关键词: 菊花, 切花菊, 异戊烯基转移酶基因IPT, 亚细胞定位, 组织特异性表达, 过表达

Abstract: Branching is a limiting factor in highly effective production of Chrysanthemum. It is known that isopentenyl transferase is the key enzyme which catalyzes cytokinin biosythesis in plants. Here，we isolated full length cDNA of DgIPT3，a gene encoding isopentenyl transferase in Chrysanthemum using RACE. The DgIPT3 is 1 171 bp in length and its ORF encodes 331 amino acids.GenBank accession No. JQ711176. Phylogenetic analysis showed that DgIPT3 had the highest similarity withPtXP02321061 from Populus trichocarpa. qRT-PCR indicated that expression level of DgIPT3 in leaves is much higher than roots and stems，suggesting that expression pattern of DgIPT3 was organ-specific in Chrysanthemum. The DgIPT3 protein was located in cytoplasm by transient expression of DgIPT3 in mesophyll protoplast of Arabidopsis. Overexpression of DgIPT3 obviously increased the number of rosette branches in Arabidopsis，indicating that DgIPT3 is probably the key gene involved in branching of Chrysanthemum.

Key words: Chrysanthemum, cut chrysanthemum, DgIPT3, isopentenyl transferases gene, subcellular localization, organ-specific pattern, overexpression