WorldWideScience

Sample records for cleistogamy

  1. Pollination in the Antarctic flowering plant Colobanthus quitensis (Kunth Bartl.

    Directory of Open Access Journals (Sweden)

    Irena Giełwanowska

    2012-12-01

    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.

  2. The effect of pollen source vs. flower type on progeny performance and seed predation under contrasting light environments in a cleistogamous herb.

    Science.gov (United States)

    Munguía-Rosas, Miguel A; Campos-Navarrete, María J; Parra-Tabla, Víctor

    2013-01-01

    Dimorphic cleistogamy is a specialized form of mixed mating system where a single plant produces both open, potentially outcrossed chasmogamous (CH) and closed, obligately self-pollinated cleistogamous (CL) flowers. Typically, CH flowers and seeds are bigger and energetically more costly than those of CL. Although the effects of inbreeding and floral dimorphism are critical to understanding the evolution and maintenance of cleistogamy, these effects have been repeatedly confounded. In an attempt to separate these effects, we compared the performance of progeny derived from the two floral morphs while controlling for the source of pollen. That is, flower type and pollen source effects were assessed by comparing the performance of progeny derived from selfed CH vs. CL and outcrossed CH vs. selfed CH flowers, respectively. The experiment was carried out with the herb Ruellia nudiflora under two contrasting light environments. Outcrossed progeny generally performed better than selfed progeny. However, inbreeding depression ranges from low (1%) to moderate (36%), with the greatest value detected under shaded conditions when cumulative fitness was used. Although flower type generally had less of an effect on progeny performance than pollen source did, the progeny derived from selfed CH flowers largely outperformed the progeny from CL flowers, but only under shaded conditions and when cumulative fitness was taken into account. On the other hand, the source of pollen and flower type influenced seed predation, with selfed CH progeny the most heavily attacked by predators. Therefore, the effects of pollen source and flower type are environment-dependant and seed predators may increase the genetic differences between progeny derived from CH and CL flowers. Inbreeding depression alone cannot account for the maintenance of a mixed mating system in R. nudiflora and other unidentified mechanisms must thus be involved. PMID:24260515

  3. Biology, genetics, and management of ergot (Claviceps spp.) in rye, sorghum, and pearl millet.

    Science.gov (United States)

    Miedaner, Thomas; Geiger, Hartwig H

    2015-02-25

    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.

  4. Serrated leaf mutant in mungbean (Vigna radiata (L) Wilczek)

    International Nuclear Information System (INIS)

    Dry dormant seeds of mungbean (Vigna radiata (L) Wilczek) were treated with gamma rays (15, 30 and 60 kR). The serrated leaf mutation was noticed in M2 of cultivar Pak 32 treated with 60 kR. Cf 14 plants, 3 showed the altered leaf structure and the others were normal. The feature of this mutant was the deep serration of leaflet margins. The mutant had large thick leaflets with prominent venation. The mutant bred true in the M3 and successive generation. Details of the morphological characteristics of the mutant are presented. The mutant exhibited slower growth particularly during the early stages of development, flowered later and attained shorter height. There was an increase in the number of pods, in seed weight and in seed protein content, but number of seed per pod was considerably reduced. The seed coat colour showed a change from green to yellowish green. In the mutant's flowers the stamina were placed much below the stigma level and the stigma sometimes protruded the corolla. Outcrossing of 4% recorded in some of the mutant lines revealed a reduced cleistogamy. The low number of seeds per pod in the mutant could be due to reduced pollen fertility. The mutant behaved as monogenic recessive. The symbols SL/sl are proposed for this allelic pair. The mutant may have use as a green manure crop because of its large foliage and for the breeders as a genetic marker

  5. Biology, Genetics, and Management of Ergot (Claviceps spp. in Rye, Sorghum, and Pearl Millet

    Directory of Open Access Journals (Sweden)

    Thomas Miedaner

    2015-02-01

    Full Text Available 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.

  6. Research Progress on the Biological Containment to Control Transgene Flow%限控基因飘流的生物学措施研究进展

    Institute of Scientific and Technical Information of China (English)

    靳茜; 王志兴; 王旭静; 贾士荣

    2012-01-01

    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.

  7. 三个不同品种费约果的花粉-胚珠比及花粉粒形态的扫描电镜观察%Pollen-ovule ratio and scanning electron microscope observation to pollen morphology of Feijoa sellowiana

    Institute of Scientific and Technical Information of China (English)

    杨霞; 王丹; 张猛

    2012-01-01

    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.

  8. Floral miniaturisation and autogamy in boreal-arctic plants are epitomised by Iceland's most frequent orchid, Platanthera hyperborea.

    Science.gov (United States)

    Bateman, Richard M; Sramkó, Gábor; Rudall, Paula J

    2015-01-01

    migration route that may have begun in East Asia before passing through North America and presumably Greenland. The incohesive pollinia, rapidly desiccating anther locules, weakly developed rostellum, exceptionally adhesive stigma and the close juxtaposition of compact male and female reproductive organs together conspire to cause routine autogamy and frequent cleistogamy, despite the continued production of substantial nectar reservoirs in the spur and consequent ongoing attraction to the flowers of insects, including mosquitoes. When considered in combination with independently derived lineages of Platanthera on the Azorean and Hawaiian archipelagos also bearing small green flowers, our observations show allometric and paedomorphic reductions in flower size as the primary evolutionary driver, but also indicate strong developmental and functional constraints. PMID:25893148

  9. Floral miniaturisation and autogamy in boreal-arctic plants are epitomised by Iceland’s most frequent orchid, Platanthera hyperborea

    Directory of Open Access Journals (Sweden)

    Richard M. Bateman

    2015-04-01

    represents the terminus of a migration route that may have begun in East Asia before passing through North America and presumably Greenland. The incohesive pollinia, rapidly desiccating anther locules, weakly developed rostellum, exceptionally adhesive stigma and the close juxtaposition of compact male and female reproductive organs together conspire to cause routine autogamy and frequent cleistogamy, despite the continued production of substantial nectar reservoirs in the spur and consequent ongoing attraction to the flowers of insects, including mosquitoes. When considered in combination with independently derived lineages of Platanthera on the Azorean and Hawaiian archipelagos also bearing small green flowers, our observations show allometric and paedomorphic reductions in flower size as the primary evolutionary driver, but also indicate strong developmental and functional constraints.

  10. 甘草花粉超微鉴定及花粉活力、柱头可受性荧光显微镜观察%Identification of Pollen Ultrastructure and Fluorescence Microscope Observation of Pollen Viability and Stigma Activity of Liquorice

    Institute of Scientific and Technical Information of China (English)

    马春英; 屈平; 王文全

    2011-01-01

    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.

  11. Tribute to a Leading Personality of World Horticultural Science

    Directory of Open Access Journals (Sweden)

    Radu E. SESTRAS

    2010-12-01

    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

  12. Size-dependent of Qinghai-Tibetan Plateau Viola tuberifera (Violaceae)bulbs allocation%青藏高原东缘块茎堇菜鳞茎分配的个体大小依赖性

    Institute of Scientific and Technical Information of China (English)

    郝楠; 苏雪; 吴琼; 常立博; 张世虎; 孙坤

    2016-01-01

    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