Calmodulin-binding protein CBP60g is a positive regulator of both disease resistance and drought tolerance in Arabidopsis
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Calmodulin-binding proteins (CBPs) have been known to be involved in both biotic and abiotic stress responses. Recently, two closely related CBPs, Arabidopsis SAR Deficient 1 and CBP60g, were found to belong to a new family of transcription factors that regulate salicylic acid (SA) biosynthesis triggered by microbe-associated molecular patterns. In this study, we found that overexpression of CBP60g in Arabidopsis caused elevated SA accumulation, increased expression of the defense genes, and enhanced resistance to Pseudomonas syringae. In addition to the enhanced defense response, the CBP60g overexpression lines showed hypersensitivity to abscisic acid (ABA) and enhanced tolerance to drought stress. We also found that treatment with ABA and drought stress leads to a higher expression level of the ICS1 gene, which encodes isochorismate synthase, in the CBP60g overexpression lines than in the wild-type control plants. Our results suggest that CBP60g serves as a molecular link that positively regulates ABA- and SA-mediated pathways in plants.
Key message Overexpression of CBP60g in Arabidopsis enhanced the defense response, hypersensitivity to abscisic acid and tolerance to drought stress.
KeywordsArabidopsis thaliana CBP60g Overexpression Salicylic acid Drought tolerance Abscisic acid
We thank Dr. Yee-yung Charng and Dr. Hao Chen for critical reading of the manuscript, Dr. Jian-min Zhou and Dr. Yuelin Zhang for providing the P. syringae strain and the mutant sard1-1 cbp60g-1, respectively, the Arabidopsis Biological Resource Center for seed stocks, and Kathleen M. Buckley, M.S. for editing assistance. This work was supported by Chinese National Programs for High Technology Research and Development (No. 2011AA100203), National Natural Science Foundation of China (No. 30860030), the Program for New Century Excellent Talents of University (No. NCET-08-0871) from Ministry of Education (China), and the Innovative Research Group Fund (No. NDPYTD2010-3) from Inner Mongolia Agricultural University (China) to Guojing Li. The authors declare that they have no conflict of interest.
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