大白菜的适宜AFLP-Pst I/Mse I引物组合

基于PCR的DNA指纹鉴定技术AFLP广泛应用于生物多样性、遗传图谱构建、基因定位、分子系统发育和品种鉴定等方面.为了筛选出大白菜适宜的AFLP引物组合,研究以抗根肿病大白菜双单倍体CR Shinki、感病自交系94SK及其后代F2构成的纯合抗病和纯合感病DNA混合池为材料,利用256对Pst I/Mse I引物组合进行了AFLP分析.结果表明:平均每个组合检测到55条带,共扩增13 079条带,平均每1 000条带检测到1.30个根肿病抗性基因连锁标记;多态性带数为3 167条,双亲间多态性频率约为0.24;扩增带数与多态性带数呈线性正相关,引物组合中的不同GC含量与扩增带数和多态性带数存在显著性差异,并表现出线性负相关.筛选出的适宜53对引物组合共扩增出4 381条带,占总扩增片断的33.50%,平均每对扩增出83条,其中9个组合扩增出与抗根肿病基因连锁标记.     

葎草DNA的提取及AFLP标记反应体系的建立

本文对CTAB法、改良CTAB法和SDS法提取雌雄异株植物葎草(Humulus scandens L.)基因组的方法进行了比较分析,并在此基础上对影响葎草AFLP扩增的关键因素模板浓度、酶切时间、选择性扩增模板浓度进行了优化.结果表明,改良的CTAB法更适合葎草基因组DNA的提取;同时利用AFLP分子标记技术,采用EcoI-Mse I酶切组合,共筛选27对引物组合,确定了适用于葎草AFLP反应的最佳酶切连接、预扩和选扩体系.同时发现2对引物组合E-ACG M-CTA和E-AAC M-CAC共扩增出5条雌雄性别特异条带.     

大豆RN型细胞质雄性不育系及保持系cDNA-AFLP分析

本研究利用cDNA-AFLP技术对大豆RN型细胞质雄性不育系及其同核异质保持系进行多态性分析。提取不育系和保持系的总RNA,反转录成cDNA。以cDNA为模板,通过PCR对64对AFLP引物进行扩增筛选,对不育系或保持系中特有的差异带进行回收测序,通过NCBI-Blast同源比对分析得到12条同源序列,其中8条序列为已知功能的基因,4条为未知功能基因。其中与线粒体基因同源的序列A4,编码ATP合成酶γ亚基蛋白基因同源的序列A1,编码减数分裂不联会突变蛋白同源的序列B1可能与不育有关。这些片段的发现为不育机制的深入研究提供帮助,同时可作为不育系及保持系快速鉴定的依据,对缩短育种年限,加快育种进程具有重要意义。     

应用AFLP技术检测水稻遗传多样性的研究

利用扩增片断长度多态性（Amplified fragment lenth polymorphism简作AFLP)分子标记技术研究了23个水稻品种的遗传多样性从49对AFLP引物中筛选出4对多态性高，分辨能力强的引物。4个AFLP引物组合分别扩增出43、37、49、33条多态性带，平均每个引物组合扩出40．5条多态性带，4个引物组合共扩增出246条带。利用AFLP数据进行聚类分析，将23个品种聚为10个类群，结果表明，AFLP在水稻类群划分的应用是可行的。     

AFLP在水稻类群划分研究中的应用

利用AFLP分子标记技术研究了22个水稻品种的遗传多样性，从49对AFLP引物中筛选出了4对多态性高，分辨能力强的引物，4个AFLP引物组合分别扩增出43、37、49、33条多态性带，平均每个引物组合扩出40．5条多态性带，4个引物组合共扩增出246条带。利用AFLP数据进行聚类分析，将22个品种聚为8群，结果表明，AFLP在水稻类群划分的应用是可行的。     

野生榆叶梅遗传多样性的AFLP分析

本研究利用AFLP分子标记技术,对野生榆叶梅6个居群进行分析.利用已筛选出的8对引物组合进行扩增,共产生256条谱带,其中206条谱带具有遗传多态性,占总谱带的80.47％;平均每对引物组合扩增产生129条多态条带,平均多态率为50.26％.6个居群观察等位基因数Na平均值为1.502 6,总Na值为1.804 7;有...     

