Kulkarni, Raghavendra N; Baskaran, Kuppusamy
Periwinkle (Catharanthus roseus [L.] G. Don), an important medicinal plant, is an allogamous species in which the stigma is below the anthers. The receptive portion is at the base of the stigmatic head and thus automatic intra-flower self-pollination is excluded. The structure of the flower is of typical reverse herkogamy and pollination occurs through nectar-seeking insects. A few self-pollinating strains are also reported in which self-pollination is brought about by an increase in length of the style or of the ovary. Self-pollination is governed by allelic duplicate genes recessive to allogamy. An induced monogenic recessive mutant (EMS 17-1) with caducous closed corolla (corolla abscising before anthesis), isolated from variety, Dhawal, was crossed with two self-pollinating strains to study the possibility of obtaining cleistogamous recombinants combining closed corolla and self-pollination traits. Cleistogamous plants were obtained in which development of fruits and seeds occurred without opening of the corolla. Closed corolla and self-pollination were found to be independently inherited. A dominant gene in the parent in which self-pollination occurred due to an increase in length of the ovary, appeared to completely or partially inhibit expression of the gene for closed corolla in homozygous or heterozygous condition, respectively. The genetic basis of development of cleistogamy is described. Cleistogamy in periwinkle would facilitate in ensuring genetic purity, pollen containment, and seed production even in the absence of pollinators. This appears to be the first report on the development of cleistogamous plants in an allogamous species.
Full Text Available Colobanthus quitensis forms chasmogamic and cleistogamic flowers. Their structure signals the possibility of both cross-pollination and self-pollination. In favorable conditions (natural or laboratory, flowers open creating a possibility for cross-pollination. The occurrence of cleistogamy in the investigated species may be conditioned by abiotic factors: low temperature, high air humidity, and strong wind. In closed flowers, a part of pollen grains reaches the stigma surface, and the rest remains inside the microsporangium. Pollen grains germinate on the stigma surface or inside the microsporangium. Often, two or more pollen tubes grow from a single pollen grain. Closed flowers and the direct contact between the style stigma and anther prove the preference for autogamy. Autogamy ensures the reproductive success of the investigated plant in the exceptionally harsh Antarctic environment.
Miedaner, Thomas; Geiger, Hartwig H
Ergot is a disease of cereals and grasses caused by fungi in the genus Claviceps. Of particular concern are Claviceps purpurea in temperate regions, C. africana in sorghum (worldwide), and C. fusiformis in pearl millet (Africa, Asia). The fungi infect young, usually unfertilized ovaries, replacing the seeds by dark mycelial masses known as sclerotia. The percentage of sclerotia in marketable grain is strictly regulated in many countries. In winter rye, ergot has been known in Europe since the early Middle Ages. The alkaloids produced by the fungus severely affect the health of humans and warm-blooded animals. In sorghum and pearl millet, ergot became a problem when growers adopted hybrid technology, which increased host susceptibility. Plant traits reducing ergot infection include immediate pollination of receptive stigmas, closed flowering (cleistogamy), and physiological resistance. Genetic, nonpollen-mediated variation in ergot susceptibility could be demonstrated in all three affected cereals. Fungicides have limited efficacy and application is weather dependent. Sorting out the sclerotia from the harvest by photocells is expensive and time consuming. In conclusion, molecular-based hybrid rye breeding could improve pollen fertility by introgressing effective restorer genes thus bringing down the ergot infection level to that of conventional population cultivars. A further reduction might be feasible in the future by selecting more resistant germplasm.
Douglas, Norman A; Manos, Paul S
The four o'clock family (Nyctaginaceae) has a number of genera with unusual morphological and ecological characters, several of which appear to have a "tendency" to evolve repeatedly in Nyctaginaceae. Despite this, the Nyctaginaceae have attracted little attention from botanists. To produce a phylogeny for the Nyctaginaceae, we sampled 51 species representing 25 genera (of 28-31) for three chloroplast loci (ndhF, rps16, rpl16, and nrITS) and included all genera from North America. Parsimony, likelihood, and Bayesian methods were used to reconstruct the phylogeny for the family. The family is neotropical in origin. A radiation of woody taxa unites Pisonia and Pisoniella with the difficult tropical genera Neea and Guapira, which also form a clade, though neither appears to be monophyletic. This group is sister to a clade containing Bougainvillea, Belemia, and Phaeoptilum. A dramatic radiation of genera occurred in the deserts of North America. The tribe Nyctagineae and its subtribes are paraphyletic, due to over-reliance on a few homoplasious characters, i.e., pollen morphology and involucre presence. Two notable characters associated with the desert radiation are cleistogamy and edaphic endemism on gypsum soils. We discuss evolutionary trends in these traits in light of available data about self-incompatibility and gypsum tolerance in Nyctaginaceae.
