Inducible and constitutive expression of an elicitor gene Hrip1 from Alternaria tenuissima enhances stress tolerance in Arabidopsis
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Hrip1 is a novel hypersensitive response-inducing protein secreted by Alternaria tenuissima that activates defense responses and systemic acquired resistance in tobacco. This study investigates the role that Hrip1 plays in responses to abiotic and biotic stress using transgenic Arabidopsis thaliana expressing the Hrip1 gene under the control of the stress-inducible rd29A promoter or constitutive cauliflower mosaic virus 35S promoter. Bioassays showed that inducible Hrip1 expression in rd29A∷Hrip1 transgenic lines had a significantly higher effect on plant height, silique length, plant dry weight, seed germination and root length under salt and drought stress compared to expression in 35S∷Hrip1 lines and wild type plants. The level of enhancement of resistance to Botrytis cinerea by the 35S∷Hrip1 lines was higher than in the rd29A∷Hrip1 lines. Moreover, stress-related gene expression in the transgenic Arabidopsis lines was significantly increased by 200 mM NaCl and 200 mM mannitol treatments, and defense genes in the jasmonic acid and ethylene signaling pathway were significantly up-regulated after Botrytis inoculation in the Hrip1 transgenic plants. Furthermore, the activity of some antioxidant enzymes, such as peroxidase and catalase increased after salt and drought stress and Botrytis infection. These results suggested that the Hrip1 protein contributes to abiotic and biotic resistance in transgenic Arabidopsis and may be used as a useful gene for resistance breeding in crops. Although the constitutive expression of Hrip1 is suitable for biotic resistance, inducible Hrip1 expression is more responsive for abiotic resistance.
KeywordsProtein elicitor Hrip1 Transgenic Arabidopsis Drought stress Salt stress Botrytis
Cauliflower mosaic virus 35S promoter
Promoter of desiccation-responsive rd29A gene in Arabidopsis thaliana
Catalase (Kong et al. 2011)
Days post inoculate
Hours post inoculate
We thank Dr. Jianping Yang (Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China) for assistance with Arabidopsis planting. This work was supported by the National technology research and development program (863 program) project (Grant Nos. 2011AA10A205 and 2012AA101504), The State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant protection, Chinese Academy of Agricultural science, No. 12 Zhong-guan-cun South Street, Beijing, China.