Genetic variation among populations of wild safflower, <Emphasis Type="Italic">Carthamus oxyacanthus</Emphasis> analyzed by agro-morphological traits and ISSR markers

Wild species of safflower, Carthamus oxyacanthus Bieb., is highly crossable with cultivated species, C. tinctorius L. and could be directly exploited in broadening safflower gene pool and improving the crop for biotic and abiotic stress environments. In this study, genetic diversity among accessions of C. oxyacanthus and their relationships with cultivated safflower were evaluated using agro-morphological traits and polymorphic inter-simple sequence repeats (ISSR) markers. Significant variation was observed among accessions particularly for seeds per capitulum, seed yield per plant, harvest index and capitula per plant. Cluster analysis based on agro-morphological traits classified the wild accessions in two groups according to their geographical regions, and separated them from the cultivated genotypes. ISSR marker also revealed a high genetic variation among the accessions, and cluster analysis based on this marker divided genotypes into four groups, with cultivated ones in a separate clade. Genetic variation observed among the wild safflower germplasm at the DNA level was higher than the agro-morphological traits, indicating that ISSR is an effective marker system for detecting diversity among safflower genotypes and their genetic relationships. Accessions of C. oxyacanthus with high genetic relationship to cultivated species could be used for interspecific hybridization in breeding programs of safflower.     

Genetic diversity of cowpea [<Emphasis Type="Italic">Vigna unguiculata</Emphasis> (L.) Walp.] in four West African and USA breeding programs as determined by AFLP analysis

Cowpea is an important grain legume and hay crop of many tropical and subtropical regions, especially in the dry savanna region of West Africa. The cowpea gene pool may be narrow because of a genetic bottleneck during domestication. Genetic variation within specific breeding programs may be further restricted due to breeding methods, ‘founder effects’ and limited exchange of germplasm between breeding programs. Genetic relationships among 60 advanced breeding lines from six breeding programs in West Africa and USA, and 27 landrace accessions from Africa, Asia, and South America were examined using amplified fragment length polymorphism (AFLP) markers with six near infrared fluorescence labeled EcoRI + 3/1bases/MseI + 3/1bases primer sets. A total of 382 bands were scored among the accessions with 207 polymorphic bands (54.2%). Despite a diverse origin, the 87 cowpea accessions shared a minimum 86% genetic similarity. Principal coordinates analysis showed clustering of breeding lines by program origin, indicating lack of genetic diversity compared to potential diversity. Accessions from Asia and the Americas overlapped and were distinct from West African breeding lines, indicating that germplasm from Asia and the Americas have common origins outside West Africa. US and Asian breeding programs could increase genetic variability in their programs substantially by incorporating germplasm from West Africa, while national programs in West Africa should consider introgression of Asian germplasm and germplasm from other parts of Africa into their programs to ensure long-term gains from selection.     

Characterization of sesame (<Emphasis Type="Italic">Sesamum indicum</Emphasis> L.) germplasm regenerated in Georgia,USA

Sesame, Sesamum indicum L. is used worldwide for cooking oil and food. The United States Department of Agriculture, Agricultural Research Service, Plant Genetic Resources Conservation Unit (USDA, ARS, PGRCU) conserves 1,226 accessions originating from Europe, Africa, Asia, North America, and South America. Sesame accessions were directly seeded to the field in Griffin, GA between 15 May and 01 June 2003–2007. At 50% maturity, 192 accessions were characterized for morphological, phenological, and reproductive traits during the regeneration cycles. High quality plants regenerated from all accessions produced 131 to more than 80,000 seeds per accession. Sesame can be successfully grown and regenerated in Griffin, GA. Coefficients of variation and principal component analysis revealed considerable variability among accessions for phenological, morphological and reproductive traits. Assuming appropriate levels of heritability, sufficient variation among sesame accessions exists for days to maturity, plant height, and reproductive traits among these sesame accessions to warrant breeding programs for new sesame cultivar development.     

