铁皮石斛蔗糖合酶DoSUS2基因克隆与表达分析OA北大核心CSTPCD

Sucrose synthase family is a crucial enzyme that regulates sucrose metabolism.It catalyzes the conversion of sucrose into various metabolic pathways and plays a significant role in plant growth and development,signal transduction,stress resistance and so on.In order to explore the regulatory mechanism of sucrose synthase gene 2 from Dendrobium officinale(DoSUS2),in polysaccharide anabolism and response to abiotic stress,the DoSUS2 gene(GenBank No.OQ657188)was cloned from leaves of D.officinale using homologous sequence method,the bioinformatics and expression characteristics were analyzed.The results showed that the ORF of DoSUS2 was 2 424 bp and encoded 807 amino acids,which had 36 bases differences compared with the reference sequence(Gene ID:LOC110110417),but all of them were synonymous substitutions.The theoretical molecular weight and isoelectric point of DoSUS2 protein were 92.05 kD and 5.97,respectively.It was a hydrophobic stable protein with only one signal peptide and 69 phosphorylation sites but no transmembrane domains,which contained conserved domain with SUS protein,such as sucrose synthase and glycosyl transferase domains.Tertiary structure modeling of DoSUS2 was highly homologous with AtSUS1 of Arabidopsis thaliana(73.82%),and belongs to the SUSⅠ subgroup of monocotyledonous.The expression of DoSUS2 had obvious differences among different tissues,which were relatively high in roots and floral organs while lower in leaves and stems.The promoter element analysis revealed that DoSUS2 contained several cis-acting elements in response to stress,and it was significantly induced by cold,drought stress and abscisic acid(ABA)treatment.The expression of DoSUS2 was up-regulated significantly(P＜0.01)and peaked at 6 h after cold and ABA treatment,which reached 267 and 233 times compared with untreated.Similarly,the expression was also up-regulated accompanying with drought treatment time increased,and reached its peak at 9 h,its expression reached a extremely significant difference level significantly(P＜0.01)which was 18.6 times then untreated group.The results showed that the DoSUS2 gene might participate in the response process to low temperature and drought stress through the ABA signaling pathway.At last,an DoSUS2 protein interaction network was generated with several enzymes closely related to glucose metabolism.These findings above suggested that DoSUS2 might respond to abiotic stress by regulating the expression of related enzyme genes and glucose metabolism pathways,thereby improving the stress resistance of D.officinale.The results would provide valuable theoretical basis for the further investigations of DoSUS2 function and its molecular mechanism in polysaccharide biosynthesis and abiotic stress response.