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Overexpression of PP2A‐C5 that encodes the catalytic subunit 5 of protein phosphatase 2A in Arabidopsis confers better root and shoot development under salt conditions

Hu, Rongbin, Zhu, Yinfeng, Wei, Jia, Chen, Jian, Shi, Huazhong, Shen, Guoxin, Zhang, Hong
Plant, cell and environment 2017 v.40 no.1 pp. 150-164
Arabidopsis, crops, eukaryotic cells, gain-of-function mutation, gene overexpression, genes, knockout mutants, loss-of-function mutation, plant growth, protein subunits, proteins, roots, salt tolerance, shoots, signal transduction, sodium chloride, transgenic plants, two hybrid system techniques, vacuoles
Protein phosphatase 2A (PP2A) is an enzyme consisting of three subunits: a scaffolding A subunit, a regulatory B subunit and a catalytic C subunit. PP2As were shown to play diverse roles in eukaryotes. In this study, the function of the Arabidopsis PP2A‐C5 gene that encodes the catalytic subunit 5 of PP2A was studied using both loss‐of‐function and gain‐of‐function analyses. Loss‐of‐function mutant pp2a‐c5‐1 displayed more impaired growth during root and shoot development, whereas overexpression of PP2A‐C5 conferred better root and shoot growth under different salt treatments, indicating that PP2A‐C5 plays an important role in plant growth under salt conditions. Double knockout mutants of pp2a‐c5‐1 and salt overly sensitive (sos) mutants sos1‐1, sos2‐2 or sos3‐1 showed additive sensitivity to NaCl, indicating that PP2A‐C5 functions in a pathway different from the SOS signalling pathway. Using yeast two‐hybrid analysis, four vacuolar membrane chloride channel (CLC) proteins, AtCLCa, AtCLCb, AtCLCc and AtCLCg, were found to interact with PP2A‐C5. Moreover, overexpression of AtCLCc leads to increased salt tolerance and Cl⁻ accumulation in transgenic Arabidopsis plants. These data indicate that PP2A‐C5‐mediated better growth under salt conditions might involve up‐regulation of CLC activities on vacuolar membranes and that PP2A‐C5 could be used for improving salt tolerance in crops.