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Sample records for apomixis

  1. Apomixis and F1 hybrids

    International Nuclear Information System (INIS)

    Apomixis, or asexual reproduction through seeds, has the potential to revolutionize crop production worldwide. It can maximize production through fixation of hybrid vigour and greatly simplify the hybrid seed production process. Genes controlling apomixis are being transferred by traditional backcrossing methods from wild to cultivated species in maize, wheat and pearl millet. Progress is being made in developing molecular markers and maps so that the gene(s) controlling apomixis can be cloned and transferred to any sexual species. Increased emphasis on apomixis by a number of research programmes around the world is helping to develop this reproductive mechanism as an important plant breeding tool. (author). 18 refs

  2. Annual habit and apomixis as drought adaptations in Selaginella tenerrima

    Directory of Open Access Journals (Sweden)

    J. Kornaś

    1983-12-01

    Full Text Available Selaginella tenerrima A. Braun ex Kuhn, widely distributed in the savanna-woodland and savanna zones of tropical Africa, is strictly annual. Dormant megaspores survive the yearly drought. Apomixis has been confirmed through laboratory cultures. Microsporangia are usually absent or very few. and the sporophyte chromosome number is triploid: 2n = 30.

  3. Apomixie, sexualité et amélioration des graminées tropicales

    Directory of Open Access Journals (Sweden)

    Gobbe, J.

    1983-01-01

    Full Text Available Apomixis, sexuality and improvement of tropical grasses. Gametophytic apomixis together with sexuality can be used for the improvement of tropical grasses. Apomixis is researched for providing an easy spreading of cultivars. Apomictic and sexual species are found in the genus Brachiaria ; hybridizations are carried out between a tetraploid, colchicine induced form of the sexual species B. ruziziensis Germain et Evrard, and natural tetraploid apomicts, B. brizantha Stapf. and B. decumbens (Hochst Stapf.

  4. Apomixis is not prevalent in subnival to nival plants of the European Alps

    OpenAIRE

    Hörandl, Elvira; Dobeš , Christoph; Suda, Jan; Vít, Petr; Urfus, Tomáš; Temsch, Eva M.; Cosendai, Anne-Caroline; Wagner, Johanna; Ladinig, Ursula

    2011-01-01

    Background and Aims High alpine environments are characterized by short growing seasons, stochastic climatic conditions and fluctuating pollinator visits. These conditions are rather unfavourable for sexual reproduction of flowering plants. Apomixis, asexual reproduction via seed, provides reproductive assurance without the need of pollinators and potentially accelerates seed development. Therefore, apomixis is expected to provide selective advantages in high-alpine biota. Indeed, apomictic s...

  5. Evolution of the apomixis transmitting chromosome in Pennisetum

    Science.gov (United States)

    2011-01-01

    Background Apomixis is an intriguing trait in plants that results in maternal clones through seed reproduction. Apomixis is an elusive, but potentially revolutionary, trait for plant breeding and hybrid seed production. Recent studies arguing that apomicts are not evolutionary dead ends have generated further interest in the evolution of asexual flowering plants. Results In the present study, we investigate karyotypic variation in a single chromosome responsible for transmitting apomixis, the Apospory-Specific Genomic Region carrier chromosome, in relation to species phylogeny in the genera Pennisetum and Cenchrus. A 1 kb region from the 3' end of the ndhF gene and a 900 bp region from trnL-F were sequenced from 12 apomictic and eight sexual species in the genus Pennisetum and allied genus Cenchrus. An 800 bp region from the Apospory-Specific Genomic Region also was sequenced from the 12 apomicts. Molecular cytological analysis was conducted in sixteen Pennisetum and two Cenchrus species. Our results indicate that the Apospory-Specific Genomic Region is shared by all apomictic species while it is absent from all sexual species or cytotypes. Contrary to our previous observations in Pennisetum squamulatum and Cenchrus ciliaris, retrotransposon sequences of the Opie-2-like family were not closely associated with the Apospory-Specific Genomic Region in all apomictic species, suggesting that they may have been accumulated after the Apospory-Specific Genomic Region originated. Conclusions Given that phylogenetic analysis merged Cenchrus and newly investigated Pennisetum species into a single clade containing a terminal cluster of Cenchrus apomicts, the presumed monophyletic origin of Cenchrus is supported. The Apospory-Specific Genomic Region likely preceded speciation in Cenchrus and its lateral transfer through hybridization and subsequent chromosome repatterning may have contributed to further speciation in the two genera. PMID:21975191

  6. Evolution of the apomixis transmitting chromosome in Pennisetum

    Directory of Open Access Journals (Sweden)

    Yamada-Akiyama Hitomi

    2011-10-01

    Full Text Available Abstract Background Apomixis is an intriguing trait in plants that results in maternal clones through seed reproduction. Apomixis is an elusive, but potentially revolutionary, trait for plant breeding and hybrid seed production. Recent studies arguing that apomicts are not evolutionary dead ends have generated further interest in the evolution of asexual flowering plants. Results In the present study, we investigate karyotypic variation in a single chromosome responsible for transmitting apomixis, the Apospory-Specific Genomic Region carrier chromosome, in relation to species phylogeny in the genera Pennisetum and Cenchrus. A 1 kb region from the 3' end of the ndhF gene and a 900 bp region from trnL-F were sequenced from 12 apomictic and eight sexual species in the genus Pennisetum and allied genus Cenchrus. An 800 bp region from the Apospory-Specific Genomic Region also was sequenced from the 12 apomicts. Molecular cytological analysis was conducted in sixteen Pennisetum and two Cenchrus species. Our results indicate that the Apospory-Specific Genomic Region is shared by all apomictic species while it is absent from all sexual species or cytotypes. Contrary to our previous observations in Pennisetum squamulatum and Cenchrus ciliaris, retrotransposon sequences of the Opie-2-like family were not closely associated with the Apospory-Specific Genomic Region in all apomictic species, suggesting that they may have been accumulated after the Apospory-Specific Genomic Region originated. Conclusions Given that phylogenetic analysis merged Cenchrus and newly investigated Pennisetum species into a single clade containing a terminal cluster of Cenchrus apomicts, the presumed monophyletic origin of Cenchrus is supported. The Apospory-Specific Genomic Region likely preceded speciation in Cenchrus and its lateral transfer through hybridization and subsequent chromosome repatterning may have contributed to further speciation in the two genera.

  7. Apomixis in plant reproduction: a novel perspective on an old dilemma.

    Science.gov (United States)

    Barcaccia, Gianni; Albertini, Emidio

    2013-09-01

    Seed is one of the key factors of crop productivity. Therefore, a comprehension of the mechanisms underlying seed formation in cultivated plants is crucial for the quantitative and qualitative progress of agricultural production. In angiosperms, two pathways of reproduction through seed exist: sexual or amphimictic, and asexual or apomictic; the former is largely exploited by seed companies for breeding new varieties, whereas the latter is receiving continuously increasing attention from both scientific and industrial sectors in basic research projects. If apomixis is engineered into sexual crops in a controlled manner, its impact on agriculture will be broad and profound. In fact, apomixis will allow clonal seed production and thus enable efficient and consistent yields of high-quality seeds, fruits, and vegetables at lower costs. The development of apomixis technology is expected to have a revolutionary impact on agricultural and food production by reducing cost and breeding time, and avoiding the complications that are typical of sexual reproduction (e.g., incompatibility barriers) and vegetative propagation (e.g., viral transfer). However, the development of apomixis technology in agriculture requires a deeper knowledge of the mechanisms that regulate reproductive development in plants. This knowledge is a necessary prerequisite to understanding the genetic control of the apomictic process and its deviations from the sexual process. Our molecular understanding of apomixis will be greatly advanced when genes that are specifically or differentially expressed during embryo and embryo sac formation are discovered. In our review, we report the main findings on this subject by examining two approaches: i) analysis of the apomictic process in natural apomictic species to search for genes controlling apomixis and ii) analysis of gene mutations resembling apomixis or its components in species that normally reproduce sexually. In fact, our opinion is that a novel

  8. Evolution of apomixis loci in Pilosella and Hieracium (Asteraceae) inferred from the conservation of apomixis-linked markers in natural and experimental populations

    Czech Academy of Sciences Publication Activity Database

    Hand, M. L.; Vít, Petr; Krahulcová, Anna; Johnson, S. D.; Oelkers, K.; Siddons, H.; Chrtek, Jindřich; Fehrer, Judith; Koltunow, A. M. G.

    2015-01-01

    Roč. 114, č. 1 (2015), s. 17-26. ISSN 0018-067X R&D Projects: GA ČR GA206/08/0890; GA ČR GAP506/10/1363 Institutional support: RVO:67985939 Keywords : gametophytic apomixis * Hieracium * marker inheritance Subject RIV: EF - Botanics Impact factor: 3.805, year: 2014

  9. Increased apomixis expression concurrent with genetic and epigenetic variation in a newly synthesized Eragrostis curvula polyploid

    Science.gov (United States)

    Zappacosta, Diego C.; Ochogavía, Ana C.; Rodrigo, Juan M.; Romero, José R.; Meier, Mauro S.; Garbus, Ingrid; Pessino, Silvina C.; Echenique, Viviana C.

    2014-04-01

    Eragrostis curvula includes biotypes reproducing through obligate and facultative apomixis or, rarely, full sexuality. We previously generated a ``tetraploid-dihaploid-tetraploid'' series of plants consisting of a tetraploid apomictic plant (T), a sexual dihaploid plant (D) and a tetraploid artificial colchiploid (C). Initially, plant C was nearly 100% sexual. However, its capacity to form non-reduced embryo sacs dramatically increased over a four year period (2003-2007) to reach levels of 85-90%. Here, we confirmed high rates of apomixis in plant C, and used AFLPs and MSAPs to characterize the genetic and epigenetic variation observed in this plant in 2007 as compared to 2003. Of the polymorphic sequences, some had no coding potential whereas others were homologous to retrotransposons and/or protein-coding-like sequences. Our results suggest that in this particular plant system increased apomixis expression is concurrent with genetic and epigenetic modifications, possibly involving transposable elements.

  10. Annual habit and apomixis as drought adaptations in Selaginella tenerrima

    OpenAIRE

    J. Kornaś; A. Jankun

    1983-01-01

    Selaginella tenerrima A. Braun ex Kuhn, widely distributed in the savanna-woodland and savanna zones of tropical Africa, is strictly annual. Dormant megaspores survive the yearly drought. Apomixis has been confirmed through laboratory cultures. Microsporangia are usually absent or very few. and the sporophyte chromosome number is triploid: 2n = 30.

  11. Increased apomixis expression concurrent with genetic and epigenetic variation in a newly synthesized Eragrostis curvula polyploid

    OpenAIRE

    Zappacosta, Diego C.; Ochogavía, Ana C.; Rodrigo, Juan M.; Romero, José R; Meier, Mauro S.; Garbus, Ingrid; Pessino, Silvina C.; Viviana C. Echenique

    2014-01-01

    Eragrostis curvula includes biotypes reproducing through obligate and facultative apomixis or, rarely, full sexuality. We previously generated a “tetraploid-dihaploid-tetraploid” series of plants consisting of a tetraploid apomictic plant (T), a sexual dihaploid plant (D) and a tetraploid artificial colchiploid (C). Initially, plant C was nearly 100% sexual. However, its capacity to form non-reduced embryo sacs dramatically increased over a four year period (2003–2007) to reach levels of 85–9...

  12. Presencia de apomixis en cruzas de nopales mexicanos y su identificación molecular preliminar

    OpenAIRE

    Candelario Mondragón Jacobo; Bruce B. Bordelon

    2002-01-01

    El nopal es endémico de México y se ha convertido en cultivo alternativo para producir fruta, verdura y forraje en zonas semiáridas; solamente cinco variedades soportan el mercado nacional de tuna. A nivel comercial el nopal es propagado vegetativamente, pero para su mejoramiento se requiere la propagación sexual. A diferencia de otros cultivos propagados por semilla, una limitante seria del mejoramiento genético del nopal es la apomixis, ya que dificulta la selección de individuos obtenidos ...

  13. [Expression of the apomictic potential and selection for apomixis in sorghum line AS-1a].

