton NBS-LRR-encoding gene GbaNA1 that confers resistance to the highly virulent V. dahliae isolate Vd991. In this study, we expressed cotton GbaNA1 in the heterologous system of Arabidopsis thaliana and investigated the defense response mediated by GbaNA1 following inoculations with V. dahliae. Heterologous expression of GbaNA1 conferred Verticillium wilt resistance in A. thaliana. Moreover, overexpression of GbaNA1 enabled recovery of the resistance phenotype of A. thaliana mutants that had lost the function of GbaNA1 ortholog gene. Investigations of the defense response in A. thaliana showed that the reactive oxygen species (ROS production and the expression of genes associated with the ethylene signaling pathway were enhanced significantly following overexpression of GbaNA1. Intriguingly, overexpression of the GbaNA1 ortholog from Gossypium hirsutum (GhNA1 in A. thaliana did not induce the defense response of ROS production due to the premature termination of GhNA1, which lacks the encoded NB-ARC and LRR motifs. GbaNA1 therefore confers Verticillium wilt resistance in A. thaliana by the activation of ROS production and ethylene signaling. These results demonstrate the functional conservation of the NBS-LRR-encoding GbaNA1 in a heterologous system, and the mechanism of this resistance, both of which may prove valuable in incorporating GbaNA1-mediated resistance into other plant species.
Langenbach, Caspar; Schultheiss, Holger; Rosendahl, Martin; Tresch, Nadine; Conrath, Uwe; Goellner, Katharina
Fungal pathogens pose a major challenge to global crop production. Crop varieties that resist disease present the best defence and offer an alternative to chemical fungicides. Exploiting durable nonhost resistance (NHR) for crop protection often requires identification and transfer of NHR-linked genes to the target crop. Here, we identify genes associated with NHR of Arabidopsis thaliana to Phakopsora pachyrhizi, the causative agent of the devastating fungal disease called Asian soybean rust. We transfer selected Arabidopsis NHR-linked genes to the soybean host and discover enhanced resistance to rust disease in some transgenic soybean lines in the greenhouse. Interspecies NHR gene transfer thus presents a promising strategy for genetically engineered control of crop diseases. © 2015 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.
Makarova, Kira S. [National Center for Biotechnology Information; Omelchenko, Marina [National Center for Biotechnology Information; Gaidamakova, Elena [Uniformed Services University of the Health Sciences (USUHS); Matrosova, Vera [Uniformed Services University of the Health Sciences (USUHS); Vasilenko, Alexander [Uniformed Services University of the Health Sciences (USUHS); Zhai, Min [Uniformed Services University of the Health Sciences (USUHS); Lapidus, Alla L. [U.S. Department of Energy, Joint Genome Institute; Copeland, A [U.S. Department of Energy, Joint Genome Institute; Kim, Edwin [U.S. Department of Energy, Joint Genome Institute; Land, Miriam L [ORNL; Mavromatis, K [U.S. Department of Energy, Joint Genome Institute; Pitluck, Samual [U.S. Department of Energy, Joint Genome Institute; Richardson, P M [U.S. Department of Energy, Joint Genome Institute; Detter, J. Chris [U.S. Department of Energy, Joint Genome Institute; Brettin, Tom [Los Alamos National Laboratory (LANL); Saunders, Elizabeth H [Los Alamos National Laboratory (LANL); Lai, Barry [Argonne National Laboratory (ANL); Ravel, Bruce [Argonne National Laboratory (ANL); Kemner, Kenneth M [Argonne National Laboratory (ANL); Wolf, Yuri [National Center for Biotechnology Information; Sorokin, Alexei [Genetique Microbienne; Gerasimova, Anna [Research Institute of Genetics and Selection of Industrial Microorganisms, Mosco; Gelfand, Mikhail [Moscow State University; Fredrickson, James K [Pacific Northwest National Laboratory (PNNL); Koonin, Eugene [National Center for Biotechnology Information; Daly, Michael [Uniformed Services University of the Health Sciences (USUHS)
Bacteria of the genus Deinococcus are extremely resistant to ionizing radiation (IR), ultraviolet light (UV) and desiccation. The mesophile Deinococcus radiodurans was the first member of this group whose genome was completely sequenced. Analysis of the genome sequence of D. radiodurans, however, failed to identify unique DNA repair systems. To further delineate the genes underlying the resistance phenotypes, we report the whole-genome sequence of a second Deinococcus species, the thermophile Deinococcus geothermalis, which at its optimal growth temperature is as resistant to IR, UV and desiccation as D. radiodurans, and a comparative analysis of the two Deinococcus genomes. Many D. radiodurans genes previously implicated in resistance, but for which no sensitive phenotype was observed upon disruption, are absent in D. geothermalis. In contrast, most D. radiodurans genes whose mutants displayed a radiation-sensitive phenotype in D. radiodurans are conserved in D. geothermalis. Supporting the existence of a Deinococcus radiation response regulon, a common palindromic DNA motif was identified in a conserved set of genes associated with resistance, and a dedicated transcriptional regulator was predicted. We present the case that these two species evolved essentially the same diverse set of gene families, and that the extreme stress-resistance phenotypes of the Deinococcus lineage emerged progressively by amassing cell-cleaning systems from different sources, but not by acquisition of novel DNA repair systems. Our reconstruction of the genomic evolution of the Deinococcus-Thermus phylum indicates that the corresponding set of enzymes proliferated mainly in the common ancestor of Deinococcus. Results of the comparative analysis weaken the arguments for a role of higher-order chromosome alignment structures in resistance; more clearly define and substantially revise downward the number of uncharacterized genes that might participate in DNA repair and contribute to
Makarova, Kira S.; Omelchenko, Marina V.; Gaidamakova, Elena K.; Matrosova, Vera Y.; Vasilenko, Alexander; Zhai, Min; Lapidus, Alla; Copeland, Alex; Kim, Edwin; Land, Miriam; Mavrommatis, Konstantinos; Pitluck, Samuel; Richardson, Paul M.; Detter, Chris; Brettin, Thomas; Saunders, Elizabeth; Lai, Barry; Ravel, Bruce; Kemner, Kenneth M.; Wolf, Yuri I.; Sorokin, Alexander; Gerasimova, Anna V.; Gelfand, Mikhail S.; Fredrickson, James K.; Koonin, Eugene V.; Daly, Michael J.
Bacteria of the genus Deinococcus are extremely resistant to ionizing radiation (IR), ultraviolet light (UV) and desiccation. The mesophile Deinococcus radiodurans was the first member of this group whose genome was completely sequenced. Analysis of the genome sequence of D. radiodurans, however, failed to identify unique DNA repair systems. To further delineate the genes underlying the resistance phenotypes, we report the whole-genome sequence of a second Deinococcus species, the thermophile Deinococcus geothermalis, which at itsoptimal growth temperature is as resistant to IR, UV and desiccation as D. radiodurans, and a comparative analysis of the two Deinococcus genomes. Many D. radiodurans genes previously implicated in resistance, but for which no sensitive phenotype was observed upon disruption, are absent in D. geothermalis. In contrast, most D. radiodurans genes whose mutants displayed a radiation-sensitive phenotype in D. radiodurans are conserved in D. geothermalis. Supporting the existence of a Deinococcus radiation response regulon, a common palindromic DNA motif was identified in a conserved set of genes associated with resistance, and a dedicated transcriptional regulator was predicted. We present the case that these two species evolved essentially the same diverse set of gene families, and that the extreme stress-resistance phenotypes of the Deinococcus lineage emerged progressively by amassing cell-cleaning systems from different sources, but not by acquisition of novel DNA repair systems. Our reconstruction of the genomic evolution of the Deinococcus-Thermus phylum indicates that the corresponding set of enzymes proliferated mainly in the common ancestor of Deinococcus. Results of the comparative analysis weaken the arguments for a role of higher-order chromosome alignment structures in resistance; more clearly define and substantially revise downward the number of uncharacterized genes that might participate in DNA repair and contribute to
Stange, C; Sidhu, J P S; Tiehm, A; Toze, S
Widespread fecal pollution of surface water may present a major health risk and a significant pathway for dissemination of antibiotic resistance bacteria. The River Rhine is one of the longest and most important rivers in Europe and an important raw water source for drinking water production. A total of 100 coliform isolates obtained from River Rhine (Germany) were examined for their susceptibility to seven antimicrobial agents. Resistances against amoxicillin, trimethoprim/sulfamethoxazole and tetracycline were detected in 48%, 11% and 9% of isolates respectively. The antibiotic resistance could be traced back to the resistance genes bla TEM , bla SHV , ampC, sul1, sul2, dfrA1, tet(A) and tet(B). Whereby, the ampC gene represents a special case, because its presence is not inevitably linked to a phenotypic antibiotic resistance. Multiple antibiotics resistance was often accompanied by the occurrence of class 1 or 2 integrons. E. coli isolates belonging to phylogenetic groups A and B1 (commensal) were more predominant (57%) compared to B2 and D groups (43%) which are known to carry virulent genes. Additionally, six E. coli virulence genes were also detected. However, the prevalence of virulence genes in the E. coli isolates was low (not exceeding 4.3% per gene) and no diarrheagenic E. coli pathotypes were detected. This study demonstrates that surface water is an important reservoir of ARGs for a number of antibiotic classes such as sulfonamide, trimethoprim, beta-lactam-antibiotics and tetracycline. The occurrence of antibiotic resistance in coliform bacteria isolated from River Rhine provides evidence for the need to develop management strategies to limit the spread of antibiotic resistant bacteria in aquatic environment. Copyright © 2016 Elsevier GmbH. All rights reserved.
