Genetic Dissection of Drought Tolerance in Spring Wheat Under US Northern Plains Conditions.

Drought (water stress) is crucial for wheat as it affects regularly about 50% of the wheat (Triticum aestivum L.) production area worldwide. Drought can potentially hinder plant growth and development causing significant decrease in wheat productivity and quality. Developing wheat cultivars with improved drought tolerance and water-use efficiency is the most sustainable and economically viable approach to resolve drought problems. Understanding the genetics of drought tolerance in wheat is a pre-requisite to achieve this goal. Here, we decipher the genetics of drought tolerance in US spring wheat using a population of 149 RILs developed from a cross between the drought tolerant cultivar ‘Reeder’ (PI613586) and drought susceptible cultivar ‘Albany’. The RIL population was evaluated under non-irrigated field conditions at three locations for two years and phenotypic data was collected for plant height (PH), days to flowering (DH), yield (YL), test weight (TW), and thousand kernel weight (TKW). Rainfall data of the locations was collected from NDAWN website to assess drought condition. The year 2012 had lesser rainfall than 2014. Illumina 90K SNP chip was used for genotyping. High density genetic map was produced using 10,657 single nucleotide polymorphism (SNP) markers onto 28 link­age groups representing 21 wheat chromosomes. 19% of the SNP was unique loci. Analyses indicates YL and PH are genetically independent. YL has negative association with DH and positive association with TW and TKW. A total of 4 out of 9 QTL for DH, 3 out of 8 QTL for PH, 1out of 6 QTL for YLD, 3 out of 7 QTL for TW and 3 out of 8 QTL for TKW was determined to give drought tolerance by composite interval mapping. The findings of this study could be great help for marker assisted selection for drought tolerance in spring wheat of northern US. Also it can be a starting point of map based gene cloning for drought tolerance. Several QTL found was co-localized and the desirable alleles were contributed by the same parents offering an easier transmission and improvement of cultivars.