Functional Characterization of Salt-Stress Induced Rare Cold Inducible Gene from Camelina sativa (CsRCI2D)

Abstract

Rare-cold-inducible 2 (RCI2) genes are involved in plant response to abiotic stresses. In this study, we report the functional role of a Camelina RCI2, CsRCI2D, in plant salt stress response. The localization of CsRCI2D was observed in the plasma membrane and intracellular membranes by confocal analysis in tobacco leaf and western blot analysis in Camelina. The full length CsRCI2D cDNA clone was not able to complement the salt sensitivity of ospmp3 lacking the PMP3 gene. However, a C-terminal tail deleted CsRCI2D cDNA was able to restore the level of salt tolerance to that of WT. CsRCI2D-overexpressing Camelina showed better germination rate and seedling growth. CsRCI2D overexpression decreased Na+ accumulation in both roots and shoots but increased K+ accumulation in the shoots under salt stress. Furthermore, CsRCI2D-overexpressing Camelina displayed lower H2O2 and malondialdehyde (MDA) upon salt stress. Under normal growth condition, CsRCI2D-overexpressing Camelina showed higher transcript levels of all antioxidant genes (CsCuSODs, CsMnSOD1, CsFeSODs, CsCATs, CsAPX1, and CsGR), whereas salt stress significantly induced all antioxidant genes in WT. These results indicate that salt-upregulated CsRCI2D plays a positive role in Camelina seed germination and seedling growth under salt stress by maintenance of ion homeostasis and modulating the expression of antioxidant-related genes.