    Science.gov (United States)

    El'konin, L A; Beliaeva, E V; Fadeeva, I Iu

    2012-01-01

    Expression of elements of apomixis was studied for ten seasons in sorghum line AS-la and its backcross hybrids on the 9E and A3 sterile cytoplasms. Cytoembryological analysis revealed aposporous embryo sacks (apo-ESs), their initial cells, and, rare, parthenogeneic proembryos in ovules of line AS-la and its BC2 and BC3 hybrids on the 9E cytoplasm. The A3 sterile cytoplasm suppressed the development of parthenogenetic proembryos, but did not affect the apo-ES formation. The frequency of apomictic elements increased in seasons with high daily temperatures and total precipitation deficiency in the period when the ovule and megagametophyte developed (r = -0.805, P anthocyan color of coleoptyles and leaves in seedlings. Plants of the maternal type were found in the progenies of these crosses at a frequency of 1.4-28.1%. The genetic structure of the endosperm in grains with maternal-type seedlings was inferred from the electrophoretic patterns of storage proteins (kafirins). The kafirin spectra of grains producing maternal-type seedlings was similar to the spectrum of line AS-la and differed from the spectra of grains producing hybrid seedlings, indicating that the endosperm developed independently when apomictic grains formed in line AS-1a. The results showed that lines with facultative apomixis can be constructed in functionally diploid plants. PMID:22567852

  14. Apomixis does not affect visitation to flowers of Melastomataceae, but pollen sterility does.

    Science.gov (United States)

    Maia, F R; Varassin, I G; Goldenberg, R

    2016-01-01

    Apomixis is an asexual seed reproduction mechanism thorough which embryos are originated from material tissues inside the ovules, without precedent fertilisation. It allows plants to colonise new habitats, even in places where flower visitors are scarce or where plants are isolate. Apomixis seems to be related to pollen sterility and, in species with flowers that offer pollen as a reward for pollinators, the amount or quality of the pollen offered by these species may influence the amount of the visits and specific composition of the visitors. In order to test this hypothesis, we studied breeding systems of 16 species of Melastomataceae and their flower visitors, evaluating composition and abundance of the visits to apomictic and sexual species. Apomictic plants with no viable pollen or with pollen with low viability did not receive visits from pollinators, and consequently probably produce strictly apomictic fruits. On the other hand, apomictic and sexual plants with high pollen viability do receive visits; in this case, apomictic plants may produce fruits and seeds through both sexual and apomictic methods. The species composition of insects visiting Melastomataceae with high pollen viability was similar, regardless of whether the plants were apomictic or not. It seems that pollen viability levels are important to determine visits to the flowers irrespective of breeding system. PMID:26152277

  15. Expressivity of apomixis in 2n + n hybrids from an apomictic and a sexual parent: insights into variation detected in Pilosella (Asteraceae: Lactuceae)

    Czech Academy of Sciences Publication Activity Database

    Krahulcová, Anna; Krahulec, František; Rosenbaumová, R.

    2011-01-01

    Roč. 24, č. 1 (2011), s. 263-274. ISSN 0934-0882 R&D Projects: GA ČR GA206/08/0890 Institutional research plan: CEZ:AV0Z60050516 Keywords : inheritance of apomixis * residual sexuality * unreduced hybrids Subject RIV: EF - Botanics Impact factor: 1.869, year: 2011

  16. Patterns of genetic variation in Pilosella echioides and its selected relatives: results of variation in ploidy level, facultative apomixis and past and present hybridization

    Czech Academy of Sciences Publication Activity Database

    Chrtek, Jindřich; Plačková, Ivana; Dočkalová, Zuzana; Krahulcová, Anna; Trávníček, Pavel

    2014-01-01

    Roč. 300, č. 9 (2014), s. 2091-2104. ISSN 0378-2697 R&D Projects: GA ČR GAP506/10/1363; GA ČR GP13-18610P Institutional support: RVO:67985939 Keywords : Pilosella * allozymes * apomixis Subject RIV: EF - Botanics Impact factor: 1.422, year: 2014

  17. How just a few makes a lot: Speciation via reticulation and apomixis on example of European brambles (Rubus subgen. Rubus, Rosaceae).

    Science.gov (United States)

    Sochor, Michal; Vašut, Radim J; Sharbel, Timothy F; Trávníček, Bohumil

    2015-08-01

    New species are generated by many means, among which hybridization plays an important role. Interspecific hybrids can form isolated evolutionary units, especially when mechanisms increasing viability and fertility, like polyploidy and apomixis, are involved. A good model system to study reticulate evolution in plants is Rubus subgen. Rubus (brambles, blackberries), which only in Europe includes 748 accepted species, out of which only four are sexual diploids and all others are polyploid apomicts. We employed two molecular markers (ITS and cpDNA) to shed light on the evolutionary history of European bramble flora and main processes generating such high species diversity. We distinguished just six ancestral diploids (including two extinct ones) for both markers, which gave rise to all European polyploid accessions, and revealed an extreme reticulation in bramble evolution. We furthermore detected hybridogenous origins and identified putative parents for several taxa (e.g. ser. Nessenses), while in other groups (e.g. ser. Discolores) we could also infer the direction of hybridization. By comparing different cp haplotypes having clear geographic patterns, we hypothesize that the origin of European brambles can be attributed to both Holocene species range expansion and Pleistocene climate fluctuations. PMID:25882835

  18. Complex Interspecific Hybridization in Barley (Hordeum vulgare L.) and the Possible Occurrence of Apomixis

    DEFF Research Database (Denmark)

    Bothmer, R. von; Bengtsson, M.; Flink, J.;

    1988-01-01

    mixoploid with respect to alien chromosomes (19-22). In one combination, chromosome no. 7 was duplicated. Meiosis in triple hybrids showed low, but variable pairing (1.3-5.5 chiasmata per cell). The syndesis probably did not include the barley chromosomes. Direct backcrosses to di- and tetraploid...

  19. Facultative Apomixis in Garcinia atroviridis (Clusiaceae) and Effects of Different Pollination Regimes on Reproductive Success

    OpenAIRE

    Pangsuban, Sasithorn; Bamroongrugsa, Noparat; Kamnoon KANCHANAPOOM; Nualsri, Charassri

    2009-01-01

    Various aspects of the reproductive success of Garcinia atroviridis Griff. were studied. Controlled pollination experiments were carried out in an orchard located in Songkhla province, southern Thailand, from February to July 2003. Floral longevity, stigma receptivity, and pollen viability were examined before carrying out the experiments. Three pollination treatments were compared: open pollination, manual pollination with bags, and bags without pollination (apogamy). Although there was no s...

  20. Identification of apomixis in the Kentucky bluegrass (Poa pratensis L. using auxin test

    Directory of Open Access Journals (Sweden)

    Janetta Niemann

    2012-08-01

    Full Text Available The effect of auxin treatment on the formation of apomictic – endospermless grains in Poa pratensis was investigated in the study. Four Polish cultivars: Skiz, Eska 46, Alicja, Ani as well as six breeding lines: POB 13, SK-W-33, SKW-15, SKW-35A, SK-W-35A and SK-W-35B were tested by embryological methods to reveal the reproduction pathway in greenhouse and field conditions. The obtained results showed that four genotypes, i.e. Alicja, Ani, Eska 46 and SK-W-35B are facultative apomictic and the other have formed seeds only on the apomictic way. In facultative apomicts it was found that in many cases both endospermless ovules containing embryo sacs with embryos or embryo sacs with well developed endosperm were formed. In the case of apomictic genotypes only endospermless seeds were observed.

  1. Identification of Candidate Genes Related to Polyploidy and/or Apomixis in Eragrostis curvula

    OpenAIRE

    Juan-Pablo Selva; Pessino, Silvina C.; Meier, Mauro S.; Viviana C. Echenique

    2012-01-01

    This work was aimed at identifying genes that show altered expression profiles in response to changes in ploidy and/or reproductive mode (from sexual to apomictic) in the African grass Eragrostis curvula. A differential display analysis was performed on leaf and flower transcriptomes from a series of genetically related euploid plants, including tetraploid apomictic, diploid sexual, and tetraploid sexual plants. More than 100 primer combinations were used to generate 11,864 total markers, yie...

  2. Identification of Candidate Genes Related to Polyploidy and/or Apomixis in Eragrostis curvula

    Directory of Open Access Journals (Sweden)

    Juan-Pablo Selva

    2012-03-01

    Full Text Available This work was aimed at identifying genes that show altered expression profiles in response to changes in ploidy and/or reproductive mode (from sexual to apomictic in the African grass Eragrostis curvula. A differential display analysis was performed on leaf and flower transcriptomes from a series of genetically related euploid plants, including tetraploid apomictic, diploid sexual, and tetraploid sexual plants. More than 100 primer combinations were used to generate 11,864 total markers, yielding 1293 differential bands. Of these bands, 11.84% to 6.74% were related to ploidy and 0.71% to 2.17% to the reproductive mode, depending on the tissue. A small percentage of bands showed similar expressions between the tetraploid apomictic and the diploid sexual plants. Expression-based similarity dendrograms were constructed. Our data suggested that ploidy is more decisive than tissue type in defining the transcriptome structure. Out of 102 fragments sequenced, 50 showed strong homology to known genes. The differentially expressed genes were mapped in silico onto maize chromosomes. Several candidates mapped within the linkage group syntenic to the Tripsacum dactyloides diplospory-governing region. The evidence indicates that expression of genes located around the diplospory-associated region may be strongly influenced by ploidy and may be silenced in the apomictic genotype. These findings are discussed in the context of diplospory molecular control and its connection with ploidy.

  3. Desynapsis and FDR 2n-megaspore formation in diploid potato; potentials and limitations for breeding and for the induction of diplosporic apomixis.

    OpenAIRE

    Jongedijk, E.

    1991-01-01

    The cultivated potato, Solanum tuberosum L., is a highly heterozygous autotetraploid (2n=4x=48) plant species, which after its introduction into Europe in the 16th century has become one of the world's major food crops. The potato has traditionally been grown from tubers. However, as tubers are an excellent substrate for many pathogens and parasites, it is extremely difficult and expensive to produce healthy seed tubers. Most developing countries lack both the knowledge and infrastructure req...

  4. 两对互补的显性基因控制着柑桔属和枳属的无融合生殖%Two Complementary Dominant Genes Controlling Apomixis in Genus Citrus and Poncirus

    Institute of Scientific and Technical Information of China (English)

    洪棋斌; 向素琼; 陈克玲; 陈力耕

    2001-01-01

    无融合生殖具有重要的学术价值和应用价值,这种生殖方 式普遍存在于柑桔属及其近缘属植物中。对母本分别为单胚(即有性生殖)的宽皮柑桔品种克 力迈丁和韦尔金、父本分别为多胚(即无融合生殖)的甜橙品种锦橙、新会橙、桃叶橙和哈姆 林的杂种F1代群体总计8个杂交组合的229个开花结果后代,进行了胚性分离的调查,发现 F1代中既有有性生殖,也有无融合生殖;有性生殖与无融合生殖的分离比例,在韦尔金后 代中接近1∶2,而在克力迈丁后代中接近1∶1。根据该结果,结合前人的研究资料,提出在 柑桔属和枳属或者还包括其他柑桔近缘属中,无融合生殖受到位于细胞核的两对互补的显性 基因A1和A2的调控,且其中一对基因,设为A1表现显性纯合致死效应;两对基 因的分离重组符合孟德尔的分离定律和自由组合定律。按该模式可以较为合理地解释已有的 大部分常规杂交资料。

  5. Isolation of Promoters and Fragments of Genes Controlling Endosperm Development Without Fertilization in Arabidopsis and Engineering of the Antisense Constructions

    Directory of Open Access Journals (Sweden)

    Grigory A. Gerashchenkov

    2015-06-01

    Full Text Available Apomixis is asexual seed reproduction without both meiosis and fertilization based on the complex developmental processes such as apomeiosis, parthenogenesis and specific endosperm development. This investigation is aimed at engineering of apomixis in Arabidopsis thaliana with sexual seed reproduction. The fragments of known genes of endosperm formation MEA, FIE, FIS2 and gene of apomeiosis DYAD (as control were isolated using Q5 high fidelity DNA polymerase. These gene fragments of interest at the antisense orientation were fused with isolated constitutive and meiosis specific promoters of Arabidopsis at NcoI sites. The fused promoter-gene fragment modules were cloned in pCambia1301 at SalI cites. The engineered constructions will be used for the floral dip transformation of Arabidopsis and down regulation of these genes at engineering of apomixis.

  6. Next generation haplotyping to decipher nuclear genomic interspecific admixture in Citrus species: analysis of chromosome 2

    OpenAIRE

    Curk, Franck; Ancillo, Gema; Garcia-Lor, Andres; Luro, François; Perrier, Xavier; Jacquemoud-Collet, Jean-Pierre; Navarro, Luis; Ollitrault, Patrick

    2014-01-01

    Background The most economically important Citrus species originated by natural interspecific hybridization between four ancestral taxa (Citrus reticulata, Citrus maxima, Citrus medica, and Citrus micrantha) and from limited subsequent interspecific recombination as a result of apomixis and vegetative propagation. Such reticulate evolution coupled with vegetative propagation results in mosaic genomes with large chromosome fragments from the basic taxa in frequent interspecific heterozygosity....

  7. The intriguing complexity of parthenogenesis inheritance in Pilosella rubra (Asteraceae, Lactuceae)

    Czech Academy of Sciences Publication Activity Database

    Rosenbaumová, R.; Krahulcová, Anna; Krahulec, František

    2012-01-01

    Roč. 25, č. 3 (2012), s. 185-196. ISSN 0934-0882 R&D Projects: GA ČR GA206/08/0890 Institutional research plan: CEZ:AV0Z60050516 Institutional support: RVO:67985939 Keywords : apomixis * inheritance of parthenogenesis * haploid parthenogenesis Subject RIV: EF - Botanics Impact factor: 2.070, year: 2012

  8. Geographical parthenogenesis, genome size variation and pollen production in the arctic-alpine species Hieracium alpinum

    Czech Academy of Sciences Publication Activity Database

    Mráz, P.; Chrtek, Jindřich; Šingliarová, B.

    2009-01-01

    Roč. 119, č. 1 (2009), s. 41-51. ISSN 0253-1453 R&D Projects: GA ČR GA206/05/0657 Institutional research plan: CEZ:AV0Z60050516 Keywords : apomixis * Compositae * polyploidy Subject RIV: EF - Botanics Impact factor: 0.900, year: 2009

  9. Identification of genes differentially expressed during apomictic and sexual development in buffelgrass (Pennisetum ciliare)

    Science.gov (United States)

    Apomixis, an asexual method of reproduction through seeds with the absence of meiosis and fertilization holds great potential for plant breeding and hybrid seed production. Buffelgrass, an apomictic forage grass, has well characterized apomictic, facultative and sexual accessions to study apomictic...

