Central role of 70-kDa heat shock protein in adaptation of plants to drought stress

Abstract

The 70-kDa heat shock proteins (HSP70s) are a conserved class of chaperones that play critical roles during the normal life cycleof plants. HSP70s are particularly involved in the regulation of biotic and abiotic stress responses. In this paper, the potential rolesof this protein were investigated. A reverse genetic approach was employed for transient silencing ofhsp70gene in tomato(Solanum lycopersicumL.) to evaluate different growth and physiological parameters under normal conditions and during theresponse to drought stress. A combined ANOVA (analysis of variance) and HCA (hierarchical clustering analysis) showed thathsp70silencing led to severe growth retardation and mortality, significant membrane damage and leakage, decline in relativewater content, low rate of pigment accumulation, and reduced antioxidant enzyme activity under normal and drought stressconditions. Among the different parameters, proline was the only trait that was unaffected by gene silencing and accumulated bysimilar amounts to that of nonsilent plants. In conclusion, HSP70 played critical roles in maintaining the cellular homeostasis ofplants during adaptation to drought and under normal plant life conditions. It was speculated that proline was, to some extent,involved in improving the loss of protein folding or function resulting from HSP70 deficiency, and played a crucial role in theadaptation of plants on exposure to stress