OsCBE1, a Substrate Receptor of Cullin4-Based E3 Ubiquitin Ligase, Functions as a Regulator of Abiotic Stress Response and Productivity in Rice

Abstract

Ubiquitination is an important environmental stress response, and E3 ubiquitin ligases play a major role in the process. T-DNA insertion mutants of rice, Oscbe1-1, and Oscbe1-2, were identified through the screening of cold stress tolerance at seedling stage. Oscbe1 mutants showed a significantly higher cold stress tolerance in the fresh weight, chlorophyll content, and photosynthetic efficiency than wild type. Molecular prediction showed that OsCBE1 (Oryza sativa Cullin4-Based E3 ubiquitin ligase1) encoded a novel substrate receptor of Cullin4-based E3 ubiquitin ligase complex (C4E3). Whereas Oscbe1 mutants had fewer panicles and grains than wild type in the paddy field, the overexpression lines of OsCBE1 had more panicles and grains, suggesting that OsCBE1 is involved in the regulation of both abiotic stress response and development. Oscbe1 mutants also showed ABA hypersensitivity during seed germination, suggesting OsCBE1 function for the stress response via ABA signaling. In silico analysis of OsCBE1 activity predicted a CCCH-type transcription factor, OsC3H32, as a putative substrate. Co-IP (Co-immunoprecipitation) study showed that OsCBE1 interacts with OsDDB1, an expected binding component of OsCBE1 and OsC3H32. Additionally, expression of OsOLE16, OsOLE18, and OsBURP5 were negatively related with expression of OsCBE1. These results suggest that OsCBE1 functions as a regulator of the abiotic stress response via CCCH as a member of the C4E3.

OsDWD1 E3 ligase‐mediated OsNPR1 degradation suppresses basal defense in rice

“…OsCUL4 and OsDDB1, which are components of the CRL4‐based E3 ligase complex, have been little studied from the perspective of ubiquitination. Recently the interaction between OsDDB1 and, as a negative regulator for abiotic stress responsive protein, was confirmed (Choi et al., 2021). We isolated OsDDB1 (GenBank #AB037144), as reported previously (Bae et al., 2018; Choi et al., 2021; Ishibashi et al., 2003).…”

“…We therefore investigated the function of the OsDWD1 substrate receptor of the CRL4 complex and its substrates. In a recent report on rice CUL4‐based E3 ligases, OsCBE1 was a negative regulator of the abiotic stress response gene, and OsDDB1 was used to hemagglutinin (HA) tag transgenic rice plants to confirm the interaction between OsDDB1 and OsCBE1 by co‐IP (Choi et al., 2021). However, no CUL4 protein has been identified in rice to date, even though orthologs for components of the CRL4 complex in rice have been reported in annotation databases (http://rice.plantbiology.msu.edu; http://www.ncbi.nlm.nih.gov) (Marino et al., 2012).…”

“…Recently the interaction between OsDDB1 and, as a negative regulator for abiotic stress responsive protein, was confirmed (Choi et al, 2021). We isolated OsDDB1 (GenBank #AB037144), as reported previously (Bae et al, 2018;Choi et al, 2021;Ishibashi et al, 2003). For the rice ortholog of CUL4 (At5g46210), we isolated the cDNA for LOC_Os03g57290.1 using reverse transcription polymerase chain reaction (RT-PCR) based on the rice genome annotation database, and referred to this as OsCUL4.…”

Transcriptome analysis of tea (Camellia sinensis) leaves in response to ammonium starvation and recovery

“…Tea polyphenols assist the resistance of plants to damage by external factors, such as UV-B, low temperature, and drought ( Zoratti et al, 2014 ). Genes encoding for the REF/SRPP-like protein (TEA001749), E3 ubiquitin ligase (TEA022683) and carboxylesterase (CXE) (TEA001625) were involved in plant stress resistance ( Tong et al, 2017 ; Cao et al, 2019 ; Choi et al, 2021 ). Glutathione S-transferase ( GST ) (TEA006546) was also a hub gene and involved in normal metabolism of plant secondary products, such as flavonoids and cinnamic acid ( Marrs, 1996 ).…”