Abstract:

Gibberellin oxidase gene(GAox)is a key enzyme in the synthesis and regulation of gibberellin,and effect on plant height through regulating active GA level.To analyze the gene of gibberellin oxidase in castor,we identified gibberellin oxidase gene(RcGAox)from the castor bean whole genome by bioinformatics,and analyzed physicochemical properties,conserved domain,phylogeny,promoter cis-acting element.The RcGAox gene expression pattern was analyzed by tissue specific expression of online database and apical tender stem transcriptome sequencing.A total of 30 gibberellin oxidase genes were identified from the castor genome,including 7 RcGA2ox,4 RcGA3ox,and 19 RcGA20ox.The molecular weight was ranged from 26.12 to 44.31 ku,and the isoelectric point was ranged from 5.06 to 7.82.Gene structure analysis showed that the number of introns was ranged from 1 to 2.Protein conserved domain analysis showed that all the genes shared conserved Motif 1,Motif 2 and Motif 4.Phylogenetic analysis showed that RcGAox genes were clustered into five subfamilies Ⅰ,Ⅱ,Ⅲ,Ⅳand C20 GA2ox,and subfamiliesⅠ,Ⅱ,Ⅲ correspond to GA2ox,GA3ox and GA20ox respectively.Promoter cis-acting element prediction showed that light-related elements had largest number and uniform distribution in predicting region,and 18 genes had 1 to 2 gibberellin-related element.There were 7,2,and 1 RcGAox genes specifically expressed in endosperm,male flowers and leaves respectively.Transcriptome sequencing showed that 5 genes were expressed in tender stems.It was supposed that RcGA2ox7,RcGA20ox1 and RcGA20ox14 might be the main gene involved in gibberellin synthesis pathway to regulate castor plant height.These results might provide theoretical basis for further studies on the RcGAox gene function in castor bean.

Key words: Castor bean, Gibberellin oxidase, Molecular characteristics, Bioinformatics, Gene expression