Kira S Makarova
Full Text Available Bacteria of the genus Deinococcus are extremely resistant to ionizing radiation (IR, ultraviolet light (UV and desiccation. The mesophile Deinococcus radiodurans was the first member of this group whose genome was completely sequenced. Analysis of the genome sequence of D. radiodurans, however, failed to identify unique DNA repair systems. To further delineate the genes underlying the resistance phenotypes, we report the whole-genome sequence of a second Deinococcus species, the thermophile Deinococcus geothermalis, which at its optimal growth temperature is as resistant to IR, UV and desiccation as D. radiodurans, and a comparative analysis of the two Deinococcus genomes. Many D. radiodurans genes previously implicated in resistance, but for which no sensitive phenotype was observed upon disruption, are absent in D. geothermalis. In contrast, most D. radiodurans genes whose mutants displayed a radiation-sensitive phenotype in D. radiodurans are conserved in D. geothermalis. Supporting the existence of a Deinococcus radiation response regulon, a common palindromic DNA motif was identified in a conserved set of genes associated with resistance, and a dedicated transcriptional regulator was predicted. We present the case that these two species evolved essentially the same diverse set of gene families, and that the extreme stress-resistance phenotypes of the Deinococcus lineage emerged progressively by amassing cell-cleaning systems from different sources, but not by acquisition of novel DNA repair systems. Our reconstruction of the genomic evolution of the Deinococcus-Thermus phylum indicates that the corresponding set of enzymes proliferated mainly in the common ancestor of Deinococcus. Results of the comparative analysis weaken the arguments for a role of higher-order chromosome alignment structures in resistance; more clearly define and substantially revise downward the number of uncharacterized genes that might participate in DNA repair and
Full Text Available The substantial use of triclosan (TCS has been aimed to kill pathogenic bacteria, but TCS resistance seems to be prevalent in microbial species and limited knowledge exists about TCS resistance determinants in a majority of pathogenic bacteria. We aimed to evaluate the distribution of TCS resistance determinants in major pathogenic bacteria (N = 231 and to assess the enrichment of potentially pathogenic genera in TCS contaminated environments. A TCS-resistant gene (TRG database was constructed and experimentally validated to predict TCS resistance in major pathogenic bacteria. Genome-wide in silico analysis was performed to define the distribution of TCS-resistant determinants in major pathogens. Microbiome analysis of TCS contaminated soil samples was also performed to investigate the abundance of TCS-resistant pathogens. We experimentally confirmed that TCS resistance could be accurately predicted using genome-wide in silico analysis against TRG database. Predicted TCS resistant phenotypes were observed in all of the tested bacterial strains (N = 17, and heterologous expression of selected TCS resistant genes from those strains conferred expected levels of TCS resistance in an alternative host Escherichia coli. Moreover, genome-wide analysis revealed that potential TCS resistance determinants were abundant among the majority of human-associated pathogens (79% and soil-borne plant pathogenic bacteria (98%. These included a variety of enoyl-acyl carrier protein reductase (ENRs homologues, AcrB efflux pumps, and ENR substitutions. FabI ENR, which is the only known effective target for TCS, was either co-localized with other TCS resistance determinants or had TCS resistance-associated substitutions. Furthermore, microbiome analysis revealed that pathogenic genera with intrinsic TCS-resistant determinants exist in TCS contaminated environments. We conclude that TCS may not be as effective against the majority of bacterial pathogens as previously
Horn, Frederike; Habekuß, Antje; Stich, Benjamin
The results of our study suggest that genes involved in general resistance mechanisms of plants contribute to variation of BYDV resistance in maize. With increasing winter temperatures in Europe, Barley yellow dwarf virus (BYDV) is expected to become a prominent problem in maize cultivation. Breeding for resistance is the best strategy to control the disease and break the transmission cycle of the virus. The objectives of our study were (1) to determine genetic variation with respect to BYDV resistance in a broad germplasm set and (2) to identify single nucleotide polymorphism (SNP) markers linked to genes that are involved in BYDV resistance. An association mapping population with 267 genotypes representing the world's maize gene pool was grown in the greenhouse. Plants were inoculated with BYDV-PAV using viruliferous Rhopalosiphum padi. In the association mapping population, we observed considerable genotypic variance for the trait virus extinction as measured by double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) and the infection rate. In a genome-wide association study, we observed three SNPs significantly [false discovery rate (FDR) = 0.05] associated with the virus extinction on chromosome 10 explaining together 25 % of the phenotypic variance and five SNPs for the infection rate on chromosomes 4 and 10 explaining together 33 % of the phenotypic variance. The SNPs significantly associated with BYDV resistance can be used in marker assisted selection and will accelerate the breeding process for the development of BYDV resistant maize genotypes. Furthermore, these SNPs were located within genes which were in other organisms described to play a role in general resistance mechanisms. This suggests that these genes contribute to variation of BYDV resistance in maize.
Full Text Available Abstract Background The potyviruses sugarcane mosaic virus (SCMV and maize dwarf mosaic virus (MDMV are major pathogens of maize worldwide. Two loci, Scmv1 and Scmv2, have ealier been shown to confer complete resistance to SCMV. Custom-made microarrays containing previously identified SCMV resistance candidate genes and resistance gene analogs were utilised to investigate and validate gene expression and expression patterns of isogenic lines under pathogen infection in order to obtain information about the molecular mechanisms involved in maize-potyvirus interactions. Results By employing time course microarray experiments we identified 68 significantly differentially expressed sequences within the different time points. The majority of differentially expressed genes differed between the near-isogenic line carrying Scmv1 resistance locus at chromosome 6 and the other isogenic lines. Most differentially expressed genes in the SCMV experiment (75% were identified one hour after virus inoculation, and about one quarter at multiple time points. Furthermore, most of the identified mapped genes were localised outside the Scmv QTL regions. Annotation revealed differential expression of promising pathogenesis-related candidate genes, validated by qRT-PCR, coding for metallothionein-like protein, S-adenosylmethionine synthetase, germin-like protein or 26S ribosomal RNA. Conclusion Our study identified putative candidate genes and gene expression patterns related to resistance to SCMV. Moreover, our findings support the effectiveness and reliability of the combination of different expression profiling approaches for the identification and validation of candidate genes. Genes identified in this study represent possible future targets for manipulation of SCMV resistance in maize.
López, Camilo E; Acosta, Iván F; Jara, Carlos; Pedraza, Fabio; Gaitán-Solís, Eliana; Gallego, Gerardo; Beebe, Steve; Tohme, Joe
ABSTRACT A polymerase chain reaction approach using degenerate primers that targeted the conserved domains of cloned plant disease resistance genes (R genes) was used to isolate a set of 15 resistance gene analogs (RGAs) from common bean (Phaseolus vulgaris). Eight different classes of RGAs were obtained from nucleotide binding site (NBS)-based primers and seven from not previously described Toll/Interleukin-1 receptor-like (TIR)-based primers. Putative amino acid sequences of RGAs were significantly similar to R genes and contained additional conserved motifs. The NBS-type RGAs were classified in two subgroups according to the expected final residue in the kinase-2 motif. Eleven RGAs were mapped at 19 loci on eight linkage groups of the common bean genetic map constructed at Centro Internacional de Agricultura Tropical. Genetic linkage was shown for eight RGAs with partial resistance to anthracnose, angular leaf spot (ALS) and Bean golden yellow mosaic virus (BGYMV). RGA1 and RGA2 were associated with resistance loci to anthracnose and BGYMV and were part of two clusters of R genes previously described. A new major cluster was detected by RGA7 and explained up to 63.9% of resistance to ALS and has a putative contribution to anthracnose resistance. These results show the usefulness of RGAs as candidate genes to detect and eventually isolate numerous R genes in common bean.
Barozai, M.Y.; Din, M.
This research is based on synonymous codon usage which has been well-known as a feature that affects typical expression level of protein in an organism. Different organisms prefer different codons for same amino acid and this is called Codon Usage Bias (CUB). The codon usage directly affects the level or even direction of changes in protein expression in responses to environmental stimuli. Cold stress is a major abiotic factor that limits the agricultural productivity of plants. In the recent study CUB has been studied in Arabidopsis thaliana cold resistant and housekeeping genes and their homologs in rice (Oryza sativa) to understand the cold stress and housekeeping genes relation with CUB. Six cold resistant and three housekeeping genes in Arabidopsis thaliana and their homologs in rice, were subjected to CUB analysis. The three cold resistant genes (DREB1B, RCI and MYB15) showed more than 50% (52%, 61% and 66% respectively) similar codon usage bias for Arabidopsis thaliana and rice. On the other hand three cold resistant genes (MPK3, ICE1 and ZAT12) showed less than 50% (38%, 38% and 47% respectively) similar codon usage bias for Arabidopsis thaliana and rice. The three housekeeping genes (Actin, Tubulin and Ubiquitin) showed 76% similar codon usage bias for Arabidopsis thaliana and rice. This study will help to manage the plant gene expression through codon optimization under the cold stress. (author)
Atkinson, Gemma C; Hansen, Lykke H; Tenson, Tanel
The cfr gene encodes the Cfr methyltransferase that primarily methylates C-8 in A2503 of 23S rRNA in the peptidyl transferase region of bacterial ribosomes. The methylation provides resistance to six classes of antibiotics of clinical and veterinary importance. The rlmN gene encodes the Rlm......N methyltransferase that methylates C-2 in A2503 in 23S rRNA and A37 in tRNA, but RlmN does not significantly influence antibiotic resistance. The enzymes are homologous and use the same mechanism involving radical S-adenosyl methionine to methylate RNA via an intermediate involving a methylated cysteine....... The differentiation between the two classes is supported by previous and new experimental evidence from antibiotic resistance, primer extensions, and mass spectrometry. Finally, evolutionary aspects of the distribution of Cfr- and RlmN-like enzymes are discussed....
Cain, Amy K; Hall, Ruth M
The simplest form of transposon Tn5393 carries the strA and strB genes that confer resistance to streptomycin, in addition to its transposition determinants. Tn5393e, made up of Tn5393 and a second transposon, Tn6023, was found in an IncHI2 plasmid, pSRC125, recovered from a multiply antibiotic-resistant Salmonella enterica serovar Typhimurium isolate of bovine origin. Tn6023 is made up of the aphA1b gene flanked by two inversely oriented copies of insertion sequence (IS) IS26 and is flanked by an 8 bp duplication. It is related to several other transposons that carry aphA1b in fragments of differing length, also flanked by copies of IS26. Tn6023 is located in the tnpR gene of Tn5393, which lies upstream of the strA and strB genes, and the combined structure was designated Tn5393e. Although neither strA nor strB contain any mutations that would inactivate them, pSRC125 does not confer resistance to streptomycin, indicating that the strA and strB genes are not expressed. In Tn5393, strA and strB are transcribed from the tnpR promoter, and in Tn5393e neither this transcript nor the transcript from the aphA1b promoter in Tn6023 must reach strAB. Tn5393e was previously found in different locations in Corynebacteria, indicating that it can move and suggesting a wide distribution. The structures of several further variants of Tn5393 found in GenBank were analyzed and assigned variant designations Tn5393f-Tn5393i.
Rocha, G A F; Alves, D P; Oliveira, J C; Brommonschenke, S H
The goal of this study was to study resistance inheritance in the soybean (Glycine max L.) accession PI 594767-A to the Phakopsora pachyrhizi isolate PPUFV02, and map the resistance gene(s) identified using microsatellite markers. Crosses between PI 594767-A and the susceptible cultivar 'Conquista' gave rise to the segregating subpopulations 26C-2 and 26C-5, which in the F2 generation were evaluated for their reactions to PPUFV02. In addition, analyses with microsatellite markers linked to the Rpp1-Rpp5 loci were also performed. The segregation pattern obtained in 26C-2 revealed that resistance was governed by a recessive gene; a 1:2:1 segregation pattern was observed in 26C-5, indicating control by a gene with partial dominance. This variability may have been caused because environmental conditions, particularly temperature, when 26C-5 was assessed were unfavorable for pathogen development, allowing the phenotypic expression of heterozygous alleles in PI 594767-A. A resistance gene was located in the soybean linkage group G, in the genomic region between Sct_187r2 and Sat_064 that contains the Rpp1 locus. Resistance in PI 594767-A is probably conferred by a new Rpp1 gene allele, because this accession has a haplotype for Sct_187r2 and Sat_064, which differs from haplotypes of accessions that also contain resistance alleles that map the Rpp1 locus. The use of Sct_187r2 and Sat_064 will facilitate the introgression of the resistance allele from PI 594767-A and its pyramiding with other resistance genes into genotypes with superior agronomic characteristics, in order to obtain cultivars with broad-spectrum resistance to P. pachyrhizi.
