Genome-wide evolutionary characterization and expression analyses of major latex protein (MLP) family genes in Vitis vinifera.

The major latex protein/ripening-related protein (MLP/RRP) subfamily is known to be involved in a wide range of biological processes of plant development and various stress responses. However, the biological function of MLP/RRP proteins is still far from being clear and identification of them may provide important clues for understanding their roles. Here, we report a genome-wide evolutionary characterization and gene expression analysis of the MLP family in European Vitis species. A total of 14 members, was found in the grape genome, all of which are located on chromosome 1, where are predominantly arranged in tandem clusters. We have noticed, most surprisingly, promoter-sharing by several non-identical but highly similar gene members to a greater extent than expected by chance. Synteny analysis between the grape and Arabidopsis thaliana genomes suggested that 3 grape MLP genes arose before the divergence of the two species. Phylogenetic analysis provided further insights into the evolutionary relationship between the genes, as well as their putative functions, and tissue-specific expression analysis suggested distinct biological roles for different members. Our expression data suggested a couple of candidate genes involved in abiotic stresses and phytohormone responses. The present work provides new insight into the evolution and regulation of Vitis MLP genes, which represent targets for future studies and inclusion in tolerance-related molecular breeding programs.