  10. Genetic variation in the Hieracium rohacsense group (Hieracium sect. Alpina)

    Czech Academy of Sciences Publication Activity Database

    Mráz, P.; Chrtek, Jindřich; Kirschner, Jan

    2001-01-01

    Roč. 41, č. 2 (2001), s. 269-276. ISSN 0079-2047 R&D Projects: GA AV ČR KSK6005114 Institutional research plan: CEZ:AV0Z6005908 Keywords : Asteraceae, Compositae, Hieracium * Apomixis, isozymes * Flora of the Carpathians Subject RIV: EF - Botanics Impact factor: 0.275, year: 2001

  11. Plant Breeding: Surprisingly, Less Sex Is Better.

    Science.gov (United States)

    van Dijk, Peter J; Rigola, Diana; Schauer, Stephen E

    2016-02-01

    Introduction of apomixis, asexual reproduction through seeds, into crop species has the potential to dramatically transform plant breeding. A new study demonstrates that traits can be stably transferred between generations in newly produced apomictic lines, and heralds a breeding revolution needed to increase food production for the growing planet. PMID:26859270

  12. Sexual and apomictic reproduction in Hieracium sub genus Pilosella are closely interrelated developmental pathways

    NARCIS (Netherlands)

    Tucker, M.R.; Araujo, A.C.G.; Paech, N.A.; Hecht, V.; Schmidt, E.D.L.; Rossel, J.B.; Vries, de S.C.; Koltunow, A.M.

    2003-01-01

    Seed formation in flowering plants requires meiosis of the megaspore mother cell (MMC) inside the ovule, selection of a megaspore that undergoes mitosis to form an embryo sad, and double fertilization to initiate embryo and endosperm formation. During apomixis, or asexual seed formation, in Hieraciu

  13. Toward a monophyletic Cheilanthes: The resurrection and recircumscription of Myriopteris (Pteridaceae)

    OpenAIRE

    Amanda Grusz; Michael Windham

    2013-01-01

    Abstract The fern genus Cheilanthes (Pteridaceae) has perplexed taxonomists for more than two centuries. Complex patterns of evolution involving rampant morphological convergence, polyploidy, hybridization, and apomixis have made the taxonomy of this group especially difficult. Fortunately, recent phylogenetic analyses have helped to clarify relationships among cheilanthoid taxa. Based on these findings, we here formalize an updated taxonomy for one monophyletic clade comprising 47 primarily ...

  14. Development of innovative techniques and principles that may be used as models to improve plant performance. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hanna, Wayne W.; Burton, Glenn W.

    2000-06-25

    We developed fundamental methods and techniques for transferring germplasm from wild to cultivated species. Germplasm transferred included diverse cytoplasms, new genes for pest resistance, genes controlling dry matter yield and apomixis. Some of the germplasm has been shown to be valuable in plant breeding and has been incorporated into commercial cultivators.

  15. Use of the SSLP-based method for detection of rare apomictic events in a sexual AtSERK1 transgenic Arabidopsis population

    NARCIS (Netherlands)

    Kantama, L.; Lambert, J.M.; Hu, H.; Jong, de H.; Vries, de S.C.; Russinova, E.

    2006-01-01

    Here we present a screening method to evaluate the potential of genes to transfer aspects of apomixis into sexual crop plants. Based on the assumption that an apomictic progeny is an exact genetic replica of the mother plant we employed a set of single sequence length polymorphism (SSLP) markers to

  16. Chromosome studies and genetic analysis of natural and synthetic apomictic model species

    NARCIS (Netherlands)

    Kantama, L.

    2005-01-01

    Some plants have gained the ability to produce seed without fertilisation. This alternative to sexual reproduction, known as apomixis occurs most frequently in species of the families of the grasses, roses and composites, and mostly in polyploids and is considered one of the ways to escape from hybr

  17. Improvement of date palm by radiation and growth requlators

    International Nuclear Information System (INIS)

    The efficiency of date palm breeding could be improved by changing the sex of date palm flowers, the identification of sexes at early stage and the induction of a sexual embryo in date palm. Date palm breeder wishes to find out source of apomixis because of its application

  18. Genetic fine-mapping of DIPLOSPOROUS in Taraxacum (dandelion; Asteraceae) indicates a duplicated DIP-gene

    OpenAIRE

    Bakx-Schotman Tanja; Milanovic-Ivanovic Slavica; Vijverberg Kitty; van Dijk Peter J

    2010-01-01

    Abstract Background DIPLOSPOROUS (DIP) is the locus for diplospory in Taraxacum, associated to unreduced female gamete formation in apomicts. Apomicts reproduce clonally through seeds, including apomeiosis, parthenogenesis, and autonomous or pseudogamous endosperm formation. In Taraxacum, diplospory results in first division restitution (FDR) nuclei, and inherits as a dominant, monogenic trait, independent from the other apomixis elements. A preliminary genetic linkage map indicated that the ...

  19. Elementary apomictic processes in Rubus L.

    Directory of Open Access Journals (Sweden)

    Roman Czapik

    2014-02-01

    Full Text Available Two elementary apomictic processe were found in the examined Rubus species: R. saxatilis developed diplosporous and aposporous embryo sacs, R. caesius - displosporous, apart from meiotic ones. These result; confirmed the wide occurrence of facultative apomixis and intraspecific differentiation of the mode of reproduction within the taxa of the investigated genus.

  20. The detection, rate and manifestation of residual sexuality in apomictic populations of Pilosella (Asteraceae, Lactuceae)

    Czech Academy of Sciences Publication Activity Database

    Krahulcová, Anna; Rotreklová, O.; Krahulec, František

    2014-01-01

    Roč. 49, č. 2 (2014), s. 239-258. ISSN 1211-9520 R&D Projects: GA ČR GAP506/10/1363 Institutional support: RVO:67985939 Keywords : facultative apomixis * haploid parthenogenesis * interspecific hybridization * Pilosella * residual sexuality Subject RIV: EF - Botanics Impact factor: 1.778, year: 2014

  1. Taxonomic revision of Sorbus subgenus Aria occurring in the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Lepší, M.; Lepší, P.; Koutecký, P.; Bílá, J.; Vít, Petr

    2015-01-01

    Roč. 87, č. 2 (2015), s. 109-162. ISSN 0032-7786 R&D Projects: GA ČR GB14-36079G Institutional support: RVO:67985939 Keywords : apomixis * DAPI flow cytometry * hybridization Subject RIV: EF - Botanics Impact factor: 4.104, year: 2014

  2. Chromosome studies and genetic analysis of natural and synthetic apomictic model species

    OpenAIRE

    Kantama, L.

    2005-01-01

    Some plants have gained the ability to produce seed without fertilisation. This alternative to sexual reproduction, known as apomixis occurs most frequently in species of the families of the grasses, roses and composites, and mostly in polyploids and is considered one of the ways to escape from hybrid sterility. An impressive number of apomictic mechanisms have so far been described; most of them with different developmental modes of embryo and endosperm. The trait is potential very promising...

  3. Exogenous steroid hormones stimulate full development of autonomous endosperm in Arabidopsis thaliana

    OpenAIRE

    Joanna Rojek; Łukasz Pawełko; Małgorzata Kapusta; Aleksandra Naczk; Jerzy Bohdanowicz

    2015-01-01

    Most flowering plants, including important crops, require double fertilization to form an embryo and endosperm, which nourishes it. Independence from fertilization is a feature of apomictic plants that produce seeds, from which the plants that are clones of the mother plant arise. The phenomenon of apomixis occurs in some sexual plants under specific circumstances. Since the launch of a fertilization-independent mechanism is considered a useful tool for plant breeding, there have been efforts...

  4. Utah Science Vol. 53 No. 4, Winter 1992

    OpenAIRE

    1992-01-01

    The Center for Meat Processing Technologies: 106 Trimming the Meeknees from Red Meat Marketing The Center for Value Added Seed Technology: 113 Taming Apomixis to Create New Wheat Hybrids 119 Research in Brief 124 Better Resistance Against Dwarf Smut 125 Taming Range Grasses to Create Better Turf Grass 126 Removing a Biotech Bottleneck The Center for Dairy Foods Technology: 128 Helping the Dairy Industry Gear Up for the next Century 1992 Index 133 New Publicati...

  5. Sexual Hieracium pilosella plants are better inter-specific, while apomictic plants are better intra-specific competitors

    OpenAIRE

    Sailer, Christian; Schmid, Bernhard; Stöcklin, Jürg; Grossniklaus, Ueli

    2014-01-01

    Apomixis, asexual reproduction through seeds, occurs in over 40 plant families. This widespread phenomenon can lead to the fixation of successful genotypes, resulting in a fitness advantage. On the other hand, apomicts are expected to lose their fitness advantage if the environment changes because of their limited evolutionary potential, which is due to low genetic variability and the potential accumulation of deleterious somatic mutations. Nonetheless, some apomicts have been extremely succe...

  6. Enriching ploidy level diversity: the role of apomictic and sexual biotypes of Hieracium subgen. Pilosella (Asteraceae) that coexist in polyploid populations

    Czech Academy of Sciences Publication Activity Database

    Krahulcová, Anna; Rotreklová, O.; Krahulec, František; Rosenbaumová, Radka; Plačková, Ivana

    2009-01-01

    Roč. 44, č. 3 (2009), s. 281-306. ISSN 1211-9520 R&D Projects: GA ČR GA206/07/0059; GA ČR GA206/08/0890 Institutional research plan: CEZ:AV0Z60050516 Keywords : facultative apomixis * genome instability * hybrid swarms * residual sexuality * unreduced gametes Subject RIV: EF - Botanics Impact factor: 1.320, year: 2009

  7. Molecular, histological and embryological analysis of regenerants obtained during in vitro culture of immature embryos of apomictic Taraxacum belorussicum Val. N. Tikhom.

    OpenAIRE

    Monika Tuleja; Halina Ślesak; Krystyna Musiał; Joachimiak, Andrzej J.

    2014-01-01

    Dandelion as a model herbal plant has a wide application in analysis of genetic, molecular background of apomictic reproduction. Taraxacum belorussicum Val. N. Tikhom. is a triploid species belonging to Taraxacum sect. Palustria. As an obligatory apomictic plant it presents attractive experimental material for apomixis and somatic embryogenesis aspects. Here we present the preliminary studies showing direct organogenesis and genetic stability of the regenerants achieved during in vitro cultur...

  8. Range expansion in asexual dandelions: selection for general-purpose genotypes?

    OpenAIRE

    Oplaat, Carla; Verhoeven, Koen

    2015-01-01

    [KEYWORDS: Apomixis geographic parthenogenesis jack-of-all-trades strategy master-of-some strategy phenotypic plasticity Taraxacum officinale (common dandelion)] Phenotypic plasticity and broad ecological tolerance are hypothesized as important traits in the range expansion of asexual species, because individual asexual lineages have to face spatial and temporal environmental variation with limited opportunity for genetic adaptation. The hypothesis that asexual lineages are general-purpose ge...

  9. Molecular, histological and embryological analysis of regenerants obtained during in vitro culture of immature embryos of apomictic Taraxacum belorussicum Val. N. Tikhom.

    Directory of Open Access Journals (Sweden)

    Monika Tuleja

    2014-04-01

    Full Text Available Dandelion as a model herbal plant has a wide application in analysis of genetic, molecular background of apomictic reproduction. Taraxacum belorussicum Val. N. Tikhom. is a triploid species belonging to Taraxacum sect. Palustria. As an obligatory apomictic plant it presents attractive experimental material for apomixis and somatic embryogenesis aspects. Here we present the preliminary studies showing direct organogenesis and genetic stability of the regenerants achieved during in vitro culture of dandelion along with their embryological analysis.

  10. GISH and BAC-FISH study of apomictic Beta M14

    Institute of Scientific and Technical Information of China (English)

    GE Yan; HE GuangChun; WANG ZhiWei; GUO DeDong; QIN Rui; LI RongTian

    2007-01-01

    Apomixis is a means of asexual reproduction by which plants produce embryos without fertilization and meiosis, therefore the embryo is of clonal and maternal origin. Interspecific hybrids between diploid B. vulgaris (2n=2x=18) and tetraploid B. corolliflora (2n=4x=36) were established, and then backcrossed with B. vulgaris. Among their offspring, monosomic addition line M14 (2n=2x=18+1) was selected because of the apomictic phenotype. We documented chromosome transmission from B. corolliflora into M14 by using genomic in situ hybridization (GISH). Suppression of cross-hybridization by blocking DNA was not necessary, indicating that the investigated Beta genome contains sufficient species-specific DNA, thus enabling the determination of genomic composition of the hybrids. We analyzed BAC microarrays of B. corolliflora chromosome 9 by using fluorescence-specific mRNA of B.vulgaris and Beta M14. BAC clones 16-M11 and 26-L15 were detected as fluorescence-specifics of BAC DNA of Beta M14. Then both BAC clones 16-M11 and 26-L15 were in situ hybridized to M14 chromosomes. The two hybridized BAC clones were located close to the telomere region of the long arm of a single chromosome 9, and showed hemizygosity. The results of BAC microarrays showed that these developments of embryo and endosperm have conservative expression patterns, indicating that sexual reproduction and apomixis have an interrelated pathway with common regulatory components and that the induction of a modified sexual reproduction program may enable the manifestation of apomixis in Beta species. It would be sufficient for the expression of apomixes with those apomictic-specific genes on chromosome 9 of B. corolliflora.

