Abstract

Heterotrimeric G-proteins have been shown to be involved in plant responses to abiotic stress. Recent evidence has shown that a caleosin, RD20/AtCLO3, is involved in stomate and root responses to ABA treatment in addition to interacting with the G alpha subunit (GPA1) in Arabidopsis thaliana. The role of the other caleosin gene family members and their interaction with G-proteins still remains largely unknown. This work demonstrated the interaction of another caleosin, AtCLO4, with GPA1 by Bimolecular Fluorescence Complementation (BiFC). Phenotypic analysis of clo4 mutants showed significantly less inhibition of lateral root formation during salt and mannitol stress compared to wild type; while CLO4 gene expression was characterized in the roots by GUS staining during periods of stress. These results present a novel interaction between CLO4 and GPA1 and indicate a role for CLO4 in regulating GPA1 during periods of stress that culminate in inhibition of lateral root formation.