Identification of heat-tolerant rice genotypes and their molecular characterisation using SSR markers

Abstract

The effect of high-temperature stress has a critical impact in causing reduced crop yield. The focus of the current investigation is the identification of heat-tolerant rice varieties that can alleviate the effects of stress. Among the ten genotypes evaluated across various parameters such as leaf area, dry weight, photosynthetic rate, stomatal conductance and spikelet fertility, N-22 showed superior characteristics for the grain filling parameters along with CR-Dhan 307. The variety CR-Dhan 307 with significantly higher mean pollen viability (80.23%), spikelet fertility (81.18%) and 1000 grain weight (25.45 gm) can be utilized as a heat-tolerant variety. Other genotypes Ptb-7 and CR-Dhan 202 seemed to have tolerance traits beneficial at the vegetative stage. The genotype Rajalakshmi can be characterised as heat susceptible as it had significantly lower values for all parameters. Polymorphic analysis was carried out to validate SSR markers associated with heat tolerance. The polymorphic information content (PIC) was found to be the highest for RM236 and RM6100. The SSR marker RM6100 has been validated in the current investigation to be associated with heat tolerance. As the PIC value is an indication of the ability of the marker in indicating genetic diversity, the PIC values of the 11 polymorphic markers is useful for identify heat-tolerant genotypes. The genetic diversity analysis was carried out using DendroUPGMA to establish the relationship between the genotypes. The genotypes Ptb-7 and CR-Dhan 204 were thus found to be closely related to the heat-tolerant check variety, N-22 indicating genetically related traits for tolerance to heat.