Data_Sheet_1_Proteomics Reveals an Increase in the Abundance of Glycolytic and Ethanolic Fermentation Enzymes in Developing Sugarcane Culms During Sucrose Accumulation.zip

Sugarcane is an economically important crop contributing to the sugar and ethanol production of the world with 80 and 40%, respectively. Despite its importance as the main crop for sugar production, the mechanisms involved in the regulation of sucrose accumulation in sugarcane culms are still poorly understood. The aim of this work was to compare the quantitative changes of proteins in juvenile and maturing internodes at three stages of plant development. Label-free shotgun proteomics was used for protein profiling and quantification in internodes 5 (I5) and 9 (I9) of 4-, 7-, and 10-month-old-plants (4M, 7M, and 10M, respectively). The I9/I5 ratio was used to assess the differences in the abundance of common proteins at each stage of internode development. I9 of 4M plants showed statistically significant increases in the abundance of several enzymes of the glycolytic pathway and proteoforms of alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC). The changes in content of the enzymes were followed by major increases of proteins related to O2 transport like hemoglobin 2, ROS scavenging enzymes, and enzymes involved in the ascorbate/glutatione system. Besides, intermediates from tricarboxylic acid cycle (TCA) were reduced in I9-4M, indicating that the increase in abundance of several enzymes involved in glycolysis, pentose phosphate cycle, and TCA, might be responsible for higher metabolic flux, reducing its metabolites content. The results observed in I9-4M indicate that hypoxia might be the main cause of the increased flux of glycolysis and ethanolic fermentation to supply ATP and reducing power for plant growth, mitigating the reduction in mitochondrial respiration due to the low oxygen availability inside the culm. As the plant matured and sucrose accumulated to high levels in the culms, the proteins involved in glycolysis, ethanolic fermentation, and primary carbon metabolism were significantly reduced.

甘蔗是全球重要的经济作物，分别为全球食糖与乙醇生产贡献80%和40%的原料占比。尽管其作为食糖主栽作物的地位举足轻重，但甘蔗茎秆中蔗糖积累的调控机制仍不甚明晰。本研究旨在比较植株三个发育阶段下幼嫩与成熟节间的蛋白质组定量变化。本研究采用无标记鸟枪蛋白质组学（Label-free shotgun proteomics）技术，对4月龄、7月龄和10月龄甘蔗植株（分别记为4M、7M、10M）的第5节间（I5）与第9节间（I9）进行蛋白质谱分析与定量检测。以I9/I5的丰度比值，评估各节间发育阶段中共有蛋白质的丰度差异。4M植株的I9节间中，糖酵解通路的多种酶类、乙醇脱氢酶（alcohol dehydrogenase, ADH）以及丙酮酸脱羧酶（pyruvate decarboxylase, PDC）的蛋白亚型丰度均出现统计学显著上调。紧随这些酶类含量变化的是，与氧气运输相关的蛋白（如血红蛋白2）、活性氧（reactive oxygen species, ROS）清除酶类，以及抗坏血酸/谷胱甘肽系统相关酶类的丰度显著升高。此外，4M植株I9节间中的三羧酸循环（tricarboxylic acid cycle, TCA）中间代谢物含量降低，这表明糖酵解、戊糖磷酸循环与TCA通路相关酶类的丰度提升，可能推动了更高的代谢流，进而导致其代谢物含量下降。4M植株I9节间的研究结果表明，低氧胁迫可能是糖酵解与乙醇发酵通量提升的主要诱因，该过程可为植株生长提供ATP与还原力，同时缓解因茎秆内部氧气含量不足导致的线粒体呼吸作用减弱。随着植株成熟、茎秆中蔗糖积累至高水平，糖酵解、乙醇发酵与初级碳代谢相关的蛋白质丰度均显著下调。