Identification of allele for improving drought resistance and salt tolerance in wheat ( L.).

Drought and salt stress can strongly affect the growth and development of wheat. Wheat adapts to drought and salt stress through osmotic regulation. Betaine aldehyde dehydrogenase (BADH) is a key enzyme in the synthesis of betaine, an osmotic regulator. We cloned a region of the promoter and genomic DNA that included the introns and exons, from four Chinese wheat cultivars. Following the analysis of genomic DNA and promoter sequence polymorphisms of 4 cloned and 15 cultivars from the database, 7 haplotypes of gene were identified. We divided the 7 haplotypes with a 254 bp insertion or deletion (indel) into two main alleles, and . Meanwhile, a molecular marker was developed based on the 254 bp indel of the third intron of gene. Expression levels of were found to be significantly higher than those of under drought and salt stress conditions. Betaine accumulation was significantly higher in wheat containing compared to under drought and salt stress. We also identified that the average relative germination and survival rates of wheat with the allele were significantly higher than wheat with the allele. The results reveal that wheat containing has stronger drought and salt tolerance than wheat with . Meanwhile, the geographic distribution and frequency of the locus alleles indicate that has been preferred in Chinese wheat breeding programs, while , associated with favorable stress tolerance, has been neglected. The results of this study provide evidence for an excellent candidate allele for marker-assisted selection of new wheat cultivars with increased salt tolerance and drought resistance.