Gressel, Jonathan; Valverde, Bernal E
Transgenic herbicide-resistant rice is needed to control weeds that have evolved herbicide resistance, as well as for the weedy (feral, red) rice problem, which has been exacerbated by shifting to direct seeding throughout the world-firstly in Europe and the Americas, and now in Asia, as well as in parts of Africa. Transplanting had been the major method of weedy rice control. Experience with imidazolinone-resistant rice shows that gene flow to weedy rice is rapid, negating the utility of the technology. Transgenic technologies are available that can contain herbicide resistance within the crop (cleistogamy, male sterility, targeting to chloroplast genome, etc.), but such technologies are leaky. Mitigation technologies tandemly couple (genetically link) the gene of choice (herbicide resistance) with mitigation genes that are neutral or good for the crop, but render hybrids with weedy rice and their offspring unfit to compete. Mitigation genes confer traits such as non-shattering, dwarfism, no secondary dormancy and herbicide sensitivity. It is proposed to use glyphosate and glufosinate resistances separately as genes of choice, and glufosinate, glyphosate and bentazone susceptibilities as mitigating genes, with a six-season rotation where each stage kills transgenic crop volunteers and transgenic crop x weed hybrids from the previous season.
Nishizawa-Yokoi, Ayako; Endo, Masaki; Ohtsuki, Namie; Saika, Hiroaki; Toki, Seiichi
Precise genome engineering via homologous recombination (HR)-mediated gene targeting (GT) has become an essential tool in molecular breeding as well as in basic plant science. As HR-mediated GT is an extremely rare event, positive-negative selection has been used extensively in flowering plants to isolate cells in which GT has occurred. In order to utilize GT as a methodology for precision mutagenesis, the positive selectable marker gene should be completely eliminated from the GT locus. Here, we introduce targeted point mutations conferring resistance to herbicide into the rice acetolactate synthase (ALS) gene via GT with subsequent marker excision by piggyBac transposition. Almost all regenerated plants expressing piggyBac transposase contained exclusively targeted point mutations without concomitant re-integration of the transposon, resulting in these progeny showing a herbicide bispyribac sodium (BS)-tolerant phenotype. This approach was also applied successfully to the editing of a microRNA targeting site in the rice cleistogamy 1 gene. Therefore, our approach provides a general strategy for the targeted modification of endogenous genes in plants.
马春英; 屈平; 王文全
The ultrastructure of the pollen in the Glycyrrhiza uralensis Fisch. , G. glabra L. and G. inflata Batal.were observed by the scanning electron microscope(SEM). Pollination way, pollen viability stigma activity and the fertilization time ascertainment after pollination were observed by the fluorescence microscope. The results showed that the study on the ultrastructure of pollen offered certain morphology basis for the discrimination of the liquorice.The pollination way of the liquorice was cleistogamy. The pollen viability was the highest at 12:00 on daytime,and the stigma had no ability to accept the pollen exceeding four days after artificial emasculation. The pollen tube entered into the ovule to fertilize 6h after pollination when the fixed pistils were observed different time after pollination. In order to establish the correct strategy of seed selection and breeding of the liquorice in the future, the sexual reproduction properties of the liquorice was also studied.%对甘草的有性生殖特性进行了研究,利用扫描电子显微镜对乌拉尔甘草、光果甘草和胀果甘草花粉的超微结构进行观察,利用荧光显微镜确定乌拉尔甘草的授粉方式、花粉生活力和柱头活性以及授粉后受精时间.结果表明,花粉超微结构为甘草的鉴别提供了一定的形态学依据;甘草的授粉方式属于闭花受精;花粉生活力在每天12:00时最强,去雄后超过4d的柱头已经不具备接受花粉的能力;对授粉后不同时间的雌蕊进行研究得出授粉后6h花粉管进入胚珠进行受精.
杨霞; 王丹; 张猛
P/O of three varieties of Feijoa sellowiana was accounted and breeding systems class was defined;pollens of three varieties of F. selloiviana were observed with scanning electron microscope; and the morphology and taxono-my significance of the pollens were analyzed. The results showed that P/O of 'Coolidge', 'Mammoth' and 'Unique' were 6 ± 2. 37、4. 41 ± 1. 47 and 8. 52±2. 84 and the breeding systems was cleistogamy;Feijoa pollen was radial sym-metry; polar view of the pollens was approximately equilateral triangle, with a clear tricolporate (syncolpate) and go-niotreme; equatorial view of the pollens appears oval; the surface of the pollens had granulated sculpture. At the same time, the morphology of the three varieties was also slightly different, but not obvious. Compared with other four ge-nus of the same family, the pollen morphology of Feijoa was in accordance with the main features of Myrtaceae plant and had important taxonomy significance.%利用扫描电子显微镜对费约果三个品种的花粉粒显微结构形态进行观察,计算三个品种费约果的花粉-胚珠比,并据此分析费约果的形态特征和分类学意义,划分其繁育系统类型.结果表明:‘Coolidge ’、‘Mammoth’和‘Unique’三个品种的花粉-胚珠比分别为6±2.37、4.41±1.47和8.52±2.84,其繁育系统为闭花受精型；费约果花粉粒呈辐射对称,极面观近似等边三角形,有明显的三孔沟(合沟),具角萌发孔,其赤道面观为椭圆形,花粉粒表面具颗粒状雕纹；三个品种花粉粒形态相比之下也略有差异,但不明显.从费约果与同科4个属花粉粒的对比中可以得出,费约果花粉粒形态结构符合桃金娘科植物的主要特征,其花粉粒形态在分类学上具有重要意义.
