Morphological, biochemical and molecular insights on responses to heat stress in chilli

Abstract

Four heat susceptible and four heat-tolerant genotypes of chilli were grown under high temperature and control conditions to study the morphological, biochemical and molecular changes occurring in them due to high-temperature stress. It was observed that high temperature did not significantly affect vegetative growth in chilli; however, the reproductive growth was significantly affected and manifested as a reduction in fruit length, width, weight, and number of seeds per fruit. The detrimental effect was pronounced in heat susceptible chilli genotypes. On the other hand, tolerant genotypes accumulated more amounts of protein and proline. In addition, they displayed higher activities of antioxidant enzymes like SOD (superoxide dismutase) and POD (peroxidase) to combat high-temperature stress. Out of seven Capsicum annuum specific heat shock proteins studied, three genes, namely CaHSP 832 (HSP 83), Ca HSP 703(HSP70) and Ca HSP 2272 (small HSP) showed significant differences in expression level between tolerant and susceptible genotypes, thereby suggesting their utility in discriminating the genotypes for their tolerance to heat stress.