Identification of an NAP-like transcription factor BeNAC1 regulating leaf senescence in bamboo (Bambusa emeiensis'Viridiflavus').

NAC (NAM, ATAF1,2 and CUC2) proteins, which are plant-specific transcription factors, have crucial roles in plant development, abiotic stress responses, defense and leaf senescence. In this study, an NAC gene was isolated and characterized from the bamboo Bambusa emeiensis'Viridiflavus' and tentatively named BeNAC1. Sequence analysis revealed that BeNAC1 belongs to the NAP (NAC-like, activated by APETALA 3/PISTILLATA) subgroup and has a conserved NAC domain in the N-terminus. Transcriptional activation analysis in yeast indicated that BeNAC1 as well as its C-terminus have trans-activation activity. BeNAC1 localized in the nucleus and its transcript level correlated positively with the severity of leaf senescence. Driven by a 1.5-kb upstream fragment of AtNAP, BeNAC1 could rescue the delayed-senescence phenotype of nap. Constitutive overexpression of BeNAC1 resulted in various precocious senescence phenotypes in Arabidopsis. These results collectively indicate that BeNAC1 might play an important regulatory role in leaf senescence in bamboo.