ROS Regulation During Abiotic Stress Responses in Crop Plants

Abstract

Abiotic stresses such as drought, cold, salt and heat cause reduction of plant growth and loss of crop yield worldwide. Reactive oxygen species (ROS) including hydrogen peroxide (H2O2), superoxide anions (O2 (•-)), hydroxyl radical (OH•) and singlet oxygen ((1)O2) are by-products of physiological metabolisms, and are precisely controlled by enzymatic and non-enzymatic antioxidant defense systems. ROS are significantly accumulated under abiotic stress conditions, which cause oxidative damage and eventually resulting in cell death. Recently, ROS have been also recognized as key players in the complex signaling network of plants stress responses. The involvement of ROS in signal transduction implies that there must be coordinated function of regulation networks to maintain ROS at non-toxic levels in a delicate balancing act between ROS production, involving ROS generating enzymes and the unavoidable production of ROS during basic cellular metabolism, and ROS-scavenging pathways. Increasing evidence showed that ROS play crucial roles in abiotic stress responses of crop plants for the activation of stress-response and defense pathways. More importantly, manipulating ROS levels provides an opportunity to enhance stress tolerances of crop plants under a variety of unfavorable environmental conditions. This review presents an overview of current knowledge about homeostasis regulation of ROS in crop plants. In particular, we summarize the essential proteins that are involved in abiotic stress tolerance of crop plants through ROS regulation. Finally, the challenges toward the improvement of abiotic stress tolerance through ROS regulation in crops are discussed.

Keywords: abiotic stress; antioxidative enzymes; crop plants; gene regulation; reactive oxygen species; transcription factors.

FIGURE 1

Overview of major genes that involved in abiotic stress resistance through ROS regulation in crop plants. Plant cells perceive abiotic stress signals and transduce them through various signaling pathways including secondary signaling molecules, plant hormones, and transcriptional regulators. The regulation of gene expression by different transcription regulators results in the induction of various defense pathways, such as, reactive oxygen species (ROS) scavenging and antioxidative metabolism. Transcription regulators also mediate ROS producing systems and activate the expression of stress-responsive gene so as to confer tolerance to the environmental stresses. CDPK, calcium-dependent protein kinase; CIPK, calcineurin B-like protein-interacting protein kinase; MAPK, mitogen-activated protein kinase; PK, protein kinase; PP, protein phosphatase; SRO, similar to RCD one.