A comparative genomic analysis of plant hormone related genes in different species.

Plant hormones are small molecules that play important roles throughout the life span of a plant, known as auxin, gibberellin, cytokinin, abscisic acid, ethylene, jasmonic acid, salicylic acid, and brassinosteroid. Genetic and molecular studies in the model organism Arabidopsis thaliana have revealed the individual pathways of various plant hormone responses. In this study, we selected 479 genes that were convincingly associated with various hormone actions based on genetic evidence. By using these 479 genes as queries, a genome-wide search for their orthologues in several species (microorganisms, plants and animals) was performed. Meanwhile, a comparative analysis was conducted to evaluate their evolutionary relationship. Our analysis revealed that the metabolisms and functions of plant hormones are generally more sophisticated and diversified in higher plant species. In particular, we found that several phytohormone receptors and key signaling components were not present in lower plants or animals. Meanwhile, as the genome complexity increases, the orthologue genes tend to have more copies and probably gain more diverse functions. Our study attempts to introduce the classification and phylogenic analysis of phytohormone related genes, from metabolism enzymes to receptors and signaling components, in different species.