  11. Organización de la diversidad genética de los cítricos.

    OpenAIRE

    GARCÍA LOR, ANDRÉS

    2013-01-01

    Citrus es el género de la subfamilia Aurantioideae de mayor importancia económica. Su origen es la región sureste de Asia, en un área que incluye China, India y la península de Indochina y los archipiélagos de los alrededores. Aunque se han realizado múltiples estudios, la taxonomía del género Citrus aun no está bien definida, debido al alto nivel de diversidad morfológica encontrado en este grupo, la compatibilidad sexual entre sus especies y la apomixis de muchos genotip...

  12. The Behavior of Chromosomes During Parthenogenetic Oogenesis in Marmorkrebs Procambarus fallax f. virginalis.

    Science.gov (United States)

    Kato, Miku; Hiruta, Chizue; Tochinai, Shin

    2016-08-01

    Parthenogenetic oogenesis varies among and even within species. Based on cytological mechanisms, it can largely be divided into apomixis (ameiotic parthenogenesis) producing genetically identical progeny, and automixis (meiotic parthenogenesis) producing genetically non-identical progeny. Polyploidy is common in parthenogenetic species, although the association between parthenogenesis and polyploidy throughout evolution is poorly understood. Marmorkrebs, or the marbled crayfish, was first identified as a parthenogenetic decapod and was tentatively named as Procambarus fallax f. virginalis. Previous studies revealed that Marmorkrebs is triploid and produces genetically identical offspring, suggesting that apomixis occurs during parthenogenetic oogenesis. However, the behavior of chromosomes during the process of oogenesis is still not well characterized. In this study, we observed parthenogenetic oogenesis around the time of ovulation in P. fallax f. virginalis by histology and immunohistochemistry. During oogenesis, the chromosomes were separated into two groups and behaved independently from each other, and one complete division corresponding to mitosis (the second meiosis-like division) was observed. This suggests that parthenogenetic oogenesis in Marmorkrebs exhibits gonomery, a phenomenon commonly found in apomictic parthenogenesis in polyploid animals. PMID:27498802

  13. Poor sexual reproduction on the distribution limit of the rare tree Sorbus torminalis

    Science.gov (United States)

    Rasmussen, Kristine Kjørup; Kollmann, Johannes

    2004-05-01

    Plants growing in small fragmented populations under stressful environmental conditions may have reduced sexual reproduction. This can cause low gene flow between populations and eventually extinction. Here we report on a pollination experiment with Sorbus torminalis, a rare fleshy-fruited tree with a submediterranean distribution in Europe. At the northern limit of its range in SE-Denmark two relatively small and isolated populations were studied for effects of seven pollination treatments on fruit production and on the timing of fruit abortion. There was evidence that lack of pollination and spontaneous self-pollination caused particularly high fruit abortion, which indicates that apomixis is unlikely and spontaneous self-pollination not efficient. Fruit abortion was delayed after hand pollination, which suggests limitation by pollen quantity. Self-pollination caused earlier abortion than experimental cross-pollination within or between populations indicating inbreeding depression. There was no evidence for outbreeding depression as measured by fruit abortion. We conclude that generative reproduction of S. torminalis is reduced on its northern distribution limit and that it might be negatively affected by pollen limitation and inbreeding effects, which have not been compensated for by increased self-compatibility or apomixis.

  14. Genetic fine-mapping of DIPLOSPOROUS in Taraxacum (dandelion; Asteraceae indicates a duplicated DIP-gene

    Directory of Open Access Journals (Sweden)

    Bakx-Schotman Tanja

    2010-07-01

    Full Text Available Abstract Background DIPLOSPOROUS (DIP is the locus for diplospory in Taraxacum, associated to unreduced female gamete formation in apomicts. Apomicts reproduce clonally through seeds, including apomeiosis, parthenogenesis, and autonomous or pseudogamous endosperm formation. In Taraxacum, diplospory results in first division restitution (FDR nuclei, and inherits as a dominant, monogenic trait, independent from the other apomixis elements. A preliminary genetic linkage map indicated that the DIP-locus lacks suppression of recombination, which is unique among all other map-based cloning efforts of apomeiosis to date. FDR as well as apomixis as a whole are of interest in plant breeding, allowing for polyploidization and fixation of hybrid vigor, respectively. No dominant FDR or apomixis genes have yet been isolated. Here, we zoom-in to the DIP-locus by largely extending our initial mapping population, and by analyzing (local suppression of recombination and allele sequence divergence (ASD. Results We identified 24 recombinants between two most closely linked molecular markers to DIP in an F1-population of 2227 plants that segregates for diplospory and lacks parthenogenesis. Both markers segregated c. 1:1 in the entire population, indicating a 1:1 segregation rate of diplospory. Fine-mapping showed three amplified fragment length polymorphisms (AFLPs closest to DIP at 0.2 cM at one flank and a single AFLP at 0.4 cM at the other flank. Our data lacked strong evidence for ASD at marker regions close to DIP. An unexpected bias towards diplosporous plants among the recombinants (20 out of 24 was found. One third of these diplosporous recombinants showed incomplete penetrance of 50-85% diplospory. Conclusions Our data give interesting new insights into the structure of the diplospory locus in Taraxacum. We postulate a locus with a minimum of two DIP-genes and possibly including one or two enhancers or cis-regulatory elements on the basis of the bias

  15. Biología reproductiva de Convolvulus chilensis (Convolvulaceae en una población de Aucó (centro-norte de Chile Reproductive biology of Convolvulus chilensis (Convolvulaceae in a population of Aucó (north-central Chile

    Directory of Open Access Journals (Sweden)

    Lorena H. Suárez

    2004-12-01

    Full Text Available Convolvulus chilensis es una hierba perenne, única representante endémica de la familia Convolvulaceae en Chile. Se estudió el sistema de reproducción, fenología, morfología y longevidad floral de C. chilensis en una población natural ubicada en la localidad de Aucó, dentro de la Reserva Nacional Las Chinchillas, IV Región, Chile. Se montó un experimento de polinización controlada considerando los tratamientos de polinización natural, polinización cruzada, autopolinización manual, autopolinización automática y apomixis, evaluándose su efecto sobre la formación de frutos y el número de semillas producidas por fruto. Adicionalmente, se compararon los siguientes atributos de la progenie según tipo de polinización (autopolinización o polinización cruzada: peso de semilla, germinación, altura y número de hojas de plántulas de ocho semanas en condiciones de invernadero. Se encontró que C. chilensis es una especie autocompatible, parcialmente autógama (capaz de autopolinizarse sin mediador y parcialmente apomíctica (capaz de producir semillas sin participación de gameto masculino. La longevidad floral fue estimada en 5,25 h. Durante este período, aproximadamente en 1,5 h hay disponibilidad de polen en los estambres. El período de floración se extiende por 22 semanas (agosto a enero. El tratamiento de apomixis presentó el menor porcentaje de formación de frutos y la menor cantidad de semillas por flor en comparación a los tratamientos de polinización natural, cruzada manual, autopolinización automática y autopolinización manual, los cuales no mostraron diferencias entre sí en ambos atributos. El tipo de polinización (autopolinización o polinización cruzada no afecta el desempeño de la progenie en los atributos de semilla y plántula evaluadosThe perennial herb Convolvulus chilensis is the only endemic species of the Convolvulaceae in Chile. The breeding system, phenology, morphology and floral longevity of C

  16. Chromosome engineering: power tools for plant genetics.

    Science.gov (United States)

    Chan, Simon W L

    2010-12-01

    The term "chromosome engineering" describes technologies in which chromosomes are manipulated to change their mode of genetic inheritance. This review examines recent innovations in chromosome engineering that promise to greatly increase the efficiency of plant breeding. Haploid Arabidopsis thaliana have been produced by altering the kinetochore protein CENH3, yielding instant homozygous lines. Haploid production will facilitate reverse breeding, a method that downregulates recombination to ensure progeny contain intact parental chromosomes. Another chromosome engineering success is the conversion of meiosis into mitosis, which produces diploid gametes that are clones of the parent plant. This is a key step in apomixis (asexual reproduction through seeds) and could help to preserve hybrid vigor in the future. New homologous recombination methods in plants will potentiate many chromosome engineering applications. PMID:20933291

  17. Breeding systems in some representatives of the genus Lycium (Solanaceae

    Directory of Open Access Journals (Sweden)

    L. Minne

    1994-12-01

    Full Text Available The development of the ovule and the embryo sac of five of the 17 species of Lycium and of one hybrid, recorded for southern Africa, was investigated. All specimens of four of the species and the hybrid (between a hermaphroditic and a functionally dioecious species were found to be functionally dioecious: they express only one sex, although both male and female organs are present in the same tlower. One species was hermaphroditic. The embryo sacs of all species, and of the hybrid, were of the normal eight-nucleate Polygonum type. The structure of the ovary and the development of the embryo sac are similar to those of L europaeum L. The absence of unreduced embryo sacs indicates that apomixis does not occur at any ploidy level in the species studied.

  18. Determination of Apomictic Fruit Set Ratio in Several Romanian Walnut (Juglans regia L. Cultivars

    Directory of Open Access Journals (Sweden)

    Sina Niculina COSMULESCU

    2012-05-01

    Full Text Available carried out to determine the ability of apomictic fruit setting in twelve Romanian walnut cultivars. ‘Sibisel 44’, ‘Geoagiu 65’, ‘Germisara’, ‘Muscelean’, ‘Sarmis’, ‘Valcor’, ‘Valmit’, ‘Valrex’, ‘Jupanesti’, ‘Velnita’, ‘Orastie’ and ‘Argesean’ cultivars were used in the experiment. Female flowers were isolated with pergament paper bags and the apomictic fruit set was determined 8 weeks after anthesis. The apomixis degree was determined as the number of fruit calculated in relation to the number of isolated flowers. The percentage of apomictic fruit set without pollination in cultivars analyzed is low, ranging from 7.86% (‘Orastie’ cultivar up to 12.46% (‘Jupanesti’ cultivar. The results indicated that apomictic fruit set is insufficient for economical seed and crop production in these Romanian walnut cultivars.

  19. A Parthenogenesis Gene Candidate and Evidence for Segmental Allopolyploidy in Apomictic Brachiaria decumbens.

    Science.gov (United States)

    Worthington, Margaret; Heffelfinger, Christopher; Bernal, Diana; Quintero, Constanza; Zapata, Yeny Patricia; Perez, Juan Guillermo; De Vega, Jose; Miles, John; Dellaporta, Stephen; Tohme, Joe

    2016-07-01

    Apomixis, asexual reproduction through seed, enables breeders to identify and faithfully propagate superior heterozygous genotypes by seed without the disadvantages of vegetative propagation or the expense and complexity of hybrid seed production. The availability of new tools such as genotyping by sequencing and bioinformatics pipelines for species lacking reference genomes now makes the construction of dense maps possible in apomictic species, despite complications including polyploidy, multisomic inheritance, self-incompatibility, and high levels of heterozygosity. In this study, we developed saturated linkage maps for the maternal and paternal genomes of an interspecific Brachiaria ruziziensis (R. Germ. and C. M. Evrard) × B. decumbens Stapf. F1 mapping population in order to identify markers linked to apomixis. High-resolution molecular karyotyping and comparative genomics with Setaria italica (L.) P. Beauv provided conclusive evidence for segmental allopolyploidy in B. decumbens, with strong preferential pairing of homologs across the genome and multisomic segregation relatively more common in chromosome 8. The apospory-specific genomic region (ASGR) was mapped to a region of reduced recombination on B. decumbens chromosome 5. The Pennisetum squamulatum (L.) R.Br. PsASGR-BABY BOOM-like (psASGR-BBML)-specific primer pair p779/p780 was in perfect linkage with the ASGR in the F1 mapping population and diagnostic for reproductive mode in a diversity panel of known sexual and apomict Brachiaria (Trin.) Griseb. and P. maximum Jacq. germplasm accessions and cultivars. These findings indicate that ASGR-BBML gene sequences are highly conserved across the Paniceae and add further support for the postulation of the ASGR-BBML as candidate genes for the apomictic function of parthenogenesis. PMID:27206716

  20. DNA Markers and FCSS Analyses Shed Light on the Genetic Diversity and Reproductive Strategy of Jatropha curcas L.

    Directory of Open Access Journals (Sweden)

    Daria Gigliola Ambrosi

    2010-05-01

    Full Text Available Jatropha curcas L. (2n = 2x = 22 is becoming a popular non-food oleaginous crop in several developed countries due to its proposed value in the biopharmaceutical industry. Despite the potentials of its oil-rich seeds as a renewable source of biodiesel and an interest in large-scale cultivation, relatively little is known with respect to plant reproduction strategies and population dynamics. Here, genomic DNA markers and FCSS analyses were performed to gain insights into ploidy variation and heterozygosity levels of multiple accessions, and genomic relationships among commercial varieties of Jatropha grown in different geographical areas. The determination of ploidy and the differentiation of either pseudogamous or autonomous apomixis from sexuality were based on the seed DNA contents of embryo and endosperm. The presence of only a high 2C embryo peak and a smaller 3C endosperm peak (ratio 2:3 is consistent with an obligate sexual reproductive system. Because of the lack of either 4C or 5C endosperm DNA estimates, the occurrence of gametophytic apomixis seems unlikely in this species but adventitious embryony cannot be ruled out. The investigation of genetic variation within and between cultivated populations was carried out using dominant RAPD and Inter-SSR markers, and codominant SSR markers. Nei’s genetic diversity, corresponding to the expected heterozygosity, was equal to He = 0.3491 and the fixation index as low as Fst = 0.2042. The main finding is that seeds commercialized worldwide include a few closely related genotypes, which are not representative of the original Mexican gene pool, revealing high degrees of homozygosity for single varieties and very low genetic diversity between varieties.

