Abstract: This work aims to reveal the function of MeTPS9 gene in abiotic stresses（e.g.,drought,cold,and shade）in cassava. RT-PCR method was applied to clone MeTPS9 gene（GenBank accession number：MF276889）from cassava leaves,MEGA software to construct its phylogenetic tree,DnaSP software to analysze its structural variation,PlantCARE software to analyze its promoter cis-element,and quantitative RT-PCR（qRT-PCR）to explore its expression patterns in different tissues and in response to different abiotic stresses. Results showed that a TPS（trehalose-6-phosphate synthase）gene,MeTPS9,was cloned from cassava. This gene had a 2598-bp open reading frame,encoded 865 amino acids,and contained a TPS conserved domain. Phylogenetic analysis revealed that MeTPS9 had close genetic relationship with its homologs from Capsella grandiflora and Arabidopsis thaliana,and the sequence similarity was up to 76.2% and 75.6%,respectively. Gene structural variation demonstrated that a total of 66 mutation sites were identified between wild and cultivated cassava species,of which 11 were mis-sensed. Promoter assay showed that MeTPS9 contained drought-related motif MBS,cold-related motif LTR,heat-related motif HSE,and ABA-related motif ABRE. qRT-PCR analysis revealed that MeTPS9 expressed the highest in fibrous root but the lowest in leaf. In addition,the expression of MeTPS9 was significantly induced by drought,cold,and shade stress. MeTPS9 played a regulatory role in abiotic stress such as drought,cold,and shade treatment at the transcriptional level and it could be served as a candidate to further study its functions in abiotic stress defense in cassava.

Key words: cassava, MeTPS9, trehalose-6-phosphate synthase, structure variation, expression analysis, abiotic stress