Genetic diversity in sorghum [<Emphasis Type="Italic">Sorghum bicolor</Emphasis> (L.) Moench] germplasm from Southern Africa as revealed by microsatellite markers and agro-morphological traits

Cultivated sorghum [Sorghum bicolor (L.) Moench] is an important food security crop in the semi-arid regions of the world including Asia and Africa. Its genetic diversity is contained mostly in traditional varieties and modern cultivars used by farmers. In this study, agro-morphological traits and molecular markers were used to assess genetic diversity in 22 accessions of cultivated sorghum from five countries (Botswana, Namibia, Swaziland, Zambia and Zimbabwe) in the Southern African Development Community (SADC) region. The study revealed a significant variation among 22 accessions in both qualitative and quantitative morphological traits, indicating the accessions’ promising potential as breeding material. For molecular analysis, 11 microsatellite primer-pairs were used, and generated a total of 70 alleles across 20 accessions. Analysis of molecular variance revealed a high level of genetic variation; 67 % among the accessions and 10 % among the five countries. The patterns of genetic diversity and the relationships observed in this study should provide insights for genetic resource conservation and utilization of sorghum germplasm in the SADC region.     

Relationships among different geographical groups,agro-morphology,fatty acid composition and RAPD marker diversity in Safflower (<Emphasis Type="Italic">Carthamus tinctorius</Emphasis>)

Patterns of geographical diversity, and the relationship between agro-morphological traits and fatty acid composition were assessed for 193 safflower (Carthamus tinctorius) accessions representing forty countries. Accessions were assigned to eight groups based on geographical proximity. Cluster and Principal Component analyses were performed to assess patterns of diversity among the accessions and to select the most distant accessions from each of eight groups for analysis of randomly amplified polymorphic DNA (RAPD) markers. There was a large amount of diversity for agro-morphological traits, fatty acid composition, and RAPD markers. Most correlations among different traits were rather low. Plant height showed a positive correlation with days to flowering (r = 0.63**). Palmitic acid was positively correlated with stearic acid and oleic acid values, and negatively correlated with linoleic acid (P < 0.01). Oleic acid and linoleic acid showed a strong negative correlation (r = −0.89**). The first three principal components together explained 59% of the variation, however, neither principal component analysis (PCA) nor marker analysis revealed a clear relationship between diversity pattern and geographical origin. Accessions from some geographical regions tended to group together, such as accessions from South Western Asia, Central Western Europe, and the Mediterranean region. The correlation between the morphological matrix and the genetic matrix based on RAPD markers was not significant (r = 0.027). Wide diversity in safflower germplasm indicates a considerable potential for improving this crop for both agronomic and quality traits.     

A multi-species assessment of genetic variability in Nigerian Amaranthus accessions: potential for improving intra- and interspecies hybridization breeding

Amaranthus yields could benefit from our growing understanding of the genetic variability within and among individual species of local germplasm collections. Thirty-seven Amaranthus accessions representing three different species were evaluated for seed yield and yield components across two seasons. The objectives were to characterize the genetic variability of seed yield and its components across species and determine relationships among seed yield and its components by phenotypic correlation. Significant differences (P < 0.01) existed for all the evaluated traits among the accessions. Characters such as seed yield, stem girth and leaf length showed higher heritability estimates in A. cruentus (14) than in A. hypochondriacus (12) and A. dubius (11) accessions. Seed yield was significantly and positively correlated with stem girth and thousand seed weight. However, it was significantly and negatively correlated with number of days to flowering, plant height, leaf number, number of branches. The clustering of the accessions, which was partially in agreement with species grouping, will help in the identification of diverse parents for use in the breeding program. Enormous amount of genetic variability found in seed yield and its components among Nigerian Amaranthus accessions will offer opportunity for grain and leaf yield improvement through breeding.     

Agronomical,quality, and molecular characterization of twenty Italian emmer wheat (<Emphasis Type="Italic">Triticum dicoccon</Emphasis>) accessions

Emmer wheat (Triticum dicoccon Schrank, 2n = 4x = 28) consists in a hulled wheat; its cultivation has been drastically reduced during the last century as a consequence of its low yield. Recently, its agronomic and nutritive values, as well as the increase of popularity of organic agriculture, have led to a renewed interest making its cultivation economically viable in the marginal lands with an increase of the cultivated areas. In Italy, it mainly survives in few marginal lands of central and southern Italy, where local varieties, adapted to the natural environment from where they originate, are used; moreover, some selected lines have also been developed. In the present work, agro-morphological and qualitative traits, together with molecular analyses of 20 emmer accessions consisting of Italian landraces, breeding lines, and cultivars, were performed. The field experiments were conducted for two consecutive years (2001/2002–2002/2003) in two locations: Viterbo in central Italy, and Foggia in south Italy. The analyzed emmer wheat accessions showed a good amount of genetic variability for both evaluated agro-morphological and molecular traits. This study illustrates an increase in earliness, GY, TW, TKW, and YI going from landraces, breeding lines to cultivars, while the variability does not change proportionally.     

