Molecular cloning and cultivar specific expression of MAP kinases from Capsicum annuum

Two MAP kinases, MK1 and MK2, were cloned from Capsicum annuum (pepper) cv, Subicho using a parsley MAP kinase gene as a heterologous probe. MK1 and M K2 encode stress-inducible protein kinases that can contribute to the respo nse to wounding, UV-C, and cold, MK1 has a 92% amino acid identity with WIP K of tobacco. It was transcriptionally induced in response to wounding. In contrast, no detectable MK1 transcript was found in unwounded leaves of pep per. MK2 has a high level of amino acid homology to MAP kinases, such as NT F4 and SIPK and nas constitutively expressed in all tissues. Both MK transc ripts were downregulated by W-C treatment. Each MK protein activation was i ndependently wound-inducible in a cultivar dependent manner. MK1 is phospho rylated in cv, Pungchon but not cv, Subicho; whereas, the MK2 protein activ ation by wounding is restricted to cv, Subicho, In addition, de novo synthe sis of the MK1 protein and tyrosine phosphorylation was rapidly and transie ntly induced in cv, Pungchon by wounding, In contrast, it is highly unlikel y that the MK1;I protein is produced in cv, Subicho, even though there is a n abundant expression of MK1 mRNA after wounding in this cultivar, In Esche richia coli, which overexpresses MK1, autophosphorylation is observed at co nserved threonine and tyrosine phosphorylation sites.