Abstract
The astringency of Chinese pollination-constant non-astringent (C-PCNA) persimmon (Diospyros kaki Thunb.) can be naturally removed on the tree. This process is controlled by a single locus and is dominant against other types of persimmons; therefore, this variant is an important candidate for commercial cultivation and the breeding of PCNA cultivars. In our previous study, six full-length coding sequences (CDS) for pyruvate kinase genes (DkPK1-6) were isolated, and DkPK1 is thought to be involved in the natural deastringency of C-PCNA persimmon fruit. Here, we characterize the eight other DkPK genes (DkPK7-14) from C-PCNA persimmon fruit based on transcriptome data. The transcript changes in DkPK7-14 genes and correlations with the proanthocyanidin (PA) content were investigated during different fruit development stages in C-PCNA, J-PCNA, and non-PCNA persimmon; DkPK7 and DkPK8 exhibited up-regulation patterns during the last developmental stage in C-PCNA persimmon that was negatively correlated with the decrease in soluble PAs. Phylogenetic analysis and subcellular localization analysis revealed that DkPK7 and DkPK8 are cytosolic proteins. Notably, DkPK7 and DkPK8 were ubiquitously expressed in various persimmon organs and abundantly up-regulated in seeds. Furthermore, transient over-expression of DkPK7 and DkPK8 in persimmon leaves led to a significant decrease in the content of soluble PAs but a significant increase in the expression levels of the pyruvate decarboxylase (DkPDC) and alcohol dehydrogenase genes (DkADH), which are closely related to acetaldehyde metabolism. The accumulated acetaldehyde that results from the up-regulation of the DkPDC and DkADH genes can combine with soluble PAs to form insoluble PAs, resulting in the removal of astringency from persimmon fruit. Thus, we suggest that both DkPK7 and DkPK8 are likely to be involved in natural deastringency via the up-regulation of DkPDC and DkADH expression during the last developmental stage in C-PCNA persimmon.
Highlights
Persimmon (Diospyros kaki Thunb.), which is native to China, is the most economically important species of the genus Diospyros and is mainly cultivated in China, Japan, and Korea
Compared with the J-pollination-constant nonastringent (PCNA) persimmon, the soluble PAs in non-PCNA persimmon fruit remained at a high level throughout all stages of development; the consistently high level demonstrates that natural deastringency does not occur naturally in non-PCNA persimmon
It is worth noting that the reaction exhibited a pale color for fresh Chinese pollination-constant non-astringent (C-PCNA) persimmon fruit at the last developmental stage, suggesting that the concentration of soluble PAs decreased to a low level during astringency removal
Summary
Persimmon (Diospyros kaki Thunb.), which is native to China, is the most economically important species of the genus Diospyros and is mainly cultivated in China, Japan, and Korea. The acetaldehyde metabolism-related genes pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) are key elements involved in astringency removal from ‘Mopanshi’ (non-PCNA) persimmon (Min et al, 2012). Acetaldehyde metabolism-related genes ADH, PDC, and pyruvate kinase (PK) are considered key candidates for involvement in the natural removal of astringency during the last developmental stage in C-PCNA persimmon (Guan et al, 2016; Mo et al, 2016). Considering the roles of PKc in plants and the previous study of DkPK1 involvement in the natural deastringency, the PK cytosolic protein family is more likely to be an important contributor to the natural removal of astringency in C-PCNA persimmon. Our study will be helpful for understanding the mechanism of astringency removal and but will contribute to the breeding of PCNA cultivars in the future
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
