Overexpression of OsNAC14, a NAC domain transcription factor, enhances tolerance to drought stress in rice

Abstract

Environmental stresses such as drought, negatively affects crop production and food security, hence the development of stress tolerant crops has been greatly needed for modern agricultural areas. Transcription factors (TFs) are good candidates for genetic engineering to improve stress tolerance in crops because of their roles as master regulators of many stress-responsive genes. Here, we generated transgenic rice plants overexpressing OsNAC14 to examine its function in drought tolerance. Overexpression of OsNAC14 in rice improved drought tolerance not only during the vegetative stage but also during the reproductive stage. In addition, RNA sequencing analysis showed that overexpression of OsNAC14 altered the expression of around 273 genes, directly or indirectly OsNAC14-dependent manner. From these differentially regulated genes, we selected 16 genes based on gene ontology, including programmed cell death (GO:0012501) and DNA repair (GO:0006281) for further verification. These were confirmed through the qRT-PCR analysis with a transgenic rice and transient assay system using protoplast. Most noticeably, OsRAD51A1, a DNA repair related protein gene, and Piz-t, Pyricularia oryzae resistance Z, were significantly up-regulated in OsNAC14 transgenic rice. Furthermore, OsNAC14 directly interacts with the OsRAD51A1 promoter region as revealed through ChIP analysis in vivo. Finally, these results suggest that OsRAD51A1 is directly regulated by the OsNAC14 transcription factor and overexpression of OsNAC14 improves drought tolerance of rice.