Identification and analysis of copine/BONZAI proteins among evolutionarily diverse plant species.

Copines are evolutionarily conserved calcium-dependent membrane-binding proteins with potentially critical biological functions. In plants, the function of these proteins has not been analyzed except for in Arabidopsis thaliana where they play critical roles in development and disease resistance. To facilitate functional studies of copine proteins in crop plants, genome-wide identification, curation, and phylogeny analysis of copines in 16 selected plant species were conducted. All the identified 32 plant copines have conserved features of the two C2 domains (C2A and C2B) and the von Willebrand factor A (vWA) domain. Different from animal and protozoa copines, plant copines have glycine at the second residue potentially acquiring a unique protein myristoylation modification. Phylogenetic analysis suggests that copine was present as one copy when evolving from green algae to basal flowering plants, and duplicated before the divergence of monocots and dicots. In addition, gene expression and protein localization study of rice copines suggests both conserved and different properties of copines in dicots and monocots. This study will contribute to uncovering the role of copine genes in different plant species.