High-CO/Hypoxia-Responsive Transcription Factors DkERF24 and DkWRKY1 Interact and Activate Promoter.

Identification and functional characterization of hypoxia-responsive transcription factors is important for understanding plant responses to natural anaerobic environments and during storage and transport of fresh horticultural products. In this study, yeast one-hybrid library screening using the persimmon () pyruvate decarboxylase () promoter identified three ethylene response factor (ERF) genes (//) and four WRKY transcription factor genes (//) that were differentially expressed in response to high CO (95%, with 4% N and 1% oxygen) and high N (99% N and 1% oxygen). Yeast one-hybrid assays and electrophoretic mobility shift assays indicated that DkERF23, DkERF24, DkERF25, DkWRKY6, and DkWRKY7 could directly bind to the promoter.

A transcription factor network responsive to high CO2/hypoxia is involved in deastringency in persimmon fruit.

Plant responses to anaerobic environments are regulated by ethylene-response factors (ERFs) in both vegetative and productive organs, but the roles of other transcription factors (TFs) in hypoxia responses are poorly understood. In this study, eight TFs (DkbHLH1, DkMYB9/10/11, DkRH2-1, DkGT3-1, DkAN1-1, DkHSF1) were shown to be strongly up-regulated by an artificial high-CO2 atmosphere (1% O2 and 95% CO2). Dual-luciferase assays indicated that some TFs were activators of previously characterized DkERFs, including DkMYB10 for the DkERF9 promoter, DkERF18/19 and DkMYB6 for the DkERF19 promoter, and DkERF21/22 for the DkERF10 promoter.

Involvement of DkTGA1 Transcription Factor in Anaerobic Response Leading to Persimmon Fruit Postharvest De-Astringency.

Persimmon fruit are unique in accumulating proanthocyanidins (tannins) during development, which cause astringency in mature fruit. In 'Mopanshi' persimmon, astringency can be removed by treatment with 95% CO2, which increases the concentrations of ethanol and acetaldehyde by glycolysis, and precipitates the soluble tannin. A TGA transcription factor, DkTGA1, belonging to the bZIP super family, was isolated from an RNA-seq database and real-time quantitative PCR indicated that DkTGA1 was up-regulated by CO2 treatment, in concert with the removal of astringency from persimmon fruit.