Functional Analysis of a NAC-type Transcription Factor OsNAC6 Involved in Abiotic and Biotic Stress-responsive Gene Expression in Rice

Abstract

The OsNAC6 gene is a member of the NAC transcription factor gene family in rice. Expression of OsNAC6 is induced by abiotic stress including cold, drought, and high salinity. OsNAC6 gene expression is also induced by wounding and blast disease. Both transgenic Arabidopsis and rice plants overexpressing OsNAC6 exhibited growth retardation. The results of microarray analysis revealed that many abiotic- and biotic-stress-inducible genes were upregulated in Arabidopsis and rice plants overexpressing OsNAC6. A transient transactivation assay showed that OsNAC6 activates the expression of at least three genes including a gene encoding peroxidase. The transgenic rice plants overexpressing OsNAC6 not only showed an improved tolerance to dehydration and high-salt stresses, they also exhibited increased tolerance to blast disease. By utilizing stress-inducible promoters, such as the OsNAC6 promoter, it is hoped that inducible overexpression of OsNAC6 in rice can improve stress tolerance without growth retardation.