Inheritance of new genetic markers in lentil (Lens Miller)

Summary We report on the inheritance of 11 morphological markers and 17 isozymes in lentil (Lens culinaris). The monogenic inheritance of 11 morphological markers and 11 isozymes is confirmed. The inheritance of six isozymes (Aco-2, Enp, Est-3, Est-4, Lap-3, and Mdh-m) is reported for the first time in lentil. This brings the total number of described genes in lentil to 78. Cases of disturbed segregation were more frequent than expected by chance. It is suggested that disturbed segregation was in most cases caused by linkage with a piece of chromosome that showed preferential elimination in crosses between Lens culinaris ssp. odemensis and other subspecies. The prevalence of disturbed segregation in crosses with Lens culinaris ssp. odemensis could limit the usefulness of this subspecies in genetic and linkage studies.     

Development,characterization and mapping of microsatellite markers for lentil (Lens culinaris Medik.)

Lentil is the sixth most important pulse crop terms of production in the world, but the number of available and mapped SSR markers are limited. To develop SSR markers in lentil, four genomic libraries for (CA)n, (GA)n, (AAC)n and (ATG)n repeats were constructed. A total of 360 SSR primers were designed and validated using 15 Turkish lentil cultivars and genotypes. The most polymorphic repeat motifs were GA and CT, with a mean number of alleles per locus of 7.80 and 6.55, respectively. Seventy‐eight SSR primers amplified a total of 400 polymorphic alleles, whereas 71 SSR primers produced markers within the expected size range. For 78 polymorphic SSR primers, the average number of alleles per locus was 5.1 and PIC value ranged from 0.07 to 0.89, with an average of 0.58. A linkage map was constructed using 92 individual F₂ plants derived from a cross between Karacada? × Silvan, with 47 SSR markers. The SSR markers developed in this study could be used for germplasm classification and identification and mapping of QTL in lentil.     

Molecular Marker based Genetic Diversity Analysis in Rice (Oryza sativa L.) using RAPD and SSR markers

The availability of an array of molecular marker systems allowed comparing the efficiency of two of these marker systems to estimate the relationships among various taxa. The objective of this study was to assess the genetic diversity among 40 cultivated varieties and five wild relatives of rice, Oryza sativa L. involving simple sequence repeat (SSR) randomly amplified polymorphic DNA (RAPD) markers. The accessions were evaluated for polymorphisms after amplification with 36 decamer primers and 38 SSR primer pairs. A total of 499 RAPD markers were produced among the 40 cultivated varieties and five wild relatives with a polymorphism percentage of 90.0. Out of 38 SSR primer pairs used, only one locus viz., RM115 was monomorphic. The average Polymorphism Information Content (PIC) value was 0.578 and it ranged from a low of zero (RM 115) to a high of 0.890 (RM 202). The Mantel matrix correspondence test was used to compare the similarity matrices and the correlation coefficient was 0. 582. The test indicated that clusters produced based on RAPD and SSR markers were not conserved since matrix correlation value was 0.582 as against the minimum required value of 0.800. The two marker systems contrasted most notably in pair-by-pair comparisons of relationships. SSR analysis resulted in a more definitive separation of clusters of genotypes indicating a higher level of efficiency of SSR markers for the accurate determination of relationships between accessions that are too close to be accurately differentiated by RAPD markers. This revised version was published online in July 2006 with corrections to the Cover Date.     

Identification and genetic diversity analysis of date palm (Phoenix dactylifera L.) varieties from Morocco using RAPD markers

Genetic variation among 43 date palm (Phoenix dactylifera L.) accessions, including 37 accessions from Morocco and 6 cultivars from Iraq and Tunisia, was studied using Random Amplified Polymorphic DNA (RAPD) markers. The pre-screening of 123 primers on four genotypes allowed selection of 19 primers which revealed polymorphism and gave reproducible results. All 43 analysed genotypes were distinguishable by their band patterns. RAPD technology therefore appears very effective for identifying accessions of date palm. RAPD-based genetic distance was used to determine the relationships between the accessions. The grouping-association identified by cluster analysis was rather weak. However, morphologically similar varieties clustered together. A relatively low polymorphism and a lack of evident organisation are observed among the date palm varieties grown in Morocco. This could be related to the mode of introduction and maintenance of the Moroccan date palm germplasm involving limited foundation germplasm, exchange of cultivars between plantations, and periodic development of new recombinant cultivars following sexual reproduction. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genetic diversity and identification of cymbidium cultivars as measured by random amplified polymorphic DNA (RAPD) markers

