Foxtail millet SiCDPK7 gene enhances tolerance to extreme temperature stress in transgenic plants

Global climate change has resulted in increasingly harsh environments that have become the restriction factors for plants growth and development. Calcium-dependent protein kinases (CDPKs) in plants play critical roles in resisting various abiotic stresses, such as heat and cold stresses. Using the expression pattern analysis of foxtail millet CDPK family members under heat- and cold-treatments, respectively, and the SiCDPK7 was found to respond to extreme temperature stress and was selected for further study. The results suggested that overexpression of SiCDPK7 in Arabidopsis conferred tolerance to heat stress by increasing seedling survival rates and hypocotyl elongation compared with wild type (WT) plants, and also can enhance heat stress tolerance in foxtail millet. Analysis of physiological and biochemical indexes showed that SiCDPK7 transgenic plant lines had the markedly higher catalase (CAT) activity and the significantly lower malonaldehyde (MDA) content than WT plants. In addition, qRT-PCR analysis showed that the transcription levels of heat and cold stress-responsive genes were significantly increased in SiCDPK7 transgenic Arabidopsis and foxtail millet under stress conditions. This supporting evidence suggests that SiCDPK7 facilitated the extreme temperature tolerance capabilities in plants