甜瓜雌雄异花同株近等基因系的构建及近等性评价

雌雄异花同株类型在甜瓜杂交制种时可部分免除人工去雄,确保杂交种纯度,所以,对杂种优势利用中有着重要价值.为了研究和利用控制甜瓜雌雄异花同株基因A,用雌雄异花同株材料Mr作母本P1,雄花两性花材料Mm作父本P2,用P1做轮回亲本与F1杂交,经连续回交并最终自交纯化,获得雌雄异花同株近等基因系(BC6F4).用形态相似法和AFLP标记对获得的近等基因系和轮回亲本进行分析,结果表明:(1)Mr xMm的F2与BC6S1分离群体中,雌雄异花同株株数与雄花两性花株数符合3:1比例,回交群体中雌雄异花同株株数和雄花两性花株数符合1:1的比例;在发育期、果皮色、网纹等农艺性状上没有明显差异;(2)用448对AFLP引物检测轮回亲本和近等基因系之间多态性,有417对引物没有多态性,31对有多态性,统计得其遗传相似系数为99.73%;(3)平均每个AFLP引物对可扩增出46.8条带,说明AFLP揭示的遗传信息量很高,是一种评价近等性较理想的分子标记,这与以往结果一致.     

AFLP分析小豆种(Vigna angularis)内遗传多样性

利用12对AFLP引物,对来自于世界6个国家的146份小豆(Vigna angularis)栽培变种(var. angularis)和野生变种(var. nipponensis)种质的基因组DNA进行扩增,得到580条清晰的显带,其中313(53.93%)条呈多态性,平均每对AFLP引物得到26.08条多态性带;平均遗传距离0.35,变异幅度为0.00～0.87.利用AFLP多态性数据进行的Jaccard''s遗传距     

一个与亚洲百合无花粉性状紧密连锁的SRAP标记

为了探讨亚洲百合无花粉性状的分子遗传机制,筛选与该性状紧密连锁的分子标记,实现分子辅助选择。本研究以无花粉与有花粉亚洲百合杂交创制的F1单株为试验材料,采用BSA法,对亚洲百合无花粉性状进行SRAP标记分析。在无花粉基因池和有花粉基因池之间共筛选了108对SRAP引物组合,获得了1对在两基因池间扩增存在显著差异的引物组合EM2/ME3,并成功对两基因池间扩增出的差异片段进行回收、克隆和测序,得到了该片段375 bp的碱基序列,并将该特异标记命名为E2M3-375。     

西瓜种质资源的遗传多样性及亲缘关系的AFLP分析

利用AFLP指纹图谱分析技术对57个西瓜材料进行了基因组DNA多态性分析.结果表明,18对AFLP引物共产生709条DNA带,平均每个引物组合扩增出39.4条带,其中440条为多态性带,占总带数的61.4%;根据DNA谱带计算品种间遗传相似系数,其变化范围在0.24～0.99之间,平均相似系数为0.70,说明西瓜品种间遗传基础狭窄.用NTSYS软件进行聚类分析,57个西瓜品种被划分为2个类群.其中类群1包括1个野生西瓜,类群2均为栽培种.在类群2中引进的资源聚在一起,杂交种和双亲或其一聚在一起.此外,本研究表明,AFLP指纹分析技术具有很高的分辨率,能够揭示西瓜品种间的差异,是鉴定西瓜品种的有力工具.     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

Mechanisms and diversity of resistance to sorghum shoot fly,Atherigona soccata

Sorghum shoot fly, Atherigona soccata, is one of the important pests of postrainy season sorghums. Of the 90 sorghum genotypes evaluated for resistance to this pest, RHRB 12, ICSV 713, 25026, 93046 and 25027, IS 33844‐5, Giddi Maldandi and RVRT 3 exhibited resistance in postrainy season, while ICSB 463, Phule Anuradha, RHRB 19, Parbhani Moti, ICSV 705, PS 35805, IS 5480, 5622, 17726, 18368 and 34722, RVRT 1, ICSR 93031 and Dagidi Solapur showed resistance in rainy season, suggesting season‐specific expression of resistance to A. soccata. ICSB 461, ICSB 463, Phule Yasodha, M 35‐1, ICSV 700, 711, 25010, 25019 and 93089, IS 18662, Phule Vasudha, IS 18551 and 33844‐5 and Barsizoot had fewer deadhearts than plants with eggs across seasons, suggesting antibiosis as one of the resistance mechanism. Five genotypes exhibited resistance with high grain yield across seasons. Correlation, path and stepwise regression analyses indicated that leaf glossiness, seedling vigour, trichome density, oviposition and leaf sheath pigmentation were associated with the expression of resistance/susceptibility to shoot fly, and these can be used as marker traits to select and develop shoot fly‐resistant sorghums.     