DNA from thirty-six cymbidium cultivars was examined using polymerase chain reaction (PCR) to determine the efficiency of randomly amplified polymorphic DNA (RAPD) markers in identifying cultivars and determining levels of genetic variability. A total of 132 RAPD markers, 78% of which were polymorphic, were produced from 15 10mer arbitrary primers. All the cultivars were distinguishable when a number of primers was considered. One cultivar, Blue Smoke ‘Green Meadow’ could be distinguished from all the rest based only on lack of the OPA5-370 fragment. Genetic distances among the cultivars were estimated based on the amount of band sharing and ranged from 0.08–0.50 with an average of 0.29. Cluster analysis of genetic distance estimates grouped siblings together with each other and parents with offsprings, thereby agreeing with known parentage information and corroborating isozyme data obtained from a separate study. The possible application of the observed polymorphism and variation to cymbidium breeding is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

49份旱稻种质RAPD标记遗传多样性分析

旱稻具有耐旱、耐贫瘠、适应性广等特点,是稻作育种中的一种特殊的遗传资源。为了更好地利用旱稻种质资源指导稻作育种,采用RAPD分子标记技术对49份旱稻种质（24份海南山栏稻,4份热大系列,21份其他地区旱稻）的遗传基础进行分析。结果表明,利用筛选出的22条多态性较强的引物,构建了49份旱稻种质的RAPD指纹图谱,这22条引物共扩增出375个条带,多态性条带为306条,其多态性为81.60%。参试的49份旱稻种质的遗传相似系数变化范围在0.546~0.952,平均为0.828。聚类分析表明,随着相似系数品种结合线的不同,可将参试的旱稻种质中海南山栏稻与其他地区的种质、大部分旱稻与水旱杂交稻、中国旱稻种质与国外旱稻种质区分开来,第C类海南山栏稻与第D类其他地区种亲缘关系最近,而与第Ⅰ大类亲缘关系较远。多数的品种的RAPD聚类结果与系谱基本吻合。该研究可为稻作种质鉴定及新品种选育等方面提供一定的分子生物学依据。     

澳洲棉种遗传多样性的RAPD分析

利用ＲＡＰＤ（ＲａｎｄｏｍｌｙＡｍｐｌｉｆｉｅｄＰｏｌｙｍｏｒｐｈｉｃＤＮＡ）对斯特提棉（Ｇ．ｓｔｕｒｔｉａｎｕｍ）、南岱华棉（Ｇ．ｎａｎｄｅｗａｒｅｎｓｅ）、鲁滨逊氏棉（Ｇ．ｒｏｂｉｎｓｏｎｉ）、澳洲棉（Ｇ．ａｕｓｔｒａｌｅ）、比克氏棉（Ｇ．ｂｉｃｋｉ）和奈尔逊氏棉（Ｇ．ｎｅｌｓｏｎｉ）进行了研究,结果表明：６个澳洲棉种具有丰富的遗传多样性,在这６个澳洲棉种中,澳洲棉与鲁滨逊氏棉、南岱华棉与斯特提棉具有较近的亲缘关系。聚类分析发现,鲁宾逊氏棉和比克氏棉是两个较为特殊的棉种。此外,本文对比克氏棉和木槿组（Ｈｉｂｉｓ－ｃｏｉｄｅａ）的其它棉种的染色体组的归属问题进行了讨论     

我国陆地棉品种的遗传多样性研究初报

选用１８个随机引物，对２１个陆地棉品种作ＲＡＰＤ分析，并对各品种的指纹图谱进行了聚类和相似性分析。结果表明大部分品种与其系谱吻合。研究结果充分展示了ＲＡＰＤ技术可以作为棉花品种分类和遗传多样性研究的可行方法。     

Attempts to overcome postfertilization barrier in interspecific crosses of the genus Lens

