Transcriptional Regulatory Mechanism Of ERF On Postharvest Persimmon Fruit Deastringency

Persimmon fruit can be divided into astringent and nonastringent types. Most of commercial cultivars were astringent persimmon in China. Astringent persimmon accumulates abundant proanthocyanins in the fruit flesh even at maturity. In present research,’Mopan shi’(Diospyros kaki) was chosen to study ADH, PDC and ERF genes expression during deastringency. Transcriptional regulatory mechanisms of ERF on ADH and PDC were studied. The main results are as follows:1. CO2(95%) treatment was more effective than ethylene (100μl/1) in acceleration on deastringency. CO2treatment and ethylene treatment were applied to remove astringency. Soluble tannins were decreased faster in CO2treated fruit than that of ethylene.2. Analysis on DkADH and DkPDC genes expression during deastringency. Seven genes were cloned using NCBI EST database, designed as DkADHl-3, DkPDC-3and DkPDC5, respectively. DkADH and DkPDC genes were differentially expressed in various persimmon tissues. Expression of DkADHl, DkPDCl, DkPDC2and DkPDC3were induced by deastringent treatments, which negatively correlated with soluble tannins and positively correlated ADH and PDC enzyme activities. Transient over-expression of DkPDC2in the persimmon leaves led to a small but significant decrease in levels of soluble tannins.3. Analysis on DkERF genes expression during deastringency. Fourteen DkERF genes were cloned using RNA-Seq, designed DkERF9-22(JX117848, JX145122, KJ170911-KJ170922), respectively. Phylogenetic analysis of the deduced amino acid sequences showed that the14ERF genes were clustered into7subfamilies. Most of14DkERF genes were induced by CO2and ethylene treatments, while DkERF19was only affected by CO2.4. Researches on transcriptional regulatory mechanisms of DkERF on DkADH and DkPDC. A dual luciferase assay in Nicotiana benthamiana leaves show that DkERF9, DkERF10, DkERF19and DkERF22acted selectively as activators of DkADH1, DkPDC2and DkPDC3promoters, respectively. Furthermore, combination of DkERF9and DkERF19had a higher activation on the target promoter. Yeast one-hybrid results showed that DkERF9interacted with DkPDC2promoter.The present research investigated molecular mechanisms and transcriptional regulatory mechanisms on persimmon fruit postharvest deastringency. DkERF induced the increase of DkADH and DkPDC gene expression by activating DkADH and DkPDC promoter, which accelerated the accumulation of acetaldehyde, and then acetaldehyde interacted with soluble tannins into insoluble and the astringency of fruit have been removed, which were transcriptionally regulated by combination of DkERF genes.