Overexpression of a NF-YC transcription factor from bermudagrass confers tolerance to drought and salinity in transgenic rice.

Nuclear factor Y (NF-Y) is a ubiquitous transcription factor formed by three distinct subunits, namely NF-YA, NF-YB and NF-YC. A stress-responsive cDNA of NF-YC (Cdt-NF-YC1) was isolated from triploid bermudagrass (Cynodon dactylon × Cynodon transvaalensis), and its role in abiotic stress tolerance was investigated in this study. Cdt-NF-YC1 transcript was detected in all vegetative tissues with higher levels being observed in roots. Transcription of Cdt-NF-YC1 in leaves was induced by dehydration, salinity, and treatments with abscisic acid (ABA), hydrogen peroxide (H2 O2 ) or nitric oxide (NO), but not altered by cold. The dehydration- or salt-induced transcription of Cdt-NF-YC1 was blocked by inhibitor of ABA synthesis and scavenger of H2 O2 or NO, indicating that ABA, H2 O2 and NO were involved in the dehydration- and salt-induced transcription of Cdt-NF-YC1. Overexpression of Cdt-NF-YC1 resulted in elevated tolerance to drought and salt stress and increased sensitivity to ABA in transgenic rice. Transcript levels of stress/ABA responsive genes (OsLEA3, OsRAB16A, OsLIP9 and OsP5CS1), ABA synthesis and signalling genes (OsNCED3 and OsABI2), and ABA-independent genes (OsDREB1A, OsDREB1B and OsDREB2A) were substantially higher in transgenic rice than in wild-type plants. The results suggested that that Cdt-NF-YC1 is a good candidate gene to increase drought and salinity tolerance in transgenic rice through modulating gene regulation in both ABA-dependent and ABA-independent pathways.