基于SSR标记的马铃薯种质遗传多样性及群体结构分析

明确鉴定种质材料间的群体遗传结构及遗传多样性对构建核心种质库、准确筛选杂交亲本具有重要作用。本研究利用分子标记和农艺性状相结合的方法初步分析了收集保存的62份马铃薯资源的遗传多样性和群体结构。结果表明,参试种质的8个农艺性状的变异系数介于9.50%～52.90%。农艺性状聚类分析表明,在欧氏距离19.0处62份供试材料被分为3个类群,其中类群Ⅰ中包含的材料最多,约占供试材料的96.8%,该结果从特定农艺性状方面较好地揭示了马铃薯种质资源间的表型差异。应用均匀分布在12条染色体上的13对SSR引物从分子水平进一步探究了参试材料的群体遗传结构。Structure软件分析表明,供试材料被划分为3个群体,不同群体间的界限较为明显,PopⅠ亚群和PopⅡ亚群中各材料的遗传背景较单一,PopⅢ亚群具有混合来源,遗传背景较复杂。NTSYS软件计算结果表明,62份马铃薯种质间的遗传相似性系数介于0.50～1.00,SSR标记聚类分析将62份马铃薯种质总体分为3个大群,类群Ⅰ所包括的马铃薯材料占总数的11.3%,类群Ⅱ占17.7%,类群Ⅲ占供试材料的71%。总体来看,农艺性状聚类与SSR分子标记聚类结果相似。本研究对马铃薯进行了综合分析农艺性状与SSR分子标记,有助于准确评价马铃薯种质遗传背景。     

转基因抗虫水稻后代农艺性状变异的比较研究

采用群体分离法（Bulk sergeant analysis,BSA）和比较分析方法,以转基因水稻高代材料与非转基因水稻杂交得到的3个F2群体和1个DH群体为材料,分析遗传背景与外源基因对转基因水稻后代农艺性状变异的影响。结果发现,父本的遗传背景对农艺性状表现存在一定的影响;在消除环境因素影响的条件下,F2群体中外源基因对农艺性状变异起到重要作用,并促使农艺性状的分离程度增加。而DH群体中尽管外源基因促进株系变异系数增加,但对主要农艺性状变异的作用不显著。说明组织培养是产生农艺性状变异的主要原因,而外源基因的导入增加了农艺性状变异发生的机会。     

国内外烤烟品种农艺性状的遗传多样性及与SRAP标记的关联分析

选取258份国内外烤烟品种,在2个试验点调查13个农艺性状,利用16对引物组合获得的597个SRAP标记进行分子遗传多样性和群体结构分析,选取适宜的模型进行农艺性状与SRAP标记间关联分析。结果表明,参试品种表型和基因型变异丰富,国内品种的遗传多样性低于国外品种。总材料可分为7个亚群,分类结果与材料的地理来源和遗传背景显著相关,国外材料遗传结构相对复杂。通过比较发现MIM_Q+K和MIM_PCA+K为该群体最优的关联分析模型,共检测到18个SRAP标记与6个农艺性状显著关联(–Log P>2, P<0.01),其中me1/em9-16,me1/em9-36,me4/em9-1与株高、me1/em2-14,me7/em5-34与叶片数、me6/em2-6与脚叶宽、me2/em6-15与腰叶长在不同环境下均显著关联。     

甘蔗细茎野生种(Saccharum spontaneum L.)的遗传多样性和系统演化研究

利用RAPD技术,采用25个随机引物对来自中国不同生态环境的195份甘蔗细茎野生种材料进行了地理群体结构的遗传多样性研究。结果表明：甘蔗细茎野生种的种内遗传变异较大,各地理类群的遗传分化明显,具有丰富的遗传多样性。基于分子聚类分析,推论中国甘蔗细茎野生种的起源演化方式为：起源于云南,然后由云南→四川→贵州→     

大豆遗传群体选择与品质QTL的获得

本文以高油品种哈交97-5404-1为母本,以哈交99-5448-4为父本,建立重组自交系群体.应用SSR技术,对不同世代F2∶3,F2∶6、F2∶9遗传群体中的油份QTL定位进行了分析,不同世代大豆分离遗传群体中油份含量均接近于正态分布,油份含量性状表达偏向于母本哈交97-5404-1,F2∶3代获得了对油份贡献率较高的QTL,F2∶9代则获多个与油份相关的QTL,大豆F2∶3和F2∶9代的遗传群体适宜用做品质性状的QTL定位,不同世代定位的油份QTL,均与SSR位点Satt193有关,通过对来自全国不同品种的SSR进行了分析和方差分析证实,Satt193在第一等位变异下(即DNA片段长度为270 bp)做为油份的筛选标记具有实用性,而在第三等位变异下(即DNA片段长度为220 bp)做为蛋白质材料的筛选标记具有应用性.     

