OsIAA18, an Aux/IAA Transcription Factor Gene, Is Involved in Salt and Drought Tolerance in Rice

Auxin/indoleacetic acid (Aux/IAA) proteins play an important regulatory role in the developmental process of plants and their responses to stresses. A previous study has shown that constitutive expression of OsIAA18, an Aux/IAA transcription factor gene of rice improved salt and osmotic tolerance in transgenic Arabidopsis plants. However, little work is known about the regulatory functions of the OsIAA18 gene in regulating the abiotic stress tolerance of rice. In this study, the OsIAA18 gene was introduced into the rice cultivar, Zhonghua 11 and the OsIAA18 overexpression in rice plants exhibited significantly enhanced salt and drought tolerance compared to the wild type (WT). Moreover, overexpression of OsIAA18 in rice increased endogenous levels of abscisic acid (ABA) and the overexpression of OsIAA18 in rice plants showed hypersensitivity to exogenous ABA treatment at both the germination and postgermination stages compared to WT. Overexpression of OsIAA18 upregulated the genes involved in ABA biosynthesis and signaling pathways, proline biosynthesis pathway, and reactive oxygen species (ROS)-scavenging system in the overexpression of OsIAA18 in rice plants under salt and drought stresses. Proline content, superoxide dismutase (SOD), and peroxidase (POD) activities were significantly increased, whereas malonaldehyde (MDA), hydrogen peroxide (H2O2), and superoxide anion radical (O2–) content were significantly decreased in the transgenic plants under salt and drought stresses. Taken together, we suggest that OsIAA18 plays a positive role in drought and salt tolerance by regulating stress-induced ABA signaling. The OsIAA18 gene has a potential application in genetically modified crops with enhanced tolerance to abiotic stresses.

A novel maspardin protein gene OsMas is involved in salt and drought tolerance in rice

Drought and salt stresses, as major environmental abiotic stresses in agricultural worldwide, affect plant growth and crop productivity and quality. The development of crops with higher drought and salt tolerance is therefore highly desirable. Here, we reported the isolation and biological function and molecular characterization of a novel maspardin gene, OsMas, from rice cultivar Yangjing 805 (Oryza sativa L.). The expression levels of OsMas were up-regulated under mannitol, PEG6000, NaCl and ABA treatments in rice. Heterologous expression of OsMas enhanced salt and drought tolerance in Escherichia coli and Arabidopsis. Moreover, the OsMas gene was introduced into rice cultivar Zhonghua 11 (wild-type, WT) and the OsMas-overexpression (OsMas-OE) rice plants exhibited significantly enhanced salt and drought tolerance, while the OsMas-interference (OsMas-RNAi) rice plants exhibited decreased tolerance to salt and drought stresses, compared with WT plants. The OsMas-OE plants exhibited enhanced hypersensitive, while the OsMas-RNAi plants showed less sensitive to exogenous ABA treatment at both germination and post-germination stages. The content of ABA, proline and K+ and the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and photosynthesis were significantly increased, while the content of malonaldehyde (MDA), hydrogen peroxide (H2O2), superoxide anion radical (O2-) and Na+ were significantly decreased in OsMas-OE plants compared with OsMas-RNAi and WT plants. Overexpression of OsMas up-regulated the genes involved in ABA biosynthesis and signaling pathways, proline biosynthesis pathway, ROS-scavenging system, photosynthesis and ion transport pathways under salt and drought stresses. Collectively, our results indicate that the OsMas gene functions in improving salt and drought tolerance in rice, which may serve as a candidate gene for use in enhancing the resistance to abiotic stresses in crops.