Plant height and flowering time are key agronomic traits affecting yield in rice (Oryza sativa). In this study, we investigated the functions in rice growth and development ofOsNAC2,encoding a NAC transcription factor in rice. Transgenic plants that constitutively expressedOsNAC2had shorter internodes, shorter spikelets, and were more insensitive to gibberellic acid (GA3). In addition, the levels of GAs decreased inOsNAC2overexpression plants, compared with the wild-type. Moreover, flowering was delayed for approximately 5 days in transgenic lines. The transcription ofHd3a,a flowering-time related gene, was suppressed in transgenic lines. In addition, transgenic Arabidopsis plants expressingOsNAC2were also more insensitive to GA3. The expression levels of GA biosynthetic genesOsKO2andOsKAOwere repressed. The expression ofOsSLRL,encoding a repressor in the GA signal pathway, andOsEATB,which encodes a repressor of GA biosynthesis, were both enhanced. Western blotting indicated that DELLA also accumulated at the protein level. Dual-luciferase reporter analyses, yeast one-hybrid assays and ChIP-qPCR suggested that OsNAC2 directly interacted with the promoter ofOsEATBandOsKO2.Taken together, we proposed thatOsNAC2is a negative regulator of the plant height and flowering time, which acts by directly regulating key genes of the GA pathway in rice.Significance Statement
Our data suggest that OsNAC2 is a negative regulator of the plant height and flowering time, which acts by directly regulating key genes of the GA pathway in rice. OsNAC2 is the known NAC transcription factor involved in regulation of plant height through directly mediating key components of GA pathway in rice. And such a finding would be valuable to the understanding of the regulation of plant development.