  1. Laser-assisted Microdissection (LAM) as a Tool for Transcriptional Profiling of Individual Cell Types.

    Science.gov (United States)

    Florez Rueda, Ana Marcela; Grossniklaus, Ueli; Schmidt, Anja

    2016-01-01

    The understanding of developmental processes at the molecular level requires insights into transcriptional regulation, and thus the transcriptome, at the level of individual cell types. While the methods described here are generally applicable to a wide range of species and cell types, our research focuses on plant reproduction. Plant cultivation and seed production is of crucial importance for human and animal nutrition. A detailed understanding of the regulatory networks that govern the formation of the reproductive lineage (germline) and ultimately of seeds is a precondition for the targeted manipulation of plant reproduction. In particular, the engineering of apomixis (asexual reproduction through seeds) into crop plants promises great improvements, as it leads to the formation of clonal seeds that are genetically identical to the mother plant. Consequently, the cell types of the female germline are of major importance for the understanding and engineering of apomixis. However, as the corresponding cells are deeply embedded within the floral tissues, they are very difficult to access for experimental analyses, including cell-type specific transcriptomics. To overcome this limitation, sections of individual cells can be isolated by laser-assisted microdissection (LAM). While LAM in combination with transcriptional profiling allows the identification of genes and pathways active in any cell type with high specificity, establishing a suitable protocol can be challenging. Specifically, the quality of RNA obtained after LAM can be compromised, especially when small, single cells are targeted. To circumvent this problem, we have established a workflow for LAM that reproducibly results in high RNA quality that is well suitable for transcriptomics, as exemplified here by the isolation of cells of the female germline in apomictic Boechera. In this protocol, procedures are described for tissue preparation and LAM, also with regard to RNA extraction and quality control

  2. Study of Genetics and Embryology of Polyembryonic Mutant of Autotetraploid Rice Induced by N+ Beam Implantation

    Science.gov (United States)

    Dai, Ximei; Huang, Qunce; Li, Guoping; Hu, Xiuming; Qin, Guangyong; Yu, Zengliang

    2006-11-01

    In the present study autotetraploid rice IR36-4X was treated by an ion implantation technique with nitrogen ion beams. A polyembryonic mutant (named IR36-Shuang) was identified in the M2 generation. The mutant line and its offspring were systematically investigated in regard to their major agronomic properties and the rate of polyembryonic seedling in the M3-M6 generation. The abnormal phenomena in the embryo sac development and the cytological mechanism of the initiation of additional embryo in IR36-Shuang were observed by Laser Scanning Confocal Microscopy. The results were as follows. 1) The plant height, the panicle length and 1000 grain weight of IR36-Shuang were lower than that of its control by 35.41%, 5.08% and 15.72% respectively, Moreover, the setting percentage decreased 12.39% compared with that in normal IR36-4X plants. 2) The polyembryonic trait of IR36-Shuang was genetically stable and the frequency of the polyembryonic seedlings in the IR36-Shuang line was also relatively stable. 3) The rate of abnormal embryo sacs in IR36-Shuang was significantly higher than that in the control IR36-4X. 4) The additional embryo in IR36-Shuang might arise from the double set of embryo sacs in a single ovary, antipodal cells or endosperm cells. These results suggest that IR36-Shuang is a polyembryonic mutant and a new apomixis rice line induced by low energy ion implantation. The prospects for the application in production of the IR36-Shuang line are also discussed. The present study may provide a basis for future investigations of apomixis rice breeding via the ion implantation biotechnology.

  3. Biologia floral e polinização artificial de pinhão-manso no norte de Minas Gerais Floral biology and artificial polinization in physic nut in the north of Minas Gerais state, Brazil

    Directory of Open Access Journals (Sweden)

    Ana Cristina Pinto Juhász

    2009-09-01

    Full Text Available O objetivo deste trabalho foi avaliar alguns aspectos da biologia floral e do sistema reprodutivo de Jatropha curcas, em Janaúba, MG. Foram registrados: o número de flores femininas e masculinas; o intervalo de abertura das flores femininas; e a formação de frutos por apomixia, autofecundação, geitonogamia e xenogamia. A proporção de flores masculinas para femininas foi de 20:1. O intervalo de abertura das flores femininas variou de um a sete dias, conforme o número delas na inflorescência. No teste de apomixia, houve formação de frutos em apenas 5% das flores avaliadas. A percentagem de frutificação variou de 79 a 88% na autofecundação manual, na geitonogamia e na xenogamia. Na autofecundação sem a polinização manual a frutificação foi de 20%, e os frutos formados foram significativamente menores, com número inferior de sementes por fruto e menor índice de velocidade de emergência. As sementes foram semelhantes às formadas por polinização natural. é possível a realização de cruzamentos controlados em pinhão-manso, e não há autoincompatibilidade nesta espécie.The aim of this work was to evaluate some aspects of the floral biology and of the reproductive system of Jatropha curcas, in Janaúba county, MG, Brazil. The number of female and male flowers, the interval between the opening of female flowers, and the formation of fruits by apomixis, self-pollination, geitonogamy and by xenogamy were registered. The ratio of male to female flowers was 20:1. The interval of opening of female flowers was of one to seven days, depending on the number of female flowers in the inflorescence. On the apomixy test, the formation of fruits occurred in only 5% of the evaluated flowers. The fruit set was between 79 and 88% through the manual self-pollination, and through the geitonogamy, and the xenogamy. In the self-pollination treatment, without the hand-pollination, the fruit set was of 20%, and the fruits formed were

  4. Evidence of Allopolyploidy in Urochloa humidicola Based on Cytological Analysis and Genetic Linkage Mapping.

    Science.gov (United States)

    Vigna, Bianca B Z; Santos, Jean C S; Jungmann, Leticia; do Valle, Cacilda B; Mollinari, Marcelo; Pastina, Maria M; Pagliarini, Maria Suely; Garcia, Antonio A F; Souza, Anete P

    2016-01-01

    The African species Urochloa humidicola (Rendle) Morrone & Zuloaga (syn. Brachiaria humidicola (Rendle) Schweick.) is an important perennial forage grass found throughout the tropics. This species is polyploid, ranging from tetra to nonaploid, and apomictic, which makes genetic studies challenging; therefore, the number of currently available genetic resources is limited. The genomic architecture and evolution of U. humidicola and the molecular markers linked to apomixis were investigated in a full-sib F1 population obtained by crossing the sexual accession H031 and the apomictic cultivar U. humidicola cv. BRS Tupi, both of which are hexaploid. A simple sequence repeat (SSR)-based linkage map was constructed for the species from 102 polymorphic and specific SSR markers based on simplex and double-simplex markers. The map consisted of 49 linkage groups (LGs) and had a total length of 1702.82 cM, with 89 microsatellite loci and an average map density of 10.6 cM. Eight homology groups (HGs) were formed, comprising 22 LGs, and the other LGs remained ungrouped. The locus that controls apospory (apo-locus) was mapped in LG02 and was located 19.4 cM from the locus Bh027.c.D2. In the cytological analyses of some hybrids, bi- to hexavalents at diakinesis were observed, as well as two nucleoli in some meiocytes, smaller chromosomes with preferential allocation within the first metaphase plate and asynchronous chromosome migration to the poles during anaphase. The linkage map and the meiocyte analyses confirm previous reports of hybridization and suggest an allopolyploid origin of the hexaploid U. humidicola. This is the first linkage map of an Urochloa species, and it will be useful for future quantitative trait locus (QTL) analysis after saturation of the map and for genome assembly and evolutionary studies in Urochloa spp. Moreover, the results of the apomixis mapping are consistent with previous reports and confirm the need for additional studies to search for a co

  5. Analysis of conserved microRNAs in floral tissues of sexual and apomictic Boechera species

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    Vogel Heiko

    2011-10-01

    Full Text Available Abstract Background Apomixis or asexual seed formation represents a potentially important agronomic trait whose introduction into crop plants could be an effective way to fix and perpetuate a desirable genotype through successive seed generations. However, the gene regulatory pathways underlying apomixis remain unknown. In particular, the potential function of microRNAs, which are known to play crucial roles in many aspects of plant growth and development, remains to be determined with regards to the switch from sexual to apomictic reproduction. Results Using bioinformatics and microarray validation procedures, 51 miRNA families conserved among angiosperms were identified in Boechera. Microarray assay confirmed 15 of the miRNA families that were identified by bioinformatics techniques. 30 cDNA sequences representing 26 miRNAs could fold back into stable pre-miRNAs. 19 of these pre-miRNAs had miRNAs with Boechera-specific nucleotide substitutions (NSs. Analysis of the Gibbs free energy (ΔG of these pre-miRNA stem-loops with NSs showed that the Boechera-specific miRNA NSs significantly (p ≤ 0.05 enhance the stability of stem-loops. Furthermore, six transcription factors, the Squamosa promoter binding protein like SPL6, SPL11 and SPL15, Myb domain protein 120 (MYB120, RELATED TO AP2.7 DNA binding (RAP2.7, TOE1 RAP2.7 and TCP family transcription factor 10 (TCP10 were found to be expressed in sexual or apomictic ovules. However, only SPL11 showed differential expression with significant (p ≤ 0.05 up-regulation at the megaspore mother cell (MMC stage of ovule development in apomictic genotypes. Conclusions This study constitutes the first extensive insight into the conservation and expression of microRNAs in Boechera sexual and apomictic species. The miR156/157 target squamosa promoter binding protein-like 11 (SPL11 was found differentially expressed with significant (p ≤ 0.05 up-regulation at the MMC stage of ovule development in apomictic

  6. Pollination deficit in open-field tomato crops (Solanum lycopersicum L., Solanaceae in Rio de Janeiro state, Southeast Brazil

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    Mariana Scaramussa Deprá

    2014-02-01

    Full Text Available More than 70% of world’s crops benefit from biotic pollination, and bees are their main pollinators. Despite the fact that some of these insects have been broadly studied, understanding the interactions between plant crops and their pollinators with a local scale approach is necessary when aiming to apply proper protective and management measures to pollinators and their respective crops. In this context, we analyzed the pollination status of open-field tomato crops (Solanum lycopersicum L., regarding fruit-set, visitation rate and the quality of fruits. We recorded the formation of fruits through spontaneous self-pollination and open-pollination, and the occurrence of pollinators in 24 areas of open-field tomato crops. We performed experiments of apomixis, spontaneous self-pollination, manual cross pollination and supplemental cross pollination (simulating the pollinator behavior in a greenhouse. The fruit quality was evaluated according to circumference, weight, volume and number of seeds. Higher production of fruits after open-pollination compared to spontaneous self-pollination indicates the importance of pollinators to increment productivity of S. lycopersicum in the study area. The circumference and the number of seeds from tomatoes of the greenhouse plantation did not differ between spontaneous self-pollination and the manual cross pollination. In the open-field crops the number of seeds was higher for fruits resulting from open-pollination. Our results indicate that the importance of bees is mainly related to the increase in fruit production, thus incrementing the productivity of tomato crops.

  7. Pollination deficit in open-field tomato crops (Solanum lycopersicum L., Solanaceae in Rio de Janeiro state, Southeast Brazil

    Directory of Open Access Journals (Sweden)

    Maria Cristina Gaglianone

    2013-10-01

    Full Text Available More than 70% of world’s crops benefit from biotic pollination, and bees are their main pollinators. Despite the fact that some of these insects have been broadly studied, understanding the interactions between plant crops and their pollinators with a local scale approach is necessary when aiming to apply proper protective and management measures to pollinators and their respective crops. In this context, we analyzed the pollination status of open-field tomato crops (Solanum lycopersicum L., regarding fruit-set, visitation rate and the quality of fruits. We recorded the formation of fruits through spontaneous self-pollination and open-pollination, and the occurrence of pollinators in 24 areas of open-field tomato crops. We performed experiments of apomixis, spontaneous self-pollination, manual cross pollination and supplemental cross pollination (simulating the pollinator behavior in a greenhouse. The fruit quality was evaluated according to circumference, weight, volume and number of seeds. Higher production of fruits after open-pollination compared to spontaneous self-pollination indicates the importance of pollinators to increment productivity of S. lycopersicum in the study area. The circumference and the number of seeds from tomatoes of the greenhouse plantation did not differ between spontaneous self-pollination and the manual cross pollination. In the open-field crops the number of seeds was higher for fruits resulting from open-pollination. Our results indicate that the importance of bees is mainly related to the increase in fruit production, thus incrementing the productivity of tomato crops.

