Genetic diversity in local cultivars of garden pea (Pisum sativum L.) conserved ‘on farm’ and in historical collections

During a national Swedish collection mission of vegetable varieties conserved ‘on farm’ more than 70 pea accessions were obtained, many of which had been grown locally for more than 100 years. In spite of a likely origin in the multitude of obsolete commercial pea varieties available on the Swedish seed market in the nineteenth century, the rediscovered local cultivars have lost their original names and cultivar identity while being maintained ‘on farm’. To analyze genetic diversity in the repatriated material, 20 accessions were genotyped with twelve SSR markers and compared with 15 obsolete cultivars kept in genebanks and 13 cultivars preserved as non-viable seeds collected in 1877–1918. Most of the local cultivars were genetically distinct from each other, and in only a few cases could a possible origin in a tested obsolete cultivar be suggested. These results reflect the wide diversity of pea cultivars present in Sweden during the nineteenth century. Both between and within accession genetic diversity was larger among the historical samples of obsolete cultivars compared to local cultivars and cultivars preserved in genebanks, indicating genetic erosion over time both in genebanks and during conservation ‘on farm’. The constraints on identifying and verifying historical cultivars using genetic markers are discussed.     

大蒜种质遗传多样性的SSR分析

为了探索中国大蒜种质个体的SSR位点的分布情况,为品种鉴定、保存及遗传改良提供分子生物学依据,利用6对SSR引物对40个大蒜(Allium sativumL.)品种进行聚类分析、主成分分析及遗传多样性评价。共检测到21个多态性位点,平均每对引物可扩增出约3.5条多态性片段,多态性百分率为56.76%;SSR引物组合平均有效等位基因数、Nei基因多样度和Shannon信息指数分别为1.5551、0.3414和0.5188。聚类分析显示,6对SSR引物可把40份大蒜种质资源从0.59相似系数水平上3个类群。第一类群包含28份种质,在相似系数为0.73的水平上进一步又被分成了3个亚类;第二亚类仅包含2份种质;第三亚类包含10份种质,在0.68的相似系数水平上分成了2个亚类。主成分分析和UPGMA的结果基本一致。不同地理来源的大蒜种质的Shannon-Weaver多样性指数的变幅为0.0576~0.4179,说明大蒜种质遗传多样性丰富。本研究利用SSR分子标记技术较准确地解析大蒜不同材料间的亲缘关系及遗传多样性,为中国大蒜SSR分子标记提供基础资料。     

我国部分冬小麦新品种（系）SSR标记遗传差异的研究

本研究利用53对SSR引物对全田1999－2000年北方冬麦区及黄淮冬麦区观察圃中选出的48个新品种（系）进行遗传差异研究，共检测出58个SSR位点上的367个等位变异，平均每个位点有6.33个等位变异，其中B组每个位点的等位变异最多，这表明B基因组化更快，分化更大。48个品种（系）在全基因组及A、B、D基因组聚类结果表明这些品种的相似系数聚类的范围较小，为0.75－0.98。全基因组聚类结果与品种的系谱来源及育成地区相吻合。研究结果表明我国冬小麦品种的种质基础相对较狭窄。加强不同来源种质的利用和特异亲本类型的培育对我国冬小麦遗传改良非常重要，利用5个多态性高的SSR标记就可以将这48个小麦新品种（系）区分开，每个品种（系）都有各自独特的指纹图谱。     

Genetic diversity of melon landraces (<Emphasis Type="Italic">Cucumis melo</Emphasis> L.) in the Xinjiang Uygur Autonomous Region on the basis of simple sequence repeat markers

