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Germplasm Collections (germplasm + collection)
Selected AbstractsIsolation and characterization of microsatellite loci in tropical forage Stylosanthes capitata VogelMOLECULAR ECOLOGY RESOURCES, Issue 1 2009M. O. SANTOS Abstract Stylosanthes capitata is an important tropical pasture legume. Knowledge of genetic diversity and structure of S. capitata populations is of great importance for the conservation and germplasm management of this species. Thus, eight microsatellite markers were developed from an S. capitata -enriched library. They were characterized in 20 accessions from the germplasm collection of the Empresa Brasileira de Pesquisa Agropecuįria (Embrapa). The observed and expected heterozygosities ranged from 0.16 to 0.85 and from 0.40 to 0.85, respectively. These microsatellites are the first set of molecular markers from this species and will contribute towards studies of genetic diversity, conservation and breeding of S. capitata. [source] Characterization of new microsatellite markers in mung bean, Vigna radiata (L.)MOLECULAR ECOLOGY RESOURCES, Issue 4 2006JAE-GYUN GWAG Abstract The present work reports the isolation and characterization of new polymorphic microsatellites in mung bean (Vigna radiata L.). Of 93 designed primer pairs, seven were found to amplify polymorphic microsatellite loci, which were then characterized using 34 mung bean accessions. The number of alleles ranged from two to five alleles per locus with an average of three alleles. Observed and expected heterozygosity values ranged from 0 to 0.088 and from 0.275 to 0.683, respectively. All seven loci showed significant deviations from Hardy,Weinberg equilibrium, whereas only one pairwise combination (GBssr-MB77 and GBssr-MB91) exhibited significant departure from linkage disequilibrium. These newly developed markers are currently being utilized for diversity assessment within the mung bean germplasm collection of the Korean Gene Bank. [source] Sources of resistance to broomrape (Orobanche crenata Forsk.) in narbon vetchPLANT BREEDING, Issue 1 2007S. Nadal Abstract Little is known about the levels of resistance to Orobanche crenata available in narbon vetch. A germplasm collection of 200 accessions of narbon vetch (Vicia narbonensis L.) originating from different countries was screened for resistance to crenate broomrape under field conditions. Thirteen accessions were selected for more detailed screening under controlled conditions and for additional field testing. Resistance to O. crenata was manifested by lower germination of broomrape seeds, reduced emergence of Orobanche shoots and fewer root attachments per narbon vetch plant. Differences in pod yield among narbon vetch accessions were also found in response to Orobanche infestation. Finally, eight accessions were selected and identified as new sources of narbon vetch resistant to broomrape. [source] Genetic relationships of sesame germplasm collection as revealed by inter-simple sequence repeatsPLANT BREEDING, Issue 3 2002D. H. Kim Abstract Inter-simple sequence repeats (ISSR) polymorphism was used to determine genetic relationships among 75 Sesamum indicum L. accessions of Korean and exotic sesame. Fourteen reliable ISSR primers were selected for the assessment of genetic diversity, yielding 79 amplification products. Of these polymerase chain reaction products, 33% revealed polymorphism among the 75 accessions. Genetic distances ranged from 0 to 0.255, with a mean genetic distance of 0.0687. The 75 accessions were divided into seven groups on the basis of unweighted pair-group method with arithmetic averages (UPGMA) cluster analysis. The largest group consisted of 25 Korean cultivars, eight Korean breeding lines and 17 world-wide accessions. The other groups included 25 accessions, several of which contained useful traits. The dendrogram did not indicate any clear division among sesame accessions based on their geographical origin. However, all Korean sesame cultivars except ,Namsankkae' were clustered in the same group, indicating a narrow gene pool. Some of the Korean breeding lines were spread along the dendrogram, showing enlargement of genetic diversity. The genetic diversity data uncovered in this study can be used in future breeding programmes. [source] Molecular cytogenetic analysis of a durum wheat ×Thinopyrum distichum hybrid used as a new source of resistance to Fusarium head blight in the greenhousePLANT BREEDING, Issue 5 2001Q. Chen Abstract Fusarium head blight (FHB, scab), caused by Fusarium graminearum Schwabe, is a serious and damaging disease of wheat. Although some hexaploid wheat lines express a good level of resistance to FHB, the resistance available in hexaploid wheat has not yet been transferred to durum wheat. A germplasm collection of Triticum durum× alien hybrid lines was tested as a potential source of resistance to FHB under controlled conditions. Their FHB reaction was evaluated in three tests against conidial suspensions of three strains of F. graminearum at the flowering stage. Two