基于EST-SSR的木薯分子标记遗传连锁图谱的构建

此实验以木薯推广品种‘KU50’为母本,‘SC124’为父本通过杂交得到包含240个单株的F1分离群体,利用300对EST-SSR引物,20对SSR和20对SRAP引物组合对亲本和部分群体株系进行多态性分子标记筛选,共获得具有多态性的引物110对。在此基础上,利用这110对多态性引物对该F1群体进行分子标记的多态性分析,共获得269个多态性标记。利用JoinMap 3.0软件对这269个多态性标记进行分组和遗传图谱构建,最后获得了一张包含140个标记的木薯分子遗传连锁图谱,其中EST-SSR标记111个,SSR标记22个,SRAP标记7个;共21个连锁群,其中连锁群1和3（LG1、LG3）上的标记位点最多（15个）,LG21标记位点最少（2个）。此遗传连锁图谱的总长度为1314.775 cM,单个连锁群最长为132.904 cM（LG3）,最短为0.431 cM（LG19）,标记间平均长度9.391 cM。     

应用SRAP、ISSR和TRAP标记构建金针菇分子遗传连锁图谱

本研究应用金针菇(Flammulina filiformis)的两个菌株,黄色金针菇Y1701和白色金针菇W3082为作图亲本,采用分子标记以构建高密度的金针菇分子遗传连锁图谱。通过F1代产生的71个单孢为遗传连锁图谱作图群体,应用SRAP、ISSR和TRAP标记引物,利用PCR对得到的作图群体进行多态性分析,构建了一张拥有11个连锁群以及125个标记位点,总长度860.3 cM的遗传连锁图谱。连锁群平均长度为78.21 cM,最长的连锁群为132.9 c M,最短的连锁群为16.3 c M。多态性标记间最大遗传距离为38.4 cM,最小距离为0.5 cM,连锁图中出现了6个大于20 cM的间隙,标记密度6.88 cM,是迄今以来金针菇遗传连锁图谱相关研究中密度最高的。本研究所获得的高密度遗传连锁图谱有助于金针菇QTL定位,分子辅助育种和基因定位的研究。     

烟草SRAP和ISSR分子遗传连锁图谱构建

采用烤烟品种台烟7号与白肋烟品种白肋21杂交,构建了187个单株的F₂遗传作图群体,利用所筛选的68个能扩增出多态性条带的SRAP和ISSR引物,对F₂作图群体进行PCR扩增和遗传连锁分析,初步构建了一张包含26个连锁群、112个(92个SRAP和20个ISSR)标记位点的烟草遗传连锁图谱。该图谱覆盖长度为1 560.2 cM,平均图距18.1 cM。有16个标记未进入连锁群。26个连锁群包含2~20标记不等,连锁群遗传距离0~291.0 cM。连锁群上有24.1%的标记出现偏分离,主要集中在LG1和LG4连锁群上,其余分散在不同连锁群。该图谱为烟草重要农艺性状的基因定位、以及分子标记辅助选择等研究奠定基础。     

冀豆12遗传图谱初步构建

以优良大豆品种冀豆12与野生大豆ZYD02738杂交建立基础群体,利用F2为作图群体,研究SSR标记位点在该群体中的多态性、偏分离并构建遗传图谱.结果表明,两亲本间SSR位点多态性比例79.9%,偏分离位点比例9.7%,构建的遗传图谱包含25个连锁群,总长度837.1 cM,标记间平均距离11.2 cM,标记间排列顺序与公共连锁图一致性较强.该研究为国内学者研究冀豆12遗传网络和重要农艺性状的基因、QTL定位等研究奠定了初步基础.     

ET-ISJ标记的开发及陆地棉遗传图谱构建

根据植物结构基因外显子拼接位点的保守序列,设计扩增外显子的ET-ISJ (exon targeted intron-exon splice junction)标记引物。利用1 280对ET-ISJ引物组合,在陆地棉品种渝棉1号和T586中,筛选获得69对多态性引物组合,占引物组合的5.4%。用多态性ET-ISJ引物组合检测(渝棉1号×T586)F_2:7重组近交系群体,得到70个位点。以70个ET-ISJ标记位点与523个SSR、59个IT-ISJ、29个SRAP和8个形态标记进行连锁分析,构建的遗传连锁图谱包括59个连锁群和673个位点(68个ET-ISJ、510个SSR、58个IT-ISJ、29个SRAP和8个形态标记)。连锁图覆盖3 216.7 cM,占棉花基因组的72.3%,标记间平均长度为4.8 cM。68个ET-ISJ标记分布于20条染色体。研究表明ET-ISJ标记多态性较高、稳定性好,可有效用于棉花与其他植物遗传连锁图谱构建。     

