Salt Stress in Arabidopsis： Lipid Transfer Protein AZI1 and Its Control by Mitogen-Activated Protein Kinase MPK3  

作　　者：Andrea Pitzschke Sneha Datta Helene Persak 

机构地区：[1]Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria

出　　处：《Molecular Plant》2014年第4期722-738,共17页分子植物（英文版）

摘　　要：A plant＇s capability to cope with environmental challenges largely relies on signal transmission through mitogen-activated protein kinase （MAPK） cascades. In Arabidopsis thaliana, MPK3 is particularly strongly associated with numerous abiotic and biotic stress responses. Identification of MPK3 substrates is a milestone towards improving stress resistance in plants. Here, we characterize AZI1, a lipid transfer protein （LTP）-related hybrid proline-rich protein （HyPRP）, as a novel target of MPK3. AZI1 is phosphorylated by MPK3 in vitro. As documented by co-immunoprecipitation and bimolecular fluorescence complementation experiments, AZI1 interacts with MPK3 to form protein complexes in planta. Furthermore, null mutants of azil are hypersensitive to salt stress, while AZIl-overexpressing lines are markedly more tolerant. AZI1 overexpression in the mpk3 genetic background partially alleviates the salt-hypersensitive phenotype of this mutant, but functional MPK3 appears to be required for the full extent of AZIl-conferred robustness. Notably, this robustness does not come at the expense of normal development. Immunoblot and RT-PCR data point to a role of MPK3 as positive regulator of AZI1 abundance.A plant＇s capability to cope with environmental challenges largely relies on signal transmission through mitogen-activated protein kinase （MAPK） cascades. In Arabidopsis thaliana, MPK3 is particularly strongly associated with numerous abiotic and biotic stress responses. Identification of MPK3 substrates is a milestone towards improving stress resistance in plants. Here, we characterize AZI1, a lipid transfer protein （LTP）-related hybrid proline-rich protein （HyPRP）, as a novel target of MPK3. AZI1 is phosphorylated by MPK3 in vitro. As documented by co-immunoprecipitation and bimolecular fluorescence complementation experiments, AZI1 interacts with MPK3 to form protein complexes in planta. Furthermore, null mutants of azil are hypersensitive to salt stress, while AZIl-overexpressing lines are markedly more tolerant. AZI1 overexpression in the mpk3 genetic background partially alleviates the salt-hypersensitive phenotype of this mutant, but functional MPK3 appears to be required for the full extent of AZIl-conferred robustness. Notably, this robustness does not come at the expense of normal development. Immunoblot and RT-PCR data point to a role of MPK3 as positive regulator of AZI1 abundance.

关 键 词：salt stress ARABIDOPSIS MAPK MPK3 lipid transfer protein AZI1 PHOSPHORYLATION in vivo interaction. 

分 类 号：Q26[生物学—细胞生物学] Q945.78