DkNAC7, a novel high-CO2/hypoxia-induced NAC transcription factor, regulates persimmon fruit de-astringency

Abstract

Artificial high-CO2 atmosphere (AHCA, 95% CO2 and 1% O2) has been widely applied as a postharvest de-astringency treatment for persimmon fruit. AHCA increases expression of transcription factors, including ethylene response factors (DkERF), that target de-astringency genes. Here, the promoter of DkERF9, a previously characterized AHCA-inducible and de-astringency regulator, was utilized to screen a cDNA library by yeast one hybrid assay. A novel NAC transcription factor, named DkNAC7, was identified. Dual-luciferase assay indicated that DkNAC7could not only trans-activate the promoter of DkERF9, but also activated the previously identified deastringency-related gene DkPDC2. Real-time PCR analysis showed that DkNAC7was up-regulated by AHCA treatment, in concert with the removal of astringency from persimmon fruit and subcellular localization showed DkNAC7was located in the nucleus. Thus, these results indicate that DkNAC7is a putative transcriptional activator involved in regulating persimmon fruit deastringency by trans-activition on both DkERF9and DkPDC2, which encodes pyruvate decarboxylase.