‘新世纪梨’ב崇化大梨’F1代分子遗传连锁图谱的构建

本研究目的在于为以后控制重要农艺性状的QTL定位、梨分子标记辅助育种及品种改良提供基础理论。利用‘新世纪梨’ב崇化大梨’杂交得到的210株F₁代实生苗为作图群体,对分离群体进行了ISSR、SRAP、SSR标记的多态性检测,共得到154条多态性条带,其中偏离孟德尔遗传比例的含21.4%(P<0.01)。应用JoinMap 4.0软件对154个多态性条带进行遗传连锁分析,构建了一张包括9个SSR标记,79个SRAP标记,8个ISSR标记,合计96个标记分属于14个连锁群的遗传图谱,图谱总长度为1530 cM,平均图距为16.1 cM,最大的连锁群含有64个标记,最小遗传距离小于0.1 cM。

     

芒果杂交F_1代群体的遗传多样性分析及遗传图谱的构建

以芒果品种贵妃、金煌及其98株杂交F_1代为材料,利用SRAP标记构建了芒果的遗传图谱,并对杂交后代的遗传多样性进行分析。从266对SRAP引物中筛选了35对多态性引物,扩增出200条多态性条带,多态性条带比率为43.18%。UPGMA聚类分析表明,材料间的遗传相似系数为0.52~0.92,有8份材料表现出较强的变异。用JoinMap4.0作图,构建了一张总长801.6 cM的芒果遗传图谱,包含20个连锁群,113个标记位点,标记间的平均距离为9.32 cM。这是首张芒果SRAP标记的遗传图谱,可为芒果高密度遗传图谱的构建提供参考。     

花生栽培种SSR遗传图谱的构建

花生栽培种品种间分子多态性相对缺乏, 至今未构建出较完整的分子遗传图谱。本研究以粤油13和阜95-5为亲本, 通过杂交构建包含184个F6重组自交系的遗传作图群体。采用652对genomic-SSR引物和392对EST-SSR引物对亲本进行多态性检测, 从中筛选出121对多态性引物, 在亲本中共检测到123个多态性位点。利用作图群体对多态性SSR位点进行遗传连锁分析, 获得包含108个SSR标记(102个genomic-SSR标记和6个EST-SSR标记), 涉及20个连锁群, 总长568 cM, 平均图距为6.45 cM的花生栽培种遗传图谱。与前人构建的花生野生种(A. duranensis × A. stenosperma, AA genome)SSR遗传图谱比较, 初步确定本研究构建的遗传图谱中有11个连锁群与野生种遗传图谱的6个连锁群存在同源关系。     

高粱AFLP分子连锁图谱的构建

利用感蚜高粱品种千三与抗蚜品种河农16杂交获得的100个F2单株作为图谱构建群体,以AFLP标记构建高粱连锁图谱。通过对192对AFLP引物组合进行筛选,共得到75对多态性引物,利用筛选出的75对引物进行选择性扩增,得到了154个AFLP多态性位点。经Map maker/EXP 3.0软件处理,构建了包含12个连锁群,93个遗传标记的连锁图谱,该图谱覆盖686 cM,平均图距为7.38 cM。     

‘新世纪梨’ב崇化大梨’F1代分子遗传连锁图谱的构建

研究目的在于为以后控制重要农艺性状的QTL定位、梨分子标记辅助育种及品种改良提供基础理论。利用‘新世纪梨’ב崇化大梨’杂交得到的210 株F1代实生苗为作图群体,对分离群体进行了ISSR、SRAP、SSR 标记的多态性检测,共得到154 条多态性条带,其中偏离孟德尔遗传比例的含21.4%(P＜0.01)。应用JoinMap 4.0 软件对154 个多态性条带进行遗传连锁分析,构建了一张包括9 个SSR标记,79个SRAP标记,8个ISSR标记,合计96个标记分属于14个连锁群的遗传图谱,图谱总长度为1530 cM,平均图距为16.1 cM,最大的连锁群含有64个标记,最小遗传距离小于0.1 cM。     

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.