Molecular characterization of Oryza sativa arsenic-induced RING E3 ligase 1 (OsAIR1): Expression patterns, localization, functional interaction, and heterogeneous overexpression.

High levels of arsenic (As) in plants are a serious threat to human health, and arsenic accumulation affects plant metabolism and ultimately photosynthesis, growth, and development. We attempted to isolate As-responsive Really Interesting New Gene (RING) E3 ubiquitin ligase genes from rice, and we have designated one such gene Oryza sativa arsenic-induced RING E3 ligase 1 (OsAIR1). OsAIR1 expression was induced under abiotic stress conditions, including drought, salt, heat, and As exposure. Results from an in vitro ubiquitination assay showed that OsAIR1 possesses E3 ligase activity. Within the cell, the expression of this gene was found to be localized to the vacuole. In a network-based analysis, we found significantly enriched gene ontology (GO) functions, which included ribonucleoprotein complexes such as ribosomes, suggesting that the function of OsAIR1 are related to translation. Differences in the proportion of seedlings with expanded cotyledons and root lengths, and the lack of differences in germination rates between OsAIR1-overexpressing lines and control plants under AsV stress, suggest that OsAIR1 may positively regulate post-germination plant growth under stress conditions.