  8. Floral display and breeding system of Jatropha curcas L.

    Institute of Scientific and Technical Information of China (English)

    Luo Chang-wei; Li Kun; Chen You; Sun Yong-yu

    2007-01-01

    Plant flowering and breeding characteristics are important for us to understand the reproduction of plant populations. In this paper, we studied the reproduction characteristics of Jatropha curcas in Yuanjiang County (23°36'N, 101°00'E), Yunnan Province.The plant produces flowers in dichasial inflorescences. Normally, the flowers are unisexual, and male and female flowers are produced in the same inflorescence. Only a few male flowers are produced in an inflorescence, and fruits are produced only through pollination between different flowers from the same or different plants. By the treatments of emasculation, bagging and artificial pollination in this experiment, there were few but same fruit set ratios when the inflorescences were emasculated, bagged, or bagged with net, except artificial pollination treatments, which showed that Jatropha curcas could produce fruit through apomixis but not wind pollination. When the inflorescences were unbagged, unemasculated and with free pollination treatments, or bagged, emasculated and with artificial cross-pollination treatments, or unbagged, emasculated and with free pollination treatments, there were many fruits produced. It showed that Jatropha curcas shows outcrossing, is self-compatible, and demanding for pollinators. Normally, the male flowers open first and a few flowers bloom in one day in a raceme. These flowers last a long time in bloom. However, a large number of female flowers open from the third to the fifth day, with some female flowers opening first in a few raceme. This shows a tendency to promote xenogamy and minimize geitonogamy.

  9. Development of innovative techniques and principles that may be used as models to improve plant performance. Technical progress report, February 1, 1990--January 31, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Hanna, W.W.; Burton, G.W.

    1992-06-01

    Methods and techniques for transferring germplasm from wild to cultivated species are being developed. The transferred germplasm is being shown to be valuable in plant breeding and in cultivar development. In the primary gene pool of the grassy Pennisetum glaucum subspecies monodii germplasm, some cytoplasms are being identified that appear to have significant effects on forage yields and morphological characteristics. One cytoplasm, A{sub 4}, is very stable for male sterility and fertility is not easily restored by other lines. It should be a valuable cytoplasm for producing commercial forage hybrids. Disease resistance and yield genes transferred from monodii to cultivated pearl millet lines are having a major impact on increasing production of animals grazing disease resistant Tifleaf 2 pearl millet. Genes controlling resistance to many of the world-wide diseases on pearl millet are being identified in the monodii germplasm. Valuable germplasm has been transferred from the secondary gene pool P. purpuroum) which is used as the pollinator of the first pearl millet grain hybrid in the US Production of 7-chromosome gametes in 42-chromosome interspecific hybrids appears to be genotype specific and makes possible transfer of germplasm from the secondary gene pool to cultivated diploid pearl millet. Significant progress has been made in transferring genes controlling apomixis from P. squamulatum (tertiary gene pool) to cultivated pearl millet. Highly apomictic BC{sub 4} plants have been recovered, one of which sets five times as much seed as the best BC{sub 3} plant.

  10. New insights into the variability of reproduction modes in European populations of Rubus subgen. Rubus: how sexual are polyploid brambles?

    Science.gov (United States)

    Šarhanová, Petra; Vašut, Radim J; Dančák, Martin; Bureš, Petr; Trávníček, Bohumil

    2012-12-01

    Rubus subgen. Rubus includes common European species with highly complicated taxonomy, ongoing hybridisation and facultative apomixis. Out of approximately 750 species recognised in Europe, only 3 diploid sexual species are known, along with numerous apomictic brambles that are highly connected to polyploidy. One exception of a tetraploid taxon is R. ser. Glandulosi, which is known for prevalent sexuality. This taxon highly hybridises with tetraploid members of R. ser. Discolores and leads to the origin of many hybridogenous populations and individuals. In this study, we verify reproduction modes in different diploid, triploid and tetraploid species of subgen. Rubus, with focus on taxa putatively involved in such hybridisation by applying flow cytometric seed screen analysis. We found 100 % sexuality of diploid species, whereas triploid species had obligate unreduced embryo sac development. In contrast, tetraploid plants had varying degrees of sexuality. Additionally, we discovered that R. bifrons has the ability to undergo a reproduction mode switch as a reaction to environmental conditions. These results provide insight into reproductive modes of European brambles and shed light on their reticulate evolution and speciation. PMID:23114637

  11. Expressed sequence tag analysis and development of gene associated markers in a near-isogenic plant system of Eragrostis curvula.

    Science.gov (United States)

    Cervigni, Gerardo D L; Paniego, Norma; Díaz, Marina; Selva, Juan P; Zappacosta, Diego; Zanazzi, Darío; Landerreche, Iñaki; Martelotto, Luciano; Felitti, Silvina; Pessino, Silvina; Spangenberg, Germán; Echenique, Viviana

    2008-05-01

    Eragrostis curvula (Schrad.) Nees is a forage grass native to the semiarid regions of Southern Africa, which reproduces mainly by pseudogamous diplosporous apomixis. A collection of ESTs was generated from four cDNA libraries, three of them obtained from panicles of near-isogenic lines with different ploidy levels and reproductive modes, and one obtained from 12 days-old plant leaves. A total of 12,295 high-quality ESTs were clustered and assembled, rendering 8,864 unigenes, including 1,490 contigs and 7,394 singletons, with a genome coverage of 22%. A total of 7,029 (79.11%) unigenes were functionally categorized by BLASTX analysis against sequences deposited in public databases, but only 37.80% could be classified according to Gene Ontology. Sequence comparison against the cereals genes indexes (GI) revealed 50% significant hits. A total of 254 EST-SSRs were detected from 219 singletons and 35 from contigs. Di- and tri- motifs were similarly represented with percentages of 38.95 and 40.16%, respectively. In addition, 190 SNPs and Indels were detected in 18 contigs generated from 3 to 4 libraries. The ESTs and the molecular markers obtained in this study will provide valuable resources for a wide range of applications including gene identification, genetic mapping, cultivar identification, analysis of genetic diversity, phenotype mapping and marker assisted selection. PMID:18196464

  12. CITOLOGIA Y METODO DE REPRODUCCION EN DOS ESPECIES DE PASPALUM (GRAMINEAE

    Directory of Open Access Journals (Sweden)

    Guillermo A Norrman

    2010-11-01

    Full Text Available

    Se han estudiado la microsporogénesis, megasporogenesis, el desarrollo del saco embrionario, y la fertilidad en P.regnellii Mez y Henr P.hydrophilum.
    El número de cromosomas de P.regnellii (2n = 40 se informa por primera vez. Un bivalente apareamiento de cromosomas sugiere el origen alotetraploide de esta especie con la fórmula de RRSS genoma. No hay homología entre los genomas R y S. El análisis citológico sugiere que P.hydrophilum (2n = 40 tiene una fórmula H H H' H' genoma con homología entre los genomas segmentaria H y H'. Observaciones sobre megasporogenesis y el desarrollo del saco embrionario indican que P.regnelli reproduce sexualmente y P.hydrophilum por medio de la apomixis facultativa.

  13. Karyotype conservation in 2 populations of the parthenogenetic scorpion Tityus serrulatus (Buthidae): rDNA and its associated heterochromatin are concentrated on only one chromosome.

    Science.gov (United States)

    Schneider, Marielle C; Cella, Doralice M

    2010-01-01

    Within the order Scorpiones, the parthenogenetic mode of reproduction has been described for 11 species, 6 of which belong to the genus Tityus. In this work, an investigation of the chromosome characteristics of 2 populations of Tityus serrulatus, the first scorpion species known to be thelytokously parthenogenetic, is described. An analysis of 40 individuals revealed holocentric chromosomes of large, medium, and small sizes and an invariable diploid number of 2n = 12. In addition to the conserved macrokaryotype structure, specific chromosome regions also appeared unchanged within and between the samples studied; that is, each sample displayed only one chromosome carrier of the active nucleolar organizer region containing ribosomal genes (5.8S, 18S, and 28S) and AT-rich heterochromatin associated with the ribosomal DNA. The high conservation of the chromosomal features observed in T. serrulatus differed from that verified in certain species of other groups of animals that possess both holocentric chromosomes and parthenogenetic reproduction. Moreover, the cytogenetic results obtained herein permit us to suggest how the eggs of T. serrulatus develop, whether by apomixis or automixis. PMID:20231264

  14. Reproductive biology of an Alpic paleo-endemic in a changing climate.

    Science.gov (United States)

    Guerrina, Maria; Casazza, Gabriele; Conti, Elena; Macrì, Carmelo; Minuto, Luigi

    2016-05-01

    Climate change is known to have a profound influence on plant reproduction, mainly because it affects plant/pollinator interactions, sometimes driving plants to extinction. Starting from the Neogene, the European climate was subjected to severe alterations. Nevertheless, several genera, including Berardia, survived these climatic changes. Despite the numerous studies performed about the relationship between climate change and plant reproductive biology, equivalent studies on ancient species are lacking, even though they may furnish crucial information on the strategies that allowed them to survive drastic climatic fluctuations. We investigated floral and reproductive features in Berardia subacaulis (Asteraceae), describing pollen vectors, capitulum and florets phenology, evaluating reproductive efficiency and defining the reproductive mode of the plant with bagging experiments and test of apomixis. B. subacaulis grows in habitats with low pollination services; it is self-compatible, but many typical features favouring cross-pollination are still present: florets are characterized by incomplete protandry, capitulum protogyny and high pollen-ovule ratio. The plant is not apomictic and self-fertilization is allowed within each capitulum. Similarly to other European Alpine endemics supposed to belong to the Mediterranean ancient tropical flora, the reproductive mode observed in the monospecific genus Berardia assured reproduction also under a pollinator decline. Differently from the other endemics, it took advantage of its spontaneous self-pollination and compatibility and its generalist pollination service, common both among high altitude plants and in the Asteraceae. PMID:26886434

  15. Effect of temperature and irradiance on the growth and reproduction of Enteromorpha prolifera J. Ag.(Chlorophycophyta, Chlorophyceae)

    Institute of Scientific and Technical Information of China (English)

    FU Gang; DUAN Delin; YAO Jianting; LIU Fuli; LIU Jidong; WANG Xiuliang; FU Wandong; LI Dapeng; ZHOU Mingjiang; SUN Song

    2008-01-01

    Effect of temperature and irradiance on growth and reproduction of Enteromorpha prolifera that bloomed offshore along the Qingdao coast in summer 2008, was studied. It was showed that E. prolifera propagated mainly asexually with specific growth rate (SGR) of 10.47 at 25°C/40 μmol m-2s-1. Under this condition, gametes with two flagellate formed and released in 5 days. At the beginning of the development, the unicell gamete divided into two cells with heteropolarity, and then the apical cell developed into thalli primordial cells, whereas the basal cell developed into rhizoid primordial cells. In 8-day culture, the monoplast gamete developed into juvenile germling of 240 μm in length. Unreleased gametes can develop directly within the alga body. E. prolifera could either reproduce through lateral branching or fragmenting except apomixis revealed by Microscopic observation. On aged tissue of E. prolifera, although the degraded pigments partially remained in faded algal filaments, numerous vegetative ceils could still divide actively in the algal tissues.

  16. Salt Stress Induced Proteome and Transcriptome Changes in Sugar Beet Monosomic Addition Line M14

    Institute of Scientific and Technical Information of China (English)

    Le Yang; ChuanHong Kang; Sixue Chen; Haiying Li

    2012-01-01

    Sugar beet monosomic addition line M14 displays interesting phenotypes such as apomixis and salt stress tolerance.Here we reported proteomic and transcriptomic analysis of M14 leaves and roots under 500 mmol/L NaCI treatment for seven days.Proteins from control and treated samples were extracted and separated using two-dimensional difference gel electrophoresis (2D-DIGE).A total of 40 protein spots from leaf gels and 36 protein spots from root gels exhibited significant changes.Using mass spectrometry and database searching,38 unique proteins in leaves and 29 unique proteins in roots were identified.The proteins included those involved in metabolism,protein folding,photosynthesis,and protein degradation.In addition,cDNA libraries of differentially expressed genes were constructed using suppression subtractive hybridization (SSH).Fifty-eight unigenes including 14 singletons and 44 contigs were obtained.Some salt-responsive genes were identified to function in metabolism,photosynthesis,stress and defense,energy,protein synthesis and protein degradation.This research has revealed candidate genes and proteins for detailed functional characterization,and set the stage for further investigation of the salt tolerance mechanisms in sugar beet.

  17. Explosive pollination mechanism in Periandra mediterranea (Vell. Taub. (Fabaceae in the Guaribas Biological Reserve, Paraíba, Brazil

    Directory of Open Access Journals (Sweden)

    Andressa Cavalcante Meireles

    2015-12-01

    Full Text Available Periandra mediterranea (Vell. Taub. has papilionaceous flowers with a complex pollination mechanism. This study examined pollination and reproduction in P. mediterranea from November 2009 to October 2011 at the Guaribas Biological Reserve, Paraíba, Brazil. The petals are modified in a keel that protects the stamens and stigma; two wings surround the keel, and a standard that serves as landing platform for floral visitors. Periandra mediterranea exhibits an explosive type pollination mechanism in which the bee species Xylocopa frontalis, Acanthopus excellens and Epicharis sp., land on the standard and, due to body weight, expose the reproductive organs in the wing-keel complex. As a result, the reproductive organs of the flower come into contact with the dorsal region of the bee body, depositing pollen (i.e., nototríbic pollination. Reproductive assays showed 20% fruiting in spontaneous auto-pollination, 33% in manual auto-pollination, 33% in manual cross-pollination, and 100% in the control group, with no reproductive success while in apomixis. These results demonstrate self-compatibility in this species, however it depends on pollinators to ensure reproductive success.

