Identification of main-effect and environmental interaction QTL and their candidate genes for drought tolerance in a wheat RIL population between two elite spring cultivars

Authors: AL RABBI, HISAM - North Dakota State University; KUMAR, AJAY - North Dakota State University; NARAGHI, SEPEHR - North Dakota State University; SAPKOTA, SURAJ - University Of Georgia; ALAMRI, MOHAMMED - King Saud University; ELIAS, ELIAS - North Dakota State University; Kianian, Shahryar; SEETAN, RAED - Slippery Rock University; MISSAOUI, ALI - University Of Georgia; SOLANKI, SHYAM - Washington State University; MERGOUM, MOHAMED - University Of Georgia

Submitted to: Frontiers in Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/13/2021
Publication Date: 6/17/2021
Citation: Al Rabbi, H.S., Kumar, A., Naraghi, S.M., Sapkota, S., Alamri, M.S., Elias, E.M., Kianian, S., Seetan, R., Missaoui, A., Solanki, S., Mergoum, M. 2021. Identification of main-effect and environmental interaction QTL and their candidate genes for drought tolerance in a wheat RIL population between two elite spring cultivars. Frontiers in Genetics. 12. Article e656037. https://doi.org/10.3389/fgene.2021.656037.
DOI: https://doi.org/10.3389/fgene.2021.656037

Interpretive Summary: Wheat (Triticum aestivum L.) is a major crop worldwide contributing about 20% of calories to the human population. Current genetic and genomic improvement in wheat have helped increase its production; however, further improvements are essential to increase wheat productivity to feed the world’s population. Wheat production is often reduced by several biotic and abiotic stresses including drought and heat. Understanding the genetics of drought tolerance in hard red spring wheat (HRSW) in the northern USA is a prerequisite for developing drought-tolerant cultivars for this region. A study for drought tolerance in spring wheat in the northern USA was undertaken using a genetic population derived from adapted cultivars and a 90K Single Nucleotide polymorphism (SNP) molecular marker platform. The genotypes were evaluated in different 9 locations of North Dakota (ND) for plant height (PH), days to heading (DH), yield (YLD), test weight (TW), and thousand kernel weight (TKW) under rain-fed conditions. Quantitative trait loci (QTL) analysis detected a total of 11 consistent QTL for drought tolerance-related traits. Of these, six QTL were exclusively identified in drought-prone environments, and five were constitutive QTL (identified under both drought and normal conditions). One major QTL on chromosome 7B was identified exclusively under drought environments and explained 13.6% of the phenotypic variation (PV) for YLD. Two other major QTL were detected, one each on chromosomes 7B and 2B under drought-prone environments, and explained 14.86 and 13.94% of phenotypic variation for GVW and YLD, respectively. The findings of this study can be used in marker-assisted selection for drought-tolerance breeding in spring wheat.

Technical Abstract: Understanding the genetics of drought tolerance can expedite the development of drought-tolerant cultivars in wheat. In this study, we dissected the genetics of drought tolerance in spring wheat using a recombinant inbred line (RIL) population derived from a cross between a drought-tolerant cultivar, 'Reeder' (PI613586), and a high yielding but drought-susceptible cultivar, 'Albany'. The RIL population was evaluated for grain yield (YLD), grain volume weight (GVW), thousand kernel weight (TKW), plant height (PH), and days to heading (DH) at nine different environments. The Infinium 90 k-based high-density genetic map was generated using 10,657 polymorphic SNP markers representing 2,057 unique loci. Quantitative trait loci (QTL) analysis detected a total of 11 consistent QTL for drought tolerance-related traits. Of these, six QTL were exclusively identified in drought-prone environments, and five were constitutive QTL (identified under both drought and normal conditions). One major QTL on chromosome 7B was identified exclusively under drought environments and explained 13.6% of the phenotypic variation (PV) for YLD. Two other major QTL were detected, one each on chromosomes 7B and 2B under drought-prone environments, and explained 14.86 and 13.94% of phenotypic variation for GVW and YLD, respectively. One novel QTL for drought tolerance was identified on chromosome 2D. In silico expression analysis of candidate genes underlaying the exclusive QTLs associated with drought stress identified the enrichment of ribosomal and chloroplast photosynthesis associated proteins showing the most expression variability, thus possibly contributing to stress response by modulating the glycosyltransferase (TraesCS6A01G116400) and hexosyl transferase (TraesCS7B01G013300) unique genes present in QTL 21 and 24, respectively. While both parents contributed favorable alleles to these QTL, unexpectedly, the high-yielding and less drought-tolerant parent contributed desirable alleles for drought tolerance at four out of six loci. Regardless of the origin, all QTL with significant drought tolerance could assist significantly in the development of drought-tolerant wheat cultivars, using genomics-assisted breeding approaches.