Overexpression of Rat Neurons Nitric Oxide Synthase in Rice Enhances Drought and Salt Tolerance.

Wei Cai,Tong-Tong Han,Wen-Shu Wang,Ying-Tang Lu,Zheng-Wei Fu,Wen Liu

doi:10.1371/journal.pone.0131599

Abstract

Nitric oxide (NO) has been shown to play an important role in the plant response to biotic and abiotic stresses in Arabidopsis mutants with lower or higher levels of endogenous NO. The exogenous application of NO donors or scavengers has also suggested an important role for NO in plant defense against environmental stress. In this study, rice plants under drought and high salinity conditions showed increased nitric oxide synthase (NOS) activity and NO levels. Overexpression of rat neuronal NO synthase (nNOS) in rice increased both NOS activity and NO accumulation, resulting in improved tolerance of the transgenic plants to both drought and salt stresses. nNOS-overexpressing plants exhibited stronger water-holding capability, higher proline accumulation, less lipid peroxidation and reduced electrolyte leakage under drought and salt conditions than wild rice. Moreover, nNOS-overexpressing plants accumulated less H2O2, due to the observed up-regulation of OsCATA, OsCATB and OsPOX1. In agreement, the activities of CAT and POX were higher in transgenic rice than wild type. Additionally, the expression of six tested stress-responsive genes including OsDREB2A, OsDREB2B, OsSNAC1, OsSNAC2, OsLEA3 and OsRD29A, in nNOS-overexpressing plants was higher than that in the wild type under drought and high salinity conditions. Taken together, our results suggest that nNOS overexpression suppresses the stress-enhanced electrolyte leakage, lipid peroxidation and H2O2 accumulation, and promotes proline accumulation and the expression of stress-responsive genes under stress conditions, thereby promoting increased tolerance to drought and salt stresses.

Highlights

Abiotic environmental factors, such as drought and high salinity, are significant plant stressors that greatly impact on plant development and productivity, leading to serious losses in yield
Overexpressing rat neuronal NO synthase (nNOS) in rice increases both nitric oxide synthase (NOS) activity and Nitric oxide (NO) content To modulate NO content in rice, we overexpressed the nNOS gene in japonica rice Zhonghua11 (ZH11) by inserting the coding region of the rat nNOS [22] into the pUbiO plant expression vector, which was introduced into ZH11 via Agrobacterium-mediated transformation [28]
Our results showed that all three lines had much higher levels of NO compared with the wild type (Fig 1C and 1D)

Summary

Introduction

Abiotic environmental factors, such as drought and high salinity, are significant plant stressors that greatly impact on plant development and productivity, leading to serious losses in yield. Rice is the most important food crop in Asia. In an era of rapid population growth and environmental problems, improving drought and salt tolerance of rice through biotechnology, besides its scientific interest, might have an important applied relevance. NNOS Overexpression Enhances Drought and Salt Tolerance of Rice. Plants have developed a series of strategies to cope with drought and salt stresses, including regulating the expression of stress-responsive genes, scavenging ROS, accumulating proline, inducing stomatal closure, and maintaining low Na+ concentration in the cytosol by controlling Na+ efflux across the PM and tonoplast [1]. Plant hormones including abscisic acid (ABA), gibberellin, auxin, jasmonic acid and NO, play important roles in stress adaptive signaling [1,2,3,4]

Methods

Results

Conclusion