Radu E. SESTRAS
Full Text Available Following the proposal of Academic Council of Horticulture Faculty, the Senate of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca accepted nominee Professor Jules Janick for Doctor Honoris Causa award. The title was awarded in festive ceremony on September 30, 2010. Jules Janick, Professor at Purdue University has a long and distinguished career devoted to horticulture in all its facets. In horticultural research, he has made important advances including the genetics of sex determination including the synthesis of heteromorphic sex chromosomes, fireblight resistance, cleistogamy, cucurbitacins, artemisisin production, anthocyanin pigmentation, as well as in vitro metabolite production from somatic embryos and the production of synthetic seed. In crop improvement, he has been associated with the release of 21 scab-resistant apple cultivars, three pear cultivars with tolerance to fireblight, delayed-bolting arugula, crack resistant tomato, and the first release of a pelargonium cultivar from somaclonal variation. Professor Janick has made contributions to the historical aspects of horticulture and explored the relation of art and horticultural technology with special studies on the iconography of Rubus, Cucurbitaceae, and Solanaceae, opening up a new approach to the study of plant diversity, origins, cultivar evolution, and diversity. Professor Janick has been a prolific author and editor in horticulture. He was the editor of HortScience and editor of the Journal of ASHS. He is the founder and editor of both Horticultural Reviews and Plant Breeding Reviews. Since 2002 he has been the science editor of Chronica Horticulturae (ISHS. Janick has edited and produced six proceedings of New Crops symposia since 1990 that have had a deep impact on new crop information. The development of a new crop website has become a major world resource for information on crops. He is the author of the texts Horticultural Science, Plant Science
靳茜; 王志兴; 王旭静; 贾士荣
转基因作物种植面积逐年增加,到2011年全球转基因作物的种植面积达到1.6亿hm2,较1996年增长了近94倍.随着转基因作物的大面积商业化种植,由此带来的生物安全问题越来越受到人们的关注,其中花粉介导的基因飘流是人们关注的焦点问题之一.探索限控转基因飘流的生物学措施是当前国际上关于生物安全研究的热点和焦点.因此,就目前研究较多的生物学措施如叶绿体转化技术、基因剔除技术、转基因弱化技术、雄性不育技术、种子不育技术、闭花受精和无融合生殖技术、基因拆分技术、可控转基因技术等进行了综述,并对将来的研究方向进行了展望.%GM crop acreage increased year by year,the global acreage of GM crops has reached 160 million hra2 in 2011 ,an increase of nearly 94 times compared to acreage of 1996. With a large area of commercial cultivation of GM crops,the resulting bio-security issues are attracted more and more attention,which the pollen-mediated gene flow is one of the focus problems. It is the current international hot spot and focus on biosafety research to explore the biological measures for transgenic drift control. Therefore,more biological measures were reviewed,such as plastid transformation technology,transgene excision technology,transgene mitigation technology,male and female sterility technology,seed sterility technology,cleistogamy and apomixis technology,split transgenic technology and controlled transgenic technology,future research directions were also prospected.
郝楠; 苏雪; 吴琼; 常立博; 张世虎; 孙坤
Viola tuberifera is a typical dimorphic cleistogamous plant which endemic to Qinghai-Tibetan Plateau and its eastern neighbour region, belongs to perennial herb, possessing mixed-mating reproductive system, which conducts not only sexual propagation via both open, aerial chasmogamous (CH) flowers in spring and closed, obligate self-pollinating aerial and subterranean cleistogamous (CL) flowers in summer, but also asexual reproduction via new bulbs in autumn reproducing offsprings through winter. Chasmogamous flowers depend on pollinator, such as bumblebees, obligate cross-fertilization producting bigger and few seeds. Cleistogamous flowers do not need pollinators, they can pollinate by them-selves and produce smaller and abundant seeds. Further to say, survival ratio of chasmogamous flowers seedings is lower than the cleistogamous flowers offprings. In particular, while plant under harsh environment, cleistogamy can provide re-productive assurance and cost economically. Three flowers are all sexual propagation. Only vegetative organ-bulbs via asexual propagation. Bulbs prapagation can also assure reproduction under adverse habitat. Especially in alpine ecosys-tem, plants always face to pollination limatation, at this time vegetative propagation can produce offsprings which are similar to stock plant and form ramets to fight for habitats and resources. Parents and offsprings together resist stern cli-mate and through cold environment. That is to say, bulbs reproduction can ensure V. tuberifera surivial and continuation in the high alpine environment and cost mininum resources to through winter. Sexual reproduction is conducted before asexual reproduction and two opposite reproductive strategies can ensure survival together in the whole life history. In the alpine district, allogamy always face pollen limitation and cannot assure plants reproduction, whereas autogamy and clonal reproduction are alternative choices to ensure propagation of plants populations, as well