Water is crucial for plant growth and survival. The transcellular water movement is facilitated by aquaporins (AQPs) that rapidly and reversibly modify water permeability. The abundance of AQPs is regulated by its synthesis, redistribution and degradation. However, the molecular mechanism of proteasomal degradation of AQPs remains unclear. Here, we demonstrate that a novel E3 ligase, OsRINGzf1, mediated the degradation of AQPs in rice. OsRINGzf1 is the candidate gene from a drought-related quantitative trait locus (QTL) on the long arm of chromosome 4 in rice (Oryza sativa) and encodes a Really Interesting New Gene (RING) zinc finger protein 1. OsRINGzf1 possesses the E3 ligase activity, ubiquitinates and mediates OsPIP2;1 degradation, thus reducing its protein abundance. The content of OsPIP2;1 protein was decreased in OsRINGzf1 overexpression (OE) plants. The degradation of OsPIP2;1 was inhibited by MG132. The OsRINGzf1 OE plants, with higher leaf-related water content (LRWC) and lower leaf water loss rate (LWLR), exhibited enhanced drought resistance, whereas the RNAi and knockout plants of OsRINGzf1 were more sensitive to drought. Together, our data demonstrate that OsRINGzf1 positively regulates drought resistance through promoting the degradation of OsPIP2;1 to enhance water retention capacity in rice.

中文翻译：

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泛素连接酶 OsRINGzf1 通过控制 OsPIP2 的转换来调节抗旱性；1

水对植物的生长和生存至关重要。水通道蛋白 (AQP) 促进了跨细胞的水运动，它可以快速且可逆地改变水的渗透性。AQP 的丰度受其合成、再分布和降解的调节。然而，蛋白酶体降解 AQPs 的分子机制仍不清楚。在这里，我们证明了一种新的 E3 连接酶 OsRINGzf1 介导了水稻中 AQP 的降解。OsRINGzf1是水稻4 号染色体长臂上干旱相关数量性状位点 (QTL) 的候选基因。) 并编码一个真正有趣的新基因 (RING) 锌指蛋白 1。OsRINGzf1 具有 E3 连接酶活性，泛素化并介导 OsPIP2;1 降解，从而降低其蛋白质丰度。OsRINGzf1过表达（OE）植物中OsPIP2;1蛋白的含量降低。OsPIP2;1 的降解被MG132 抑制。OsRINGzf1 OE植物具有较高的叶片相关水分含量（LRWC）和较低的叶片失水率（LWLR），表现出增强的抗旱性，而OsRINGzf1的RNAi和敲除植物对干旱更敏感。总之，我们的数据表明OsRINGzf1通过促进 OsPIP2;1 的降解来正向调节抗旱性，从而增强水稻的保水能力。