Wild relatives are a potential source of genetic diversity to lentil (Lens culinaris Medik). The objective of this research was to obtain viable interspecific hybrids between the domesticated lentil and its wild relatives. The paper details the results of a number of interspecific crosses among L. culinaris, L. orientalis, L. odemensis, L. ervoides and L. nigricans. Viable hybrids were produced between L. culinaris × L. orientalis, L. culinaris × L. nigricans, L. culinaris × L. ervoides and between L. culinaris × L. odemensis. Further viable hybrids were obtained between L. culinaris and L. ervoides, which have the potential to be a ‘bridge’ in hybridization to L. culinaris for specific L. nicrigans lines which proved recalcitrant in L. culinaris × L. nigricans crosses. This is the first time that four wild species of lentils have been used successfully in hybridization with cultivated lentils, and viable hybrids produced. This paper also suggests that the artificial supplement of GA₃, hormone is needed after fertilization for the normal growth of the hybrid embryo, possibly as the natural GA₃ production is restricted with alien pollinations in cultivated lentils in both F₁ and backcross hybrids.     

Assessing genetic diversity in the cassava (Manihot esculenta Crantz) germplasm collection in Brazil using PCR-based markers

Knowledge of the origin, organization and nature of the cassava (Manihot esculenta Crantz) germplasm collection in Brazil is incomplete due to lack of critical information on several aspects of the collection. This study verifies the utility of SSR-primed PCR markers for germplasm assessment and then utilizes these markers as well as RAPD's to characterize the Brazilian collection. We specifically address the following questions: 1)what is the relationship of morphologically closely related species to cultivated cassava? 2) What is the genetic diversity of cultivars within and between different habitats in Brazil? 3) Do agronomic traits and molecular markers reveal the same relationship among cassava accessions? 4) How complete is the Brazilian cassava collection and how well is it represented in the Word Core Collection of cassava, maintained by CIAT? Results of the interspecific studies of cassava and its wild relatives confirms the close relationship of cassava, Manihot esculenta ssp. esculenta to Manihot esculenta ssp. flabellifolia as well identifying several other closely related wild species. Next, PCR-based markers indicate a strong grouping of varieties related to the region of cultivation in Brazil. Moreover, important regions such as Cerrados and Amazon are relatively poorly represented in germplasm collections. Interestingly, the relationships of accessions based on agronomic traits are not fully congruent with relationships revealed with RAPD markers. Finally, the genetic diversity of the Brazilian cassava collection is not fully represented in the Core of the Word Core Collection of CIAT.     

Association of isozyme markers with quantitative trait loci in random single seed descent derived lines of lentil (Lens culinaris Medik.)

Summary Polymorphism at isozyme loci was used to locate factors responsible for variation in quantitative traits of lentil. Eight sets of random single seed descent (RSSD) derived lines were developed by advancing individual F₃ plants of interspecific (L. culinaris Medik. × L. orientalis Boiss.) hybrids to the F₆. The RSSD lines in each of the eight sets differed for alleles at 2–8 isozyme loci. In each set, association of isozyme loci with variation in seven quantitative traits (days to flower, days to mature, plant height, biomass, seed yield, harvest index, seed weight) was determined for each pairwise combination of a quantitative trait with a marker locus. Loci affecting variation in all seven quantitative traits were detected by their association with 14 isozyme markers (Aat-c, Aat-m, Aat-p, Adh-1, Fk, Gal-1, Gal-2, Lap-1, Lap-2, Pgd-p, Pgi, Pgm-c, Pgm-p, Skdh). The known position of 10 the 14 isozyme loci on the lentil genetic map was used to mark the genomic regions for possible location of associated quantitative trait loci (QTL). Detected QTL were found to be located in six of the seven linkage groups on lentil genetic map. Regions of the genome represented by linkage groups, 1, 5 and 7 appeared to affect a greater number of traits than other genomic regions represented by linkage groups 2, 3 and 4. Results indicated that the mean expression of quantitative traits at segregating marker locus classes can be used to locate the genetic factors in lentil which influence the behavior of economically important traits.     