Xu, Wenping; Liu, Songlin; Zhang, Yang; Gao, Jufang; Yang, Mingjun; Liu, Xiao; Tao, Liming
In order to elucidate the molecular mechanisms of cypermethrin resistance in Culex pipiens pallens Coq, the susceptible strain (SS strain) and cypermethrin resistant strain (CR strain) of Cx. p. pallens were investigated in this paper. The cypermethrin resistance ratio of CR strain to SS strain was measured by biological assays method, the cDNA sequence of sodium channel was cloned and analyzed. Real-time quantitative RT-PCR was used to detect the expression levels of the detoxification-related genes across between CR strain and SS strain of Cx. p. pallens. Bioassays indicated that CR strain was 283.06 and 80.68-fold resistance to cypermethrin and permethrin as compared to the susceptible strain, respectively. The sequence variability analysis of sodium channel gene between SS strain and CR strain shows that 4 point mutations (R954Q, L1023F, S1775G and A1989E) appear on the amino acid sequence of sodium channel of CR strain. The transcriptional levels of CYP6Z10, CYP9M10, CPGSTd1 and CPGSTd2 in the resistant strain are significantly higher than it is in the susceptible. The transcripts of CYP4H34 and E4 esterase have no significant difference between the CR strain and SS strain. The results indicated that sodium channel mutations, combined with elevated levels of P450s and GSTs, are associated with cypermethrin resistance in CR strain. Copyright © 2017 Elsevier B.V. All rights reserved.
Andrew M Hammond
Full Text Available Gene drives have enormous potential for the control of insect populations of medical and agricultural relevance. By preferentially biasing their own inheritance, gene drives can rapidly introduce genetic traits even if these confer a negative fitness effect on the population. We have recently developed gene drives based on CRISPR nuclease constructs that are designed to disrupt key genes essential for female fertility in the malaria mosquito. The construct copies itself and the associated genetic disruption from one homologous chromosome to another during gamete formation, a process called homing that ensures the majority of offspring inherit the drive. Such drives have the potential to cause long-lasting, sustainable population suppression, though they are also expected to impose a large selection pressure for resistance in the mosquito. One of these population suppression gene drives showed rapid invasion of a caged population over 4 generations, establishing proof of principle for this technology. In order to assess the potential for the emergence of resistance to the gene drive in this population we allowed it to run for 25 generations and monitored the frequency of the gene drive over time. Following the initial increase of the gene drive we observed a gradual decrease in its frequency that was accompanied by the spread of small, nuclease-induced mutations at the target gene that are resistant to further cleavage and restore its functionality. Such mutations showed rates of increase consistent with positive selection in the face of the gene drive. Our findings represent the first documented example of selection for resistance to a synthetic gene drive and lead to important design recommendations and considerations in order to mitigate for resistance in future gene drive applications.
Rzeczycka, Marzenna; Miernik, Antoni; Krawczyk-Balska, Agata; Walsh, Fiona; Duffy, Brion
This study examined differences in antibiotic-resistant soil bacteria and the presence and quantity of resistance genes in soils with a range of management histories. We analyzed four soils from agricultural systems that were amended with manure from animals treated with erythromycin and exposed to streptomycin and/or oxytetracycline, as well as non-manure-amended compost and forest soil. Low concentrations of certain antibiotic resistance genes were detected using multiplex quantitative real-time PCR (qPCR), with tet(B), aad(A), and str(A) each present in only one soil and tet(M) and tet(W) detected in all soils. The most frequently detected resistance genes were tet(B), tet(D), tet(O), tet(T), and tet(W) for tetracycline resistance, str(A), str(B), and aac for streptomycin resistance, and erm(C), erm(V), erm(X), msr(A), ole(B), and vga for erythromycin resistance. Transposon genes specific for Tn916, Tn1549, TnB1230, Tn4451, and Tn5397 were detected in soil bacterial isolates. The MIC ranges of isolated bacteria for tetracycline, streptomycin, and erythromycin were 8 to >256 μg/ml, 6 to >1,024 μg/ml, and 0.094 to >256 μg/ml, respectively. Based on 16S rRNA gene similarity, isolated bacteria showed high sequence identity to genera typical of soil communities. Bacteria with the highest MICs were detected in manure-amended soils or soils from agricultural systems with a history of antibiotic use. Non-manure-amended soils yielded larger proportions of antibiotic-resistant bacteria, but these had lower MICs, carried fewer antibiotic resistance genes, and did not display multidrug resistance (MDR). PMID:22203596
Popowska, Magdalena; Rzeczycka, Marzenna; Miernik, Antoni; Krawczyk-Balska, Agata; Walsh, Fiona; Duffy, Brion
This study examined differences in antibiotic-resistant soil bacteria and the presence and quantity of resistance genes in soils with a range of management histories. We analyzed four soils from agricultural systems that were amended with manure from animals treated with erythromycin and exposed to streptomycin and/or oxytetracycline, as well as non-manure-amended compost and forest soil. Low concentrations of certain antibiotic resistance genes were detected using multiplex quantitative real-time PCR (qPCR), with tet(B), aad(A), and str(A) each present in only one soil and tet(M) and tet(W) detected in all soils. The most frequently detected resistance genes were tet(B), tet(D), tet(O), tet(T), and tet(W) for tetracycline resistance, str(A), str(B), and aac for streptomycin resistance, and erm(C), erm(V), erm(X), msr(A), ole(B), and vga for erythromycin resistance. Transposon genes specific for Tn916, Tn1549, TnB1230, Tn4451, and Tn5397 were detected in soil bacterial isolates. The MIC ranges of isolated bacteria for tetracycline, streptomycin, and erythromycin were 8 to >256 μg/ml, 6 to >1,024 μg/ml, and 0.094 to >256 μg/ml, respectively. Based on 16S rRNA gene similarity, isolated bacteria showed high sequence identity to genera typical of soil communities. Bacteria with the highest MICs were detected in manure-amended soils or soils from agricultural systems with a history of antibiotic use. Non-manure-amended soils yielded larger proportions of antibiotic-resistant bacteria, but these had lower MICs, carried fewer antibiotic resistance genes, and did not display multidrug resistance (MDR).
Full Text Available Hypersaline environments are considered one of the most extreme habitats on earth and microorganisms have developed diverse molecular mechanisms of adaptation to withstand these conditions. The present study was aimed at identifying novel genes involved in salt resistance from the microbial communities of brines and the rhizosphere from the Es Trenc saltern (Mallorca, Spain. The microbial diversity assessed by pyrosequencing of 16S rRNA gene libraries revealed the presence of communities that are typical in such environments. Metagenomic libraries from brine and rhizosphere samples, were transferred to the osmosensitive strain Escherichia coli MKH13, and screened for salt resistance. As a result, eleven genes that conferred salt resistance were identified, some encoding for well known proteins previously related to osmoadaptation as a glycerol and a proton pump, whereas others encoded for proteins not previously related to this function in microorganisms as DNA/RNA helicases, an endonuclease III (Nth and hypothetical proteins of unknown function. Furthermore, four of the retrieved genes were cloned and expressed in Bacillus subtilis and they also exhibited salt resistance in this bacterium, broadening the spectrum of bacterial species where these genes can operate. This is the first report of salt resistance genes recovered from metagenomes of a hypersaline environment.
Full Text Available Abstract Background Acinetobacter baumannii is an important nosocomial pathogen that can develop multidrug resistance. In this study, we characterized the genome of the A. baumannii strain DMS06669 (isolated from the sputum of a male patient with hospital-acquired pneumonia and focused on identification of genes relevant to antibiotic resistance. Methods Whole genome analysis of A. baumannii DMS06669 from hospital-acquired pneumonia patients included de novo assembly; gene prediction; functional annotation to public databases; phylogenetics tree construction and antibiotics genes identification. Results After sequencing the A. baumannii DMS06669 genome and performing quality control, de novo genome assembly was carried out, producing 24 scaffolds. Public databases were used for gene prediction and functional annotation to construct a phylogenetic tree of the DMS06669 strain with 21 other A. baumannii strains. A total of 18 possible antibiotic resistance genes, conferring resistance to eight distinct classes of antibiotics, were identified. Eight of these genes have not previously been reported to occur in A. baumannii. Conclusions Our results provide important information regarding mechanisms that may contribute to antibiotic resistance in the DMS06669 strain, and have implications for treatment of patients infected with A. baumannii.
Full Text Available The enzymatic modification of aminoglycosides by aminoglycoside-acetyltransferases (AAC, aminoglycoside-adenyltransferases (AAD, and aminoglycoside-phosphotransferases (APH, is the most common resistance mechanism in P. aeruginosa and these enzymes can be coded on mobile genetic elements that contribute to their dispersion. One hundred and thirty seven P. aeruginosa isolates from the University Hospital, Cumana, Venezuela (HUAPA were evaluated. Antimicrobial susceptibility was determined by the disk diffusion method and theaac, aadB and aph genes were detected by PCR. Most of the P. aeruginosa isolates (33/137 were identified from the Intensive Care Unit (ICU, mainly from discharges (96/137. The frequency of resistant P. aeruginosaisolates was found to be higher for the aminoglycosides tobramycin and amikacin (30.7 and 29.9%, respectively. Phenotype VI, resistant to these antibiotics, was the most frequent (14/49, followed by phenotype I, resistant to all the aminoglycosides tested (12/49. The aac(6´-Ib,aphA1 and aadB genes were the most frequently detected, and the simultaneous presence of several resistance genes in the same isolate was demonstrated. Aminoglycoside resistance in isolates ofP. aeruginosa at the HUAPA is partly due to the presence of the aac(6´-Ib, aphA1 andaadB genes, but the high rates of antimicrobial resistance suggest the existence of several mechanisms acting together. This is the first report of aminoglycoside resistance genes in Venezuela and one of the few in Latin America.
Dumont, F J; Staruch, M J; Grammer, T; Blenis, J; Kastner, C A; Rupprecht, K M
Rapamycin (RAP) disrupts signaling events implicated in cytokine-dependent proliferation of lymphocytes and other cells. This action is known to involve the formation of molecular complexes between the drug and intracellular binding proteins, termed FKBPs. However, the biochemical target(s) for the effector RAP-FKBP complexes remain uncharacterized. As an approach to explore the mechanism of action of RAP, we have isolated three independent sets of somatic mutants of the YAC-1 murine T cell line with markedly reduced sensitivity to the drug's inhibitory effects on proliferation and on IL-1-induced IFN-gamma production. These mutants were still fully sensitive to FK-506, an immunosuppressant structurally related to RAP whose mode of action also involves an interaction with FKBPs. Furthermore, the 12-kDa FKBP, FKBP12, was detectable in immunoblots from cytosolic extracts and eluates from RAP-affinity matrix in the mutants as in wild-type cells, suggesting that the resistance to RAP in the mutants is not due to a lack of FKBP12 expression. Cell fusion experiments were conducted to further define the nature of the alterations imparting RAP resistance in these mutants. Clones deficient in either thymidine kinase or hypoxanthine-guanine phosphoribosyltransferase, suitable as fusion partners for aminopterin-based selection of hybrids were generated from the wild-type or mutant lines. In most instances, the hybrids derived from the fusion between RAP-sensitive clones and RAP-resistant clones exhibited a RAP-resistant phenotype. Similar results were obtained with hybrids between RAP-resistant YAC-1 clones and the RAP-sensitive EL-4 cell line. Therefore, the mutations that confer resistance to RAP in the present system are dominant. Altogether, our observations are consistent with a model where pharmacologically relevant targets for the RAP-FKBP complex, rather than FKBP, might be altered in the mutants such that the inactivation of these targets by the effector complex is
Full Text Available Molecular screening of major rice blast resistance genes was determined with molecular markers, which showed close-set linkage to 11 major rice blast resistance genes (Pi-d2, Pi-z, Piz-t, Pi-9, Pi-36, Pi-37, Pi5, Pi-b, Pik-p, Pik-h and Pi-ta2, in a collection of 32 accessions resistant to Magnaporthe oryzae. Out of the 32 accessions, the Pi-d2 and Pi-z appeared to be omnipresent and gave positive express. As the second dominant, Pi-b and Piz-t gene frequencies were 96.9% and 87.5%. And Pik-h and Pik-p gene frequencies were 43.8% and 28.1%, respectively. The molecular marker linkage to Pi-ta2 produced positive bands in eleven accessions, while the molecular marker linkage to Pi-36 and Pi-37 in only three and four accessions, respectively. The natural field evaluation analysis showed that 30 of the 32 accessions were resistant, one was moderately resistant and one was susceptible. Infection types were negatively correlated with the genotype scores of Pi-9, Pi5, Pi-b, Pi-ta2 and Pik-p, although the correlation coefficients were very little. These results are useful in identification and incorporation of functional resistance genes from these germplasms into elite cultivars through marker-assisted selection for improved blast resistance in China and worldwide.
