The R2R3-MYB transcription factor MdMYB73 is involved in malate accumulation and vacuolar acidification in apple
The R2R3-MYB transcription factor MdMYB73 is involved in malate accumulation and vacuolar acidification in apple
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DOI：
10.1111/tpj.13579
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发表时间：
2017-08-01
期刊：
影响因子：
7.2
通讯作者：
Hao, Yu-Jin
中科院分区：
文献类型：
--
作者：
Hu, Da-Gang;Li, Yuan-Yuan;Hao, Yu-Jin
苹果酸是许多水果中主要的有机酸，是水果感官品质的重要组成部分，包括味道和风味。影响苹果酸盐代谢的遗传和环境机制已被广泛研究。然而，苹果酸代谢酶和空泡转运蛋白的转录调控仍然知之甚少。我们之前的研究表明，MdMYB1通过直接激活液泡转运体MdVHA-B1、MdVHA-E、MdVHP1和MdtDT来调节花青素积累和液泡酸化。有趣的是，我们在这项研究中分离并鉴定了一个MYB转录因子MdMYB73，它是MdMYB1的远亲。随后发现MdMYB73蛋白直接结合到MdALMT9（铝活化苹果酸转运蛋白9）、MdVHA-A（液泡atp酶亚基A）和MdVHP1（液泡焦磷酸酶1）的启动子上，转录激活了它们的表达，从而增强了它们的活性。对转基因苹果愈伤组织的分析表明，MdMYB73影响苹果酸积累和液泡ph。此外，MdCIbHLH1与MdMYB73相互作用，增强了其对下游靶基因的活性。这些发现有助于阐明MdMYB73如何直接调节苹果酸盐的液泡运输系统，从而影响苹果酸盐的积累和液泡pH。
Malate, the predominant organic acid in many fruits, is a crucial component of the organoleptic quality of fruit, including taste and flavor. The genetic and environmental mechanisms affecting malate metabolism in fruit cells have been studied extensively. However, the transcriptional regulation of malate-metabolizing enzymes and vacuolar transporters remains poorly understood. Our previous studies demonstrated that MdMYB1 modulates anthocyanin accumulation and vacuolar acidification by directly activating vacuolar transporters, including MdVHA-B1, MdVHA-E, MdVHP1 and MdtDT. Interestingly, we isolated and identified a MYB transcription factor, MdMYB73, a distant relative of MdMYB1 in this study. It was subsequently found that MdMYB73 protein bound directly to the promoters of MdALMT9 (aluminum-activated malate transporter 9), MdVHA-A (vacuolar ATPase subunit A) and MdVHP1 (vacuolar pyrophosphatase 1), transcriptionally activating their expression and thereby enhancing their activities. Analyses of transgenic apple calli demonstrated that MdMYB73 influenced malate accumulation and vacuolar pH. Furthermore, MdCIbHLH1 interacted with MdMYB73 and enhanced its activity upon downstream target genes. These findings help to elucidate how MdMYB73 directly modulates the vacuolar transport system to affect malate accumulation and vacuolar pH in apple.