BTB-BACK-TAZ domain protein MdBT2-mediated MdMYB73 ubiquitination negatively regulates malate accumulation and vacuolar acidification in apple
BTB-BACK-TAZ domain protein MdBT2-mediated MdMYB73 ubiquitination negatively regulates malate accumulation and vacuolar acidification in apple
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DOI：
10.1038/s41438-020-00384-z
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发表时间：
2020-09
影响因子：
8.7
通讯作者：
Quan-Yan Zhang;Kai-Di Gu;Jia-hui Wang;Jian-qiang Yu;Xiao-Fei Wang;Shuai Zhang;C. You;Da-Gang Hu-Da-Ga
中科院分区：
文献类型：
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作者：
Quan-Yan Zhang;Kai-Di Gu;Jia-hui Wang;Jian-qiang Yu;Xiao-Fei Wang;Shuai Zhang;C. You;Da-Gang Hu-Da-Ga
苹果酸作为一种重要的初级代谢物，在调节苹果的渗透压、pH稳态、抗逆性和果实品质等方面起着关键作用。R2R3-MYB转录因子（TF） MdMYB73通过直接调控苹果铝活化苹果酸转运蛋白9 （MdALMT9）、空泡atp酶亚基a （MdVHA-A）和空泡焦磷酸酶1 （MdVHP1）的转录，在苹果苹果酸积累和空泡酸化过程中起关键作用。此外，bHLH TF MdCIbHLH1与MdMYB73相互作用，增强MdMYB73的转录活性。我们之前的研究表明，BTB-BACK-TAZ结构域蛋白MdBT2可以降解MdCIbHLH1，从而影响苹果酸积累和液泡酸化。然而，MdMYB73的潜在上游调控因子目前尚不清楚。在本研究中，我们发现MdBT2通过泛素/26S蛋白酶体途径直接与MdMYB73相互作用并降解，调节苹果酸积累和空泡酸化。对苹果愈伤组织和果实的一系列功能分析表明，MdBT2以依赖mdmyb73的方式控制苹果酸积累和液泡酸化。总的来说，我们的研究结果揭示了BTB-BACK-TAZ结构域蛋白MdBT2通过靶向MdMYB73和MdCIbHLH1泛素化调控苹果酸积累和液泡酸化的机制。这些信息可能有助于指导传统育种计划和果树分子育种，并导致果实质量和抗逆性的改善。
As an important primary metabolite, malate plays a key role in regulating osmotic pressure, pH homeostasis, stress tolerance, and fruit quality of apple. The R2R3-MYB transcription factor (TF) MdMYB73 was identified as a protein that plays a critical role in determining malate accumulation and vacuolar acidification by directly regulating the transcription of aluminum-activated malate transporter 9 (MdALMT9), vacuolar ATPase subunit A (MdVHA-A), and vacuolar pyrophosphatase 1 (MdVHP1) in apple. In addition, the bHLH TF MdCIbHLH1 interacts with MdMYB73 and enhances the transcriptional activity of MdMYB73. Our previous studies demonstrated that the BTB-BACK-TAZ domain protein MdBT2 can degrade MdCIbHLH1 to influence malate accumulation and vacuolar acidification. However, the potential upstream regulators of MdMYB73 are currently unknown. In this study, we found that MdBT2 directly interacts with and degrades MdMYB73 through the ubiquitin/26S proteasome pathway to regulate malate accumulation and vacuolar acidification. A series of functional assays with apple calli and fruit showed that MdBT2 controls malate accumulation and vacuolar acidification in an MdMYB73-dependent manner. Overall, our findings shed light on the mechanism by which the BTB-BACK-TAZ domain protein MdBT2 regulates malate accumulation and vacuolar acidification by targeting MdMYB73 and MdCIbHLH1 for ubiquitination in apple. This information may help guide traditional breeding programs and fruit tree molecular breeding, and lead to improvements in fruit quality and stress tolerance.