Scientists from Shanghai Agrobiological Gene Center published a research paper named “Ubiquitin Ligase OsRINGzf1 Regulates Drought Resistance by Controlling the Turnover of OsPIP2;1” on Plant Biotechnology Journal.

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.

Figure Description:

Functional identification of OsRINGzf1 gene on rice drought resistance. (a) The target QTL interval was narrowed down with a backcrossing population (BC₅F_2:3). (b) Drought stress response of the recombinant plants containing the target QTL interval. Genome schematic of two recombinant plants was indicated. Red represents the genome from receptor parent (Zhenshan97B) and green represent the genome from donor parent (IRAT109). Survival rate (SR) was calculated after 14 days of drought stress and 7 days of rehydration. (c) Expression profile of OsRINGzf1 under normal and drought conditions. (d) Differences in OsRINGzf1 expression between parents under normal conditions. (e) Relative luciferase activity of proOsRINGzf1-LUC in N. benthamiana plants. The promoter fragment of Zhenshan97B was fused in proOsRINGzf1^ZS97B, the promoter fragment of IRAT109 was fused in proOsRINGzf1^IRAT109. Relative reporter activity (LUC/REN) was calculated. (f) OsRINGzf1 improves the adaptation of rice to PEG simulated drought stress at the seedling stage. (g) The survival rate (SR) of WT, OE plants indicated in (f). (h) OsRINGzf1 improves the drought resistance of rice at the reproductive stage. (i) Grain yield of WT and OE plants under normal and drought stress conditions. Values in c, d, e, and g are means ± SD based on three independent biological replicates. Asterisks represent the statistically significant differences according to a two-tailed Student’s t-test. *P<0.05, **P<0.01, ***P<0.001.

DOI:  https://doi.org/10.1111/pbi.13857