We investigated the genetic variation and relationships among 35 melon landraces collected from the Xinjiang Uygur Autonomous Region in northwestern China by using 19 polymorphic simple sequence repeat markers (SSRs). A total of 55 polymorphic alleles were amplified. The number of alleles per SSR locus ranged from 2 to 5 with an average of 2.89 alleles per locus. The average gene diversity (GD) was 0.42 with a range of 0.06–0.71, and the average observed heterozygosity was 0.22 with a range of 0.06–0.97, indicating that the genetic diversity among the Xinjiang melon landraces was abundant. Genetic variation was also detected between the landrace populations in different regions in Xinjiang. The most abundant genetic diversity was observed among the landraces in Eastern Xinjiang, with the highest GD of 0.45 and PIC of 0.39. Eleven alleles (20 %) were found exclusively in the landraces from Eastern Xinjiang, and two alleles (3.6 %) were unique to the landraces from Southern and Northern Xinjiang. The genetic similarity matrix was defined on the basis of Jaccard coefficient to determine the genetic relationships among Xinjiang landraces. Cluster analysis was performed using the unweighted pair group method with arithmetic means, showing that the ‘wild Hami’ (XJ-34) landrace was distinct from the 34 other landraces that were divided into three clusters. Therefore, the genetic background of XJ-34 differed from that of the other landraces. The landraces were not precisely separated on the basis of their geographic origins, although most of these landraces were likely grouped near one another, as visualized through principal coordinate analysis. Thus, western China is one of the primary or secondary centers of melon diversity because of the relatively higher genetic variation detected among Xinjiang landraces. Except the ‘wild Hami’ landrace, Xinjiang melon landraces could be classified into two botanical varieties, namely, var. inodorus and var. cantalupensis. However, the distinction between these two genotypes was not significantly different.     

Microsatellite-based analysis of genetic diversity in 91 commercial Brassica oleracea L. cultivars belonging to six varietal groups

Brassica oleracea L. includes various types of important vegetables that show extremely diverse phenotypes. To elucidate the genetic diversity and relationships among commercial cultivars derived by different companies throughout the world, we characterized the diversity and genetic structure of 91 commercial B. oleracea cultivars belonging to six varietal groups, including cabbage, broccoli, cauliflower, kohlrabi, kale and kai-lan. We used 69 polymorphic microsatellite markers showing a total of 359 alleles with an average number of 5.20 alleles per locus. Polymorphism information content (PIC) values ranged from 0.06 to 0.73, with an average of 0.40. Among the six varietal groups, kohlrabi cultivars exhibited the highest heterozygosity level, whereas kale cultivars showed the lowest. Based on genetic similarity values, an UPGMA clustering dendrogram and a two-dimensional scale diagram (PCoA) were generated to analyze genetic diversity. The cultivars were clearly separated into six different clusters with a tendency to cluster into varietal groups. Model-based structure analysis revealed six genetic groups, in which cabbage cultivars were divided into two subgroups that were differentiated by their head shape, whereas cauliflower and kai-lan cultivars clustered together into a single group. Furthermore, we identified 18 SSR markers showing 27 unique alleles specific to only one cultivar that can be used to discriminate 22 cultivars from the others. Our phylogenetic and population structure analysis presents new insights into the genetic structure and relationships among 91 B. oleracea cultivars and provides valuable information for breeding of B. oleracea species. In addition, we demonstrate the utility of SSR markers as a powerful tool for discriminating between the cultivars. The SSR markers described herein will also be helpful for Distinctness, Uniformity and Stability (DUS) test of new cultivars.     

Classification of elite cassava varieties (<Emphasis Type="Italic">Manihot esculenta</Emphasis> Crantz) cultivated in Benin Republic using farmers’ knowledge,morphological traits and simple sequence repeat (SSR) markers

