关键词: 苹果, 液泡膜蔗糖转运蛋白, SUT4, 表达分析, 功能鉴定, 亚细胞定位

Abstract:

MdSUT4 was cloned from‘Hongcui 1’apple and the recombinant protein was obtained by
the prokaryotic induction technology，then，it was analyzed using bio-information. The expression level of
MdSUT4 in different tissues and different development stages were studied by the qRT-PCR，and we also
identified the function of MdSUT4 by the subcellular localization and transgenosis. The results showed that
the molecular mass of MdSUT4 was about 55 kD，it was located in the chromosome 8 of the apple
genome，included 5 exons and 4 introns. A phylogenetic tree indicated MdSUT4，AtSUC4 and PpSUT4
were located in the same evolutionary branch. The qRT-PCR showed that the MdSUT4 has the higher expression level in flowers，leaves and young fruits of apples，and its expression had a significant negative
correlation with the content of sucrose during the development stage of fruits. The promoter of MdSUT4
contained several typical cis-acting elements ， including sugar signaling responsive elements and
phytohormone responsive elements. We overexpressed MdSUT4 in‘Orin’callus，then found that it could
increase the content of flavonoid and decrease the content of sucrose. MdSUT4 was located in the
tonoplast of‘Orin’callus. These results indicated that MdSUT4 might participate in the efflux of sucrose
from the vacuole and promote the synthesis of flavonoid.

Key words: apple, vacuolar sucrose transporter, SUT4, expression analysis, functional identification, subcellular localization