Abstract Sugar transport is an essential physiological aspect with a crucial role in metabolism, growth and development in most living organisms. A specific class of protein (sugar transporter) is responsible for this sugar transportation task; with SWEET being one of the recently reported. Here, we used the PCR based rapid amplification of cDNA ends (RACE) technique to isolate a SWEET gene from fruits of a mutant white-flesh loquat designated as EjSWEET15. Our findings based on qRT-PCR revealed that EjSWEET15 was highly expressed in leaves and fruits. Interestingly, this expression was at a significant higher level in fruits of mutant white-flesh loquat as to that of the wild-type red-flesh loquat counterpart. EjSWEET15 presents 4 polymorphic loci in mutant of white-flesh loquat attributing to amino acid changes with one located in the promoter region and three within the open reading frame as disclosed by nucleotide polymorphism analysis. It is speculated that these differential gene expression and sequence modification may affect the enzymatic activity of EjSWEET15 and thus letting EjSWEET15to play an important role in the regulation of sugar transport in loquat.

中文翻译：

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EjSWEET15的分子克隆和表达分析，编码枇杷糖转运蛋白

摘要 糖转运是重要的生理方面，在大多数生物体的代谢、生长和发育中起着至关重要的作用。一类特定的蛋白质（糖转运蛋白）负责这种糖运输任务；SWEET 是最近报道的其中之一。在这里，我们使用基于 PCR 的 cDNA 末端快速扩增 (RACE) 技术从名为 EjSWEET15 的突变白肉枇杷的果实中分离出 SWEET 基因。我们基于 qRT-PCR 的发现表明 EjSWEET15 在叶子和果实中高度表达。有趣的是，与野生型红肉枇杷对应物相​​比，突变白肉枇杷果实中的这种表达水平显着更高。根据核苷酸多态性分析，EjSWEET15在白肉枇杷突变体中存在4个氨基酸变化引起的多态性位点，其中1个位于启动子区，3个位于开放阅读框内。推测这些差异基因表达和序列修饰可能会影响EjSWEET15的酶活性，从而使EjSWEET15在枇杷糖类转运的调控中发挥重要作用。