Multivariate Analysis of Diversity of Tetraploid Wheat Germplasm from Ethiopia

The variability of 2420 plants of tetraploid (2n = 4x = 28, AABB genome) wheat germplasm representing 121 accessions from Ethiopia were evaluated for 23 agro-morphological traits at Debre Zeit Agricultural Research Center area, Akaki substation, during the 2003 main season using multivariate methods. This enabled to assess the extent and pattern of variation of the germplasm with respect to regions, altitude classes and species and to identify the major traits contributing to the diversity. The first three and two principal components explained about 83 and 80% of the total variance among regions and altitudinal class, respectively. In the first principal component plant height, days to heading, the length and density of the spike, and kernel color were the most important traits contributing to variation that explained about 50% of regional variance. Cluster analysis grouped the accessions into 15 clusters, with 9 accessions remaining ungrouped. Based on the observed patterns of variation, it is concluded that there exists great variation in the germplasm, which provides opportunities to be utilized for genetic improvement.     

Variations in morphological and agronomic traits among Jerusalem artichoke (Helianthus tuberosus L.) accessions

Jerusalem artichoke is a diversely-utilized crop. Selection for high yield, inulin content and other economically important traits are useful for improving this crop. The objectives of the present study were to evaluate genetic variability for qualitative and quantitative traits among Jerusalem artichoke accessions and to identify different groups of accessions using morphological and agronomic traits. Seventy-nine accessions were evaluated in a randomized complete block design with two replications in the late rainy season 2008, the early rainy season 2009 and the late rainy season 2009 at Khon Kaen University agronomy farm, Thailand. Morphological and agronomic characteristics were evaluated for genetic variations. High variations were found among Jerusalem artichoke accessions for qualitative and quantitative characters, and selection for these characters is possible. High variations were observed for tuber width, number of tubers/plant, biomass, fresh tuber yield and tuber size. Correlation coefficient between fresh tuber yield and tuber size was positive and significant (0.58, P ≤ 0.01). Improvement of tuber size is a means to improve yield and tuber quality. Based on morphological and agronomic characteristics, Jerusalem artichoke accessions were clustered into four distinct groups (R² = 0.88). These groups may be used as parental material to generate progenies for further improvement of this crop. This information will enable breeders to make informed decisions about possible heterotic groups for their breeding programs and germplasm conservation.     

Collection of Lupinus angustifolius L. Germplasm and Characterisation of Morphological and Molecular Diversity

Lupinus angustifolius L. is a Mediterranean species, domesticated in the 20th century, representing an important grain legume crop in Australia and other countries. This work is focused on the collection of wild germplasm and on the characterisation of morphological and molecular diversity of germplasm accessions. It reports the collection of 81 wild L. angustifolius accessions from the South and Centre of Portugal, available at the ‘Instituto Superior de Agronomia Gene Bank’, with subsequent morphological and molecular characterisation of a selection of these and other accessions. A multivariate analysis of morphological traits on 88 L. angustifolius accessions (including 59 wild Portuguese accessions, 15 cultivars and 14 breeding lines) showed a cline of variation on wild germplasm, with plants from Southern Portugal characterised by earlier flowering, higher vegetative development and larger seeds. AFLP and ISSR molecular markers grouped modern cultivars as sub-clusters within the wider diversity of wild germplasm, revealing the narrow pool of genetic diversity on which domesticated accessions are based. The importance of preserving, characterising and using wild genetic resources for L. angustifolius crop improvement is outlined by the results obtained.     

