Effects of seasonal temperature changes on <Emphasis Type="Italic">DkMyb4</Emphasis> expression involved in proanthocyanidin regulation in two genotypes of persimmon (<Emphasis Type="Italic">Diospyros kaki</Emphasis> Thunb.) fruit |
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Authors: | Takashi Akagi Tomoyuki Tsujimoto Ayako Ikegami Keizo Yonemori |
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Institution: | (1) Laboratory of Pomology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan;(2) Laboratory of Pomology, Department of Bioproduction Sciences, Ishikawa Prefectural University, Nonoichi Ishikawa, 921-8836, Japan; |
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Abstract: | Persimmon fruits accumulate a large amount of proanthocyanidin (PA). Fruits of the mutant non-astringent (NA) type lose their
ability to accumulate PA at an early stage of fruit development, whereas fruits of the normal astringent (A) type sustain
PA accumulation until ripening. This allelotype is determined by the genotype of a single ASTRINGENCY (AST) locus. It is possible that the reduction in PA accumulation in NA-type fruits is due to phenological down-regulation of
DkMyb4 (a PA regulator) and the resultant down-regulation of structural genes in the PA pathway. In this study, attempts were made
to identify the regulatory mechanisms of phenological PA accumulation in A- and NA-type fruits, focusing particularly on the
effects of ambient temperature. Continuous cool temperature conditions caused sustained expression of DkMyb4 in NA-type fruits, as well as in A-type fruits, resulting in increased expression of PA pathway genes and PA accumulation.
However, the expression of some A/NA phenotypic marker genes was not significantly affected by the cool temperature conditions.
In addition, PA composition in NA-type fruits exposed to cool temperatures differed from that in A-type fruits. These results
indicate that a cool ambient temperature may have induced DkMyb4 expression and resultant PA accumulation, but did not directly affect the expression of the AST gene. |
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