Preliminary screening for water stress tolerance and genetic diversity in wheat (Triticum aestivum L.) cultivars from Sudan

The present study was carried out to screen 12 Sudanese wheat (Triticum aestivum L.) cultivars for their response to water stress at early germination stages and to characterize sources that could be used in breeding programs to develop wheat cultivars with better adaptation to water stress. The effect of osmotic stress on the early growing stages was evaluated, in vitro, using five concentrations of Polyethylene glycol. Genetic diversity was studied using 24 allele specific simple sequence repeats (SSR) markers associated with drought tolerance in wheat. The presence of the drought genes and their chromosomal location was also investigated by isolating and sequencing the dehydration responsive element binding protein (dreb1). Results of the in vitro screening among the cultivars showed significant differences in the root length, shoot length and root/shoot ratio. The 24 drought specific SSR markers used revealed 50 alleles, with an average of 2.0 alleles per locus. Of these, 60% were polymorphic with polymorphism information content (PIC) ranging from 0.16 to 0.89. A dendrogram based on the similarity values generated from the SSR data revealed three major clusters. Of the five specific primers for dreb1 genes, only primer P25F/PR produced amplification products with the expected fragment sizes. Sequencing and BLAST results of the cloned fragments excised from the gels showed 99% homology to the dreb1 gene on chromosome 3A.