Study of genetic diversity in Indian and exotic sesame (Sesamum indicum L.) germplasm using random amplified polymorphic DNA (RAPD) markers

Fifty-eight accessions of sesame (Sesamum indicum L.), an important oil seed crop of the tropics and subtropics were analysed using random amplified polymorphic DNA (RAPD) technique. The material analysed comprised 36 collections from 18 different states of India and four adjoining countries of the Indian subcontinent, and 22 exotic accessions from 21 sesame growing countries around the world. The results from PCR amplifications with the selected 24 random 10-mer primers were statistically analysed. The value of Jaccard’s similarity coefficients ranged from 0.19 to 0.89. The results indicated the presence of high level of genetic diversity. However, the extent of genetic diversity was greater in the collections from Indian subcontinent as compared to the exotics. Among the Indian accessions, the collections from Rajasthan and North-eastern states were highly diverse. The phenetic analysis grouped 48 out of 58 accessions in six clusters and the remaining highly diverse accessions were placed outside these close-knit clusters. The Bootstrap estimates obtained by Wagner parsimony analysis were significant for seven out of 49 nodes in the majority-rule consensus tree (<95% occurrence). The results of both the analyses were, however, broadly comparable when the constitution of the individual clusters were considered. The principal components analysis indicated that the first two components accounted for only 21% of the total variations and in order to explain <75% of variations 18 components were required. The high level of genetic diversity prevalent among the Indian collections is probably indicative of the nativity of this crop species. Similarly, the relatively lower level of polymorphism in exotic germplasm could be ascribed to the comparatively recent introductions of limited germplasm of this crop into some of the non-traditional sesame growing countries. This revised version was published online in August 2006 with corrections to the Cover Date.     

Molecular analysis of Lathyrus sativus L. (grasspea) and related Lathyrus species

Eight Lathyrus sativus L. accessions from a variety of geographic origins were used to study intraspecific genetic diversity using RAPD analysis. Fourteen decamer primers produced 64 amplification products, 50% of which were polymorphic between the samples. Jaccard's coefficient of genetic similarity was calculated between samples and a dendrogram was constructed by an unweighted pair-group method with arithmetical averages (UPGMA). The dendrogram showed that most of the L. sativus plants clustered into accessions or common geographical areas. The average genetic similarity coefficient within accessions was 0.12 and between accessions was 0.20, indicating a low level of intraspecific genetic variation. Interspecific genetic diversity and phylogenetic relationships of eight Lathyrus species, including L. sativus and Pisum sativum L. (field pea) were examined using 14 decamer primers which produced 283 amplification products. All amplification products were polymorphic across the nine species. In the dendrogram the Lathyrus species clustered into three distinct groups which correlated with the Sections Lathyrus, Clymenum and Linearicarpus. This supports traditional taxonomic classifications of the genus Lathyrus which are based on morphological traits. Of the species from Section Lathyrus, L. gorgoni and L. cicera were the most similar to L. sativus. The results suggest that a strategy of breeding for producing lines of L. sativus with increased genetic variation would be effectively achieved through hybrid production between accessions from wide geographic areas particularly the Mediterranean area and the Indian subcontinent. However, the most effective method would be introgression of germplasm from other species in Section Lathyrus. This revised version was published online in July 2006 with corrections to the Cover Date.     

不同类型抗虫棉品种基于RAPD的遗传多样性分析

以97014、 BR-S-10和sGK321等14份不同类型的抗虫棉花品种(系)为基础,利用RAPD分子标记技术,对这些棉花品种(系)的遗传多样性进行了研究.结果表明,从210个随机引物中筛选出21个引物能在14份抗虫棉品种(系)间扩增出稳定性较好的多态性片段,筛选的21个引物在该品种(系)群体中共扩增了137个RAPD标记,其中多态性标记57个,占总标记数的42.2%,平均每条引物扩增6.52条带.利用Jaccard遗传相似系数计算了14份抗虫棉品种(系)的RAPD数据的距离矩阵,按UPGMA方法进行聚类,发现14个品种(系)间的遗传距离在0.0351～1.056之间.聚类分析表明,14个棉花品种可分为2大类4亚类,揭示了抗虫棉花品种种质资源的多样性,大多数品种的遗传基础比较狭窄.     