Reaction of tritordeum to Fusarium culmorum and Septoria nodorum

Summary Hordeum chilense is a wild barley extensively used in wide crosses in the Triticeae. It could be a valuable source of resistance to Fusarium culmorum and Septoria nodorum. Some H. chilense x Triticum spp. amphiploids, named tritordeums, were more resistant than the parental wheat line to these diseases, others were not. Average contents of ergosterol and deoxynivalenol (DON) suggested that resistance to colonization by Fusarium was the highest for Hordeum chilense, followed by tritordeum and wheat in decreasing order. In particular, the H. chilense genotypes H7 and H17 enhanced the wheat resistance to F. culmorum in its tritordeum offsprings. Resistance to S. nodorum in tritordeum was not associated with tall plant height. There is sufficient genetic variation for resistance to F. culmorum and S. nodorum among tritordeum to allow the breeding of lines combining short straw and resistance to both diseases.     

Disease resistance in protected crops and mushrooms

Summary Cultivars of tomatoes, cucumbers, lettuce and peppers have been bred for resistance to one or more pathogens. Some tomato and cucumber cultivars have resistance to a wide range of diseases. Resistance has been transient in many cases and a succession of cultivars with new genes or new combinations of resistance genes has been necessary to maintain control. There has been a number of notable exceptions and these have included durable resistance to such pathogens asFulvia fulva and tomato mosaic virus. With lettuce the resistance situation is complicated by the occurrence of fungicide resistant pathotypes. There are no strains ofAgaricus bisporus purposely bred for disease resistance.In protected flower crops only resistance to Fusarium wilt in carnations has been purposely bred but differences in disease resistance are apparent in cultivars of many ornamental crops. This is particularly so in chrysanthemums where there are cultivars with resistance to many of the major pathogens. Similar situations occur with other flower crops and pot plants. Cultivars of some species have not been systematically investigated for resistance.The need for genetic resistance will increase with the further reduction, in the limits on pesticide use and an increasing public awareness and importance of pesticide pollution.ADAS is an executive agency of the Ministry of Agiculture, Fisheries and Food and the Welsh Office.     

Genetic constitution and diversity in four narrow endemic redwoods from the family Cupressaceae

The genetic constitution and diversity of four relictual redwoods are discussed in this review. These include monotypic genera of the family Cupressaceae: coast redwood (Sequoia sempervirens), giant sequoia (Sequoiadendron giganteum), dawn redwood (Metasequoia glyptostroboides), and alerce (Fitzroya cupressoides). All four species are narrow endemics, share a number of common phenotypic traits, including red wood, and are threatened species. Fossil history suggests that the ancestors of redwoods probably originated during the Cretaceous and Tertiary periods and flourished thereafter for millions of years. Towards the end of the Tertiary period began their decline and struggle for existence that continued during the subsequent geologic upheavals and climate changes, until the survival of the present-day redwoods in the current restricted locations in the world (USA, China, and South America). Although two species, Sequoiadendron and Metasequoia, are diploids (2n = 22), and the other two are polyploids: Fitzroya a tetraploid (2n = 4x = 44), and Sequoia a hexaploid (2n = 6x = 66); they all share the same basic chromosome number x = 11. The genome size in the hexaploid Sequoia is one of the largest (31,500 MB) in the conifers, while the genome sizes of diploid Metasequoia and Sequoiadendron are about one-third (~10,000 MB) of Sequoia. Genetic diversity in the redwoods is lower than most other gymnosperms, except in Sequoia, which seems to rank near the upper quarter of the coniferous forest trees. Genomic research is sparse in the redwoods, and should be pursued for a better understanding of their genome structure, function, and adaptive genetic diversity.     

The induction in vitro of adventitious shoots in Rosa

Summary Adventitious shoots were formed on excised leaves, roots and callus of Rosa persica x xanthina and on excised leaves of R. laevigata and R. wichuraiana on culture media that included BAP and NAA as growth regulators. Shoots formed freely on freshly cultured callus of R. persica x xanthina but their production declined in successive cultures and ceased after twelve weeks. Transplantation to soil was improved by rooting plantlets in cellulose plugs in vitro and transferring plantlets to soil while still in the plugs.     

