Nucleocytoplasmic shuttling of ETHYLENE RESPONSE FACTOR 5 mediated by nitric oxide suppresses ethylene biosynthesis in apple fruit

提出问题：Nitric oxide (NO) is known to modulate the action of several phytohormones. This includes the gaseous hormone ethylene, but the molecular mechanisms underlying the effect of NO on ethylene biosynthesis are unclear.

已知一氧化氮（NO）可调节几种植物激素的作用。这包括气态激素乙烯，但NO对乙烯生物合成影响的分子机制尚不清楚。

研究内容：Here, we observed a decrease in endogenous NO abundance during apple (Malus domestica) fruit development and exogenous treatment of apple fruit with a NO donor suppressed ethylene production, suggesting that NO is a ripening suppressor.

主要发现：在这里，我们观察到苹果果实发育过程中内源NO丰度的降低，以及外源处理抑制了乙烯的产生，表明NO是一种成熟抑制因子。

研究结果：Expression of the transcription factor MdERF5 was activated by NO donor treatment. NO induced the nucleocytoplasmic shuttling of MdERF5 by modulating its interaction with the protein phosphatase, MdPP2C57. MdPP2C57 induced dephosphorylation of MdERF5 at Ser260 is sufficient to promote nuclear export of MdERF5. As a consequence of this export, MdERF5 proteins in the cytoplasm interacted with and suppressed the activity of MdACO1, an enzyme that converts 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene. The NO-activated MdERF5 was observed to increase in abundance in the nucleus and bind to the promoter of the ACC synthase gene MdACS1 and directly suppress its transcription.

研究结果：转录因子MdERF5的表达在没有供体处理的情况下被激活。NO通过调节MdERF5与蛋白磷酸酶MdPP2C57的相互作用，诱导MdERF5的核质穿梭。MdPP2C57诱导的Ser260处MdERF5的去磷酸化足以促进MdERF5的核输出。作为这种输出的结果，细胞质中的MdERF5蛋白与MdACO1相互作用并抑制其活性，MdACO1是一种将1-氨基环丙烷-1-羧酸（ACC）转化为乙烯的酶。观察到NO激活的MdERF5在细胞核中大量增加，并与ACC合成酶基因MdACS1的启动子结合，并直接抑制其转录。

结论：Together, these results suggest that NO-activated nucleocytoplasmic MdERF5 suppresses the action of ethylene biosynthetic genes, thereby suppressing ethylene biosynthesis and limiting fruit ripening.

总之，该研究结果表明，没有激活的核质MdERF5抑制乙烯生物合成基因的作用，从而抑制乙烯生物合成并限制果实成熟。

全文链接：https://nph.onlinelibrary.wiley.com/doi/abs/10.1111/nph.18071

作者简介：王爱德   主要研究方向为果实成熟分子机理以及果实品质发育与调控

Journal: New Phytologist

Published date: March 07, 2021​