Evaluation of Wild Lens Taxa for Agro-Morphological Traits, Fungal Diseases and Moisture Stress in North Western Indian Hills

Exploitation of wild gene pool for breeding is a common practice in an increasing number of cultivated plants. The cultivated lentil could not attain the substantial improvement in the yield potential due to loss of genes for higher productivity and lack of resistance against biotic and abiotic stresses. The absence of evaluation data of wild lentils for characters of economic importance, besides biotic and abiotic stresses, is one of the constraints in their use in lentil breeding programme. In the present study, 70 wild accessions from four wild Lens subsp./sp. (L. culinaris subsp. orientalis, L. odomensis, L. ervoides and L. nigricans) along with 3 checks (Precoz, PL-406 and PL-639) were evaluated for phenological and agro-morphological characters, for their reaction to three fungal diseases (wilt, powdery mildew and rust) and screened for tolerance to moisture stress. The wild accessions showed higher performance for branches/plant as compared to cultivated genotypes. Similarly, a few accessions of L. culinaris subsp. orientalis were earlier to flower and had higher seeds and seed yield/plant as compared to cultivated lentil. However, some were comparable with cultivated genotypes for flowers/peduncle, peduncle length and plant height. The mean performance for flowers per peduncle, leaflets per leaf, plant height, seeds and seed yield per plant increased, while decreased for days to flowering and maturity, and branches per plant during the evolution of cultivated lentil from the wild Lens taxa. Of Lens taxa, L. nigricans had the maximum resistant accessions for biotic and tolerance to abiotic stresses. The valuable variation existing among wild accessions can be exploited following introgression with cultivated lentils. It will help in the flow of useful genes from wild to cultivated lentil for generating wide spectrum of variability and its subsequent use in genetic restructuring of lentil.     

Relationships of Vigna unguiculata (L.) Walp., V. vexillata (L.) A. Rich. and species of section Vigna based on isozyme variation

Summary Isozyme variation in 25 accessions of wild and cultivated Vigna unguiculata, 49 accessions of seven wild species belonging to section Vigna, and 11 accessions of V. vexillata (subgenus Plectrotropis) was scored at 17 putative loci to assess genetic relationships within and among species. The wild species selected for this study are among those which carry important agronomical traits useful in cowpea (V. unguiculata) breeding programs. Allelic frequencies were calculated and Nei's genetic distances were obtained. Low levels of intraspecific variation were observed for V. heterophylla, V. luteola and V. racemosa, whereas the other species showed a higher polymorphism. Vigna unguiculata possessed intraspecific genetic distances comparable to those previously found by other authors. Most of the isozyme variation was apportioned among species. Although V. luteola and V. marina had an interspecific genetic distance resembling the range observed at intraspecific level, all the other species showed very high interspecific distances. Vigna unguiculata was relatively closer genetically to V. vexillata than to the species belonging to section Vigna.Abbreviations AUS Australia - BDI Burundi - BRA Brazil - BWA Botswana - CAF Central African Republic - GHA Ghana - CMR Cameroon - COG Congo - RI Costa Rica - EGY Egypt - ETE Ethiopia - GAB Gabon - GRC Greece - ITA Italy - KEN Kenya - MOZ Mozambique - NER Niger - NGA Nigeria - PAN Panama - RWA Rwanda - TCD Chad - TZA Tanzania - ZAF South Africa - ZAR Zaire - ZMB Zambia     

Morphological and reproductive characterization of guar (<Emphasis Type="Italic">Cyamopsis tetragonoloba</Emphasis>) genetic resources regenerated in Georgia,USA

Guar, Cyamopsis tetragonoloba is used worldwide for food stabilization, fiber source, food, and industry. The United States Department of Agriculture, Agricultural Research Service, Plant Genetic Resources Conservation Unit (USDA, ARS, PGRCU) conserves 1,298 accessions originating from India, Pakistan, and breeding lines from the USA. My objectives were to determine: (1) if these guar accessions can successfully be regenerated in Georgia, USA, (2) which traits contribute the most variation, and (3) to provide estimates for genetic relatedness among these accessions. Guar accessions were directly seeded to the field in Griffin, GA between early May and mid June 2006–2008. At 50% maturity, 73 accessions were characterized for morphological, phenological, and reproductive traits during the regeneration cycles. High quality plants regenerated from most of the accessions and produced 80 to more than 9,300 seeds per accession. Guar can be successfully grown and regenerated in Griffin, GA. Coefficients of variation and principal component analysis revealed variability among accessions for these traits evaluated. Cluster analysis separated guar accessions into three groups (clusters) based on low, intermediate or high seed numbers. Guar accessions clustered in groups 2 and 3 appear to be more genetically related than those in group 1.     

