Molecular Evolutionary Analysis Of The Key Gene Families COI/JAZ/MYC In Jasmonic Acid Signaling Pathway

Jasmonic Acid (Jasmonic Acid, JA) is an important plant hormone, which not only canregulate plant growth and development, but also can be used as a signaling molecule involvedin plant defense response. JA signal response contains signal generation and signal transduction,the COI1/JAZ/MYC2is the core module in JA signal transduction. At present,COI1/JAZ/MYC2genes were studied in the Arabidopsis thaliana, however, the molecularevolution mechanism of COI JAZ/MYC gene families were still unclear in the whole plantgenome. In this study, using comparative genomics and phylogenetic analysis to study theevolution of gene family from the signal pathway and multi-lineages (algae, moss, ferns,gymnosperms, monocots and eudicots) and the results are as follows:1. Using public databases resources of plant genome,55COIs,82JAZs and61MYCs geneswere selected in15representative plants genome (algae, moss, ferns, gymnosperms, monocotsand eudicots). However, there were not identified COI/JAZ/MYC homologous genes in thealgae. Because aquatic algae lacks JA signal of key components, therefore, JA signal may beoriginated from lant plants.2. Phylogenetic analysis found that COI, JAZ and MYC gene families can be divided into4,10and5conservative subfamily in plant genome. The COIs of Sub III (Fig.2-2), JAZs of Subs.II, IV and VIII (Fig.3-3) and MYCs of Subs. I (Fig.4-2) may be involved in jasmonic acidpathway. JAZ is the core of the JA signal transduction, however, JAZs candidate genes are notincluded in the PpJAZs of moss, that is to say, PpJAZs may not participate in JA signaltransduction, therefore, JA signal may be originated from ferns.3. The result of genes chromosome location show that the tandem repeat of the COI andMYC gene family did not found in monocot Oryza sativa, Sorghum bicolor and eudicotArabidopsis thaliana, Populus trichocarpa, but JAZ gene families tandem repeat events werefound in Oryza sativa and Sorghum bicolor.The result of segmental duplication within speciesfound that the COI and JAZ gene families exist homologous genes segmental duplication inmonocot Sorghum bicolor and eudicot Arabidopsis thaliana, Populus trichocarpa, andsegmental duplication of MYC gene family only in eudicot Arabidopsis thaliana, Populustrichocarpa. Segmental duplication plays an important role in COI/JAZ/MYC gene familyamplification. 4. Genetic structure analysis showed that the lengths and number of gene introns are diversein COI/JAZ/MYC gene family. Further analysis found that loss of introns is the importantreason for introns numbers changes, and indels lead to intron length changes. Intron loss andindels is likely to be an effective mechanism of plant evolution.The results can provide valuable information for full understanding the origin and evolutionof JA signaling pathwany in plants, and provide theoretical basis for understanding the originof plant hormone.