Cloning, Expression And Function Analysis Of SYP Gene In Cassava

Cassava(Manihot esculenta Crantz) is one of the typical tropical root crops with high light efficiency, high starch yield and other excellent agronomic traits, which is the world’s sixth largest food crop. As its tolerance to drought and barren, cassava could be used as an excellent material for drought tolerance reserach. Syntaxin protein of plant (syntaxin protein, SYP) is a kind of vesicle mediated transporter related protein in plant cells. Several SYP genes were reported to response to biotic and abiotic stress.Object:This research isolated15MeSYP genes in cassava. Then, according to analysis of the transcriptional expression patterns, this work established a foundation for a genome-wide study of the MeSYP genes mechanism for responsing drought stress in cassava.Methods:The bioinformatics softwares were used to analyze gene structure, physical and chemical properties of the protein and the phylogenetic tree; The expression pattern of MeSYP genes was studied using semi-quantitative RT-PCR; Besides, this research also constructed protoplast expression vector pBSK::MeSYP121-GFPIpBSK:MeSYP122-GFP and the plant expression vector p35S::MeSYP121lp35S::MeSYP122and We transformed these plant expression vectors into wild genotype Arabidopsis plants through floral dipping.Results:(1) we got a total of15cassava SYP genes with complete length cDNA sequences. Protein domain analysis showed all of the15MeSYP proteins have Syntaxin domain and SNARE domain. Besides, there was a transmembrane structure in the C-terminal of the15MeSYP proteins. The identities of MeSYP gene coding sequence between the cultivated species AM560and the wild species W14were very high. The phylogenic analysis showed that these MeSYP genes were often clustered together with the castor bean SYP genes in the10/15branches which contained the MeSYP proteins and all of the15MeSYP genes can be divided into two subfamilies.(2) We also used the semi-quantitative RT-PCR to analyze tissue specificity of MeSYP genes expression patterns in cassava. There was the highest expression level of MeSYP1, MeSYP3and MeSYP6in root and leaf and lowest in petiole. Expression level of MeSYP5and MeSYP10were very low in all the three organs. MeSYP122specially expressed in leaf. Other members of SYP family were not found the tissue specificity.(3) MeSYP gene expression patterns between different organizations under ABA and drought stress treatments were as followings:MeSYP5and MeSYP10expression have tissue specificity and are subject to the regulation of ABA, at the same time ABA treatment activated MeSYP122in leaf and petiole; Under drought stress, expression level of MeSYP13, MeSYP121had not obviously changed in the contol, but the expression level was gradually rising through days of drought treatment. Expression level of MeSYP6was significantly raised afer drought treatment8d, and in the subsequent period of time at a higher level. These three genes might be involved in the drought stress response.(4) T1transgenic plants resulted in significant accelerated flowering compared with wild-type plants under the same growing conditions. Detected by PCR, MeSYP121gene has been integrated into the genome of Arabidopsis thaliana.Conclusion:This work established a foundation for a genome-wide study of this important gene family and the MeSYP genes mechanism for responsing drought stress in cassava.