河北省和中棉所育成陆地棉品种的遗传多样性分析

分别选取河北省历年育成的 1 9个陆地棉品种 ,中国农业科学院棉花研究所自 2 0世纪 70年代末到 90年代中期选育的品种中的 1 6个陆地棉品种 ,利用 RAPD分子标记研究各自育成品种的遗传多样性。 41个带型清晰、重复性好的多态性引物用于 RAPD分析 ,河北省育成的 1 9个品种得到 6 6个多态性位点 ,而中棉所育成的 1 6个品种扩增到 6 4个多态性位点。分析采用 Jaccard' s相似系数 ,使用 NTSYS- pc1 .80数据分析软件 ,非加权组平均法 (UPGMA)聚类。成对相似系数比较表明 ,中棉所在 2 0世纪 70年代末到 90年代中期育成的品种的遗传多样性水平高于河北省育成的品种。河北省育成的 1 9个品种的遗传基础很狭窄 ,斯字棉和岱字棉是河北省棉花两个最重要的基础种质 ,其中的 1 5个品种在聚类图上可以被分为两类 ,分别属于岱字棉和斯字棉系统。中棉所育成的 1 6个品种在聚类图上可被划分为三个类群。     

利用RAPD标记对彩色棉遗传多样性的分析

以新彩棉1号、2号和71份彩色棉材料为基础,利用RAPD标记对彩棉品种之间分子标记遗传差异进行研究。从240个随机引物中筛选出10个引物能在73份彩棉材料间扩增出稳定性较好的多态性片段。73份彩棉材料的欧氏遗传距离在1.00～4.79之间。按类平均距离法进行聚类分析表明,这些彩色棉材料可分为7组,品种间的遗传关系与品种自身的系谱有关,大多数品种的遗传基础比较狭窄。     

Genetic diversity of late blight resistant and susceptible Indian potato cultivars revealed by RAPD markers

Twenty-four tetraploid Indian potato cultivars were characterized by using RAPD markers to assess diversity within and between late blight resistant and susceptible cultivars. Sixty-four random decamer primers generated802 fragments, ranging in size from 60–3200 bp, with 96.4% fragment polymorphism. Shannon's index of diversity was used to quantify the degree of variability present within and between the variety types. Most of the diversity was detected within variety types, with 88% of variation being within and 12% being between the resistant and susceptible cultivars. No clear groupings based on late blight resistance and susceptibility or kinship was reflected on the dendogram. The late blight resistant cultivars exhibited higher variability compared to susceptible cultivars and they were more dispersed on the PCO plot. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genetic diversity and relationships among Lablab purpureus genotypes evaluated using RAPD as markers

Summary Genetic variation in 40 accessions of Lablab purpureus was evaluated using random amplified polymorphic DNA as markers. A high level of genetic variation in this species was detected but this was mainly restricted to the difference between cultivated and wild forms. Of the cultivated genotypes, genetic variation among Asian collections was significantly higher than that among African collections. The three most divergent cultivated genotypes were all from Asia. Four of the five wild accessions, two from Zimbabwe and the other two from Zambia, were closely related. The other one, CPI 31113 collected from Uganda, was highly divergent. The two commercial forage varieties used in Australia, Rongai from Kenya and Highworth from India, were not very different.     

烟草赤星病菌遗传多样性ISSR和RAPD标记比较分析

对分离出的链格孢菌株用ISSR和RAPD分子标记技术分析研究其遗传多样性,比较2种分子生物学方法在链格孢遗传分析中的优劣,为研究烟草赤星病菌遗传多样性及烟草抗病品种的培育奠定基础。采用ISSR和RAPD分子标记方法对来自不同地区的28份烟草赤星病菌进行遗传多样性分析,筛选出10个ISSR引物和10个RAPD引物;ISSR扩增出多态性条带112条,多态性条带比率为86.82%,菌株间相似性系数为0.53~0.97;RAPD引物扩增出多态性条带70条,多态性条带比率为81.39%,菌株间相似性系数为0.57~0.94。用SPSS 17.0 软件对2种标记遗传距离进行相关性分析,发现2种分子标记结果呈显著正相关,表明2种分子标记方法都适合于烟草赤星病菌遗传多样性研究,ISSR是一种多态性优于RAPD的标记技术。根据2种标记的结果,利用NTSYS软件按UPGMA方法进行聚类分析,发现烟草赤星病菌遗传多样性与地理差异没有显著相关性。