Cloning,Bioinformatics and Expression Analysis of SAI Gene in Fritillaria thunbergii
To study the mechanism of soluble acid invertase(SAI)gene in the biosynthesis of Fritillaria thunbergii,a soluble acid invertase gene(FtSAI)with open reading frame was cloned from F.thunbergii by RT-PCR in this study.The full-length cDNA of SAI gene was 2 095 bp,encoded 634 amino acids.The SAI protein sequence of F.thunbergii had more than 76%similarty with the L.davidii,T.gesneriana,dessert banana and date palm.Sequence alignment analysis showed that SAI had a β-furan fruit glycosidase active site WMN-DPN-G/A box,Cysteone(Cys)WECXDF and Glyco-32 conserved domains.The SAI protein of F.thunbergii was grouped together with that of T.gesneriana(CAA64953.1)and L.davidii(AGW23637.1),which belong to the same family of Liliaceae.The SAI gene was expressed in all tissues of F.thunbergii,and the expression level was the lowest in bulb.The expression of SA I gene was also significantly different at different developmental stages of bulb,and the expression level of SA I gene was at a high level in the early and middle stages of bulb development,while the expression level was significantly reduced in the late stage.The results lay a foundation for further study on the function of SAI protein in F.thunbergii and reveal the role of starch-sucrose synthesis in the scale of F.thunbergii.