T. durum×Thinopyrum distichum hybrid lines, ,AFR4' and ,AFR5,, expressed a significantly higher level of resistance to the spread of FHB than other durum-alien hybrid lines and a resistant common wheat line ,Nyu-Bay'. Genomic in situ hybridization using total genomic DNA from alien grass species demonstrated that ,AFR5' had 13 or 14 alien genome chromosomes plus 27 or 28 wheat chromosomes, while ,AFR4' had 22 alien genome and 28 wheat chromosomes. All of the alien chromosomes present in these two lines belonged to the J genome. ,AFR5' is likely to be more useful as a source of FHB resistance than ,AFR4' because of its relatively normal meiotic behaviour, high fertility and fewer number of alien chromosomes. ,AFR5' shows good potential as a source for transferring FHB resistance gene into wheat. The development of T. durum addition lines carrying resistance genes from ,AFR5' is underway. [source] The genetic diversity of perennial Leymus chinensis originating from ChinaGRASS & FORAGE SCIENCE, Issue 1 2007Z. P. Liu Summary Leymus chinensis is an economically and ecologically important grass that is widely distributed across eastern areas of the Eurasian steppe. A better knowledge of genetic diversity of L. chinensis could be valuable in the efficient utilization, conservation and management of germplasm collections. Genetic diversity in thirty-seven morphological characters of 293 accessions was assessed in three successive years. Based on these qualitative and quantitative characters, the genetic diversity indices (Shannon indices) of traits and geographical populations were estimated, and a principal coordinates analysis and a path analysis were undertaken. Compared with the yellow-green type of L. chinensis, the grey-green type had significantly (P < 0·05) more genetic diversity. In addition, the path analysis suggested that the combined effects of genetic diversity and vegetative traits could explain 0·206 of the total variance in plant reproductive traits. The highest Shannon genetic diversity index of accessions (H = 2·252) was observed in accessions from the region of longitude of 124,128°E, suggesting the most abundant germplasm of L. chinensis in this region. [source] Assessment of Genetic Variation Within Indian Mustard (Brassica juncea) Germplasm Using Random Amplified Polymorphic DNA MarkersJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 4 2008Muhammad Ayub Khan Abstract Genetic diversity among 45 Indian mustard (Brassica juncea L.) genotypes comprising 37 germplasm collections, five advance breeding lines and three improved cultivars was investigated at the DNA level using the random amplified polymorphic DNA (RAPD) technique. Fifteen primers used generated a total of 92 RAPD fragments, of which 81 (88%) were polymorphic. Of these, 13 were unique to accession ,Pak85559'. Each primer produced four to nine amplified products with an average of 6.13 bands per primer. Based on pairwise comparisons of RAPD amplification products, Nei and Li's similarity coefficients were calculated to evaluate the relationships among the accessions. Pairwise similarity indices were higher among the oilseed accessions and cultivars showing narrow ranges of 0.77,0.99. An unweighted pair-group method with arithmetic averages cluster analysis based on these genetic similarities placed most of the collections and oilseed cultivars close to each other, showing a low level of polymorphism between the accessions used. However, the clusters formed by oilseed collections and cultivars were comparatively distinct from that of advanced breeding lines. Genetically, all of the accessions were classified into a few major groups and a number of individual accessions. Advanced breeding lines were relatively divergent from the rest of the accessions and formed independent clusters. Clustering of the accessions did not show any pattern of association between the RAPD markers and the collection sites. A low level of genetic variability of oilseed mustard was attributed to the selection for similar traits and horticultural uses. Perhaps close parentage of these accessions further contributed towards their little diversity. The study demonstrated that RAPD is a simple and fast technique to compare the genetic relationship and pattern of variation among the gene pool of this crop. [source] Characterizing diversity in composition and pasting properties of tuber flour in yam germplasm (Dioscorea spp.) from Southern EthiopiaJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 10 2008Muluneh Tamiru Abstract BACKGROUND: Studies on composition and functional properties in germplasm collections are important in determining their diversity and suitability for food and non-food applications. The diversity in 65 yam accessions collected from Southern Ethiopia and belonging largely to a yet unknown species and to Dioscorea bulbifera L. (aerial yam) was analyzed based on protein, starch and amylose contents, and pasting properties of tuber flour, applying descriptive and multivariate statistics. RESULT: Starch content varied from 65.2% to 76.6% dry