Chapter 12 - Antioxidant Enzymes: Defense against High Temperature Stress

Abstract

Plants encounter several abiotic stresses including drought and heat stresses in their natural habitats. Although responses of drought and heat stress in plants have been widely studied, still little is known about the combined impact of these stresses on plants. Cellular changes due to high temperature stress results in the overaccumulation of toxic compounds, such as reactive oxygen species (ROS). Plants have evolved mechanisms to acquire thermotolerance that minimize damage and ensure protection of cellular homeostasis. One of the mechanisms of high temperature stress (HTS) tolerance is ROS detoxification mediated by antioxidant compounds and antioxidant enzyme systems. However, limited knowledge is available on cellular factors essential for this response. HSPs are the central control proteins during the heat stress response, and thus maintain cellular homeostasis. Previous efforts to improve plant tolerance to HTS through breeding and genetic engineering have limited success due to the complex network of stress responses. Advancement on comparative genomics, high-throughput sequencing, gene expression analysis, and gene function validation is expected to provide the necessary insights into the mechanisms of stress tolerance and critical genes that may enhance the pace of genetic improvement in heat tolerance of crops.