Transcriptomic changes at the cessation of sugar accumulation in the pericarp of Vitis vinifera were addressed on single berries re-synchronized according to their individual growth patterns. The net rates of water, sugars and K+ accumulation inferred from individual growth and solute concentration confirmed that these inflows stopped simultaneously in the ripe berry, while the small amount of malic acid remaining at this stage was still being oxidized at low rate. Re-synchronized individual berries displayed negligible variations in gene expression among triplicates. RNA-Seq studies revealed sharp reprogramming of cell wall enzymes and structural proteins at the stop of phloem unloading, associated with an 80% repression of multiple sugar transporters and aquaporins on the plasma or tonoplast membranes, with the noticeable exception of H+/sugar symporters, that were rather weakly and constitutively expressed. This was verified in three genotypes placed in contrasted thermo-hydric conditions. The prevalence of SWEET suggests that electrogenic transporters would play a minor role on the plasma membranes of SE/CC complex and the one of the flesh, while sucrose/H+ exchangers dominate on its tonoplast. Cis-regulatory elements present in their promoters allowed to sort these transporters in different groups, also including specific TIPs and PIPs paralogs, and cohorts of cell wall related genes. Together with simple thermodynamic considerations, these results lead to propose that H+/sugar exchangers at the tonoplast, associated with a considerably acidic vacuolar pH, may exhaust cytosolic sugars in the flesh and alleviate the need for supplementary energization of sugar transport at the plasma membrane.

中文翻译：

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在韧皮部卸载停止时关闭的笔录突出显示了成熟的V. vinifera果实中糖进口的能量效率。

葡萄果皮中糖分积累停止时的转录组变化，是针对根据其个体生长方式重新同步的单个浆果进行的。由个体生长和溶质浓度推断出的水，糖和钾离子的净积累速率证实，这些流入在成熟浆果中同时停止，而在此阶段残留的少量苹果酸仍以低速率被氧化。重新同步的单个浆果在一式三份之间显示出可忽略不计的基因表达差异。RNA-Seq研究显示，在韧皮部卸荷停止时，细胞壁酶和结构蛋白会发生急剧的重新编程，这与血浆或液泡膜上多种糖转运蛋白和水通道蛋白的80％抑制相关，除了明显的H + /糖同向转运蛋白外，这些转运蛋白的表达相对较弱。这在放置在相反的热-水条件下的三种基因型中得到了验证。SWEET的流行表明，电转运蛋白将在SE / CC复合物和其中一种肉质的质膜上起次要作用，而蔗糖/ H +交换子在其液泡膜中占主导地位。存在于其启动子中的顺式调节元件允许将这些转运蛋白分到不同的组中，包括特定的TIP和PIP旁系同源物以及细胞壁相关基因的队列。结合简单的热力学考虑，这些结果表明，液泡膜中的H + /糖交换剂与明显酸性的液泡pH相关，