苦荞遗传群体农艺性状分析

为探明苦荞(Fagopyrum tartaricum Gaertn.)主要农艺性状间的遗传关系,利用性状差异较大的双亲构建遗传分离群体,研究了农艺性状的变异范围及其相关性,并综合农艺性状参数进行育种优势群划分。结果表明,苦荞遗传群体农艺性状连续分布,变异范围较大,并呈现超亲分离现象;株高与主茎分枝数,主茎粗,主茎节数呈正相关,百粒重与其他性状相关性不高。运用综合指数分群,将197份遗传群体材料划分为3个类群。     

高丹草重组自交系群体的遗传变异与高产种质的创新

高丹草是一年生禾本科新型饲用牧草,提高其饲草产量是高丹草育种的重要目标.以高粱314A×棕壳苏丹草的F2:3遗传作图群体的后代材料建立的重组自交系(Recombinant inbred line,RIL)群体为材料, 对后代进行遗传变异和DNA多样性分析.结果表明:通过采用两种方法(性状和分子标记)进行同时选择,获得了9个高产的超亲重组后代.通过SSR标记分析RIL群体的DNA多样性,可知家系间存在较大的遗传变异,杂交重组产生的超亲高产种质分布在不同类群中.鉴定获得了2组SSR遗传距离接近0而且在主要农艺性状和产量等方面相似,只在抗性方面有差异的不同家系.农艺性状和抗性等鉴定试验筛选了4份性状优良的高丹草新种质并已有2份进入区域试验.     

显性核不育亚麻种质资源聚类分析及核心种质库的建立

为核不育亚麻资源的有效利用提供依据,构建了核不育亚麻核心种质库。以78份核不育亚麻资源材料为研究材料,通过10个农艺性状的形态学观察、RAPD标记和聚类分析,采用随机抽样和最大遗传距离法结合的策略,构建了由22个材料组成的核心种质库。通过各性状的均值、方差、变幅及变幅保持率等进行评价。结果表明,根据10个农艺性状聚类分析结果,将78份不育亚麻种质资源,可分为8个类群,其欧氏距离在0.394 0～10.709 1之间,均值为4.050 0。而根据RAPD遗传多样性分析结果,将其可分为3个类群,其遗传相异系数在0.013～0.897之间,均值为0.361。构建的核不育亚麻核心种质库基本上能够代表原有种质资源的遗传多样性。     

陆地棉品质性状遗传效应分析

采用数量性状的加性-显性遗传模型和统计分析方法，对陆地棉30个杂交亲本及其部分F1的纤维长度、整齐度、马克隆值、强度等纤维品质性状进行分析，估算各项遗传方差分量、参试亲本的加性效应值以及组合的显性效应值。结果表明，纤维长度、整齐率、强度受显性与加性遗传效应共同控制，其中以加性效应为主，而马克隆值主要受基因的显性效应控制。各主要纤维品质性状遗传率均较小，选择时宜在中晚期世代。 A5、A9、A17、A20、A28和A30等亲本可以作为杂交后代提高纤维品质性状的首选亲本材料加以利用。     

小豆百粒重性状遗传体系分析

小豆百粒重是具有重要经济价值的商品品质性状。研究百粒重的遗传体系对杂交亲本的选配、杂种分离世代的选择具有实践指导意义。本文利用子粒大小不同的5个小豆亲本组配了4个杂交组合,对其衍生后代家系群体百粒重性状的遗传体系应用主基因+多基因家系世代联合分离分析方法进行了分析。结果表明,B-1(大粒)×HB801(大粒)和HB8     

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.     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

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.     

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 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.     

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.