Expression Of OSNOX2 Gene In Rice And Its Response To Drought Stress

Plasma membrane NADPH oxidase(PM-NOX) is a major source of H2O2 in plant cells. The NADPH oxidase in protection against the microorganisms, resistance to heavy metal toxicity and regulation of the plant growth development play an important role. There were 11 homologous genes encoding PM-NOX at least in the rice genome in the present database. The expression of OSNOX2 gene was significantly upregulated under drought stress. For further prehension of the relationship between OsNOX2 gene expression and drought stress, a homozygote of OSNOX2 gene knockout mutant of rice was identified from the T-DNA insertion mutant line PFG₁A-09601.L, which was ordered from POSTECH (Pohang University of Science and Technology) by means of PCR and RT-PCR. The homozygote with OSNOX2 gene knockout mutant has smaller plant, shorter flag leaf in length and width, with a percentage of 32.9% of chl a/b higher than WT. The activity of various antioxidant enzymes, the content of H2O2 and O2 in osnox2 were higher than WT according to the results. The activity of PM-NOX was lower in the mutant than WT with a percentage. of 18.9% when the soil moisture was reduced to 8.48%. By means of the whole genome gene expression test, we found that there were 152 genes with more than two-fold changes in expression (p≤0.05) between osnox2 and WT under normal growth conditions, including transposon genes, reverse transcription protein genes, protein kinase genes, heat shock protein genes, ATP synthase genes, DNA binding protein genes, reverse transcriptase genes, hydrolase genes, NADPH oxidase genes and anti-pathogenic bacteria protein genes. There were also dehydrogenation/redox protease genes, peroxidase genes, hydratase genes, carrier protein genes, subunit binding protein genes, and many other functional genes. Those genes not only involved in many important cellular processes but also played an important role in plant growth and development and stress resistance. In addition, there were 65 protein genes with unknown functions among these 152 genes. In conclusion, OSNOX2 gene play an important role in the plant response to environmental stresses such as drought, as well as in the regulation of plant growth and development.