​Phosphorylation of MdERF17 by MdMPK4 Promotes Apple Fruit Peel Degreening during Light/Dark Transitions

第一作者：Shuai Wang

第一单位：中国农业大学

第一通讯：Ting Wu

 Abstarct 

背景回顾：As apple fruits (Malus domestica) mature, they accumulate anthocyanins concomitantly with losing chlorophyll (Chl); however, the molecular pathways and events that coordinate Chl degradation and fruit coloration have not been elucidated. 

在苹果果实成熟时，其会在积累花色苷的同时失去叶绿素；但是其协调叶绿素降解和果实着色的分子途径和事件尚不清楚。

前期基础：We showed previously that the transcription factor ETHYLENE RESPONSE FACTOR17 (MdERF17) modulates Chl degradation in apple fruit peels and that variation in the pattern of MdERF17 serine (Ser) residues is responsible for differences in its transcriptional regulatory activity. 

作者在先前的研究中发现，转录因子MdERF17在苹果的果皮中调控叶绿素的降解，并且MdERF17丝氨酸残基的变异是影响其转录调控活性差异的关键影响因素。

主要发现：Here, we report that MdERF17 interacts with and is phosphorylated by MAP KINASE4 (MdMPK4-14G). 

本文中，作者发现MdERF17能够与MdMPK4-14G互作，并且被MdMPK4-14G磷酸化。

结果1-MdMPK4-14G磷酸化MdERF17：Phosphorylation of MdERF17 at residue Thr67 by MdMPK4-14G is necessary for its transcriptional regulatory activity and its regulation of Chl degradation. 

MdERF17蛋白在67号位上的苏氨酸被MdMPK4-14G磷酸化，这对于MdERF17的转录调控活性及其对于叶绿素降解的调控是必要的。

结果2-丝氨酸重复：We also show that MdERF17 mutants with different numbers of Ser repeat insertions exhibit altered phosphorylation profiles, with more repeats increasing its interaction with MdMPK4. 

作者还发现，带有不同数量丝氨酸重复插入的MdERF17突变，会存在不同的磷酸化图谱，丝氨酸重复越多，其与MdMPK4的互作越强。

结果3-光暗转换：MdMPK4-14G can be activated by exposure to darkness and is involved in the dark-induced degreening of fruit peels. We also demonstrate that greater phosphorylation of MdERF17 by MdMPK4-14G is responsible for the regulation of Chl degradation during light/dark transitions. 

另外，黑暗处理能够激活MdMPK4-14G蛋白的活性，该蛋白参与了黑暗诱导的苹果果皮褪绿。此外，作者发现在苹果经历光暗转换时，MdMPK4-14G对于MdERF17的磷酸化增强，是苹果果皮中叶绿素降解的关键因素。

结论：Overall, our findings reveal the mechanism by which MdMPK4 controls fruit peel coloration.

综上，本文的研究揭示了一个由MdMPK4控制的苹果果皮着色的分子机制。

** 吴 婷 **

doi: https://doi.org/10.1093/plcell/koac049

Journal: The Plant Cell

 Published date: February 15, 2022