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Glycine betaine‐mediated potentiation of HSP gene expression involves calcium signaling pathways in tobacco exposed to NaCl stress
Author(s) -
Li Meifang,
Guo Shangjing,
Xu Ying,
Meng Qingwei,
Li Gang,
Yang Xinghong
Publication year - 2014
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/ppl.12067
Subject(s) - nicotiana tabacum , heat shock protein , gene expression , microbiology and biotechnology , chemistry , signal transduction , betaine , calcium , hsp70 , heat shock factor , biochemistry , transcription factor , heat shock , intracellular , biology , gene , organic chemistry
Glycine betaine ( GB ) can enhance heat tolerance and the accumulation of heat‐shock protein ( HSP ) in plants, but the effects of GB on HSP accumulation during salt stress were not previously known. To investigate the mechanism of how GB influences the expression of HSP , wild‐type tobacco ( Nicotiana tabacum ) seedlings pretreated with exogenous GB and BADH ‐transgenic tobacco plants that accumulated GB in vivo were studied during NaCl stress. A transient Ca 2+ efflux was observed in the epidermal cells of the elongation zone of tobacco roots after NaCl treatment for 1–2 min. After 24 h of NaCl treatment, an influx of Ca 2+ was observed; a low concentration of GB significantly increased NaCl ‐induced Ca 2+ influx. GB increased the intracellular free calcium ion concentration and enhanced the expression of the calmodulin ( CaM ) and heat‐shock transcription factor ( HSF ) genes resulting in potentiated levels of HSPs . Pharmacological experiments confirmed that Ca 2+ and CaM increased HSFs and HSPs gene expression, which coincided with increased the levels of HSP70 accumulation. These results suggest a mechanism by which GB acted as a cofactor in the NaCl induction of a Ca 2+ ‐permeable current. A possible regulatory model of Ca 2+ ‐ CaM in the signal transduction pathway for induction of transcription and translation of the active HSPs is described.