Distribution,ecology and reproductive biology of wild tomatoes and related nightshades from the Atacama Desert region of northern Chile

Over the past 20 years, several expeditions were made to northern Chile to collect populations of wild tomatoes (Solanum chilense, S. peruvianum) and allied nightshades (S. lycopersicoides, S. sitiens), and obtain information about their geographic distribution, ecology and reproductive biology. Restricted mainly to drainages of the Andean and the coastal cordillera, populations are geographically fragmented. The two nightshade species are rare and threatened by human activities. Adaptation to extreme aridity and soil salinity are evident in S. chilense and S. sitiens (the latter exhibits several xerophytic traits not seen in the tomatoes) and to low temperatures in S. lycopersicoides and S. chilense. All tested accessions are self-incompatible, with the exception of one S. peruvianum population collected at the southern limit of its distribution. Several distinguishing reproductive traits—anther color, attachment, and dehiscence, pollen size, and flower scent—suggest S. sitiens and S. lycopersicoides attract different pollinators than S. chilense and S. peruvianum. The four Solanum spp. native or endemic to Chile provide a variety of novel traits which, through hybridization and introgression with cultivated tomato, could facilitate development of improved varieties, as well as research on a variety of basic topics, including plant-pollinator interactions, abiotic stress responses, and evolution of reproductive barriers.     

The exploration of genetic resources of Portuguese cabbage and kale for resistance to several Brassica diseases

Summary Twenty three accessions of nine Portuguese cabbage and kale land races from different geographic origins were tested at the seedling stage for resistance to several important brassica diseases. Resistance to downy mildew (Peronospora parasitica), expressed as necrosis of the cotyledon mesophyll, was found in all the accessions. Type A resistance to cabbage yellows (Fusarium oxysporum f. sp. conglutinans race 1) was present in most of the landraces. Resistance to clubroot (Plasmodiophora brassicae race 6) was found in one accession of the Portuguese tree kale. High resistance to blackleg (Leptosphaeria maculans) and white rust (Albuco candida) was not detected, although several accessions showed 20 to 30% of plants with intermediate expression of resistance. All Portuguese cole accessions were susceptible to blackrot (Xanthomonas campestris pv. campestris).     

Production and characterization of intergeneric diploid cybrids derived from symmetric fusion between Microcitrus papuana Swingle and sour orange (Citrus aurantium)

Plants were regenerated from intergeneric somatic hybridization between embryogenic protoplasts of Microcitrus papuana Swingle and leaf-derived protoplasts of sour orange (Citrus aurantium L.) via electrofusion. The regenerated plants were morphologically similar to the leaf parent in growth vigor, leaf and branch structure. FCM analysis showed that they were diploids. Simple-sequence-repeat (SSR) and cleaved-amplified-polymorphic-sequence(CAPS) were employed for hybridity characterization. SSR banding patterns of the regenerated plants were identical to the leaf parent, sour orange, indicating that they possessed nuclear component derived from sour orange. DNA amplification with chloroplast and mitochondrial universal primers, followed by restriction endonuclease digestion, revealed polymorphism between the fusion parents. Therefore, this method was used to determine the cytoplasmic compositions of the regenerated plants. Banding patterns for all the polymorphic primer/enzyme combinations of the regenerated plants were similar to those of the embryogenic parent, M. papuana, suggesting that only the cytoplasmic components derived from the embryogenic parent were present in the regenerated plants. FCM, SSR and CAPS demonstrated that intergeneric diploid cybrids have been successfully obtained by symmetric fusion. Related results concerning nuclear and cytoplasmic composition of previous diploid somatic hybrids and potential mechanism for regeneration of such kind of plants are discussed herein. This revised version was published online in July 2006 with corrections to the Cover Date.     

Breeding barriers between the cultivated strawberry, Fragaria × ananassa, and related wild germplasm

Five-hundred interspecific and intergeneric crosses were performed among accessions of the wild strawberries Fragaria vesca(2x), Duchesnea indica (8x), Potentilla tucumanensis (2x) and 9 genotypes of the cultivated strawberry, Fragaria×ananassa (8x), following an incomplete diallele mating design. Crosses between D. indica and F.×ananassa produced many putative hybrids when D. indica was used as female but a few achenes and plants when used as male; therefore, pollen-pistil compatibility relations were analyzed by fluorescence microscopy in this direction of the cross. Of the genotypic combinations, 78.6% were incompatible at the stigma level and 17.2% at the first third of the style. Only 3.6% were pollen-pistil compatible and produced fruits with achenes (seven did not germinate or originated short-lived plants and nine produced normal plants). F.vesca×F.×ananassa crosses produced 35 hybrid achenes but only 14% germinated, yielding short-lived plants; histological analyses revealed that inviable seeds had less developed (or collapsed) endosperms and smaller embryos than control plump F. vesca seeds. P.tucumanensis was only used as male, with negative results. These species and genera are partially isolated by a complex system of pre- and post-zygotic barriers. Knowledge of their nature would allow the breeder to devise strategies to put the genetic variability available in the group into a useful form. This revised version was published online in July 2006 with corrections to the Cover Date.