A study of genetic diversity of sesame (<Emphasis Type="Italic">Sesamum indicum</Emphasis> L.) in Vietnam and Cambodia estimated by RAPD markers

Sesame (Sesamum indicum L.) is a traditional oil crop cultivated throughout South East Asia. To estimate the genetic diversity of this crop in parts at the region, 22 sesame accessions collected in Vietnam and Cambodia were analyzed using 10 RAPD markers. The 10 primers generated 107 amplification products of which 88 were polymorphic fragments (83%). Genetic diversity of all populations was H_t = 0.34 when estimated by Nei’s genetic diversity and species diversity was H′_sp = 0.513 when estimated by Shannon diversity index. Genetic distance ranged from 0.03 to 0.43, with a mean genetic distance of 0.23. The unweighted pair group method with arithmetic averages (UPGMA) cluster analysis for the 22 accessions divided the material in four groups. The dendrogram revealed a clear division among the sesame accessions based on their geographical region. Interestingly, some geographically distant accessions clustered in the same group, which might indicate the human factor involved in the spreading of sesame varieties. The high level of polymorphism shown suggests that RAPD techniques can also be useful for the selection of parents in sesame (Sesamum indicum L.) breeding program and for cultivar differentiation.     

Evaluation of European emmer wheat germplasm for agro-morphological,grain quality traits and molecular traits

A total of 38 emmer wheat accessions, collected in several European countries, have been evaluated using agro-morphological traits, grain quality characteristics and molecular markers. The agronomic traits evaluated were: vernalisation response, winter hardiness, date of heading and flowering, lodging, plant height at harvest and resistances against powdery mildew (Erysiphe graminis), leaf rust (Puccinia recondita) and yellow rust (Puccinia striiformis). Evaluation of quality traits has been performed measuring the protein content, gluten quality and quantity. In addition, a baking test has been executed. The assessment of genetic variability has been carried out at the molecular level utilizing 6 SSR, 6 EST-SSR markers for genes with known function, and 6 ISSR primers for a total of 107 loci analyzed. Mean 1,000 kernel weight ranged from 31.6 to 39.0 g for winter emmer accessions and from 22.9 to 42.6 for spring emmer accessions. The protein content for both winter and spring emmer was considerably affected by environment and genotype. Nearly, all the spring emmer accessions showed resistance to powdery mildew. Measurement of wet gluten content revealed high values, ranging from 37.0 to 56.6 %. The molecular analysis showed a great value of genetic distance between accessions; the expected heterozygosity and the variance between accessions indicate an equal distribution of the alleles (i.e. alleles frequency almost equal) and the presence of great variability in the analyzed material. Finally, no defined clusters were obtained considering winter versus spring accessions as well as the molecular markers did not discriminate the accessions respect their origin.     

Genetic diversity of 38 spinach (<Emphasis Type="Italic">Spinacia oleracea</Emphasis> L.) germplasm accessions and 10 commercial hybrids assessed by TRAP markers

Target region amplification polymorphism (TRAP) markers were used to assess genetic variability among 38 germplasm accessions and 10 commercial hybrids of spinach (Spinacia oleracea L.), an economically important leafy vegetable crop in many countries. Germplasm accessions with different geographic origins and 10 commercial hybrids were examined. For assessing genetic diversity within accessions, DNA was extracted from 12 individual seedlings from six germplasm accessions and two hybrids. A relatively high level of polymorphism was found within accessions based on 59 polymorphic TRAP markers generated from one fixed primer derived from the Arabidopsis-like telomere repeat sequence and two arbitrary primers. For evaluating interaccession variability, DNA was extracted from a bulk of six to 13 seedlings of each accession. Of the 492 fragments amplified by 12 primer combinations, 96 (19.5%) were polymorphic and discriminated the 48 accessions from each other. The average pair-wise genetic similarity coefficient (Dice) was 57.5% with a range from 23.2 to 85.3%. A dendrogram indicated that the genetic relationships among the accessions were not highly associated with the geographic locations in which the germplasms were collected. The seven commercial hybrids were grouped in three separate clusters, suggesting that the phenotype-based breeding activities tended to reduce the genetic variability. This preliminary study demonstrated that TRAP markers are effective for fingerprinting and evaluating genetic variability among spinach germplasms. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture. The U.S. Government's right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged.