The calcium-dependent protein kinase (CDPK) and CDPK-related kinase gene families in -comparison with five other plant species in structure, evolution, and expression.

Calcium-dependent protein kinases (CDPKs or CPKs) play important roles in various physiological processes of plants, including growth and development, stress responses and hormone signaling. Although the CDPK gene family has been characterized in several model plants, little is known about this gene family in (the Para rubber tree). Here, we characterize the entire CDPK and CDPK-related kinase (CRK) gene families comprising 30 genes ( to ) and nine genes ( to ). Structure and phylogeny analyses of these and genes demonstrate evolutionary conservation in these gene families across and other plant species. The expression of and genes was investigated via Solexa sequencing in a range of experimental conditions (different tissues, phases of leaf development, ethylene treatment, and various abiotic stresses). The results suggest that and genes are important components in growth, development, and stress responses of . Parallel studies on the and gene families were also extended to five other plant species (, , , and ). The and genes from different plant species that exhibit similar expression patterns tend to cluster together, suggesting a coevolution of gene structure and expression behavior in higher plants. The results serve as a foundation to further functional studies of these gene families in as well as in the whole plant kingdom.