论文标题：Hyperacidification of Citrus fruits by a vacuolar proton-pumping P-ATPase complex

期刊：Nature Communications

作者：Pamela Strazzer, Cornelis E. Spelt, Shuangjiang Li, Mattijs Bliek, Claire T. Federici, Mikeal L. Roose, Ronald Koes, Francesca M. Quattrocchio

发表时间：2019/02/26

数字识别码： 10.1038/s41467-019-08516-3

原文链接：http://t.cn/EIhVjJf

微信链接：https://mp.weixin.qq.com/s/JuTHRZwOvCr8fnNJEU2Cvg

《自然-通讯》本周发表的一篇论文Hyperacidification of Citrus fruits by a vacuolar proton-pumping P-ATPase complex指出了与柑橘属水果的酸味有关的基因。

图1：甜味和酸味柑橘品种的分析。图源：Strazzer等

水果的酸味取决于液泡（植物细胞内的单层膜细胞器）的酸度，由于氢离子会泵入液泡，大多数植物细胞的液泡呈温和的酸性。在特定水果的出汁细胞中，这种泵入过程会增强，从而导致液泡酸度增加。不过，研究人员此前并不清楚这一过程是如何完成的。

荷兰阿姆斯特丹大学的Ronald Koes和同事对比了不同甜酸口味的柑橘属品种，包括柠檬、橙、柚子和青柠。作者发现，酸味品种会表达CitPH1和CitPH5两个基因，这两个基因会编码增强质子泵过程的转运蛋白，使液泡的氢离子浓度上升。而这两个基因在味甜不酸的水果品种中的表达则有所减少。该转运蛋白与作者先前发现决定矮牵牛紫色花色的蛋白类型相同。

图2：与矮牵牛合成的柑橘类水果。图源：Strazzer等

作者总结称，这一发现或能帮助水果育种者更快选出口味更佳的水果。通过对幼树进行DNA检测，育种者或能提前预测水果的酸度，而不用等到果树成熟。

摘要：The sour taste of Citrus fruits is due to the extreme acidification of vacuoles in juice vesicle cells via a mechanism that remained elusive. Genetic analysis in petunia identified two vacuolar P-ATPases, PH1 and PH5, which determine flower color by hyperacidifying petal cell vacuoles. Here we show that Citrus homologs, CitPH1 and CitPH5, are expressed in sour lemon, orange, pummelo and rangpur lime fruits, while their expression is strongly reduced in sweet-tasting “acidless” varieties. Down-regulation of CitPH1 and CitPH5 is associated with mutations that disrupt expression of MYB, HLH and/or WRKY transcription factors homologous to those activating PH1 and PH5 in petunia. These findings address a long-standing enigma in cell biology and provide targets to engineer or select for taste in Citrus and other fruits.

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（来源：科学网）