Zhaowu Li

The exocyst is a hetero-octameric complex that exhibits significant functional diversity in regulating biological processes and defense responses. In plants, the EXO70 proteins are important components of the exocyst complex and are involved in membrane trafficking, biotic and abiotic interactions, as well as cell wall formation. A previous study has indicated that a member of the EXO subfamily, EXO70E2, interacts with RIN4 to mediate plant immunity. In this study, we found that EXO70E2 interacts with the RING-type E3 ligase Botrytis susceptible1 interactor (BOI), and the C-terminal domain of BOI is necessary for its interaction with EXO70E2. Moreover, the protein level of EXO70E2 was degraded and ubiquitinated by BOI in vitro. Collectively, our study reveals a mechanism for regulating the stability of EXO70E2 by a RING-type E3 ligase BOI-mediated ubiquitination.

Abiotic stimuli severely restrict the growth and development of plants, resulting in massive losses in the quality and yield of crops. Exploring genes that can improve crop tolerance to abiotic stress is important. In a previous study, we found that overexpression of the Arabidopsis nucleotide-binding domain leucine-rich repeat (NB-LRR) gene AtRPM1(D505V) increased disease resistance in rice. In this research, we found that AtRPM1(D505V) transgenic plants were more sensitive to abscisic acid (ABA) than wild type (WT) plants. Abiotic-stress resistance in AtRPM1(D505V) transgenic plants was investigated. We found that AtRPM1(D505V) transgenic plants exhibited improved resistance to drought and salt stress; the phonotype and survival rates of transgenic rice were better than WT plants. The expression of stress responsive genes including OsDREB2A, OsDREB2B, OsRD22, and OsRD29A were significantly upregulated in AtRPM1(D505V) overexpressed plants than in WT plants. Moreover, the activities of catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) were significantly increased in AtRPM1(D505V) overexpressed plants than in WT plants under drought and salt stress. Under cold stress, the expression of stress responsive genes and the activities of antioxidant enzymes in AtRPM1(D505V) transgenic plants were significantly lower than in WT plants. Our research demonstrated that AtRPM1(D505V) confers drought and salt resistance to transgenic rice. Therefore, AtRPM1(D505V) could act as a potential candidate gene to cultivate drought- and salt-tolerant plants.