Overexpression of OsHAP2E for a CCAAT-binding factor confers resistance to Cucumber mosaic virus and Rice necrosis mosaic virus

Abstract

HAP (CBF/NF-Y) transcription factors have important functions in regulating plant growth, development, and stress responses. In this study, we examined whether the endogenous gene OsHAP2E and the GUS transgene driven by the promoter of OsHAP2E respond to virus infection. RT-PCR analyses showed OsHAP2E expression was induced after inoculation with Cucumber mosaic virus (CMV) or Rice necrosis mosaic virus (RNMV). After inoculating OsHAP2E::GUS-transgenic plants with either virus, the levels of GUS expression increased significantly. The expression levels of GUS or OsHAP2E reached a plateau 5 days after inoculation of rice with CMV, which paralleled the accumulation of CMV RNA level. Furthermore, transgenically over-expressed lines of OsHAP2E (OsHAP2E-OX) had lower levels of CMV and RNMV RNAs than in in nontransgenic control plants. The OsHAP2E-OX lines developed no significant symptoms from RNMV while control plants had yellowing and stunting. These results suggested that OsHAP2E is induced by virus infection and contributes to resistance against viral pathogens.