Population structure, genetic diversity and selection of terminal heat stress tolerant synthetic derivative wheat genotypes

Abstract

Due to climate change, terminal heat stress has become a major constraint to wheat production throughout the world. Wild relatives of wheat have proved their potential to meet these challenges. In the following study, we explored 52 synthetic derivative wheats (developed through crossing of wild parents) for genetic diversity, population structure and selection of heat tolerant genotypes. Under field conditions, plant material was evaluated under terminal heat stress for two years i.e., 2016-18. Heat tolerance was assessed through the plant traits like days to heading (DTH), days to physiological maturity (DPM), canopy temperature (CT), SPAD value (SPD), flag leaf length (FL), spikes per plant (Sp./P), plant height (PH), spike length (Sp. L), individual spike weight (ISW), harvest index (HI), thousand grain weight (TGW), grains per spike (G/Sp) and grain yield (GY). Analysis of variance depicted significant variation among genotypes, treatments and years for the studied traits. Heat tolerant genotypes i.e., BW/SH-126, BW/SH-17, BW/SH-116, BW/SH-42, BW/SH-30, BW/SH-138, BW/SH-113, BW/SH-73, BW/SH-79 and BW/SH-146 were identified by Biplot analysis based on heat stress tolerance index. Molecular analyses, following the characterization of genotypes with SSR markers, revealed average PIC and gene diversity values as 0.27 and 0.332, respectively. Population Structure analysis divided the genotypes into three sub-populations. The analysis of molecular variance revealed a maximum of 79% variation within the populations and 21% among populations. The results revealed that studied germplasm has a great potential to overcome the losses due to terminal heat stress which occur due to late sowing and early arrival of spring and summer in climate change scenario.