Abstract: To reveal the roles of MeNCED3 gene in abiotic stresses（e.g.,drought）in cassava. RT-PCR method was applied to clone MeNCED3 gene from cassava leaves,MEGA software was used to construct its phylogenetic tree,DnaSP software was used to analysis its structural variation,and quantitative RT-PCR（qRT-PCR）was used to explore its expression patterns in response to different abiotic stresses. Results showed that a NCED（9-cis-epoxycarotenoid dioxygenase）gene,MeNCED3,was cloned from cassava. This gene had a 1 803 bp open reading frame,encoded 600 amino acids,and contained a NCED conserved domain. Phylogenetic analysis showed that MeNCED3 had close genetic relationship with its homologs from Populus trichocarpa and Salix purpurea,and the sequence similarity was up to 83.9% and 82.5%,respectively. Genetic structural variation revealed that a total of eight mis-sense mutations were identified between wild and cultivated cassava species,of which five may be associated with the different expression levels of MeNCED3. qRT-PCR analysis revealed that MeNCED3 expression was higher in roots than in leaves and stems. In addition,the expression of MeNCED3 was significantly induced by PEG,ABA and NaCl treatments. MeNCED3 played a regulatory role in both salt and osmotic stresses at the transcriptional level and it could be served as a candidate to further study its functions in drought resistance in cassava.

Key words: cassava, MeNCED3, clone, structure variation, expression analysis