Molecular characterization of Indian wheat germplasm lines for stay green & other heat tolerance genes using linked SSR markers

Abstract

Heat stress in the last 20–30 years has emerged a serious threat for wheat production worldwide. In India, it is expected 20–30% less yield production till 2020. Therefore, there is a need to identify germplasm lines having substantial level of heat tolerance based on heat tolerance associated/supportive traits like stay green and cooler leaf temperature. Stay-green is a useful trait having potential to significantly enhance the radiation use efficiency by improving the longevity of photosynthetic machinery of plants even under heat stress. Keeping in view all these things, an experiment was conducted to characterize a set of forty eight Indian wheat germplasm lines to investigate the untapped variability for stay green trait in the field as well as their characterization for the QTLs associated with stay green trait i.e., QSg.bhu-3B, QSg.bhu-1A and leaf temperature i.e., QLt.ksu-1D, responsible for cooler leaves/canopy. Field evaluation of these lines was conducted at NBPGR Research Farm (New Area), New Delhi. Approximately, 55–60 plants of each germplasm line grown in plots were evaluated for heat tolerance and stay green trait. Sonalika, a nonstay green germplasm line was planted in alleys and borders for comparison. Stay green (SG) was measured following ‘0–9 ’scale and a new approach of leaf area under greenness (LAUG). All the germplasm lines were grouped into four classes viz., stay green (SG), moderate stay green (MSG), moderate non-stay green (MNSG) and non-stay green (NSG). Coloration (Chlorophyll) was recorded at three different stages viz., late anthesis, late milking and early dough stages for calculating LAUG. Stay green expression was varying from SG (3–9) to NSG (0-<1) while, LAUG was ranging from 10.5 to 75.0. Primers linked to stay green QTLs i.e., Gwm1037 (QSg.bhu-3B), Gwm691 (QSg.bhu-1A) and leaf temperature i.e., Barc271 (QLt.ksu-1D) produced distinct, reproducible bands/profiles that show the positive linkage with the traits.