Full Text Available In the presence of a bacteriophage (a bacteria-attacking virus resistance is clearly beneficial to the bacteria. As expected in such conditions, resistant bacteria emerge rapidly. However, in the absence of the phage, resistant bacteria often display reduced fitness, compared to their sensitive counterparts. The present study explored the fitness cost associated with phage-resistance as an opportunity to isolate an attenuated strain of S. aureus. The phage-resistant strain A172 was isolated from the phage-sensitive strain A170 in the presence of the M(Sa phage. Acquisition of phage-resistance altered several properties of A172, causing reduced growth rate, under-expression of numerous genes and production of capsular polysaccharide. In vivo, A172 modulated the transcription of the TNF-alpha, IFN-gamma and Il-1beta genes and, given intramuscularly, protected mice from a lethal dose of A170 (18/20. The heat-killed vaccine also afforded protection from heterologous methicillin-resistant S. aureus (MRSA (8/10 mice or vancomycin-intermediate S. aureus (VISA (9/10 mice. The same vaccine was also effective when administered as an aerosol. Anti-A172 mouse antibodies, in the dose of 10 microl/mouse, protected the animals (10/10, in two independent experiments from a lethal dose of A170. Consisting predominantly of the sugars glucose and galactose, the capsular polysaccharide of A172, given in the dose of 25 microg/mouse, also protected the mice (20/20 from a lethal dose of A170. The above results demonstrate that selection for phage-resistance can facilitate bacterial vaccine preparation.
Adelowo, Olawale O.; Fagade, Obasola E.; Agersø, Yvonne
Introduction: This study investigated the mechanisms of resistance in 36 E. coli isolated from waste, litter, soil and water samples collected from poultry farms in Southwestern Nigeria. Methodology: Minimum inhibitory concentration (MIC) distributions of the isolates were determined using the methods of the Clinical and Laboratory Standard Institute and resistance genes detected by PCR. Results: A total of 30 isolates (94%) showed resistance to more than one antimicrobial. Percentage resista...
Lanz, Roland; Kuhnert, Peter; Boerlin, Patrick
Antimicrobial susceptibility testing was performed on a total of 581 clinical Escherichia coli isolates from diarrhea and edema disease in pigs, from acute mastitis in dairy cattle, from urinary tract infections in dogs and cats, and from septicemia in laying hens collected in Switzerland between 1999 and 2001. Among the 16 antimicrobial agents tested, resistance was most frequent for sulfonamides, tetracycline, and streptomycin. Isolates from swine presented significantly more resistance than those from the other animal species. The distribution of the resistance determinants for sulfonamides, tetracycline, and streptomycin was assessed by hybridization and PCR in resistant isolates. Significant differences in the distribution of resistance determinants for tetracycline (tetA, tetB) and sulfonamides (sulII) were observed between the isolates from swine and those from the other species. Resistance to sulfonamides could not be explained by known resistance mechanisms in more than a quarter of the sulfonamide-resistant and sulfonamide-intermediate isolates from swine, dogs and cats. This finding suggests that one or several new resistance mechanisms for sulfonamides may be widespread among E. coli isolates from these animal species. The integrase gene (intI) from class I integrons was detected in a large proportion of resistant isolates in association with the sulI and aadA genes, thus demonstrating the importance of integrons in the epidemiology of resistance in clinical E. coli isolates from animals.
Diana M Horvath
Full Text Available We investigated whether lines of transgenic tomato (Solanum lycopersicum expressing the Bs2 resistance gene from pepper, a close relative of tomato, demonstrate improved resistance to bacterial spot disease caused by Xanthomonas species in replicated multi-year field trials under commercial type growing conditions. We report that the presence of the Bs2 gene in the highly susceptible VF 36 background reduced disease to extremely low levels, and VF 36-Bs2 plants displayed the lowest disease severity amongst all tomato varieties tested, including commercial and breeding lines with host resistance. Yields of marketable fruit from transgenic lines were typically 2.5 times that of the non-transformed parent line, but varied between 1.5 and 11.5 fold depending on weather conditions and disease pressure. Trials were conducted without application of any copper-based bactericides, presently in wide use despite negative impacts on the environment. This is the first demonstration of effective field resistance in a transgenic genotype based on a plant R gene and provides an opportunity for control of a devastating pathogen while eliminating ineffective copper pesticides.
Uddin, M J; Ahn, J
This study was designed to delineate the relationship between resistance phenotypes and gene expression in wild-type (SA WT ), oxacillin-induced (SA OXA ), ciprofloxacin-induced (SA CIP ) and clinically acquired antibiotic-resistant Staphylococcus aureus (SA CA ) exposed to oxacillin (β-lactam) and ciprofloxacin (fluoroquinolone). The phenotypic response and gene expression were varied with the antibiotic exposure. SA WT was highly resistant to oxacillin (MIC = 8 μg ml -1 ) after serial exposure to oxacillin, while the oxacillin susceptibility was not changed in SA WT when exposed to ciprofloxacin (MIC = 0·25 μg ml -1 ). The clinical isolate, SA CA , was highly resistant to all classes of antibiotics used in this study. The increased resistance of SA OXA and SA CIP to penicillinase-labile penicillins was attributed to the production of β-lactamase, which is in good agreement with the overexpression of blaZ (>2-fold). The overexpression of efflux pump-related genes (norA, norB, norC, mdeA, mepR, mgrA and lmrS) was associated with the increased resistance of SA CIP and SA CA to aminoglycosides and quinolones. This study confirmed that the linkage between resistance phenotypes and molecular genotypes highly varied depending on intrinsic resistance profile, response to antibiotic exposure and genes conferring resistance. This study provides useful information for understanding the mechanisms of methicillin resistance in S. aureus in association with phenotypic and genotypic resistance determinants. The improvement in current standards is essential to accurately detect methicillin-resistant Staphylococcus aureus in consideration of various resistance phenotypes and genotypes. The varied and distinctive expression patterns of antibiotic resistance-related genes were observed in S. aureus exposed to oxacillin and ciprofloxacin. It is worth noting the relationship between resistance phenotype and resistance genotype in terms of MIC values and expression of
Full Text Available Basic domain-leucine zipper (bZIP transcription factor, one type of conserved gene family, plays an important role in plant development and stress responses. Although 77 MebZIPs have been genome-wide identified in cassava, their in vivo roles remain unknown. In this study, we analyzed the expression pattern and the function of two MebZIPs (MebZIP3 and MebZIP5 in response to pathogen infection. Gene expression analysis indicated that MebZIP3 and MebZIP5 were commonly regulated by flg22, Xanthomonas axonopodis pv. manihotis (Xam, salicylic acid (SA, and hydrogen peroxide (H2O2. Subcellular localization analysis showed that MebZIP3 and MebZIP5 are specifically located in cell nucleus. Through overexpression in tobacco, we found that MebZIP3 and MebZIP5 conferred improved disease resistance against cassava bacterial blight, with more callose depositions. On the contrary, MebZIP3- and MebZIP5-silenced plants by virus-induced gene silencing (VIGS showed disease sensitive phenotype, lower transcript levels of defense-related genes and less callose depositions. Taken together, this study highlights the positive role of MebZIP3 and MebZIP5 in disease resistance against cassava bacterial blight for further utilization in genetic improvement of cassava disease resistance.
Swine manure applied to agricultural fields may lead to the transport of antibiotic resistant bacteria and antibiotic resistance genes to freshwater systems. Enterococci were studied because they are fecal indicator bacteria associated with manure. Resistance genes include genes from live cells, dea...
Anthracnose (ANT) and angular leaf spot (ALS) are devastating diseases of common bean. Ouro Negro is a highly productive Mesoamerican black-seeded common bean cultivar possessing the dominant Co-10 and Phg-ON genes that confer resistance to ANT and ALS, respectively. In this study we elucidate the ...
Gousia, Panagiota; Economou, Vangelis; Bozidis, Petros; Papadopoulou, Chrissanthy
In the present study, 500 raw beef, pork, and chicken meat samples and 100 pooled egg samples were analyzed for the presence of vancomycin-resistant enterococci, vancomycin-resistance phenotypes, and resistance genes. Of 141 isolates of enterococci, 88 strains of Enterococcus faecium and 53 strains of E. faecalis were identified. The most prevalent species was E. faecium. Resistance to ampicillin (n = 93, 66%), ciprofloxacin (n = 74, 52.5%), erythromycin (n = 73, 51.8%), penicillin (n = 59, 41.8%) and tetracycline (n = 52, 36.9%) was observed, while 53.2% (n = 75) of the isolates were multiresistant and 15.6% (n = 22) were susceptible to all antibiotics. Resistance to vancomycin was exhibited in 34.1% (n = 30) of the E. faecium isolates (n = 88) and 1.9% (n = 1) of the E. faecalis isolates (n = 53) using the disc-diffusion test and the E-test. All isolates were tested for vanA and vanB using real-time polymerase chain reaction (PCR) and multiplex PCR, and for vanC, vanD, vanE, vanG genes using multiplex PCR only. Among E. faecalis isolates, no resistance genes were identified. Among the E. faecium isolates, 28 carried the vanA gene when tested by multiplex PCR and 29 when tested with real-time PCR. No isolate carrying the vanC, vanD, vanE, or vanG genes was identified. Melting-curve analysis of the positive real-time PCR E. faecium isolates showed that 22 isolates carried the vanA gene only, 2 isolates the vanB2,3 genes only, and seven isolates carried both the vanA and vanB2,3 genes. Enterococci should be considered a significant zoonotic pathogen and a possible reservoir of genes encoding resistance potentially transferred to other bacterial species.
