State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources/Guangdong Provincial Key Laboratory of Postharvest Science of Fruit and Vegetables/Engineering Research Center of Southern Horticultural Products Preservation, Ministry of Education, College of Horticulture, South China Agricultural University, Guangzhou 510642, China.
Plant Physiol. 2023 Jul 3;192(3):1969-1981. doi: 10.1093/plphys/kiad096.
Banana (Musa acuminata) fruit ripening under high temperatures (>24 °C) undergoes green ripening due to failure of chlorophyll degradation, which greatly reduces marketability. However, the mechanism underlying high temperature-repressed chlorophyll catabolism in banana fruit is not yet well understood. Here, using quantitative proteomic analysis, 375 differentially expressed proteins were identified in normal yellow and green ripening in banana. Among these, one of the key enzymes involved in chlorophyll degradation, NON-YELLOW COLORING 1 (MaNYC1), exhibited reduced protein levels when banana fruit ripened under high temperature. Transient overexpression of MaNYC1 in banana peels resulted in chlorophyll degradation under high temperature, which weakens the green ripening phenotype. Importantly, high temperature induced MaNYC1 protein degradation via the proteasome pathway. A banana RING E3 ligase, NYC1-interacting protein 1 (MaNIP1), was found to interact with and ubiquitinate MaNYC1, leading to its proteasomal degradation. Furthermore, transient overexpression of MaNIP1 attenuated MaNYC1-induced chlorophyll degradation in banana fruits, indicating that MaNIP1 negatively regulates chlorophyll catabolism by affecting MaNYC1 degradation. Taken together, the findings establish a post-translational regulatory module of MaNIP1-MaNYC1 that mediates high temperature-induced green ripening in bananas.
香蕉（Musa acuminata）果实成熟过程中，如果温度过高（>24°C），会由于叶绿素降解失败而出现绿色成熟现象，极大地降低了商品价值。然而，香蕉果实中高温抑制叶绿素分解的机制尚不清楚。在这里，我们使用定量蛋白质组学分析，在正常黄熟和高温下绿熟的香蕉中鉴定出 375 种差异表达蛋白。其中，叶绿素降解的关键酶之一 NON-YELLOW COLORING 1（MaNYC1），在高温下香蕉果实成熟时其蛋白水平降低。瞬时过表达 MaNYC1 可导致香蕉果皮在高温下叶绿素降解，从而削弱绿熟表型。重要的是，高温通过蛋白酶体途径诱导 MaNYC1 蛋白降解。发现一种香蕉 RING E3 连接酶 NYC1-interacting protein 1（MaNIP1）与 MaNYC1 相互作用并泛素化 MaNYC1，导致其蛋白酶体降解。此外，瞬时过表达 MaNIP1 可减弱 MaNYC1 诱导的香蕉果实中叶绿素降解，表明 MaNIP1 通过影响 MaNYC1 降解来负调控叶绿素分解。总之，这些发现建立了 MaNIP1-MaNYC1 的翻译后调控模块，介导了香蕉果实的高温诱导绿色成熟。