matter, while the protein content range was 6.4,13.4% dry matter. Amylose represented between 7.1% and 30.6% of the starch fraction, and was negatively correlated (P < 0.01) with starch content. UPGMA clustering and principal component analysis clearly distinguished aerial yam from those accessions with underground tubers. The first four principal components accounted for 78% of the total variability, and were highly correlated with pasting parameters. CONCLUSION: The extent of diversity detected among accessions studied showed scope for improving the crop through selection of landraces with desirable characteristics. Similar investigations on tubers grown under different environmental conditions and additional data on physicochemical properties of isolated starch will be useful in evaluating the potential of yam for food and non-food applications. Copyright © 2008 Society of Chemical Industry [source] Citrus tristeza virus resistance in a core collection of sour orange based on a diversity study of three germplasm collections using QTL-linked markersPLANT BREEDING, Issue 4 2008G. P. Bernet Abstract Seven markers linked to QTL involved in CTV accumulation, leafminer resistance and apomictic reproduction were used to characterize 64 sour orange (Citrus aurantium L.) accessions from three national collections in order to identify a representative core in which the resistance behaviour against two Citrus tristeza virus (CTV) isolates was studied. Different degrees of apomixis were found between the foreign collections. Most of the C. aurantium accessions fall into three main groups based on three multilocus genotypes. The haplotype diversity at three CTV accumulation QTL-linked markers was further studied by sequence analysis of alleles. Genotypic and allelic diversity at one of them, tightly linked to Ctv-R2 in Poncirus trifoliata (L.) Raf., match the plant,CTV interaction types reported among Poncirus and Citrus species. Only those selected accessions from the major group presented CTV resistance during 30 months of continuous growth, but later the resistance broke down in some plants. CTV tolerance appears related to slow growing genotypes. Certain micronutrients: Mn, and B depending on the accession, might play a relevant role in this host,pathogen interaction particularly in alkaline soils. [source] Genetic diversity among populations and breeding lines from recurrent selection in Brassica napus as revealed by RAPD markersPLANT BREEDING, Issue 1 2004M. Yuan Abstract Recurrent selection facilitated by dominant male sterility has been conducted to broaden the genetic basis for cultivar development in Brassica napus. This study aimed to evaluate the genetic variation in four base populations (C0-C3) and breeding lines from two of the populations produced during recurrent selection by random amplified polymorphic DNA (Rapd) markers. Genetic variation in four populations declined gradually with the advance of selection cycles as measured by expected genetic heterozygosity (from 0.2058 in C0 to 0.1536 in C3) but the decline was not statistically significant. When compared with the average genetic distances for 21 germplasm collections with wide geographical and genetic origins (0.4712) and seven breeding lines from pedigree selection (0.2059), seven breeding lines selected from the C1 population and 11 from the C3 population had a larger average genetic distance (0.5339 and 0.5486, respectively). Clustering analysis indicated that the lines from recurrent selection had a much lower genetic similarity than lines from pedigree selection. Our results suggest that base populations derived from recurrent selection could provide a wider genetic variation for selection of breeding lines with more broad genetic bases. [source] Prunus necrotic ringspot virus isolates in stone fruit germplasm accessions and cultivars in IsraelANNALS OF APPLIED BIOLOGY, Issue 2 2004S SPIEGEL Summary Prunus necrotic ringspot virus (PNRSV) was detected in almonds, plum and apricot germplasm accessions and local almond cultivars in Israel. PNRSV was widespread both in wild and cultivated almond trees and uncommon in wild apricots and plums. The possible variation among the PNRSV isolates was initially evaluated by restriction analysis of PCR products representing the CP gene with the endonuclease RsaI and followed by nucleotide sequence analysis of selected isolates. It was concluded that all 13 isolates belong to group PV96, the largest cluster of PNRSV isolates, described previously. Two PNRSV isolates, one from a plum accession and one from an almond cultivar, were found to be distinct members of group PV96 with unique nucleotide modifications not found in other documented isolates of this virus. However, no PNRSV isolate typical to a specific host and/or to the Middle East region could be identified. This study expands the body of data on variability of PNRSV isolates and highlights the importance of assessing the virus status of germplasm collections by applying reliable diagnostic and differentiating methods. [source] | ||||||||||