Lan, Pham Thi; Chuc, Nguyen Thi Kim; Hoa, Nguyen Quynh; Nhung, Pham Hong; Thoa, Nguyen Thi Minh; Diwan, Vishal; Tamhankar, Ashok J.; Stålsby Lundborg, Cecilia
The environmental spread of antibiotic-resistant bacteria has been recognised as a growing public health threat for which hospitals play a significant role. The aims of this study were to investigate the prevalence of antibiotic resistance and antibiotic resistance genes (ARGs) in Escherichia coli isolates from hospital wastewater in Vietnam. Wastewater samples before and after treatment were collected using continuous sampling every month over a year. Standard disk diffusion and E-test were used for antibiotic susceptibility testing. Extended-spectrum beta-lactamase (ESBL) production was tested using combined disk diffusion. ARGs were detected by polymerase chain reactions. Resistance to at least one antibiotic was detected in 83% of isolates; multidrug resistance was found in 32%. The highest resistance prevalence was found for co-trimoxazole (70%) and the lowest for imipenem (1%). Forty-three percent of isolates were ESBL-producing, with the blaTEM gene being more common than blaCTX-M. Co-harbouring of the blaCTX-M, blaTEM and qepA genes was found in 46% of isolates resistant to ciprofloxacin. The large presence of antibiotic-resistant E. coli isolates combined with ARGs in hospital wastewater, even post-treatment, poses a threat to public health. It highlights the need to develop effective processes for hospital wastewater treatment plants to eliminate antibiotic resistant bacteria and ARGs. PMID:28661465
Lien, La Thi Quynh; Lan, Pham Thi; Chuc, Nguyen Thi Kim; Hoa, Nguyen Quynh; Nhung, Pham Hong; Thoa, Nguyen Thi Minh; Diwan, Vishal; Tamhankar, Ashok J; Stålsby Lundborg, Cecilia
The environmental spread of antibiotic-resistant bacteria has been recognised as a growing public health threat for which hospitals play a significant role. The aims of this study were to investigate the prevalence of antibiotic resistance and antibiotic resistance genes (ARGs) in Escherichia coli isolates from hospital wastewater in Vietnam. Wastewater samples before and after treatment were collected using continuous sampling every month over a year. Standard disk diffusion and E-test were used for antibiotic susceptibility testing. Extended-spectrum beta-lactamase (ESBL) production was tested using combined disk diffusion. ARGs were detected by polymerase chain reactions. Resistance to at least one antibiotic was detected in 83% of isolates; multidrug resistance was found in 32%. The highest resistance prevalence was found for co-trimoxazole (70%) and the lowest for imipenem (1%). Forty-three percent of isolates were ESBL-producing, with the bla TEM gene being more common than bla CTX-M . Co-harbouring of the bla CTX-M , bla TEM and qepA genes was found in 46% of isolates resistant to ciprofloxacin. The large presence of antibiotic-resistant E. coli isolates combined with ARGs in hospital wastewater, even post-treatment, poses a threat to public health. It highlights the need to develop effective processes for hospital wastewater treatment plants to eliminate antibiotic resistant bacteria and ARGs.
Tang, Yizhi; Dai, Lei; Sahin, Orhan; Wu, Zuowei; Liu, Mingyuan; Zhang, Qijing
To identify and characterize a novel cfr variant that recently emerged and confers multidrug resistance in Campylobacter , a major foodborne pathogen. WGS was initially used to identify the cfr (C) gene in Campylobacter isolates and its function was further verified by cloning into an antibiotic-susceptible Campylobacter jejuni strain. Distribution of cfr (C) in various Campylobacter isolates was determined by PCR analysis. Genotyping of cfr (C)-positive strains was done by PFGE and MLST. The cfr (C) gene is predicted to encode a protein that shares 55.1% and 54.9% identity with Cfr and Cfr(B), respectively. cfr (C) was located on a conjugative plasmid of ∼48 kb. Cloning of cfr (C) into C. jejuni NCTC 11168 and conjugative transfer of the cfr (C)-containing plasmid confirmed its role in conferring resistance to phenicols, lincosamides, pleuromutilins and oxazolidinones, and resulted in an 8-256-fold increase in their MICs in both C. jejuni and Campylobacter coli . The cfr (C) gene was detected in multiple C. coli (34 of 344; 10%) isolates derived from different cattle farms in different states, and molecular typing of the cfr (C)-positive C. coli isolates revealed its spread mainly via clonal expansion. These results identify cfr (C) as a new multidrug resistance mechanism in Campylobacter and suggest the potential transmission of this mechanism via the foodborne route, warranting enhanced efforts to monitor its spread in Campylobacter and other foodborne pathogens. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: firstname.lastname@example.org.
Full Text Available Streptococcus gallolyticus subsp. pasteurianus is an under-recognized pathogen and zoonotic agent causing opportunistic infections in humans. Despite increasing recognition of this subspecies as a cause for human infectious diseases, limited information is known about its antibiotic resistance mechanism. In this study, we aim to identify the molecular mechanism underlying the high macrolide resistance of six S. gallolyticus subsp. pasteurianus isolates from dead ducklings collected in several natural outbreaks in China during 2010–2013. All isolates exhibited multi-drug resistance including high macrolide resistance (MIC ≥ 1024 mg/L for erythromycin, and 512 mg/L for clarithromycin. Efflux-encoding mefA and mefE genes were not detectable in these isolates. The presence of 23S rRNA mutations in specific isolates did not significantly change macrolide MICs. No nucleotide substitutions were found in genes encoding ribosomal proteins L4 or L22. The ermB and ermT genes were found in the genomes of all isolates. These two genes were acquired independently in one highly virulent isolate AL101002, and clustered with Tn916 and IS1216, respectively. The expression of both ermB and ermT in all isolates was erythromycin inducible and yielded comparable macrolide MICs in all six isolates. Taken together, inducible expression of both ermB and ermT conferred high macrolide resistance in these S. gallolyticus subsp. pasterianus isolates. Our findings reveal new macrolide resistance features in S. gallolyticus subsp. pasteurianus by both ermB and ermT.
Hatakeyama, Katsunori; Niwa, Tomohisa; Kato, Takeyuki; Ohara, Takayoshi; Kakizaki, Tomohiro; Matsumoto, Satoru
To facilitate prevention of clubroot disease, a major threat to the successful cultivation of Chinese cabbage (Brassica rapa L.), we bred clubroot-resistant (CR) cultivars by introducing resistance genes from CR turnips via conventional breeding. Among 11 CR loci found in B. rapa, we identified CRb in Chinese cabbage cultivar 'CR Shinki' as a single dominant gene for resistance against Plasmodiophora brassicae pathotype group 3, against which the stacking of Crr1 and Crr2 loci was not effective. However, the precise location and pathotype specificity of CRb have been controversial, because CRa and Rcr1 also map near this locus. Previously, our fine-mapping study revealed that CRb is located in a 140-kb genomic region on chromosome A03. Here, we determined the nucleotide sequence of an approximately 64-kb candidate region in the resistant line; this region contains six open reading frames (ORFs) similar to NB-LRR encoding genes that are predicted to occur in tandem with the same orientation. Among the six ORFs present, only four on the genome of the resistant line showed a strong DNA sequence identity with each other, and only one of those four could confer resistance to P. brassicae isolate No. 14 of the pathotype group 3. These results suggest that these genes evolved through recent gene duplication and uneven crossover events that could lead to the acquisition of clubroot resistance. The DNA sequence of the functional ORF was identical to that of the previously cloned CRa gene; thus, we showed that the independently identified CRb and CRa are one and the same clubroot-resistance gene.
Mac Aogáin, Micheál; Kilkenny, Shauna; Walsh, Claire; Lindsay, Sinéad; Moloney, Geraldine; Morris, Trefor; Jones, Sophie; Rogers, Thomas R
The aim of this study was to determine whether alternative resistance mechanisms, other than mutation in the quinolone resistance-determining region (QRDR) of DNA gyrase, could confer fluoroquinolone resistance in Clostridium difficile. An in vitro-generated C. difficile mutant exhibiting increased fluoroquinolone resistance was isolated through antibiotic selection on ciprofloxacin. The QRDR of this mutant was investigated by chain-termination sequencing and was found to be devoid of mutation. To determine the nature of the non-QRDR resistance mechanism in this strain, the genomes of the mutant and wild-type strains were sequenced. The gyrBA region from a collection of clinical isolates exhibiting variable fluoroquinolone resistance levels was also sequenced and was compared with that present in 918 publicly available C. difficile genomic data sets. Whole-genome sequence analysis of the fluoroquinolone-resistant mutant revealed a single non-synonymous substitution (Ala384Asp) at the predicted primary dimer interface of GyrA, far beyond the classically defined QRDR. This novel mutation caused increased resistance to ciprofloxacin, ofloxacin, levofloxacin and moxifloxacin while conferring hypersusceptibility to novobiocin. Several novel extra-QRDR polymorphisms in C. difficile DNA gyrase were identified among clinical isolates, whilst observed fluoroquinolone resistance in strains devoid of gyrBA mutations confirmed the existence of DNA gyrase-independent resistance mechanisms in this species. In conclusion, we report the first non-QRDR mutation to confer fluoroquinolone resistance in C. difficile. Although the Ala384Asp substitution was not detected in clinical isolates, this study revealed a diversity of alternative extra-QRDR polymorphisms in DNA gyrase whose association with fluoroquinolone resistance warrants further investigation. Copyright © 2015 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.
Rinaldo, Amy; Gilbert, Brian; Boni, Rainer; Krattinger, Simon G.; Singh, Davinder; Park, Robert F.; Lagudah, Evans; Ayliffe, Michael
Summary The hexaploid wheat (Triticum aestivum) adult plant resistance gene, Lr34/Yr18/Sr57/Pm38/Ltn1, provides broad?spectrum resistance to wheat leaf rust (Lr34), stripe rust (Yr18), stem rust (Sr57) and powdery mildew (Pm38) pathogens, and has remained effective in wheat crops for many decades. The partial resistance provided by this gene is only apparent in adult plants and not effective in field?grown seedlings. Lr34 also causes leaf tip necrosis (Ltn1) in mature adult plant leaves when ...
Blast disease caused by the pathogen Pyricularia oryzae is a serious threat to rice production. Six generations viz., P1, P2, F1, F2, B1 and B2 of a cross between blast susceptible high-yielding rice cultivar ADT 43 and resistant near isogenic line (NIL) CT13432-3R, carrying four blast resistance genes Pi1, Pi2, Pi33 and Pi54 ...
Using, DNA markers and genome organization, several important disease resistance genes have been analyzed in mungbean (Vigna radiata), cowpea (Vigna unguiculata), common bean (Phaseolus vulgaris), and soybean (Glycine max). In the process, medium-density linkage maps consisting of restriction fragment length polymorphism (RFLP) markers were constructed for both mungbean and cowpea. Comparisons between these maps, as well as the maps of soybean and common bean, indicate that there is significant conservation of DNA marker order, though the conserved blocks in soybean are much shorter than in the others. DNA mapping results also indicate that a gene for seed weight may be conserved between mungbean and cowpea. Using the linkage maps, genes that control bruchid (genus Callosobruchus) and powdery mildew (Erysiphe polygoni) resistance in mungbean, aphid resistance in cowpea (Aphis craccivora), and cyst nematode (Heterodera glycines) resistance in soybean have all been mapped and characterized. For some of these traits resistance was found to be oligogenic and DNA mapping uncovered multiple genes involved in the phenotype. (author)
Full Text Available Salinity is a critical environmental factor that adversely affects crop productivity. Halophytes have evolved various mechanisms to adapt to saline environments. Salicornia europaea L. is one of the most salt-tolerant plant species. It does not have special salt-secreting structures like a salt gland or salt bladder, and is therefore a good model for studying the common mechanisms underlying plant salt tolerance. To identify candidate genes encoding key proteins in the mediation of salt tolerance in S. europaea, we performed a functional screen of a cDNA library in yeast. The library was screened for genes that allowed the yeast to grow in the presence of 1.3 M NaCl. We obtained three full-length S. europaea genes that confer salt tolerance. The genes are predicted to encode (1 a novel protein highly homologous to thaumatin-like proteins, (2 a novel coiled-coil protein of unknown function, and (3 a novel short peptide of 32 residues. Exogenous application of a synthetic peptide corresponding to the 32 residues improved salt tolerance of Arabidopsis. The approach described in this report provides a rapid assay system for large-scale screening of S. europaea genes involved in salt stress tolerance and supports the identification of genes responsible for such mechanisms. These genes may be useful candidates for improving crop salt tolerance by genetic transformation.
Nakahara, Yoshiki; Sawabe, Shogo; Kainuma, Kenta; Katsuhara, Maki; Shibasaka, Mineo; Suzuki, Masanori; Yamamoto, Kosuke; Oguri, Suguru; Sakamoto, Hikaru
Salinity is a critical environmental factor that adversely affects crop productivity. Halophytes have evolved various mechanisms to adapt to saline environments. Salicornia europaea L. is one of the most salt-tolerant plant species. It does not have special salt-secreting structures like a salt gland or salt bladder, and is therefore a good model for studying the common mechanisms underlying plant salt tolerance. To identify candidate genes encoding key proteins in the mediation of salt tolerance in S. europaea, we performed a functional screen of a cDNA library in yeast. The library was screened for genes that allowed the yeast to grow in the presence of 1.3 M NaCl. We obtained three full-length S. europaea genes that confer salt tolerance. The genes are predicted to encode (1) a novel protein highly homologous to thaumatin-like proteins, (2) a novel coiled-coil protein of unknown function, and (3) a novel short peptide of 32 residues. Exogenous application of a synthetic peptide corresponding to the 32 residues improved salt tolerance of Arabidopsis. The approach described in this report provides a rapid assay system for large-scale screening of S. europaea genes involved in salt stress tolerance and supports the identification of genes responsible for such mechanisms. These genes may be useful candidates for improving crop salt tolerance by genetic transformation.
Adelowo, Olawale O; Fagade, Obasola E; Agersø, Yvonne
This study investigated the mechanisms of resistance in 36 E. coli isolated from waste, litter, soil and water samples collected from poultry farms in Southwestern Nigeria. Minimum inhibitory concentration (MIC) distributions of the isolates were determined using the methods of the Clinical and Laboratory Standard Institute and resistance genes detected by PCR. A total of 30 isolates (94%) showed resistance to more than one antimicrobial. Percentage resistance was: tetracycline 81%, sulphamethoxazole 67%, streptomycin 56%, trimethoprim 47 %, ciprofloxacin 42%, ampicillin 36%, spectinomycin 28%, nalidixic acid 25%, chloramphenicol 22%, neomycin 14%, gentamicin 8%, amoxicillin-clavulanate, ceftiofur, cefotaxime, colistin, florfenicol and apramycin 0%. Resistance genes found among the isolates include bla-TEM (85%), sul2 (67%), sul3 (17%), aadA (65%), strA (70%), strB (61%), catA1 (25%), cmlA1 (13%), tetA (21%) and tetB (17%). Class 1 and 2 integrons were found in five (14%) and six (17%) isolates, respectively, while one isolate was positive for both classes of integrons. Seven out of eight isolates with resistance to ciprofloxacin and MIC ≤ 32 mg/L to nalidixic acid contained qnrS genes. Our findings provided additional evidence that the poultry production environment in Nigeria represents an important reservoir of antibiotic resistance genes such as qnrS that may spread from livestock production farms to human populations via manure and water.
Full Text Available Abstract Background Burkholderia cenocepacia is recognized as opportunistic pathogen that can cause lung infections in cystic fibrosis patients. A hallmark of B. cenocepacia infections is the inability to eradicate the organism because of multiple intrinsic antibiotic resistance. As Resistance-Nodulation-Division (RND efflux systems are responsible for much of the intrinsic multidrug resistance in Gram-negative bacteria, this study aims to identify RND genes in the B. cenocepacia genome and start to investigate their involvement into antimicrobial resistance. Results Genome analysis and homology searches revealed 14 open reading frames encoding putative drug efflux pumps belonging to RND family in B. cenocepacia J2315 strain. By reverse transcription (RT-PCR analysis, it was found that orf3, orf9, orf11, and orf13 were expressed at detectable levels, while orf10 appeared to be weakly expressed in B. cenocepacia. Futhermore, orf3 was strongly induced by chloramphenicol. The orf2 conferred resistance to fluoroquinolones, tetraphenylphosphonium, streptomycin, and ethidium bromide when cloned and expressed in Escherichia coli KAM3, a strain lacking the multidrug efflux pump AcrAB. The orf2-overexpressing E. coli also accumulate low concentrations of ethidium bromide, which was restored to wild type level in the presence of CCCP, an energy uncoupler altering the energy of the drug efflux pump. Conclusion The 14 RND pumps gene we have identified in the genome of B. cenocepacia suggest that active efflux could be a major mechanism underlying antimicrobial resistance in this microorganism. We have characterized the ORF2 pump, one of these 14 potential RND efflux systems. Its overexpression in E. coli conferred resistance to several antibiotics and to ethidium bromide but it remains to be determined if this pump play a significant role in the antimicrobial intrinsic resistance of B. cenocepacia. The characterization of antibiotic efflux pumps in B
Alout, H; Labbé, P; Berthomieu, A; Makoundou, P; Fort, P; Pasteur, N; Weill, M
We investigated the genetic determinism of high chlorpyrifos resistance (HCR), a phenotype first described in 1999 in Culex pipiens mosquitoes surviving chlorpyrifos doses ⩾1 mg l(-1) and more recently found in field samples from Tunisia, Israel or Indian Ocean islands. Through chlorpyrifos selection, we selected several HCR strains that displayed over 10 000-fold resistance. All strains were homozygous for resistant alleles at two main loci: the ace-1 gene, with the resistant ace-1(R) allele expressing the insensitive G119S acetylcholinesterase, and a resistant allele of an unknown gene (named T) linked to the sex and ace-2 genes. We constructed a strain carrying only the T-resistant allele and studied its resistance characteristics. By crossing this strain with strains harboring different alleles at the ace-1 locus, we showed that the resistant ace-1(R) and the T alleles act in strong synergy, as they elicited a resistance 100 times higher than expected from a simple multiplicative effect. This effect was specific to chlorpyrifos and parathion and was not affected by synergists. We also examined how HCR was expressed in strains carrying other ace-1-resistant alleles, such as ace-1(V) or the duplicated ace-1(D) allele, currently spreading worldwide. We identified two major parameters that influenced the level of resistance: the number and the nature of the ace-1-resistant alleles and the number of T alleles. Our data fit a model that predicts that the T allele acts by decreasing chlorpyrifos concentration in the compartment targeted in insects.
Pruss, Gail J.; Lawrence, Christopher B.; Bass, Troy; Li Qingshun Q.; Bowman, Lewis H.; Vance, Vicki
Helper component-protease (HC-Pro) is a plant viral suppressor of RNA silencing, and transgenic tobacco expressing HC-Pro has increased susceptibility to a broad range of viral pathogens. Here we report that these plants also exhibit enhanced resistance to unrelated heterologous pathogens. Tobacco mosaic virus (TMV) infection of HC-Pro-expressing plants carrying the N resistance gene results in fewer and smaller lesions compared to controls without HC-Pro. The resistance to TMV is compromised but not eliminated by expression of nahG, which prevents accumulation of salicylic acid (SA), an important defense signaling molecule. HC-Pro-expressing plants are also more resistant to tomato black ring nepovirus (TBRV) and to the oomycete Peronospora tabacina. Enhanced TBRV resistance is SA-independent, whereas the response to P. tabacina is associated with early induction of markers characteristic of SA-dependent defense. Thus, a plant viral suppressor of RNA silencing enhances resistance to multiple pathogens via both SA-dependent and SA-independent mechanisms
Deepti Prasad Karumathil
Full Text Available Acinetobacter baumannii is a multidrug resistant pathogen capable of causing a wide spectrum of clinical conditions in humans. Acinetobacter spp. is ubiquitously found in different water sources. Chlorine being the most commonly used disinfectant in water, the study investigated the effect of chlorine on the survival of A. baumannii in water and transcription of genes conferring antibiotic resistance. Eight clinical isolates of A. baumannii, including a fatal meningitis isolate (ATCC 17978 (~108 CFU/mL were separately exposed to free chlorine concentrations (0.2, 1, 2, 3 and 4 ppm with a contact time of 30, 60, 90 and 120 second. The surviving pathogen counts at each specified contact time were determined using broth dilution assay. In addition, real-time quantitative PCR (RT-qPCR analysis of the antibiotic resistance genes (efflux pump genes and those encoding resistance to specific antibiotics of three selected A. baumannii strains following exposure to chlorine was performed. Results revealed that all eight A. baumannii isolates survived the tested chlorine levels during all exposure times (p > 0.05. Additionally, there was an up-regulation of all or some of the antibiotic resistance genes in A. baumannii, indicating a chlorine-associated induction of antibiotic resistance in the pathogen.
Full Text Available The use of antibiotics in animal husbandry contributes to the worldwide problem of increasing antibiotic resistance in animal and human pathogens. Intensive animal production is considered an important source of antibiotic resistance genes released to the environment, while the contribution of smaller farms remains to be evaluated. Here we monitor the spread of tetracycline resistance (TC-r genes at a middle-size conventional dairy farm, where chlortetracycline (CTC, as intrauterine suppository is prophylactically used after each calving. Our study has shown that animals at the farm acquired the TC-r genes in their early age (1-2 weeks, likely due to colonization with TC-resistant bacteria from their mothers and/or the farm environment. The relative abundance of the TC-r genes tet(W, tet(Q and tet(M in fresh excrements of calves was about 1-2 orders of magnitude higher compared to heifers and dairy cows, possibly due to the presence of antibiotic residues in milk fed to calves. The occurrence and abundance of TC-r genes in fresh excrements of heifers and adult cows remained unaffected by intrauterine CTC applications, with tet(O, tet(Q and tet(W representing a ‘core TC-resistome’ of the farm, and tet(A, tet(M, tet(Y and tet(X occurring occasionally. The genes tet(A, tet(M, tet(Y and tet(X were shown to be respectively harbored by Shigella, Lactobacillus and Clostridium, Acinetobacter, and Wautersiella. Soil in the farm proximity, as well as field soil to which manure from the farm was applied, was contaminated with TC-r genes occurring in the farm, and some of the TC-r genes persisted in the field over 3 months following the manure application. Concluding, our study shows that antibiotic resistance genes may be a stable part of the intestinal metagenome of cattle even if antibiotics are not used for growth stimulation, and that smaller dairy farms may also contribute to environmental pollution with antibiotic resistance genes.
Adelowo, Olawale O.; Fagade, Obasola E.; Agersø, Yvonne
Introduction: This study investigated the mechanisms of resistance in 36 E. coli isolated from waste, litter, soil and water samples collected from poultry farms in Southwestern Nigeria. Methodology: Minimum inhibitory concentration (MIC) distributions of the isolates were determined using...... the methods of the Clinical and Laboratory Standard Institute and resistance genes detected by PCR. Results: A total of 30 isolates (94%) showed resistance to more than one antimicrobial. Percentage resistance was: tetracycline 81%, sulphamethoxazole 67%, streptomycin 56%, trimethoprim 47 %, ciprofloxacin 42......%, ampicillin 36%, spectinomycin 28%, nalidixic acid 25%, chloramphenicol 22%, neomycin 14%, gentamicin 8%, amoxicillin-clavulanate, ceftiofur, cefotaxime, colistin, florfenicol and apramycin 0%. Resistance genes found among the isolates include bla-TEM (85%), sul2 (67%), sul3 (17%), aadA (65%), strA (70%), str...
Argudín, M Angeles; Butaye, Patrick
The use of metals as feed supplement has been recognized as a potential driver for co-selection of methicillin-resistant Staphylococcus aureus in pigs. However, the prevalence of these determinants in methicillin-resistant coagulase-negative staphylococci (MRCoNS) is largely unknown. In this study, a collection of 130 MRCoNS from pigs and veal calves were investigated for the presence of metal-resistance genes (czrC, copB, cadD, arsA) associated to SCCmec. Near half of the isolates carried metal resistance genes (czrC 5.4%, copB 38.5%, cadD 7.7%, arsA 26.2%) regardless of their SCCmec type. The increased use of metals in livestock animals, especially zinc in pigs in several European countries may co-select for methicillin-resistance in several staphylococcal species. Copyright © 2016 Elsevier Ltd. All rights reserved.
Feb 19, 2008 ... plasmodiophoride-like fungus, Polymyxa betae Keskin. (1964) (Tamada and Richard, 1992). Source of resistance to rhizomania were found in Holly sugar beet company source (Lewellen, 1987). Resistance in Holly is simply inherited by a single dominant gene(Rz1). (Lewellen et al., 1987; Scholten et al., ...
The rhizomania disease is one of the most important diseases in Iran and some other parts of the world which potentially could play a role in decreasing sugar yield in fields. One approach to combat with this disease is the use of resistance varieties. This varieties have been identified which are having resistance genes to ...
Colin W Hiebert
Full Text Available Stem rust, caused by Puccinia graminis (Pgt, is a damaging disease of wheat that can be controlled by utilizing effective stem rust resistance genes. 'Thatcher' wheat carries complex resistance to stem rust that is enhanced in the presence of the resistance gene Lr34. The purpose of this study was to examine APR in 'Thatcher' and look for genetic interactions with Lr34. A RIL population was tested for stem rust resistance in field nurseries in Canada, USA, and Kenya. BSA was used to find SNP markers associated with reduced stem rust severity. A major QTL was identified on chromosome 3BL near the centromere in all environments. Seedling testing showed that Sr12 mapped to the same region as the QTL for APR. The SNP markers were physically mapped and the region carrying the resistance was searched for sequences with homology to members of the NB-LRR resistance gene family. SNP marker from one NB-LRR-like sequence, NB-LRR3 co-segregated with Sr12. Two additional populations, including one that lacked Lr34, were tested in field nurseries. NB-LRR3 mapped near the maximum LOD for reduction in stem rust severity in both populations. Lines from a population that segregated for Sr12 and Lr34 were tested for seedling Pgt biomass and infection type, as well as APR to field stem rust which showed an interaction between the genes. We concluded that Sr12, or a gene closely linked to Sr12, was responsible for 'Thatcher'-derived APR in several environments and this resistance was enhanced in the presence of Lr34.
Hiebert, Colin W; Kolmer, James A; McCartney, Curt A; Briggs, Jordan; Fetch, Tom; Bariana, Harbans; Choulet, Frederic; Rouse, Matthew N; Spielmeyer, Wolfgang
Stem rust, caused by Puccinia graminis (Pgt), is a damaging disease of wheat that can be controlled by utilizing effective stem rust resistance genes. 'Thatcher' wheat carries complex resistance to stem rust that is enhanced in the presence of the resistance gene Lr34. The purpose of this study was to examine APR in 'Thatcher' and look for genetic interactions with Lr34. A RIL population was tested for stem rust resistance in field nurseries in Canada, USA, and Kenya. BSA was used to find SNP markers associated with reduced stem rust severity. A major QTL was identified on chromosome 3BL near the centromere in all environments. Seedling testing showed that Sr12 mapped to the same region as the QTL for APR. The SNP markers were physically mapped and the region carrying the resistance was searched for sequences with homology to members of the NB-LRR resistance gene family. SNP marker from one NB-LRR-like sequence, NB-LRR3 co-segregated with Sr12. Two additional populations, including one that lacked Lr34, were tested in field nurseries. NB-LRR3 mapped near the maximum LOD for reduction in stem rust severity in both populations. Lines from a population that segregated for Sr12 and Lr34 were tested for seedling Pgt biomass and infection type, as well as APR to field stem rust which showed an interaction between the genes. We concluded that Sr12, or a gene closely linked to Sr12, was responsible for 'Thatcher'-derived APR in several environments and this resistance was enhanced in the presence of Lr34.
Hiebert, Colin W.; Kolmer, James A.; McCartney, Curt A.; Briggs, Jordan; Fetch, Tom; Bariana, Harbans; Choulet, Frederic; Rouse, Matthew N.; Spielmeyer, Wolfgang
Stem rust, caused by Puccinia graminis (Pgt), is a damaging disease of wheat that can be controlled by utilizing effective stem rust resistance genes. ‘Thatcher’ wheat carries complex resistance to stem rust that is enhanced in the presence of the resistance gene Lr34. The purpose of this study was to examine APR in ‘Thatcher’ and look for genetic interactions with Lr34. A RIL population was tested for stem rust resistance in field nurseries in Canada, USA, and Kenya. BSA was used to find SNP markers associated with reduced stem rust severity. A major QTL was identified on chromosome 3BL near the centromere in all environments. Seedling testing showed that Sr12 mapped to the same region as the QTL for APR. The SNP markers were physically mapped and the region carrying the resistance was searched for sequences with homology to members of the NB-LRR resistance gene family. SNP marker from one NB-LRR-like sequence, NB-LRR3 co-segregated with Sr12. Two additional populations, including one that lacked Lr34, were tested in field nurseries. NB-LRR3 mapped near the maximum LOD for reduction in stem rust severity in both populations. Lines from a population that segregated for Sr12 and Lr34 were tested for seedling Pgt biomass and infection type, as well as APR to field stem rust which showed an interaction between the genes. We concluded that Sr12, or a gene closely linked to Sr12, was responsible for ‘Thatcher’-derived APR in several environments and this resistance was enhanced in the presence of Lr34. PMID:27309724
Proia, Lorenzo; von Schiller, Daniel; Sànchez-Melsió, Alexandre; Sabater, Sergi; Borrego, Carles M; Rodríguez-Mozaz, Sara; Balcázar, José Luis
The extensive use of antibiotics in human and veterinary medicine and their subsequent release into the environment may have direct consequences for autochthonous bacterial communities, especially in freshwater ecosystems. In small streams and rivers, local inputs of wastewater treatment plants (WWTPs) may become important sources of organic matter, nutrients and emerging pollutants, such as antibiotic resistance genes (ARGs). In this study, we evaluated the effect of WWTP effluents as a source of ARGs in river biofilms. The prevalence of genes conferring resistance to main antibiotic families, such as beta-lactams (blaCTX-M), fluoroquinolones (qnrS), sulfonamides (sul I), and macrolides (ermB), was determined using quantitative PCR (qPCR) in biofilm samples collected upstream and downstream WWTPs discharge points in four low-order streams. Our results showed that the WWTP effluents strongly modified the hydrology, physico-chemistry and biological characteristics of the receiving streams and favoured the persistence and spread of antibiotic resistance in microbial benthic communities. It was also shown that the magnitude of effects depended on the relative contribution of each WWTP to the receiving system. Specifically, low concentrations of ARGs were detected at sites located upstream of the WWTPs, while a significant increase of their concentrations was observed in biofilms collected downstream of the WWTP discharge points (particularly ermB and sul I genes). These findings suggest that WWTP discharges may favour the increase and spread of antibiotic resistance among streambed biofilms. The present study also showed that the presence of ARGs in biofilms was noticeable far downstream of the WWTP discharge (up to 1 km). It is therefore reasonable to assume that biofilms may represent an ideal setting for the acquisition and spread of antibiotic resistance determinants and thus be considered suitable biological indicators of anthropogenic pollution by active
Shimada, Takehiko; Endo, Tomoko; Rodríguez, Ana; Fujii, Hiroshi; Goto, Shingo; Matsuura, Takakazu; Hojo, Yuko; Ikeda, Yoko; Mori, Izumi C; Fujikawa, Takashi; Peña, Leandro; Omura, Mitsuo
In order to clarify whether high linalool content in citrus leaves alone induces strong field resistance to citrus canker caused by Xanthomonas citri subsp. citri (Xcc), and to assess whether this trait can be transferred to a citrus type highly sensitive to the bacterium, transgenic 'Hamlin' sweet orange (Citrus sinensis L. Osbeck) plants over-expressing a linalool synthase gene (CuSTS3-1) were generated. Transgenic lines (LIL) with the highest linalool content showed strong resistance to citrus canker when spray inoculated with the bacterium. In LIL plants inoculated by wounding (multiple-needle inoculation), the linalool level was correlated with the repression of the bacterial titer and up-regulation of defense-related genes. The exogenous application of salicylic acid, methyl jasmonate or linalool triggered responses similar to those constitutively induced in LIL plants. The linalool content in Ponkan mandarin leaves was significantly higher than that of leaves from six other representative citrus genotypes with different susceptibilities to Xcc. We propose that linalool-mediated resistance might be unique to citrus tissues accumulating large amounts of volatile organic compounds in oil cells. Linalool might act not only as a direct antibacterial agent, but also as a signal molecule involved in triggering a non-host resistance response against Xcc. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: email@example.com.
Pandolfini, Tiziana; Molesini, Barbara; Avesani, Linda; Spena, Angelo; Polverari, Annalisa
Homology-dependent selective degradation of RNA, or post-transcriptional gene silencing (PTGS), is involved in several biological phenomena, including adaptative defense mechanisms against plant viruses. Small interfering RNAs mediate the selective degradation of target RNA by guiding a multicomponent RNAse. Expression of self-complementary hairpin RNAs within two complementary regions separated by an intron elicits PTGS with high efficiency. Plum pox virus (PPV) is the etiological agent of sharka disease in Drupaceae, although it can also be transmitted to herbaceous species (e.g. Nicotiana benthamiana). Once inside the plant, PPV is transmitted via plasmodesmata from cell to cell, and at longer distances, via phloem. The rolC promoter drives expression in phloem cells. RolC expression is absent in both epidermal and mesophyll cells. The aim of the present study was to confer systemic disease resistance without preventing local viral infection. In the ihprolC-PP197 gene (intron hair pin rolC PPV 197), a 197 bp sequence homologous to the PPV RNA genome (from base 134 to 330) was placed as two inverted repeats separated by the DNA sequence of the rolA intron. This hairpin construct is under the control of the rolC promoter.N. benthamiana plants transgenic for the ihprolC-PP197 gene contain siRNAs homologous to the 197 bp sequence. The transgenic progeny of ihprolC-PP197 plants are resistant to PPV systemic infection. Local infection is unaffected. Most (80%) transgenic plants are virus free and symptomless. Some plants (20%) contain virus in uninoculated apical leaves; however they show only mild symptoms of leaf mottling. PPV systemic resistance cosegregates with the ihprolC-PP197 transgene and was observed in progeny plants of all independent transgenic lines analyzed. SiRNAs of 23-25 nt homologous to the PPV sequence used in the ihprolC-PP197 construct were detected in transgenic plants before and after inoculation. Transitivity of siRNAs was observed in
Full Text Available Abstract Background Homology-dependent selective degradation of RNA, or post-transcriptional gene silencing (PTGS, is involved in several biological phenomena, including adaptative defense mechanisms against plant viruses. Small interfering RNAs mediate the selective degradation of target RNA by guiding a multicomponent RNAse. Expression of self-complementary hairpin RNAs within two complementary regions separated by an intron elicits PTGS with high efficiency. Plum pox virus (PPV is the etiological agent of sharka disease in Drupaceae, although it can also be transmitted to herbaceous species (e.g. Nicotiana benthamiana. Once inside the plant, PPV is transmitted via plasmodesmata from cell to cell, and at longer distances, via phloem. The rolC promoter drives expression in phloem cells. RolC expression is absent in both epidermal and mesophyll cells. The aim of the present study was to confer systemic disease resistance without preventing local viral infection. Results In the ihprolC-PP197 gene (intron hair pin rolC PPV 197, a 197 bp sequence homologous to the PPV RNA genome (from base 134 to 330 was placed as two inverted repeats separated by the DNA sequence of the rolA intron. This hairpin construct is under the control of the rolC promoter.N. benthamiana plants transgenic for the ihprolC-PP197 gene contain siRNAs homologous to the 197 bp sequence. The transgenic progeny of ihprolC-PP197 plants are resistant to PPV systemic infection. Local infection is unaffected. Most (80% transgenic plants are virus free and symptomless. Some plants (20% contain virus in uninoculated apical leaves; however they show only mild symptoms of leaf mottling. PPV systemic resistance cosegregates with the ihprolC-PP197 transgene and was observed in progeny plants of all independent transgenic lines analyzed. SiRNAs of 23–25 nt homologous to the PPV sequence used in the ihprolC-PP197 construct were detected in transgenic plants before and after inoculation
Wang, Guohong; Yin, Sheng; An, Haoran; Chen, Shangwu; Hao, Yanling
Lactic acid bacteria (LAB) encounter various types of stress during industrial processes and gastrointestinal transit. Catalase (CAT) and bile salt hydrolase (BSH) can protect bacteria from oxidative stress or damage caused by bile salts by decomposing hydrogen peroxide (H(2)O(2)) or deconjugating the bile salts, respectively. Lactobacillus casei is a valuable probiotic strain and is often deficient in both CAT and BSH. In order to improve the resistance of L. casei to both oxidative and bile salts stress, the catalase gene katA from L. sakei and the bile salt hydrolase gene bsh1 from L. plantarum were coexpressed in L. casei HX01. The enzyme activities of CAT and BSH were 2.41 μmol H(2)O(2)/min/10(8) colony-forming units (CFU) and 2.11 μmol glycine/min/ml in the recombinant L. casei CB, respectively. After incubation with 8 mM H(2)O(2), survival ratio of L. casei CB was 40-fold higher than that of L. casei CK. Treatment of L. casei CB with various concentrations of sodium glycodeoxycholate (GDCA) showed that ~10(5) CFU/ml cells survived after incubation with 0.5% GDCA, whereas almost all the L. casei CK cells were killed when treaded with 0.4% GDCA. These results indicate that the coexpression of CAT and BSH confers high-level resistance to both oxidative and bile salts stress conditions in L. casei HX01.
Marta S. Alves
Full Text Available The aim of this study was to examine antibiotic resistance (AR dissemination in coastal water, considering the contribution of different sources of faecal contamination. Samples were collected in Berlenga, an uninhabited island classified as Natural Reserve and visited by tourists for aquatic recreational activities. To achieve our aim, AR in Escherichia coli isolates from coastal water was compared to AR in isolates from two sources of faecal contamination: human-derived sewage and seagull faeces. Isolation of E. coli was done on Chromocult agar. Based on genetic typing 414 strains were established. Distribution of E. coli phylogenetic groups was similar among isolates of all sources. Resistances to streptomycin, tetracycline, cephalothin and amoxicillin were the most frequent. Higher rates of AR were found among seawater and faeces isolates, except for last-line antibiotics used in human medicine. Multi-resistance rates in isolates from sewage and seagull faeces (29% and 32% were lower than in isolates from seawater (39%. Seawater AR profiles were similar to those from seagull faeces and differed significantly from sewage AR profiles. Nucleotide sequences matching resistance genes blaTEM, sul1, sul2, tet(A and tet(B, were present in isolates of all sources. Genes conferring resistance to 3rd generation cephalosporins were detected in seawater (blaCTX-M-1 and blaSHV-12 and seagull faeces (blaCMY-2. Plasmid-mediated determinants of resistance to quinolones were found: qnrS1 in all sources and qnrB19 in seawater and seagull faeces. Our results show that seawater is a relevant reservoir of AR and that seagulls are an efficient vehicle to spread human-associated bacteria and resistance genes. The E. coli resistome recaptured from Berlenga coastal water was mainly modulated by seagulls-derived faecal pollution. The repertoire of resistance genes covers antibiotics critically important for humans, a potential risk for human health.
Bonde, Mette; Højland, Dorte Heidi; Kolmos, Hans Jørn
have previously shown that the expression of some resistance genes is abolished after treatment with thioridazine and oxacillin. To further understand the mechanism underlying the reversal of resistance, we tested the expression of genes involved in antibiotic resistance and cell wall biosynthesis...... reversal of resistance by thioridazine relies on decreased expression of specific genes involved in cell wall biosynthesis....
Colomer-Lluch, Marta; Calero-Cáceres, William; Jebri, Sihem; Hmaied, Fatma; Muniesa, Maite; Jofre, Juan
The emergence and increased prevalence of antibiotic resistance genes (ARGs) in the environment may pose a serious global health concern. This study evaluates the abundance of several ARGs in bacterial and bacteriophage DNA via real-time qPCR in samples from five different sampling points in Tunisia; three wastewater treatment plants (WWTP 1, 2 and 3) and wastewater from two abattoirs slaughtering different animals. Results are compared with those obtained in the Barcelona area, in northeast Spain. Eight ARGs were quantified by qPCR from total and phage DNA fraction from the samples. Three β-lactamases (bla(TEM), bla(CTX-M) cluster 1 and bla(CTX-M) cluster 9), two quinolone resistance genes (qnrA and qnrS), the mecA gene that confers resistance to methicillin in Staphylococcus aureus, the emerging armA gene, conferring resistance to aminoglycosides and sul1, the most extended gene conferring resistance to sulfonamides, were evaluated. Sul1 and bla(TEM) were the most prevalent ARGs detected at all five Tunisian sampling points, similarly with the observations in Barcelona. bla(CTX-M-9) was more prevalent than bla(CTX-M-1) both in bacterial and DNA within phage particles in all samples analysed. mecA and armA were almost absent in Tunisian waters from human or animal origin in contrast with Barcelona that showed a medium prevalence. qnrA was more prevalent than qnrS in bacterial and phage DNA from all sampling points. In conclusion, our study shows that ARGs are found in the bacterial and is reflected in the phage DNA fraction of human and animal wastewaters. The densities of each ARGs vary depending on the ARGs shed by each population and is determined by the characteristics of each area. Thus, the evaluation of ARGs in wastewaters seems to be suitable as marker reflecting the antibiotic resistance patterns of a population. Copyright © 2014 Elsevier Ltd. All rights reserved.
Oct 16, 2013 ... Isolation of NBS-LRR class resistant gene (I2 gene) from tomato cultivar Heamsona ... avirulence protein or effector protein secreted by fungal pathogen during the host colonization in tomato. These effector proteins .... and efficient method for isolation of genomic DNA from plant tissue. J. Cell Tissue Res.
Proia, Lorenzo; Schiller, Daniel von; Sànchez-Melsió, Alexandre; Sabater, Sergi; Borrego, Carles M.; Rodríguez-Mozaz, Sara; Balcázar, José Luis
The extensive use of antibiotics in human and veterinary medicine and their subsequent release into the environment may have direct consequences for autochthonous bacterial communities, especially in freshwater ecosystems. In small streams and rivers, local inputs of wastewater treatment plants (WWTPs) may become important sources of organic matter, nutrients and emerging pollutants, such as antibiotic resistance genes (ARGs). In this study, we evaluated the effect of WWTP effluents as a source of ARGs in river biofilms. The prevalence of genes conferring resistance to main antibiotic families, such as beta-lactams (bla CTX-M ), fluoroquinolones (qnrS), sulfonamides (sul I), and macrolides (ermB), was determined using quantitative PCR (qPCR) in biofilm samples collected upstream and downstream WWTPs discharge points in four low-order streams. Our results showed that the WWTP effluents strongly modified the hydrology, physico-chemistry and biological characteristics of the receiving streams and favoured the persistence and spread of antibiotic resistance in microbial benthic communities. It was also shown that the magnitude of effects depended on the relative contribution of each WWTP to the receiving system. Specifically, low concentrations of ARGs were detected at sites located upstream of the WWTPs, while a significant increase of their concentrations was observed in biofilms collected downstream of the WWTP discharge points (particularly ermB and sul I genes). These findings suggest that WWTP discharges may favour the increase and spread of antibiotic resistance among streambed biofilms. The present study also showed that the presence of ARGs in biofilms was noticeable far downstream of the WWTP discharge (up to 1 km). It is therefore reasonable to assume that biofilms may represent an ideal setting for the acquisition and spread of antibiotic resistance determinants and thus be considered suitable biological indicators of anthropogenic pollution by active
Full Text Available HIGHLIGHTSOverexpressing and RNA interfering OsDRAP1 transgenic rice plants exhibited significantly improved and reduced drought tolerance, but accompanied with negative effects on development and yield.The dehydration responsive element binding (DREBs genes are important transcription factors which play a crucial role in plant abiotic stress tolerances. In this study, we functionally characterized a DREB2-like gene, OsDRAP1 conferring drought tolerance (DT in rice. OsDRAP1, containing many cis-elements in its promoter region, was expressed in all organs (mainly expressed in vascular tissues of rice, and induced by a variety of environmental stresses and plant hormones. Overexpressing OsDRAP1 transgenic plants exhibited significantly improved DT; while OsDRAP1 RNA interfering plants exhibited significantly reduced DT which also accompanied with significant negative effects on development and yield. Overexpression of OsDRAP1 has a positive impact on maintaining water balance, redox homeostasis and vascular development in transgenic rice plants under drought stress. OsDRAP1 interacted with many genes/proteins and could activate many downstream DT related genes, including important transcription factors such as OsCBSX3 to response drought stress, indicating the OsDRAP1-mediated pathways for DT involve complex genes networks. All these results provide a basis for further complete understanding of the OsDRAP1 mediated gene networks and their related phenotypic effects.