Journal Article

OsBIRH1, a DEAD-box RNA helicase with functions in modulating defence responses against pathogen infection and oxidative stress

Dayong Li, Huizhi Liu, Huijuan Zhang, Xiaoe Wang and Fengming Song

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 59, issue 8, pages 2133-2146
Published in print May 2008 | ISSN: 0022-0957
Published online April 2008 | e-ISSN: 1460-2431 | DOI: http://dx.doi.org/10.1093/jxb/ern072

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DEAD-box proteins comprise a large protein family with members from all kingdoms and play important roles in all types of processes in RNA metabolism. In this study, a rice gene OsBIRH1, which encodes a DEAD-box RNA helicase protein, was cloned and characterized. The predicted OsBIRH1 protein contains a DEAD domain and all conserved motifs that are common characteristics of DEAD-box RNA helicases. Recombinant OsBIRH1 protein purified from Escherichia coli was shown to have both RNA-dependent ATPase and ATP-dependent RNA helicase activities in vitro. Expression of OsBIRH1 was activated in rice seedling leaves after treatment with defence-related signal chemicals, for example benzothiadiazole, salicylic acid, l-aminocyclopropane-1-carboxylic acid, and jasmonic acid, and was also up-regulated in an incompatible interaction between a resistant rice genotype and the blast fungus, Magnaporthe grisea. Transgenic Arabidopsis plants that overexpress the OsBIRH1 gene were generated. Disease resistance phenotype assays revealed that the OsBIRH1-overexpressing transgenic plants showed an enhanced disease resistance against Alternaria brassicicola and Pseudomonas syringae pv. tomato DC3000. Meanwhile, defence-related genes, for example PR-1, PR-2, PR-5, and PDF1.2, showed an up-regulated expression in the transgenic plants. Moreover, the OsBIRH1 transgenic Arabidopsis plants also showed increased tolerance to oxidative stress and elevated expression levels of oxidative defence genes, AtApx1, AtApx2, and AtFSD1. The results suggest that OsBIRH1 encodes a functional DEAD-box RNA helicase and plays important roles in defence responses against biotic and abiotic stresses.

Keywords: DEAD-box RNA helicase; disease resistance; OsBIRH1; oxidative stress; rice (Oryza sativa L.)

Journal Article.  8144 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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