背景回顾：Banana (Musa acuminata) fruits ripening at 30°C or above fail to develop yellow peels; this phenomenon, called green ripening, greatly reduces their marketability. 

提出问题：The regulatory mechanism underpinning high temperature-induced green ripening remains unknown. 

主要发现：Here we decoded a transcriptional and post-translational regulatory module that causes green ripening in banana. 

结果1-高温-CCG-绿熟：Banana fruits ripening at 30°C showed greatly reduced expression of five chlorophyll catabolic genes (CCGs), MaNYC1 (NON-YELLOW COLORING 1), MaPPH (PHEOPHYTINASE), MaTIC55 (TRANSLOCON AT THE INNER ENVELOPE MEMBRANE OF CHLOROPLASTS 55), MaSGR1 (STAY-GREEN 1) and MaSGR2 (STAY-GREEN 2), compared to those ripening at 20°C. 

结果2-MYB60-CCG：We identified a MYB transcription factor, MaMYB60, that activated the expression of all five CCGs by directly binding to their promoters during banana ripening at 20°C, while showing a weaker activation at 30°C. 

结果3-BAH1-MYB60：At high temperatures, MaMYB60 was degraded. We discovered a RING-type E3 ligase MaBAH1 (Benzoic Acid Hypersensitive 1) that ubiquitinated MaMYB60 during green ripening and targeted it for proteasomal degradation. 

结果4-BAH1-MYB60-CCG-绿熟：MaBAH1 thus facilitated MaMYB60 degradation and attenuated MaMYB60-induced transactivation of CCGs and chlorophyll degradation. By contrast, MaMYB60 upregulation increased CCG expression, accelerated chlorophyll degradation, and mitigated green ripening. 

香蕉果实在30°C及以上温度下成熟不会形成黄色的果皮；这一现象叫做绿熟，极大地降低了其市场价值。高温诱导的绿熟调控机制在很大程度上还是未知的。本文中，作者解码了香蕉中导致绿熟的转录和翻译后调控模块。与20°C时相比，香蕉果实在30°C成熟时会表现出叶绿素分解代谢基因MaNYC1、MaPPH、MaTIC55、MaSGR1和MaSGR2的表达下降。作者鉴定到了一个MYB转录因子MaMYB60，该转录因子在20°C时能够通过直接结合到这几个叶绿素分解代谢基因的启动子上激活他们的表达，但是在30°C时其转录激活能力明显减弱。在高温下，MaMYB60被降解。作者发现了一个RING类E3连接酶MaBAH1，该酶能够在绿熟过程中泛素化MaMYB60，导致后者经蛋白酶体途径降解。因此，MaBAH1通过促进MaMYB60的降解，扰乱MaMYB60诱导的叶绿素分解代谢基因激活和叶绿素降解。相反，MaMYB60的上调会导致叶绿素分解代谢基因的表达增加，从而加速叶绿素的降解，进而减缓绿熟。综上，本文的研究结果揭示了一个动态响应温度的MaBAH1-MaMYB60-CCG模块，通过调控叶绿色的分解代谢，控制香蕉果实的绿熟。本文的研究同样为理解植物对于高温胁迫的响应提供了新的视野。

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