Calcium-Dependent Protein Kinase Family Genes Involved in Ethylene-Induced Natural Rubber Production in Different Hevea brasiliensis Cultivars.

Natural rubber latex production can be improved by ethylene stimulation in the rubber tree (). However, the expression levels of most functional proteins for natural rubber biosynthesis are not induced after ethylene application, indicating that post-translational modifications, especially protein phosphorylation, may play important roles in ethylene signaling in . Here, we performed a comprehensive investigation on evolution, ethylene-induced expression and protein-protein interaction of calcium-dependent protein kinases (CPKs), an important serine/threonine protein kinase family, in . Nine duplication events were determined in the 30 identified genes. Expression profiling of in three rubber tree cultivars with low, medium and high ethylene sensitivity showed that , , , , , and are induced by ethylene in at least one cultivar. Evolution rate analysis suggested accelerated evolution rates in two paralogue pairs, and Analysis of proteomic data for rubber latex after ethylene treatment showed that seven HbCPK proteins could be detected, including six ethylene-induced ones. Protein-protein interaction analysis of the 493 different abundant proteins revealed that protein kinases, especially calcium-dependent protein kinases, possess most key nodes of the interaction network, indicating that protein kinase and protein phosphorylation play important roles in ethylene signaling in latex of . In summary, our data revealed the expression patterns of family members and functional divergence of two paralogue pairs, as well as the potential important roles of in ethylene-induced rubber production improvement in .