Cassava (Manihot esculenta Crantz) is an important food security crop or resource for poor rural communities particularly in Africa. The crop’s ability to produce high yields even under poor conditions and storability of its roots underground for longer periods or until needed makes it a model ‘food security crop’. In Benin Republic, cassava has been recognized as one of the major crop contributing towards dynamic value chains generating incomes for small-holder farmers. The crop is grown all over the country, however, the increased production are mainly recorded from far south and central parts of the country. Genetic improvement of cassava in Benin Republic is limited because of poor knowledge of genetic diversity present within the country. The main objective of this study was to assess the genetic diversity and relationships among elite cassava varieties collected from different regions of Benin using fluorescently labelled simple sequence repeat (SSR) markers and to compare the results with farmer’s knowledge and morphological traits. A total of 96 cultivars collected from major cassava growing areas such as Southern and Central Benin were classified into 24 different groups using farmers’ knowledge, while classification based on 18 morphological traits resulted in five groups. In total, sixteen SSR markers were tested for molecular analysis of the ninety-six cassava varieties. Among the sixteen, twelve SSR markers gave good banding pattern and were used to genotype the varieties. An average of 3.58 and 0.47 for number of alleles and polymorphism information content respectively was observed. The observed heterozygosity (H_o) ranged from 0.23 to 1.0 with an average of 0.66 indicating moderate level of diversity among the cultivars. Based on the proportion of shared alleles and hierarchical clustering, the 96 elite cassava varieties were classified as 74 unique varieties. Principal component analysis and analysis of molecular variance revealed no significant variation between the regions thus, explaining regular exchange of planting materials among cassava farmers across various regions. The moderate level of genetic diversity in famer’s field, revealed in the present study, is a good indication of the need for broadening the genetic base of cassava in Benin Republic and establishing a formal breeding program in the country.     

Genetic composition of contemporary proprietary U.S. lettuce (Lactuca sativa L.) cultivars

Pedigree history of 146 lettuce (Lactuca sativa L.) cultivars registered in the U.S. by Plant Variety Protection and/or utility patent of the era from 2000 through 2010 facilitates determination of coefficient of parentage among these cultivars, identification of ancestral parental lines, and their genetic contribution. Principal ancestors of leaf lettuce developed in this era are the cultivars ‘Malibu’, ‘Waldmann’s Green’, and ‘Salad Bowl’ contributing 6.4, 6.1, and 3.5% of the genes, respectively. The cultivars ‘Parris Island Cos’ and ‘Tall Guzmaine’ are major ancestors of romaine lettuce, contributing 25.9 and 23.4% of the genes, respectively. Three crisphead lettuce ancestors identified are the cultivars ‘Vanguard’, ‘Salinas’, and ‘Calmar’, the former two descend from interspecific crosses of L. sativa with Lactuca virosa L. and Lactuca serriola L. Among these three, ‘Vanguard’ is the major ancestor contributing 23.8% of the genes to crisphead lettuce. The crisphead cultivar ‘Salinas’ was frequently crossed with romaine lettuce types and the romaine parental cultivar ‘Parris Island Cos’ was crossed with leaf types contributing to romaine and leaf lettuce genetic diversity, respectively. Genetic similarity was less within leaf cultivars (coefficient of parentage = 0.02) than found within romaine (0.15) and crisphead (0.13) cultivars registered in the U.S. during this era.     

SSR fingerprinting of a German <Emphasis Type="Italic">Rubus</Emphasis> collection and pedigree based evaluation on trueness-to-type

Eighty-two genotypes of Rubus available in germplasm collections, nurseries and home gardens were collected and evaluated using a set of 16 simple sequence repeat (SSR) markers to estimate the level of genetic diversity and relatedness of the germplasm and for testing them on trueness-to-type. Each of the 16 SSRs was successful in amplifying alleles from most genotypes. Fifteen of the markers produced polymorphic bands, whereas marker RhM023 was monomorphic. The polymorphic information content among genotypes varied from 0.056 to 0.83 with an average of 0.348. A neighbor-joining analysis allocated the genotypes to four major clusters containing 11, 24, 39 and eight genotypes, respectively. Cluster I consists of floricane-fruiting cultivars originating from the Scottish and/or British breeding programs or cultivars which have those cultivars in their pedigree. Cluster II included cultivars that have ‘Autumn Bliss’ or ‘Tulameen’ in their pedigree. Cluster III consists of summer-bearing raspberry cultivars, some primocane-fruiting cultivars, and a few intermediate summer-fall-bearing types. Cluster IV consists of the blackberry ‘Navaho’ (R. fruticosus L.), the interspecific hybrid ‘Dorman Red’ and a few other raspberry varieties. A number of yellow fruited varieties was dispersed on three different clusters suggesting a convergent evolution of this trait. The pedigree of several genotypes could be confirmed using a Pedimap based approach, whereas other cultivars were found to be genetically identical. The results disclose the alarming narrow genetic base of Rubus resources in Germany. Broadening of this base is urgently needed.     