  18. Opportunistic out-crossing in Nicotiana attenuata (Solanaceae, a predominantly self-fertilizing native tobacco

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    Sime Karen R

    2003-07-01

    Full Text Available Abstract Background Although Nicotiana attenuata is entirely self-compatible, chemical and other floral traits suggest selection for the maintenance of advertisement for moth pollinators. Results Experimental exclusions of pollinators from plants with emasculated flowers in natural populations in southern Utah during an outbreak of the hawkmoth Hyles lineata revealed that 24% of the seed set could be attributed to insect pollination, and eliminated wind pollination and apomixis as contributing to seed set. Hence these moths can mediate gene flow when self-pollen is unavailable. To quantify gene flow when self-pollen is available, plants were transformed with two marker genes: hygromycin-B resistance and β-glucuronidase. The utility of these genetic markers to measure gene flow between plants was examined by mixing pollen from plants homozygous for both genes with self-pollen in different ratios and hand-pollinating emasculated flowers of plants growing in a natural population. The proportion of transformed seeds was positively correlated with the amount of transformed pollen applied to stigmas. In glasshouse experiments with the hawkmoth Manduca sexta and experimental arrays of transformed and wild-type plants, pollination mediated by moths accounted for 2.5% of the seed set. Conclusions Even though moth pollination is rare and highly variable for this largely selfing plant, N. attenuata opportunistically employs a mixed-mating system.

  19. Taraxacum scanicum Dahlst. group (section Erythrosperma in Poland: chorology and seed and pollen morphology of the microspecies

    Directory of Open Access Journals (Sweden)

    Jolanta Marciniuk

    2011-04-01

    Full Text Available The genus Taraxacum is taxonomically complicated due to apomixis. Therefore, there are significant differences in knowledge of regional Taraxacum-Floras among European countries. Similarly, some taxa are well characterised with well-known distribution, whereas some ones are known e.g. from a single locality. Taraxacum scanicum of section Erythrosperma is one of the most common microspecies of this section in Europe. Recently, this taxon was split into three microspecies. In this study we map the distribution of three described taxa of this group in Poland, i.e. T. scanicum s.s., T. prunicolor and T. cristatum. The survey showed that T. scanicum has a similar distribution as T. prunicolor in Poland. This is in contrast with the hitherto known distribution of both taxa. T. cristatum was found at a single locality that is quite distant from the distribution in southern central Europe. We also provide with new morphological characteristics of achenes and pollen for T. scanicum s.s. and T. prunicolor.

  20. Cytological and reproductive aspects in the Caespitosa group of Paspalum

    Directory of Open Access Journals (Sweden)

    Marisa Toniolo Pozzobon

    2013-11-01

    Full Text Available Somatic chromosome numbers are reported for thirty four germplasm accessions of Paspalum, Caespitosa group, representing five different species. All five species have shown x=10 as the basic chromosome number. The diploid 2n=20 chromosome number was confirmed for P. chacoense and P. indecorum, as well as sexuality for the latter. This is the first report of the chromosome number and cytological behavior for P. ligulare (2n=20 and 40, P. pleostachyum (2n=20, 30 and 40 and P. redondense (2n=20 and 40. The present results document regular meiosis in diploid accessions, with primarily bivalent pairing at diakinesis and metaphase I. Polyploids of these species had irregular meiosis, with univalent, trivalent, and quadrivalent chromosome associations. Diploid accessions of P. pleostachyum and P. ligulare have shown a single meiotic embryo-sac, indicating sexual reproduction, while the triploid and one of the tetraploid accessions of P. pleostachyum have shown aposporic embryo-sacs of nucelar origin, and a few meiotic sacs, suggesting facultative apomixis. Identification of the new diploid accessions may prove useful for phylogenetic studies of Paspalum, as well as for breeding programs focusing on the forage potential of species of the Caespitosa group.

  1. Induced mutations in sorghum improvement

    International Nuclear Information System (INIS)

    A critical review of different aspects of mutagen sensitivity, considering the importance of such factors as genotypic constitution of the material, pre- and post-treatment modifications, type of mutagen and dose, techniques of handling the material and treatment procedures to maximize the induction of mutations together with the scope of induced mutations in sorghum improvement is presented. Hydrazine was found to be a more effective and efficient mutagen for inducing chlorophyll and viable mutations in sorghum than ethyl methanesulphonate, methyl methanesulphonate or γ-rays. Ethyl methane-sulphonate among the alkylating agents and nitroso methyl urea among nitroso compounds were the most potent mutagens. The efficient radiation dose was within the 20-35 kr range whereas 0.015M was the effective dosage for hydrazine and ethylmethane sulphonate. The combination treatments of various physical and chemical mutagens failed to yield significant increase in the recovery of mutations, while cysteine post-treatments of γ-irradiated and hydrazine-treated material reduced seedling injury, seed sterility and increased the recovery of viable mutations compared to single treatments. There is scope for induced mutations in solving some of the current problems of sorghum improvement such as, increasing the recombination potential of tropical X temperate crosses, improving the nutritional quality of grain and forage sorghums, diversification of male sterile cytoplasmic sources, better understanding of mechanism of apomixis and augmenting the levels of resistance to sorghum insects, pests and diseases. (author)

  2. Cryptic self-incompatibility and distyly in Hedyotis acutangula Champ. (Rubiaceae).

    Science.gov (United States)

    Wu, X; Li, A; Zhang, D

    2010-05-01

    Distyly, floral polymorphism frequently associated with reciprocal herkogamy, self- and intramorph incompatibility and secondary dimorphism, constitutes an important sexual system in the Rubiaceae. Here we report an unusual kind of distyly associated with self- and/or intramorph compatibility in a perennial herb, Hedyotis acutangula. Floral morphology, ancillary dimorphisms and compatibility of the two morphs were studied. H. acutangula did not exhibit precise reciprocal herkogamy, but this did not affect the equality of floral morphs in the population, as usually found in distylous plants. Both pin and thrum pollen retained relatively high viability for 8 h. The pollen to ovule ratio was 72.5 in pin flowers and 54.4 in thrum flowers. Pistils of pin flowers remained receptive for longer than those of thrum flowers. No apparent difference in the germination rate of pin and thrum pollen grains was observed when cultured in vitro, although growth of thrum pollen tubes was much faster than that of pin pollen tubes. Artificial pollination revealed that pollen tube growth in legitimate intermorph crosses was faster than in either intramorph crosses or self-pollination, suggesting the occurrence of cryptic self-incompatibility in this species. Cryptic self-incompatibility functioned differently in the two morphs, with pollen tube growth rates after legitimate and illegitimate pollination much more highly differentiated in pin flowers than in thrum flowers. No fruit was produced in emasculated netted flowers, suggesting the absence of apomixis. Our results indicate that H. acutangula is distylous, with a cryptic self-incompatibility breeding system. PMID:20522185

  3. The breeding systems of diploid and neoautotetraploid clones of Acacia mangium Willd. in a synthetic sympatric population in Vietnam.

    Science.gov (United States)

    Griffin, A R; Vuong, T D; Vaillancourt, R E; Harbard, J L; Harwood, C E; Nghiem, C Q; Thinh, H H

    2012-12-01

    Colchicine-induced neoautotetraploid genotypes of Acacia mangium were cloned and planted in mixture with a set of diploid clones in an orchard in southern Vietnam. Following good general flowering, open-pollinated seed was collected from trees of both cytotypes and microsatellite markers were used to determine the breeding system as characterised by the proportion of outcrosses in young seedling progeny. As predicted from the literature, the progeny of diploid clones were predominantly outcrossed (t(m) = 0.97). In contrast, the progeny of the tetraploid clones were almost entirely selfs (t(m) = 0.02; 3 of 161 seedlings assayed were tetraploid outcrosses and there were no triploids). Segregation at loci heterozygous in the tetraploid mothers followed expected ratios, indicating sexual reproduction rather than apomixis. Post-zygotic factors are primarily responsible for divergence of the breeding systems. Commonly, less than 1 % of Acacia flowers mature as a pod, and after mixed pollination, diploid outcrossed seed normally develops at the expense of selfs. Selfs of the tetraploid trees appear to express less genetic load and have a higher probability of maturing. However, this does not fully explain the observed deficiency of outcross tetraploid progeny. Presumably, there are cytogenetic reasons which remain to be investigated. In nature, selfing would increase the probability of establishment of neotetraploids irrespective of cytotype frequency in the population. Breeders need to review their open-pollinated breeding and seed production strategies. It remains to be seen whether this is an ephemeral problem, with strong fertility selection restoring potential for outcrossing over generations. PMID:22865285

  4. Meiotic and reproductive behavior of facultative apomictic BC/sub 1/ offspring derived from Pennisetum americanum-P. orientale interspecific hybrids

    Energy Technology Data Exchange (ETDEWEB)

    Dujardin, M.; Hanna, W.W.

    1983-01-01

    This study reports on the chromosome numbers, meiotic behavior, method of reproduction and fertility of BC/sub 1/ progenies from Pennisetum americanum L. Leeke, pearl millet X P. orientale L.C. Rich. interspecific hybrids backcrossed to P. americanum. This information would be useful for future studies on transfer of genes controlling apomixis from the tertiary gene pool to P. americanum. Two facultatively apomictic interspecific hybrids between Pennisetum americanum, (A. chromosomes) and P. orientale (O chromosomes), 2n=25, were pollinated with P. americanum. Sixteen backcross progenies were obtained which were of three cytotypes: 32-(14 A + 18 O), 23-(14 A + 9 O), and 27-(7 A + 20 O) chromosomes. They resulted from fertilization of unreduced gametes or partially reduced gametes by a 7 A chromosome gamete, or by development or unreduced aposporic embryo sacs, respectively. In 23 chromosome plants, the 14 A chromosomes paired mainly as bivalents or remained as univalents while the 9 O chromosomes appeared as univalents. Intergenomal pairing between P. americanum and P. orientale also were observed and could make segmental exchange possible. In the 27 chromosome progeny, the 20 O chromosomes paired, while the 7 A chromosomes remained as univalents. Meiotic behavior in 32-chromosome plants was regular with 7 A bivalents plus 9 O bivalents. The backcross progenies were male sterile but partially female fertile and produced a few seeds when pollinated with P. americanum pollen. The 23-chromosome, BC/sub 1/ progeny were reconstituted in BC/sub 2/ progenies of 32-chromosomes plants X pearl millet. All BC/sub 1/ had some degree of apomicitic embryo sac development and the 23-chromosome plants showed apomictic development even though the O chromosomes were in the simplex condition.

  5. Floral Biology and Hybridization Potential of Nine Accessions of Physic Nut Jatropha curcas L. originating from Three Continents

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    Ahoton, LE.

    2012-01-01

    Full Text Available Jatropha curcas is a shrub which has an important economic and medicinal role in tropical and subtropical zones of the world. The oil of its kernels can serve as fuel feedstock to produce diesel, indicating its potential as a renewable source of energy. In an attempt to introduce new variation into cultivated Jatropha curcas, a program of intraspecific hybridization with several ecotypes originating from Africa, Asia and America was undertaken. Field studies were performed over three years 2009, 2010 and 2011. Before achieving hybridization, the floral ratio and the breeding system of physic nut were studied in Southern Benin ecological conditions. Significant differences (P< 0.05 were observed between the analysed ecotypes regarding the number of female flowers. This study has also confirmed that the breeding system of Jatropha curcas is essentially outcrossing and that foraging insects are the main pollination actors of female flowers. New intraspecific hybrid combinations were produced involving nine accessions. Crosses results varied according to the origin and the direction of the hybridization. Crosses between accessions of J. curcas originating from Africa and Asia gave hybrids without difficulty. The data obtained confirm that apomixis might play a major role in J. curcas a reproductive biology. Considering the high number of female flowers per inflorescence produced by the accession from Ecuador, and the large genetic distance existing between this accession and those from Africa and Asia, it should constitute a valuable genetic stock for the development of F1 hybrids with local ecotypes of J. curcas. However, the use of growth regulators might be necessary to improve the hybridization success rate when it is used as female parent.

