Environmental stresses activate a tomato SNF1-related protein kinase 2 homolog, SlSnRK2C

We isolated an SNF1-related kinase 2 homolog (SlSnRK2C) from tomato (Solanum lycopersicum L. cv. Micro-Tom) which has significant similarlity to AtSRK2C (72% amino acid identity). We profiled expression levels and biochemical properties of SlSnRK2C. In contrast to AtSRK2C which phosphorylates histone H1 and is mainly expressed in root chip, SlSnRK2C phosphorylates myelin basic protein but not histone H1 and SlSnRK2C mRNA is expressed in leaves, flowers and fruits but not in roots. Immunoblot by anti-SlSnRK2C-COOH terminus specific antiserum shows that SlSnRK2C is expressed remarkably in developing fruits, and weakly in flowers, mature green fruits and shoots, but marginally in mature red fruits or roots. SlSnRK2C is stimulated strongly by chilling and NaCl stress. These observations suggests that SlSnRK2C is possibly involved in fruit development and stress signaling in response to salt and chiling stress.