基于SSR标记的梨资源遗传多样性分析

本研究利用SSR标记技术对56份梨资源进行了遗传多样性分析。利用筛选出的6对SSR引物共扩增40条谱带,其中多态性位点38个,多态性位点比例为95%,每对引物产生有效等位基因6.3个。各位点期望杂合度H值在0.0354～0.491,平均为0.1964;有效等位基因Ne值在1.0367～1.9648,平均值为1.2958;香农指数I值平均值为0.3256,说明了供试梨材料的遗传多样性较低。利用SSR标记可将44个栽培品种区分开,但无法区分芽变和原种。根据SSR标记揭示的多态性,采用NTSYS-pc软件,以UPGMA法进行聚类分析,结果显示所检测的56份梨材料在相似系数0.71处可分为4组,其中中国的白梨、秋子梨和砂梨相互交错在一起,没有独自各自成组。     

Genetic diversity of anchote (Coccinia abyssinica (Lam.) Cogn.) from Ethiopia as revealed by ISSR markers

Anchote (Coccinia abyssinica) is plant endemic in Ethiopia with a high calcium content grown for its edible tuberous roots. In spite of its importance as food security crop, there is no information available on molecular genetic diversity of this crop. Therefore, the aim of this study was to assess genetic diversity within and among 12 populations of anchote using ISSR markers. Using nine ISSR primers, a total of 87 scorable bands was generated of which 74 were polymorphic. Within population diversity based on polymorphic bands ranged from 13.8 to 43.53 % with a mean of 33.05 %, Nei’s genetic diversity of 0.04–0.156 with a mean of 0.12, Shannon information index of 0.07–0.23 with a mean of 0.175 and analysis of molecular variation (AMOVA) of 51.4 % were detected. With all diversity parameters, the highest diversity was obtained from Gimbi, Bedele and Ale populations, whilst the lowest was from Manna. AMOVA showed a 48.56 % between populations variability and significantly lower than that of within population variation. Population differentiation with F_ST was 48.56 %. From Jaccard’s pairwise similarity coefficient, Decha and Nedjo were most related populations exhibiting 0.76 similarity and Manna and Nedjo were the most distantly related populations with similarity of 0.52. The only pentanucliotide primer used in the study, Primer 880 (GGAGA)3, showed a unique band in some individuals that appeared to be associated with morphological quantitative traits (lowest seed number, high protein content, largest fruit size and smallest vine length). Illubabor and Gimbi populations exhibited highest genetic diversity so that the populations should be considered as the primary sites in designing conservation areas for this crop.     

Exploitation of <Emphasis Type="Italic">Malus</Emphasis> EST-SSRs and the utility in evaluation of genetic diversity in <Emphasis Type="Italic">Malus</Emphasis> and <Emphasis Type="Italic">Pyrus</Emphasis>

A total of 8117 suitable SSR-contaning ESTs were acquired by screening from a Malus EST database, among which dinudeotide SSRs were the most abundant repeat motif, within which, CT/TC followed by AG/GA were predominant. Based on the suitable sequences, we developed 147 SSR primer pairs, of which 94 pairs gave amplifications within the expected size range while 65 pairs were found to be polymorphic after a preliminary test. Eighteen primer pairs selected randomly were further used to assess genetic relationship among 20 Malus species or cultivars. As a result, these primers displayed high level of polymorphism with a mean of 6.94 alleles per locus and UPGMA cluster analysis grouped twenty Malus accessions into five groups at the similarity level of 0.6800 that were largely congruent to the traditional taxonomy. Subsequently, all of the 94 primer pairs were tested on four accessions of Pyrus to evaluate the transferability of the markers, and 40 of 72 functional SSRs produced polymorphic amplicons from which 8 SSR loci selected randomly were employed to analyze genetic diversity and relationship among a collection of Pyrus. The 8 primer pairs produced expected bands with the similar size in apples with an average of 7.375 alleles per locus. The observed heterozygosity of different loci ranged from 0.29 (MES₉₆) to 0.83 (MES₁₃₈), with a mean of 0.55 which is lower than 0.63 reported in genome-derived SSR marker analysis in Pyrus. The UPGMA dendrogram was similar to the previous results obtained by using RAPD and AFLP markers. Our results showed that these EST-SSR markers displayed reliable amplification and considerable polymorphism in both Malus and Pyrus, and will contribute to the knowledge of genetic study of Malus and genetically closed genera.     

