AUTHOR=Bai Longqiang , Liu Yumei , Mu Ying , Anwar Ali , He Chaoxing , Yan Yan , Li Yansu , Yu Xianchang 

TITLE=Heterotrimeric G-Protein γ Subunit CsGG3.2 Positively Regulates the Expression of CBF Genes and Chilling Tolerance in Cucumber

JOURNAL=Frontiers in Plant Science

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.00488

DOI=10.3389/fpls.2018.00488

ISSN=1664-462X

ABSTRACT=<p>Heterotrimeric guanine nucleotide-binding proteins (G proteins) composed of alpha (Gα), beta (Gβ), and gamma (Gγ) subunits are central signal transducers mediating the cellular response to multiple stimuli, such as cold, in eukaryotes. Plant Gγ subunits, divided into A, B, and C three structurally distinct types, provide proper cellular localization and functional specificity to the heterotrimer complex. Here, we demonstrate that a type C Gγ subunit CsGG3.2 is involved in the regulation of the <italic>CBF</italic> regulon and plant tolerance to cold stresses in cucumber (<italic>Cucumis sativus</italic> L.). We showed that <italic>CsGG3.2</italic> transcript abundance was positively induced by cold treatments. Transgenic cucumber plants (T1) constitutively over-expressing <italic>CsGG3.2</italic> exhibits tolerance to chilling conditions and increased expression of <italic>CBF</italic> genes and their regulon. Antioxidative enzymes, i.e., superoxide dismutase, catalase, peroxidase, and glutathione reductase activities increased in cold-stressed transgenic plants. The reactive oxygen species, oxygen free radical and H<sub>2</sub>O<sub>2</sub>, production, as well as membrane lipid peroxidation (MDA) production decreased in transgenic plants, suggesting a better antioxidant system to cope the oxidative-damages caused by cold stress. These findings provide evidence for a critical role of CsGG3.2 in mediating cold signal transduction in plant cells.</p>