Molecular Evolution Of Chalcone Isomerase Gene Family In Some Wild

Abundant genetic diversity and clear lineage relationships made wide rices become dualstudy model systems to improve rice quality and solve evolution problems. Flavonoids not onlymake plants colorful, but also play important roles in plant defense and development, such asprotection against UV radiation and pathogen, as well as alteration male fertility. Chalconeisomerase (CHI, EC5.5.1.6), a key enzyme in the biosynthesis of flavonoids that catalyzsintramolecular cyclization, is a rate-limiting enzyme of flavonoids synthesis, and a member ofCHI gene family. As a key catalytic enzyme, although CHI itself has been widely studies inmany plants, few studies have been paid attentions on the gene family, especially on the aspectof the member constitution, family origin and duplication history, and evolution pattern inpolyploids. The present study, using transcriptome data and bioinformation analysis, we firstreavealed the molecular evolution characteristics of the CHI gene family in diploid wild riceOryza officinalis; then we summarized the basic evolution patterns including nucleotidediversities, evolutionary dynamics and expression preference between each duplicatedhomologues of loci Ochi4and Ochi5, respectively. The main results are as following.1. By using transcripome sequencing and bioinformation analyzing, five gene members wereidentified in the CHI gene family in diploid wide rice O. officinalis, and three of the five geneswere consided to be related with fatty acid-binding proteins. In addition, two gene membersOschi4and Oschi5were found sharing highly sequence similarity. The further phylogeneticanalysis showed that the CHI gene family had an ancient origin and the time could track to theearly ancestor of land plants.2. By using cloning and sequencing analysis, the two genes of Ochi4and Ochi5from9samplesof three species O. alta, O. grandiglumis and O. latifolia with CCDD genome were studied. Theresults showed that the two chalcone isomerase family members had similar evolutionarycharacteristics at the DNA level. Firstly, the two genes were all duplicated in three species withthe genome doubling after polyploidization, i.e. two homologues representing biparental C and Dgenome types were both found. Next, sequence length polymorphisms of duplicated homologuesderived by a specific nucleotide fragment insert in D genomic type were both revealed in twoloci. Lastly, simlar evolutionary dynamics that D genomic types had higher level of nucletoiddiverisity were all found for the both loci. At the RNA level, however, different gene expressionpatterns were displayed. Ochi4preferred to express C genomic homologue in O. alta and O.grandiglumis than D genomic ones as the case in O. latifolia, whereas Ochi5choosed to expressonly D genomic types in all three speices.