Abstract

The plant SWEET (Sugars Will Eventually be Exported Transporters) proteins, as newly discovered sugar transporters, play various important roles during plant depending on the transmembrane gradient of sugar concentration. SWEET17 protein is one of the SWEET family members transporting fructose in particular. In this study, we identified eight SWEET17s from six loquats (Eriobotrya japonica (Thunb.) Lindl.) cultivars and named them as Ej_NHB_SWEET17, Ej_BL_SWEET17a, Ej_ZH_SWEET17, Ej_MM-_SWEET17a, Ej_MM_SWEET17b, Ej_BL_SWEET17b, Ej_GY_SWEET17 and Ep_LY_SWEET17. All of the eight loquat SWEET17s have five to six transmembrane structures. Phylogenetic analysis indicated that Ej_NHB_SWEET17 had the farthest genetic relationship with other seven loquat SWEET17s, indicating that ‘Ninghaibai’ cultivar was far away from the other five loquat varieties possibly. The similarities of nucleotide and amino acid sequences between Ej_NHB_SWEET17 and the other loquat SWEET17s were only about 61 and 46%, respectively, while that among other seven SWEET17s were greater than 90%. The expression levels of loquat SWEET17s in leaves were positively correlated with the content of fructose, sorbitol and total sugar in various fruit from the six cultivars, in which the sugar contents in fruits of different cultivars varied significantly, that was probably related to expression levels of loquat SWEET17. Our results indicated that the expression level of loquat SWEET17s was probably related to the regulation of sugar contents of mature fruit, experimental confirmation needs to be performed. Together, these results indicated that EjSWEET17s possibly played important roles in the sugar accumulation of fruit, which could serve as the basis for further functional identification of such genes.

中文翻译：

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六个Lo品种八个SWEET17基因的分离与比较

摘要

作为新发现的糖转运蛋白，植物SWEET（糖最终将是出口转运蛋白）蛋白在植物生长过程中扮演着各种重要角色，具体取决于糖浓度的跨膜梯度。SWEET17蛋白是特别运输果糖的SWEET家族成员之一。在这项研究中，我们确定了八个SWEET17s从六个枇杷（枇杷叶（藤）石斛）品种和命名他们为Ej_NHB_SWEET17，Ej_BL_SWEET17a，Ej_ZH_SWEET17，Ej_MM-_SWEET17a，Ej_MM_SWEET17b，Ej_BL_SWEET17b，Ej_GY_SWEET17和Ep_LY_SWEET17。八个lo SWEET17全部具有五到六个跨膜结构。系统发育分析表明Ej_NHB_SWEET17曾与其他七个枇杷最远的亲缘关系SWEET17s，表明“宁海白”品种是远离其他五个品种枇杷可能。Ej_NHB_SWEET17与其他loSWEET17之间的核苷酸和氨基酸序列相似性分别仅为61％和46％，而其他七个SWEET17之间的相似性则大于90％。quaSWEET17的表达水平叶片中的s与六个品种中各种水果中果糖，山梨糖醇和总糖的含量呈正相关，其中不同品种水果中的糖含量变化显着，这可能与loSWEET17的表达水平有关。我们的结果表明loSWEET17s的表达水平可能与成熟果实糖含量的调节有关，需要进行实验确认。总之，这些结果表明，EjSWEET17s可能在水果糖的积累中起重要作用，这可以作为进一步鉴定此类基因的基础。