Key Laboratory of Fruit Postharvest Biology (Liaoning Province), Key Laboratory of Protected Horticulture (Ministry of Education), National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology (Liaoning), College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China.
Liaoning Institute of Pomology, Xiongyue 115009, China.
Plant Physiol. 2023 Apr 3;191(4):2475-2488. doi: 10.1093/plphys/kiad022.
Ethylene biosynthesis in apple (Malus domestica) fruit can be suppressed by calcium ions (Ca2+) during storage; however, the underlying mechanisms are unclear. In this study, we identified the apple transcription factor MCM1-AGAMOUS-DEFICIENS-SRF5 (MdMADS5), which functions as a transcriptional activator of the ethylene biosynthesis-related gene 1-AMINOCYCLOPROPANE-1-CARBOXYLIC ACID SYNTHASE1 (MdACS1), a partner of the calcium sensor CALCIUM-DEPENDENT PROTEIN KINASES7 (MdCDPK7). Ca2+ promoted the MdCDPK7-mediated phosphorylation of MdMADS5, which resulted in the degradation of MdMADS5 via the 26S proteasome pathway. MdCDPK7 also phosphorylated 1-AMINOCYCLOPROPANE-1-CARBOXYLIC ACID OXIDASE1 (MdACO1), the key enzyme in ethylene biosynthesis, leading to MdACO1 degradation and inhibition of ethylene biosynthesis. Our results reveal that Ca2+/MdCDPK7-MdMADS5 and Ca2+/MdCDPK7-MdACO1 are involved in Ca2+-suppressed ethylene biosynthesis, which delays apple fruit ripening. These findings provide insights into fruit ripening, which may lead to the development of strategies for extending the shelf life of fruit.
在苹果（Malus domestica）果实贮藏过程中，钙离子（Ca2+）可以抑制乙烯的生物合成；然而，其潜在机制尚不清楚。在本研究中，我们鉴定了苹果转录因子 MCM1-AGAMOUS-DEFICIENS-SRF5（MdMADS5），它作为乙烯生物合成相关基因 1-氨基环丙烷-1-羧酸合成酶 1（MdACS1）的转录激活因子发挥作用，MdACS1 是钙传感器钙依赖性蛋白激酶 7（MdCDPK7）的一个伙伴。Ca2+促进了 MdCDPK7 介导的 MdMADS5 磷酸化，导致 MdMADS5 通过 26S 蛋白酶体途径降解。MdCDPK7 还磷酸化乙烯生物合成的关键酶 1-氨基环丙烷-1-羧酸氧化酶 1（MdACO1），导致 MdACO1 降解和乙烯生物合成抑制。我们的结果表明，Ca2+/MdCDPK7-MdMADS5 和 Ca2+/MdCDPK7-MdACO1 参与了 Ca2+抑制的乙烯生物合成，从而延缓了苹果果实的成熟。这些发现为果实成熟提供了新的认识，可能为延长果实货架期的策略的发展提供了思路。