Evaluation of genetic diversity in a Camelina sativa (L.) Crantz collection using microsatellite markers and biochemical traits

A genomic DNA library enriched with GA/TC repeats from Camelina sativa variety Calena has been analysed. After sequencing of about 200 randomly selected clones, approximately 60 % of them showed to contain simple or compound microsatellites with a high number of repeats. Among all microsatellite markers analysed 15 primer pairs amplified polymorphic fragments. Forty C. sativa accessions of different origin were genotyped with 15 microsatellite markers that generated 134 alleles with an average of 8.93 alleles per locus. The observed heterozygosity (Ho) among the accessions ranged from 0.0 to 0.15 with an average of 0.0370, whereas the average of expected heterozygosity (He) among accessions was 0.2769. The analysis of the average total heterozygosity (H_T = 0.651), the intrapopulation genetic diversity (H_S = 0.260), the interpopulation genetic diversity (D_ST = 0.391) and the coefficient of genetic differentiation among populations (G_ST = 0.574) demonstrated that 57.4 % of the genetic diversity is among the accessions, while 42.6 % resides within them. Phylogenetic tree of the 40 C. sativa accessions was constructed based on Nei’s genetic distance. The unweighted pair group method with arithmetic mean (UPGMA) dendrogram shows, except for CAM108 and CAM170, a clear discrimination among C. sativa accessions grouping them in five subgroups. ANOVA analysis indicates significant differences in some biochemical and agronomic parameters among the C. sativa accessions grouped according to Nei’s genetic distance. The result of the Tukey HSD test demonstrated that the A4 subgroup showed a significant higher TWS and linoleic acid (LA) content, while the subgroup A1 showed a significant higher linolenic and lower LA content compared to the remaining groups.     

37份龙眼种质资源亲缘关系的ISSR分析

本研究利用ISSR技术对37份龙眼种质资源进行遗传多样性检测。研究结果表明,从100条ISSR引物中筛选出7条重复性好,条带清晰的引物对37份龙眼品种基因组DNA进行扩增,共扩增出54条带,其中43条具有多态性,比率为79．6％。不同龙眼品种间遗传相似系数变幅为0．69～0．97,平均达0．83,说明ISSR标记能够揭示材料间较高的遗传多样性。UPGMA聚类结果表明,ISSR标记能将37份龙眼品种完全区分开,并能将来源于中国、越南和泰国的37份龙眼品种分别聚类到中国、越南和泰国三大品种群,说明龙眼品种资源的亲缘关系与地理因素有关,三个国家的龙眼品种之间存在较大的遗传差异。本研究结果将为为龙眼品种资源的研究利用提供参考。     

浙江省南部地方梨品种的SSR和AFLP遗传多样性研究

为了解浙江省南部地方梨品种的遗传多样性,采用10对苹果和3对梨上的SSR引物以及6对AFLP引物对来自温岭和丽水的18个地方梨品种或类型进行了鉴定分析。结果表明10对苹果引物在梨上扩增出62条条带。13对SSR引物的观察杂和度(He)为0.056～0.944,平均值为0.57,而香农指数(I)的范围0.340～2.013,平均值为1.22。6对AFLP引物组合共扩增出364条带,平均每对引物扩增60.67条,平均多态性比例为73.35%。采用UPGMA聚类分析法构建的SSR和AFLP系统树中,云和梨、云和粗花雪梨与云和细花雪梨在2个系统树中聚在一起,虽然相互间有较高的遗传相似度,但属于不同的品种;3个同名为老雪梨的品种(老雪梨1、老雪梨2和老雪梨3)分散在不同的组中,可能为异物同名。SSR和AFLP聚类结果基本吻合,但AFLP的结果更符合品种的地域分布情况。     

