To examine the physiological role of hexose transporters in determining the sink strength of individual fruits, the regulation of hexose transporters gene expression was studied when the sink/source ratio was artificially altered under the greenhouse condition; this was done in two cultivars of tomato, i.e., 'Grandella' and 'Isabella'. The sink/source ratio treatments included: saving one fruit per truss (1F), two fruits per truss (2F), three fruits per truss (3F), and no fruit pruning (control). The results showed that fruit thinning could increase starch, sucrose and hexose contents in the fruits; it could also modulate the activity of the key enzymes and the expression of tomato hexose transporter genes (LeHTs). Based on the relative transcript levels, all examined LeHTs were unregulated at the end of cell division and the cell expansion stage of fruit development, but the strongest expression level observed at the onset of ripening was related to LeHT1 and LeHT2. Given the concomitancy of cell wall invertase (EC 3.2.1.26) activity and the LeHTs relative expression cell wall, invertase activity seemed to be involved in the expression level of LeHTs. The increased trends of the LeHTs expression with the decrease of the sink/source ratio confirmed the role of hexose transporters in determining the sink strength of the tomato fruits. This article is protected by copyright. All rights reserved.

中文翻译：

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减少的汇/源比增强了温室番茄果实中的己糖转运：基因表达和生化分析的整合

为了检验己糖转运蛋白在决定单个果实库强度中的生理作用，研究了在温室条件下人为改变库/源比时己糖转运蛋白基因表达的调控；这是在两个番茄品种中完成的，即“Grandella”和“Isabella”。汇源比处理包括：每个桁架（1F）保存一个水果，每个桁架保存两个水果（2F），每个桁架保存三个水果（3F），以及不修剪水果（对照）。结果表明疏果可提高果实中淀粉、蔗糖和己糖的含量；它还可以调节关键酶的活性和番茄己糖转运蛋白基因 (LeHTs) 的表达。基于相对转录水平，所有检测到的 LeHT 在细胞分裂末期和果实发育的细胞扩张阶段均不受调控，但在成熟开始时观察到的最强表达水平与 LeHT1 和 LeHT2 相关。鉴于细胞壁转化酶 (EC 3.2.1.26) 活性和 LeHTs 相对表达细胞壁的伴随，转化酶活性似乎与 LeHTs 的表达水平有关。LeHTs 表达随库/源比降低的增加趋势证实了己糖转运蛋白在决定番茄果实库强度中的作用。本文受版权保护。版权所有。26) 活性和 LeHTs 相对表达细胞壁，转化酶活性似乎与 LeHTs 的表达水平有关。LeHTs 表达随库/源比降低的增加趋势证实了己糖转运蛋白在决定番茄果实库强度中的作用。本文受版权保护。版权所有。26) 活性和 LeHTs 相对表达细胞壁，转化酶活性似乎与 LeHTs 的表达水平有关。LeHTs 表达随库/源比降低的增加趋势证实了己糖转运蛋白在决定番茄果实库强度中的作用。本文受版权保护。版权所有。