DkMyb4 Is a Myb Transcription Factor Involved in Proanthocyanidin Biosynthesis in Persimmon Fruit
DkMyb4 Is a Myb Transcription Factor Involved in Proanthocyanidin Biosynthesis in Persimmon Fruit
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DOI：
10.1104/pp.109.146985
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发表时间：
2009-12-01
期刊：
影响因子：
7.4
通讯作者：
Yonemori, Keizo
中科院分区：
文献类型：
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作者：
Akagi, Takashi;Ikegami, Ayako;Yonemori, Keizo
原花色素（PA）是次级代谢产物，其有助于保护植物，并且还有助于果实的味道，主要通过涩味。柿（Diospyros kaki）是一种独特的果实，能够在果肉中积累丰富的多胺。非涩（NA）型突变体的果实在果实发育的早期阶段失去产生PA的能力，而正常涩（A）型突变体的果实在完全成熟之前仍然富含PA。在果实发育的早期阶段，许多PA途径基因的表达在NA型中一致终止。编码Myb转录因子的五个基因分离自A型栽培品种（Kuramitsu）。其中DkMyb4在A型和NA型果肉中的表达模式与PA途径基因同步。DkMyb4在猕猴桃中的异位表达诱导了PA的合成，但不诱导花色素苷的合成。在柿愈伤组织中，DkMyb4的抑制导致PA途径基因和PA生物合成的显著下调。DNA结合能力分析表明，DkMyb 4可直接与PA途径基因启动子中的MYBCORE顺式基序结合。我们所有的研究结果表明，DkMyb4作为一个调节PA生物合成的柿子，因此，表明DkMyb4表达的减少导致NA型特异性下调PA生物合成和由此产生的NA性状。
Proanthocyanidins (PAs) are secondary metabolites that contribute to the protection of the plant and also to the taste of the fruit, mainly through astringency. Persimmon (Diospyros kaki) is unique in being able to accumulate abundant PAs in the fruit flesh. Fruits of the nonastringent (NA)-type mutants lose their ability to produce PA at an early stage of fruit development, while those of the normal astringent (A) type remain rich in PA until fully ripened. The expression of many PA pathway genes was coincidentally terminated in the NA type at an early stage of fruit development. The five genes encoding the Myb transcription factor were isolated from an A-type cultivar (Kuramitsu). One of them, DkMyb4, showed an expression pattern synchronous to that of the PA pathway genes in A-and NA-type fruit flesh. The ectopic expression of DkMyb4 in kiwifruit (Actinidia deliciosa) induced PA biosynthesis but not anthocyanin biosynthesis. The suppression of DkMyb4 in persimmon calluses caused a substantial down-regulation of the PA pathway genes and PA biosynthesis. Furthermore, analysis of the DNA-binding ability of DkMyb4 showed that it directly binds to the MYBCORE cis-motif in the promoters of the some PA pathway genes. All our results indicate that DkMyb4 acts as a regulator of PA biosynthesis in persimmon and, therefore, suggest that the reduction in the DkMyb4 expression causes the NA-type-specific down-regulation of PA biosynthesis and resultant NA trait.