Genetic diversity in wild and cultivated black raspberry (Rubus occidentalis L.) evaluated by simple sequence repeat markers

Breeding progress in black raspberry (Rubus occidentalis L.) has been limited by a lack of genetic diversity in elite germplasm. Black raspberry cultivars have been noted for showing very few phenotypic differences and seedlings from crosses between cultivars for a lack of segregation for important traits. Despite these challenges, little molecular work has been done to explore genetic diversity and relationships in wild and cultivated black raspberry germplasm. Microsatellite, or simple sequence repeat (SSR), markers are highly polymorphic codominant markers useful for studying genetic diversity, population genetics, genetic fingerprinting and other applications. We examined genetic diversity in 148 wild and cultivated black raspberry accessions using 21 polymorphic SSR markers. Black raspberry cultivars clustered tightly and showed higher than expected heterozygosity while that of wild accessions was low. Relationships between wild black raspberry accessions were poorly resolved and regional clusters were mostly absent from our analysis. Our results indicated that wild black raspberry germplasm is a relatively untapped resource available for future breeding.     

Ancestry and characterization of U.S. contemporary proprietary garden pea (Pisum sativum L. convar. medullare Alef.) germplasm

A major objective of this work is to elucidate the ancestry and genetic background of contemporary U.S. garden pea (Pisum sativum L. convar. medullare Alef.) cultivars used as cultivated vegetables. This is facilitated through pedigree analysis of 147 cultivars registered during the era from 1990 through 2010 by collecting data from U.S. Plant Variety Protection, U.S. utility patent, and journal publication. Proprietary breeding programs developed 141 cultivars and public programs six, with over half (82 of 147 cultivars) originating from the two (Seminis Vegetable Seeds, Inc. and Syngenta Seeds, Inc.) largest proprietary breeding programs. During this era, the semi-leafless (afila) trait was bred into cultivars to decrease lodging, and 43 % of the cultivars were afila. Registered cultivars were 86 % of determinate growth habit. Bi-parental breeding crosses were used in the development of 78 % of these cultivars. The lineages of the cultivars ‘Bolero’, ‘Spring’, ‘Genie’, and ‘Rally’ made large contributions to the genetic composition of this germplasm, ‘Bolero’ contributed 6.5 % (29 progeny), ‘Spring’ 6.4 % (29), ‘Genie’ 4.0 % (18), and ‘Rally’ 3.6 % (23) of the genes. The garden pea ancestor cultivar ‘Perfection’ fostered the most descendants (75) among the 147 cultivars of this era.     

Analysis of genetic diversity of Ruthenia Medic (Medicago ruthenica (L.) Trautv.) in Inner Mongolia using ISSR and SSR markers

Ruthenia Medic is tolerant to drought, cold, high salinity, resistance to trampling and high quality features. Inter-simple sequence repeat (ISSR) and simple sequence repeat (SSR) molecular markers were employed for the first time to access the genetic diversity and relationships of 30 wild Ruthenia Medic accessions obtained from Inner Mongolia in the present study. A total of 94 bands were amplified by ten ISSR primers, of which 83 (88.5 %) were polymorphic, and 57 polymorphic bands (80.4 %) were observed in 69 bands amplified by ten SSR primers. Shannon’s information index (I = 0.487), and average expected heterozygosis (He = 0.329) generated by ISSR primer were higher than that of SSR analysis (I = 0.372, He = 0.231). The study indicated that ISSR were more effective than SSR markers for assessing the degree of genetic variation of Ruthenia Medic. UPGMA cluster analysis revealed inconsistencies in the clustering patterns, as the Mantel’s test between the dendrograms for ISSR and SSR data indicated a poor fit for the ISSR and SSR data types (r = 0.0970). Whereas the pattern of clustering of the genotypes remained relatively the same in ISSR and combined data of ISSR and SSR. The results of principal components analysis also supports their UPGMA clustering. These results have an important implication for Ruthenia Medic germplasm characterization, improvement, and conservation.     