  6. Gene expression in diplosporous and sexual Eragrostis curvula genotypes with differing ploidy levels.

    Science.gov (United States)

    Cervigni, Gerardo D L; Paniego, Norma; Pessino, Silvina; Selva, Juan P; Díaz, Marina; Spangenberg, Germán; Echenique, Viviana

    2008-05-01

    The molecular nature of gene expression during the initiation and progress of diplosporous apomixis is still unknown. Moreover, the basis of the close correlation between diplospory and polyploidy is not clarified yet. A comparative expression analysis was performed based on expressed sequence tags (ESTs) sequencing and differential display in an Eragrostis curvula diplosporous tetraploid genotype (T, 4x apo), a sexual diploid derivative obtained from tissue culture (D, 2x sex) and an artificial sexual tetraploid obtained from the diploid seeds after colchicine treatment (C, 4x sex). From a total of 8,884 unigenes sequenced from inflorescence-derived libraries, 112 (1.26%) showed significant differential expression in individuals with different ploidy level and/or variable reproductive mode. Independent comparisons between plants with different reproductive mode (same ploidy) or different ploidy level (same reproductive mode) allowed the identification of genes modulated in response to diplosporous development or polyploidization, respectively. Surprisingly, a group of genes (Group 3) were differentially expressed or silenced only in the 4x sex plant, presenting similar levels of expression in the 4x apo and the 2x sex genotypes. A group of randomly selected differential genes was validated by QR-PCR. Differential display analysis showed that in general the 4x apo and 4x sex expression profiles were more related and different from the 2x sex one, but confirmed the existence of Group 3-type genes, in both inflorescences and leaves. The possible biological significance for the occurrence of this particular group of genes is discussed. In silico mapping onto the rice genome was used to identify candidates mapping to the region syntenic to the diplospory locus. PMID:18311543

  7. Citrus Improvement Using Mutation Techniques

    International Nuclear Information System (INIS)

    Citrus cultivar improvement is hampered by several biological factors inherent to most citrus species. Facultative apomixis, self and cross-incompatibility, long juvenility period, and high heterozygosis are some of the vast arrays of impediments faced by citrus breeders in conventional hybridization. Since oranges and grapefruits are highly polyembryonic, the production of enough numbers of zygotic offspring for selection of superior genotypes of these species is basically impossible; hence, most commercially important cultivars of these species have originated through natural or induced mutation. Star Ruby, a deep-red-fleshed grapefruit, was developed by irradiation of Hudson grapefruit seeds with thermal neutrons. Unlike Hudson, which contains over 50 seeds per fruit, Star Ruby is nearly seedless. Hensz irradiated buds of Ruby Red grapefruit with thermal neutrons and a tree that originated from one of the buds produced fruits three times redder than Ruby Red. It was named A and I-1-48. Ten trees were propagated from A and I -1-48, and out of one of the trees, a budsport mutation was found producing fruits five times redder than Ruby Red. Called Rio Red, it is currently the variety of choice for Texas and is known worldwide for its sweetness, red flesh and beautiful blush. Currently, 37 years after A and I -1-48 was first propagated, the trees are still producing several budsport mutations. So far, in the 2007/2008 season, more than 100 new mutations were obtained from a 100-tree block. In the mandarin group, the existence of several monoembryonic cultivars facilitates conventional breeding, but still, induced mutation is part of most mandarin breeding programmes, and proprietary, new seedless cultivars have been produced in the US, Italy, Israel and elsewhere. Seedless mandarins produced by the University of California Riverside include Dayse, Fairchild, Encore, and Nova. The USDA-ARS, U.S. Horticultural Research Laboratory in Florida released a seedless

  8. Ecologia da polinização de Raphiodon echinus (Nees & Mart. Schauer (Lamiaceae em Petrolina, PE, Brasil Pollination ecology of Raphiodon echinus (Nees & Mart. Schauer (Lamiaceae in Petrolina, Pernambuco State, Brazil

    Directory of Open Access Journals (Sweden)

    Carla Tatiana de Vasconcelos Dias

    2007-12-01

    Full Text Available Raphiodon echinus é uma espécie de hábito rasteiro, que ocorre espontaneamente em áreas de caatinga. No presente trabalho foram observados a biologia reprodutiva desta espécie com o objetivo de contribuir com informações sobre sua ecologia da polinização. As observações foram feitas em áreas de caatinga da Embrapa Semi-Árido, em Petrolina, PE. Para os experimentos de autopolinização espontânea, autopolinização manual, apomixia, geitonogamia, xenogamia, botões foram ensacados, emasculados e polinizados, quando necessário. Flores foram marcadas para estimar a polinização em condições naturais. Os visitantes florais foram observados das 7h30 min às 16h00, totalizando 45 horas de observações. As flores de R. echinus são infundibuliformes, de coloração violeta, exalam odor adocicado e estão reunidas em glomérulos. A antese é diurna, assincrônica, sendo mais freqüente no período da manhã, por volta das 07h00. A duração das flores é de aproximadamente 10 horas e cada inflorescência apresenta número variado de flores/dia. As flores são visitadas por abelhas e borboletas. Centris hyptidis foi responsável por 26% do total das visitas e, de acordo com o comportamento e freqüência de visitas, foi considerada como polinizador efetivo desta espécie. Quanto ao sistema de reprodução, R. echinus é autógama facultativa, produzindo frutos por autopolinização manual (70%, geitonogamia (63% e xenogamia (40%.Raphiodon echinus is a prostrate weedy species that occurs in the Caatinga. In this work, floral biology and reproductive system were observed in order to understand the pollination ecology of this species. Observations were made at Embrapa Semi-Árido, in Petrolina, Pernambuco. For the self-pollination, apomixis, geitonogamy and xenogamy experiments, buds were protected, emasculated, and pollinated when necessary. Flowers were tagged to estimate pollination success under natural conditions. Floral visitors

  9. 艳丽耳草的二型花柱及异型自交不亲和系统%Distyly and heteromorphic self-incompatibility of Hedyotis pulcherrima (Rubiaceae)

    Institute of Scientific and Technical Information of China (English)

    刘欣欣; 吴小琴; 张奠湘

    2012-01-01

    . However, pollen tube growth was arrested in the stigma with the accumulation of callose in the swollen tips in two morphs with self and intramorph pollination, indicating strict hetero-morphic self-incompatibility in H. pulcherrima. No fruit was produced in emasculated netted flowers, suggesting the absence of apomixis. Artificial intermorph pollination resulted in 100% of fruit set, significantly higher than those with open pollination. Our results indicate that H. pulcherrima is a typically distylous species with heteromorphic self-incompatibility.

  10. Complex history of admixture during citrus domestication revealed by genome analysis

    Energy Technology Data Exchange (ETDEWEB)

    Wu, G. Albert; Prochnik, Simon; Jenkins, Jerry; Salse, Jerome; Hellsten, Uffe; Murat, Florent; Perrier, Xavier; Ruiz, Manuel; Scalabrin, Simone; Terol, Javier; Takita, Marco Aur& #233; lio,; Labadie, Karine; Poulain, Julie; Couloux, Arnaud; Jabbari, Kamel; Cattonaro, Federica; Fabbro, Cristian Del; Pinosio, Sara; Zuccolo, Andrea; Chapman, Jarrod; Grimwood, Jane; Tadeo, Francisco; Estornell, Leandro H.; Mu?oz-Sanz, Juan V.; Ibanez, Victoria; Herrero-Ortega, Amparo; Aleza, Pablo; P& #233; rez, Juli& #225; n P& #233; rez,; Ramon, Daniel; Brunel, Dominique; Luro, Francois; Chen, Chunxian; Farmerie, William G.; Desany, Brian; Kodira, Chinnappa; Mohiuddin, Mohammed; Harkins, Tim; Fredrikson, Karin; Burns, Paul; Lomsadze, Alexandre; Borodovsky, Mark; Reforgiato, Giuseppe; Freitas-Astua, Juliana; Quetier, Francis; Navarro, Luis; Roose, Mikeal; Wincker, Patrick; Schmutz, Jeremy; Morgante, Michele; Machado, Marcos Antonio; Talon, Manuel; Jaillon, Olivier; Ollitrault, Patrick; Gmitter, Frederick; Rokhsar, Daniel

    2014-06-30

    vulnerable to disease outbreaks, including citrus greening disease (also known as Huanglongbing) that is rapidly spreading throughout the world's major citrus producing regions1. Understanding the population genomics and domestication of citrus will enable strategies for improvements to citrus including resistance to greening and other diseases. The domestication and distribution of edible citrus types began several thousand years ago in Southeast Asia and spread globally following ancient land and sea routes. The lineages that gave rise to most modern cultivated varieties, however, are lost in undocumented antiquity, and their identities remain controversial2, 3. Several features of Citrus biology and cultivation make deciphering these origins difficult. Cultivated varieties are typically propagated clonally by grafting and through asexual seed production (apomixis via nucellar polyembryony) to maintain desirable combinations of traits (Fig. 1). Thus many important cultivar groups have characteristic basic genotypes that presumably arose through interspecific hybridization and/or successive introgressive hybridizations of wild ancestral species. These domestication events predated the global expansion of citrus cultivation by hundreds or perhaps thousands of years, with no record of the domestication process. Diversity within such groups arises through accumulated somatic mutations, generally without sexual recombination, either as limb sports on trees or variants among apomictic seedling progeny. Two wild species are believed to have contributed to domesticated pummelos, mandarins and oranges. Based on morphology and genetic markers, pummelos have generally been identified with the wild species C. maxima (Burm.) Merrill that is indigenous to Southeast Asia. Although mandarins are similarly widely identified with the species C. reticulata Blanco 4-6, wild populations of C. reticulata have not been definitively described. Various authors have taken dif

  11. Microsporogenesis in Brachiaria bovonei (Chiov. Robyns and B. subulifolia (Mez Clayton (Poaceae Microsporogênese em Brachiaria bovonei (Chiov. Robyns e B. subulifolia (Mez Clayton (Poaceae

    Directory of Open Access Journals (Sweden)

    Claudicéia Risso-Pascotto

    2009-10-01

    Full Text Available Some African species of Brachiaria have been introduced into the Americas and became the most important forage for pastures in the tropics. New cultivars can be obtained either from direct selections from the natural existing variability in the germplasm collections or from interspecific hybridizations. Polyploidy is predominant in the genus Brachiaria and correlated with apomixis which complicates hybridization. The objective of cytological studies underway on the Brachiaria germplasm collection at Embrapa Beef Cattle is to determine the chromosome number and meiotic behavior of accessions. For the breeding of Brachiaria species, compatible sexual and apomictic accessions need to be identified. Microsporogenesis was evaluated in two accessions of Brachiaria bovonei (BO01 and BO05 and one accession of B. subulifolia (SU01. BO01 is pentaploid (2n = 5x = 45, BO05 is tetraploid (2n = 4x = 36, and SU01 is hexaploid (2n = 6x = 54, derived from x = 9. Meiotic abnormalities typical of polyploids, characterized by precocious chromosome migration to the poles in metaphases, laggard chromosomes in anaphases, and micronuclei in telophases and tetrads, were recorded in high frequency in all the accessions generating unbalanced gametes. Both accessions of B. bovonei presented chromosome stickiness. The results are discussed in the view of the Brachiaria breeding program objectives.Algumas espécies africanas de Brachiaria foram introduzidas nas Américas e tornaram-se importantes pastagens nos trópicos. Novas cultivares podem ser obtidas por seleção direta da variabilidade genética existente na coleção de germoplasma ou por hibridização interespecífica. Poliploidia é predominante no gênero Brachiaria e correlacionada com apomixia, o que complica a hibridização. O objetivo dos estudos citogenéticos na coleção de germoplasma de Brachiaria da Embrapa Gado de Corte é determinar o número de cromossomos e o comportamento meiótico dos acessos. A

  12. Determinação do modo de reprodução em capim-gordura (Melinis minutiflora Beauv. por padrões enzimáticos Detection of the mode of reproduction in molasses grass (Melinis minutiflora Beauv. by enzyme patterns

    Directory of Open Access Journals (Sweden)

    Lia Rejane Machado Silveira

    1996-04-01

    , leucine aminopeptidases and malato dehydrogenases of the parental generations with their offsprings. The high uniformity of patterns obtained in the offsprings, the identical patterns found for both the female parents and their respectives progenies and also the presence of banding patterns, characteristically shown by heterozygotes of the leucine aminopeptidase and malato dehydrogenase systems, are strong evidences for the hypothesis of apomictic reproduction in this species. In addiction, the isozymatic segregation for acid phosphatase observed in plants of CG4 and CG5 ecotypes and the detection of hybrids from CG2 x CG3 crosses, are indicating that the apomixis in molasses grass is facultative.

  13. Apple Rootstock New Variety Chistock #1%苹果砧木新品种中砧1号

    Institute of Scientific and Technical Information of China (English)

    韩振海; 王忆; 张新忠; 许雪峰; 孙扬吾; 沈隽

    2013-01-01

    The iron has a very important role in the growth and development of the plant,iron deficiency causes chlorosis in apple trees.The main producing areas of apple in China just iron deficiency,therefore,filter out iron-efficient resources from rich apple germplasm resources,and breeding new varieties of apple rootstocks through breeding means is fundamental pathway to solve due to iron deficiency affected yield and quality of apple production.Since 1984,the project team screened iron-efficient genotypes from 40 apple stocks and found Malus xiaojinensis Cheng et Jiang,grow normally and do not exhibit symptoms of chlorosisin in conditions of very low Fe content,was considered to be an excellent germplasm with tolerance to iron deficiency.Subsequently,open pollinated hybrids groups were established on the basis of M.xiaojinensis Cheng et Jiang seedlings.In 1990,excellent grades was obtained through original selection from natural seedlings.Then after multiple selection and comparison test,bred apple clonal rootstocks Chistock #1.Chistock #1 is a tetraploid in chromosome number (2n =4x =68),with a capacity of apomixis,and setting rate above 85% after emasculation bagged.Then with excellent grafting compatibility,seedling dry good standing and strong solid ground,semi-dwarf,dwarf extent,effects and yield capacity were similar with simi-dwarfing apple rootstock M7.Sweet fruit flavor,palatability,and excellent quality.Resist apple early defoliation disease and branches ring rot,high resistance to apple Chlorotic leaf spot virus(CLSV),Stem pitting virus(SPV) and the Stem groove virus(SGV) and other latent virus.Chistock #1 can effectively prevent etiolation due to iron deficiency as apple rootstock in the lime parent material soil areas.%铁是植物生长的必需微量元素,缺铁导致苹果发生失绿症,生长结果受到影响.我国苹果主产区恰在缺铁区域范围内,因此,从丰富的苹果种质资源中筛选出铁高效型资源,通