Capsicum heterotrimeric G proteins are Up-regulated under UV-B radiation stress

Heterotrimeric G-proteins (G proteins) constitute a classical signal transduction system which can operate together with G-protein coupled receptors (GPCRs) and regulators of G-protein signaling (RGS) in environmental stress-related pathways. Among several environmental factors that can cause stress in plants, ultraviolet B (UV-B) radiation affects many aspects of plant physiology and activating diverse signaling pathways. Signaling response of Capsicum plants to UV-B radiation has not been studied well. In this study, we studied the expression profile of G proteins, GPCR and RGS genes from stems and roots of Capsicum plants subjected to stress with 1, 2, 3, 6, 12, 18, 25 and 30 h of UV-B radiation. CaGα1 and CaGβ1 genes exhibited an increased expression after 18 h of UV-B radiation treatment in stems, while CaGγ1, CaGγ2, CaRGS1 and CaGPCR genes showed no significant changes in expression. In roots, CaGα1 and CaRGS1 genes showed an increasing expression profile after 3, 18 and 25 h after UV-B radiation but its expresion was not statistically significant. Signaling response to UV-B-radiation in Capsicum was mediated by G proteins in a specific-tissue manner where CaGα1 and CaGβ1 have an active role in stems. The expresion profiles found in this study were associated with UV-B induced responses in plants, however, the specific roles of G protein members induced by UV-B radiation in Capsicum remains to be elucidated. These results provide evidence of possible role of G protein signaling system in response to UV-B radiation in Capsicum, open for new insights about the search of new genes to be used as molecular markers for manipulation to enhance UV-B radiation stress tolerance in crop plants.