Abstract:

Semi-quantitative RT-PCR technique were used to reveal the expression patterns of MdSUPs in leaf buds，young leaves，flower buds，unopened flowers，flowers，bark tissue and young fruits of Malus × domestica Borkh.‘Fuji’. Expression of GUS driven by MdSUP3 native promoter and ectopic over-expression of the MdSUP3 gene were adopted to analyze the function of this gene. The results showed that the expressions of MdSUP3，MdSUP11 and MdSUP9a were detected in all tested tissues. MdSUP9b mainly expressed in vegetative organs，while MdSUP5a and MdSUP1b mainly expressed in reproductive organs. The GUS expression was observed mainly in roots，young leaves，young stems and flower organs in the transgenic Arabidopsis. Over expression of MdSUP3 in tobacco induced morphological changes，such as dwarfism，shortened internodes，curly leaves，changed flower color and abnormal floral organs. The expression levels of the NtNCED3-2 related to ABA biosynthesis and NtDFR2and NtANS1 related to anthocyanin biosynthesis were significantly increased while NtCKX（cytokinin oxidase/dehydrogenase）and a gibberelin 2-oxidase gene NtGA2ox4 were significantly decreased in the transgenic tobacco plants compared to that in the wild types. Over-expression of the MdSUP3 without the DLELRL motif did not generated morphological changes in transgenic tobacco plants，which indicated that DLELRL motif was essential for the function of MdSUP3.

Key words: Malus ×, domestica, SUPERMAN gene family, tissue-specific expression, MdSUP3, ectopic expression