College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China.
Shanghai Agrobiological Gene Center, Shanghai, China.
Plant Biotechnol J. 2022 Sep;20(9):1743-1755. doi: 10.1111/pbi.13857. Epub 2022 Jun 12.
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.
水对于植物的生长和存活至关重要。水通道蛋白（AQP）促进了细胞间的水分运动，它们能够快速且可逆地改变水的通透性。AQP 的丰度受其合成、再分配和降解的调节。然而，AQP 的蛋白酶体降解的分子机制仍不清楚。在这里，我们证明了一种新型的 E3 连接酶 OsRINGzf1 在水稻中介导 AQP 的降解。OsRINGzf1 是水稻染色体 4 长臂上与干旱相关的数量性状位点（QTL）的候选基因，它编码一种 Really Interesting New Gene（RING）锌指蛋白 1。OsRINGzf1 具有 E3 连接酶活性，能够泛素化并介导 OsPIP2;1 的降解，从而降低其蛋白丰度。在 OsRINGzf1 过表达（OE）植物中，OsPIP2;1 蛋白的含量减少。MG132 抑制了 OsPIP2;1 的降解。具有更高叶片相关水分含量（LRWC）和更低叶片水分损失率（LWLR）的 OsRINGzf1 OE 植物表现出增强的抗旱性，而 OsRINGzf1 的 RNAi 和敲除植物对干旱更为敏感。总之，我们的数据表明，OsRINGzf1 通过促进 OsPIP2;1 的降解来提高水稻的保水能力，从而正向调节抗旱性。
