Functional analysis reveals pleiotropic effects of rice RING-H2 finger protein gene OsBIRF1 on regulation of growth and defense responses against abiotic and biotic stresses
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RING finger proteins comprise a large family and play key roles in regulating growth/developmental processes, hormone signaling and responses to biotic and abiotic stresses in plants. A rice gene, OsBIRF1, encoding a putative RING-H2 finger protein, was cloned and identified. OsBIRF1 encodes a 396 amino acid protein belonging to the ATL family characterized by a conserved RING-H2 finger domain (C-X2-C-X15-C-X1-H-X2-H-X2-C-X10-C-X2-C), a transmembrane domain at the N-terminal, a basic amino acid rich region and a characteristic GLD region. Expression of OsBIRF1 was up-regulated in rice seedlings after treatment with benzothaidiazole, salicylic acid, l-aminocyclopropane-1-carboxylic acid and jasmonic acid, and was induced differentially in incompatible but not compatible interactions between rice and Magnaporthe grisea, the causal agent of blast disease. Transgenic tobacco plants that constitutively express OsBIRF1 exhibit enhanced disease resistance against tobacco mosaic virus and Pseudomonas syringae pv. tabaci and elevated expression levels of defense-related genes, e.g. PR-1, PR-2, PR-3 and PR-5. The OsBIRF1-overexpressing transgenic tobacco plants show increased oxidative stress tolerance to exogenous treatment with methyl viologen and H2O2, and up-regulate expression of oxidative stress-related genes. Reduced ABA sensitivity in root elongation and increased drought tolerance in seed germination were also observed in OsBIRF1 transgenic tobacco plants. Furthermore, the transgenic tobacco plants show longer roots and higher plant heights as compared with the wild-type plants, suggesting that overexpression of OsBIRF1 promote plant growth. These results demonstrate that OsBIRF1 has pleiotropic effects on growth and defense response against multiple abiotic and biotic stresses.
KeywordsRice OsBIRF1 RING finger proteins Disease resistance Abiotic stress
1-Amino cyclopropane-1-carboxylic acid
Cauliflower mosaic virus
Open reading frame
Polymerase chain reaction
Tobacco mosaic virus
We are grateful to Dr Zuhua He, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Science, for the rice near-isogenic lines H8R and H8S, and Mr Rongyao Chai, Zhejiang Academy of Agricultural Science, for the Magnaporthe grisea isolate 85-14B1. This study was supported by National Natural Science Foundation of China (grants no. 30571209 and 30771399), the National High-Tech (“863”) Project (2006AA10Z430), the National Key Basic Research and Development Program (2006CB101903) and the Fund for the New Century Talent Program from MOE of China.
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