Heterogeneous Overexpression of Two Oryza sativa Arsenic-Induced RING E3 Ligase4 (OsAIR4.1 and 4.2) Transcripts Enhances Plant Tolerance to Arsenic Stress

초록

High arsenic (As) concentration in groundwater is a major source of As contamination in crops, increasing toxicity, and risk of severe human health problems. This study aims to determine the As-responsive Really Interesting New Gene (RING) E3 ubiquitin (Ub) ligase gene, OsAIR4, involved in As tolerance mechanisms in rice via the Ub/26S proteasome system. We showed that OsAIR4 had two splicing variants of OsAIR4.1 and OsAIR4.2, and their expression patterns were highly induced in response to As stress in root tissues. An in vitro ubiquitination assay showed that both OsAIR4.1 and OsAIR4.2 possess E3 ligase activity. We found that both OsAIR4 proteins were localized in the cytoplasm of rice protoplasts. Heterogeneous overexpression of OsAIR4.1 and OsAIR4.2 in Arabidopsis showed As tolerance in seed germination, root growth, and whole plant growth compared with control plants under As stress conditions. This study suggests that OsAIR4 may be involved in the plant response to As stress and acts as a positive regulator of stress tolerance.

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