A worldwide bread wheat core collection arrayed in a 384-well plate

Abstract

Bread wheat (Triticum aestivum), one of the world's major crops, is genetically very diverse. In order to select a representative sample of the worldwide wheat diversity, 3,942 accessions originating from 73 countries were analysed with a set of 38 genomic simple sequence repeat (SSR) markers. The number of alleles at each locus ranged from 7 to 45 with an average of 23.9 alleles per locus. The 908 alleles detected were used together with passport data to select increasingly large sub-samples that maximised both the number of observed alleles at SSR loci and the number of geographical origins. A final core of 372 accessions (372CC) was selected with this M strategy. All the different geographical areas and more than 98% of the allelic diversity at the 38 polymorphic loci were represented in this core. The method used to build the core was validated, by using a second set of independent markers [44 expressed sequence tag (EST)-SSR markers] on a larger sample of 744 accessions: 96.74% of the alleles observed at these loci had already been captured in the 372CC. So maximizing the diversity with a first set of markers also maximised the diversity at a second independent set of locus. To relate the genetic structure of wheat germplasm to its geographical origins, the two sets of markers were used to compute a dissimilarity matrix between geographical groups. Current worldwide wheat diversity is clearly divided according to wheat's European and Asian origins, whereas the diversity within each geographical group might be the result of the combined effects of adaptation of an initial germplasm to different environmental conditions and specific breeding practices. Seeds from each accession of the 372CC were multiplied and are now available to the scientific community. The genomic DNA of the 372CC, which can be entirely contained in a 384-deep-well storage plate, will be a useful tool for future studies of wheat genetic diversity.

Fine Mapping and Marker Development for the Crossability Gene SKr on Chromosome 5BS of Hexaploid Wheat (Triticum aestivum L.)

“…The fact that the Asian wheat pool is highly crossable compared to the European pool suggests that the inhibition barrier is an ancestral state found in the Fertile Crescent where rye was domesticated at the same time as wheat and both have been maintained and cultivated in Europe ever since. In contrast, in Asia where the wheat population structure is clearly different (Balfourier et al 2007), rye has never been cultivated in high amount in the vicinity of wheat possibly allowing the development of mutation and allelic variants that became crossable with rye. A systematic analysis of crossability with rye in tetraploid and hexaploid wheat core collections (Balfourier et al 2007) would facilitate the study of the origin of high crossability in the Asian wheat pool.…”

“…In contrast, in Asia where the wheat population structure is clearly different (Balfourier et al 2007), rye has never been cultivated in high amount in the vicinity of wheat possibly allowing the development of mutation and allelic variants that became crossable with rye. A systematic analysis of crossability with rye in tetraploid and hexaploid wheat core collections (Balfourier et al 2007) would facilitate the study of the origin of high crossability in the Asian wheat pool. Preliminary data indicate the SSR markers cfb306 and cfb341 can be used also to investigate the tetraploid wheat pool and that cfb306 is highly polymorphic in T. durum accessions (4 different alleles among five varieties from Algeria, data not shown).…”

High-Resolution Mapping of Crossover Events in the Hexaploid Wheat Genome Suggests a Universal Recombination Mechanism

“…Two contrasted collections were constructed by selecting within the Asian and the North-western European wheat gene pools (which are genetic pools of origin for Cs and Re cultivars, respectively; Balfourier et al 2007); 90 accessions for each collection (Supplemental Material, Table S3), representative of the diversity within their considered genetic pools.…”

Evaluation of the genetic diversity of an Afghan wheat collection based on morphological variation, HMW glutenin subunit polymorphisms, and AFLP

“…Landraces are the only primary gene pool for bread wheat. To broaden the available genetic resources and to interpret the process of wheat spreading, the genetic diversity of wheat landraces has been investigated by a number of studies (Tsujimoto et al 1998, Bhattacharya et al 1999, Iwaki et al 2001, Ghimire et al 2005, Roussel et al 2005, Tanaka et al 2005, Balfourier et al 2007. Several studies using wheat landraces have achieved success in introducing useful agronomic traits such as semi-dwarfness (Borlaug 1968), disease resistance (Rudd et al 2001), and preferable flour quality (Nakamura et alprotein is encoded by three homoeologous loci located on group 1 chromosomes (Payne et al 1980, Lawrence andShepherd 1981).…”