Abstract
Drought and salinity are major important factors that restrain growth and productivity of rice. In plants, many really interesting new gene (RING) finger proteins have been reported to enhance drought and salt tolerance. However, their mode of action and interacting substrates are largely unknown. Here, we identified a new small RING-H2 type E3 ligase OsRF1, which is involved in the ABA and stress responses of rice. OsRF1 transcripts were highly induced by ABA, salt, or drought treatment. Upregulation of OsRF1 in transgenic rice conferred drought and salt tolerance and increased endogenous ABA levels. Consistent with this, faster transcriptional activation of key ABA biosynthetic genes, ZEP, NCED3, and ABA4, was observed in OsRF1-OE plants compared with wild type in response to drought stress. Yeast two-hybrid assay, BiFC, and co-immunoprecipitation analysis identified clade A PP2C proteins as direct interacting partners with OsRF1. In vitro ubiquitination assay indicated that OsRF1 exhibited E3 ligase activity, and that it targeted OsPP2C09 protein for ubiquitination and degradation. Cell-free degradation assay further showed that the OsPP2C09 protein is more rapidly degraded by ABA in the OsRF1-OE rice than in the wild type. The combined results suggested that OsRF1 is a positive player of stress responses by modulating protein stability of clade A PP2C proteins, negative regulators of ABA signaling.
Highlights
Drought is one of the most influential environmental problems in plant productivity
Transmembrane domain analysis using TMHMM 2.02 revealed that OsRF1 has a putative transmembrane domain in the N-terminal region (13–35 residues), which is similar to that of Arabidopsis really interesting new gene (RING)-H2 group A (RHA) 2A and Zea mays ZmXerico (Figure 1A)
Previous studies on RING finger proteins have revealed that they are a large protein family in plants that participates in various biological process such as seed germination, regulation of cell cycles, and biotic and abiotic stress responses (Lee et al, 2001, 2011; Kosarev et al, 2002; Stone et al, 2005; Ko et al, 2006; Hong et al, 2007; Zhang et al, 2007; Liu et al, 2008; Bu et al, 2009; Lim et al, 2010; Park et al, 2010)
Summary
Drought is one of the most influential environmental problems in plant productivity. Frequent occurrences of drought and abnormal weather events have been observed lately all over the world. Tons of crops are damaged by drought, which is caused by abnormal weather events. Along with the predictable increasing population in the world and decreasing bias of available water and field for. OsRF1 Targets OsPP2C09 Under Stress crop production, it is necessary to make an effort to establish strategy for improvement of crop yield under water-limiting conditions. There have been noticeable attempts to cope with drought stress through overexpression of drought-resistant genes (Fang and Xiong, 2015; Li et al, 2017; Shen et al, 2017; Yuan et al, 2019; Wang et al, 2020; Xu et al, 2020). Most of them are related to increasing of abscisic acid (ABA) responses
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