Geographic Pattern of Genetic Diversity Among 43 Ethiopian Mustard(Brassica carinata A. Braun) Accessions as Revealed by RAPD Analysis

As an oilseed crop, the cultivation of Ethiopian mustard (Brassica carinata) is restricted only to Ethiopia. Even though geographic diversity is a potent source of allelic diversity, the extent of genetic diversity among germplasm material of Ethiopian mustard from different countries has not been assessed. Forty-three accessions, comprising 29 accessions from eight different geographic regions of Ethiopia and 14 exotic accessions from Australia, Pakistan, Spain, and Zambia were analysed for their genetic diversity using random amplified polymorphic DNA (RAPD) technique. A set of 50 primers yielded a total of 275 polymorphic bands allowing an unequivocal separation of every Ethiopian mustard accession. The usefulness of the 50 RAPD primers in measuring heterozygousity and distinguishing accessions was variable such that polymorphic information content (PIC) varied from 0.05 to 0.40, band informativeness (BI) from 0.05 to 0.65 and primer resolving power (RP) from 0.15 to 6.83. Jaccard's similarity coefficients ranged from 0.44 to 0.87 indicating the presence of a high level of genetic diversity. On the average, Australian and Ethiopian accessions were the most similar while, Spanish and Zambian accessions were the most distant ones. Cluster analysis grouped the 43 accessions into four groups, which has quite a high fit (r = 0.80) to the original similarity matrix. With no prior molecular information, the RAPD technique detected large genetic diversity among the 43 accessions from five different countries and their grouping by dendrogram and principal coordinate analysis (PCoA) was inclined towards geographic differentiation of RAPD markers. Conversely, RAPD differentiation along geographic origin was not apparent within the Ethiopian accessions.     

吉富罗非鱼雌雄群体遗传差异的SSR分析

为探讨吉富罗非鱼（genetic improvement of farmed tilapia,GIFT）雌、雄群体间的遗传差异,本研究对国家级广西南宁罗非鱼良种场雌、雄吉富罗非鱼进行了遗传差异分析。研究结果表明,选取的11对SSR引物中有10对能获得稳定的目的条带;每个SSR基因座的等位基因数在2～4个之间,雌性罗非鱼的平均等位基因（Na）2.9个,稍高于雄性的2.8个;雌、雄吉富罗非鱼平均观察杂合度（HO）分别为0.4183和0.4154,多态信息含量（PIC）分别为0.4048和0.3932,属中度多态;雌雄个体间的遗传距离和相似性指数分别为0.0908和0.9132。此外,SSR基因座PRL-SO2在雄鱼中偏离Hardy Weinberg平衡（P〈0.005）。上述结果表明,吉富罗非鱼雌、雄群体的SSR多态性基本相同,推测这两者基因组间的差异较小。     

Characterization of Italian lentil (Lens culinaris Medik.) germplasm by agronomic traits, biochemical and molecular markers

Genetic relationships, agronomic, nutritional and technological traits of ten Italian landraces, two improved lines and two cultivars of lentil (Lens culinaris Medik.) were investigated using a multi-disciplinary approach. Seed storage proteins, used as biochemical markers, were able to detect polymorphisms with variability mainly related to the polypeptide abundance. Microsatellite (SSR) molecular markers provided very useful information on genetic variation and relationships among landraces, with polymorphic fragments able to discriminate all the accessions. Lentil landraces were grouped in different clusters and sub-clusters principally on the basis of their geographical origin. The highest levels of genetic diversity were observed for lentils from ‘Castelluccio di Norcia’, ‘Colliano’ and ‘Villalba’. Field trials, performed in two locations of Southern Italy, revealed a high influence of location on yield. Comparing performances at both tested locations, the best landraces were ‘Linosa’ and ‘Valle di Nevola’ suggesting that these have the highest adaptability. Technological and nutritional data together with the agronomic ones evidenced that ‘Linosa’ lentil is the best landrace, however also ‘San Gerardo’ deserves some attention.