Journal of Integrative Agriculture ›› 2023, Vol. 22 ›› Issue (3): 762-775.DOI: 10.1016/j.jia.2022.09.012

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JIA-2022-0593 苹果细胞质膜蔗糖转运蛋白MdSUT2.1的功能分析

  

  • 收稿日期:2022-05-09 接受日期:2022-07-26 出版日期:2023-03-20 发布日期:2022-09-10

Functional analysis of MdSUT2.1, a plasma membrane sucrose transporter from apple

ZHANG Bo1, 2, FAN Wen-min1, ZHU Zhen-zhen1, 2, WANG Ying1, ZHAO Zheng-yang1, 2#   

  1. 1 State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, P.R.China

    2 Shaanxi Research Center of Apple Engineering and Technology, Yangling 712100, P.R.China

  • Received:2022-05-09 Accepted:2022-07-26 Online:2023-03-20 Published:2022-09-10
  • About author:ZHANG Bo, E-mail: zhangboywzq@163.com; #Correspondence ZHAO Zheng-yang, Tel: +86-29-87082922, E-mail: zhaozy@nwsuaf.edu.cn
  • Supported by:
    This work was supported by the earmarked fund for China Agriculture Research System (CARS-27).

摘要:

糖含量决定着苹果甜度,然而苹果果实中蔗糖积累的分子机制仍然难以捉摸。本文报道了蔗糖转运蛋白MdSUT2.1在苹果果实蔗糖积累调控中的作用。MdSUT2.1基因编码一种由612个氨基酸残基构成的蛋白质。当在烟叶原生质体中表达时,该蛋白质定位于细胞质膜。MdSUT2.1在果实中高表达并与果实发育过程中的蔗糖积累呈正相关。此外,MdSUT2.1的蔗糖转运活性通过酵母突变体的生长互补实验得到验证。与WT相比,在苹果和番茄中过表达MdSUT2.1导致蔗糖、果糖和葡萄糖含量显着增加。进一步分析表明,与WT相比,过表达MdSUT2.1的苹果和番茄中糖代谢和转运相关基因SUSYsNINVsFRKsHXKsTSTs的表达水平均提高。与液泡膜糖转运蛋白MdTST1MdTST2不同,MdSUT2.1的启动子不能被外源糖诱导。这些发现为苹果果实糖分积累的分子机制提供了有价值的见解。

Abstract:

Sugar content is a determinant of apple (Malus×domestica Borkh.) sweetness.  However, the molecular mechanism underlying sucrose accumulation in apple fruit remains elusive.  Herein, this study reported the role of the sucrose transporter MdSUT2.1 in the regulation of sucrose accumulation in apples.  The MdSUT2.1 gene encoded a protein with 612 amino acid residues that could be localized at the plasma membrane when expressed in tobacco leaf protoplasts.  MdSUT2.1 was highly expressed in fruit and was positively correlated with sucrose accumulation during apple fruit development.  Moreover, complementary growth assays in a yeast mutant validated the sucrose transport activity of MdSUT2.1.  MdSUT2.1 overexpression in apples and tomatoes resulted in significant increases in sucrose, fructose, and glucose contents compared to the wild type (WT).  Further analysis revealed that the expression levels of sugar metabolism- and transport-related genes SUSYs, NINVs, FRKs, HXKs, and TSTs increased in apples and tomatoes with MdSUT2.1 overexpression compared to WT.  Finally, unlike the tonoplast sugar transporters MdTST1 and MdTST2, the promoter of MdSUT2.1 was not induced by exogenous sugars.  These findings provide valuable insights into the molecular mechanism underlying sugar accumulation in apples.

Key words: apple , MdSUT2.1 , sugar , transport , plasma membrane