Table_5_Transcriptomic and metabolomic changes in postharvest sugarbeet roots reveal widespread metabolic changes in storage and identify genes potentially responsible for respiratory sucrose loss.xlsx

Endogenous metabolism is primarily responsible for losses in sucrose content and processing quality in postharvest sugarbeet roots. The genes responsible for this metabolism and the transcriptional changes that regulate it, however, are largely unknown. To identify genes and metabolic pathways that participate in postharvest sugarbeet root metabolism and the transcriptional changes that contribute to their regulation, transcriptomic and metabolomic profiles were generated for sugarbeet roots at harvest and after 12, 40 and 120 d storage at 5 and 12°C and gene expression and metabolite concentration changes related to storage duration or temperature were identified. During storage, 8656 genes, or 34% of all expressed genes, and 225 metabolites, equivalent to 59% of detected metabolites, were altered in expression or concentration, indicating extensive transcriptional and metabolic changes in stored roots. These genes and metabolites contributed to a wide range of cellular and molecular functions, with carbohydrate metabolism being the function to which the greatest number of genes and metabolites classified. Because respiration has a central role in postharvest metabolism and is largely responsible for sucrose loss in sugarbeet roots, genes and metabolites involved in and correlated to respiration were identified. Seventy-five genes participating in respiration were differentially expressed during storage, including two bidirectional sugar transporter SWEET17 genes that highly correlated with respiration rate. Weighted gene co-expression network analysis identified 1896 additional genes that positively correlated with respiration rate and predicted a pyruvate kinase gene to be a central regulator or biomarker for respiration rate. Overall, these results reveal the extensive and diverse physiological and metabolic changes that occur in stored sugarbeet roots and identify genes with potential roles as regulators or biomarkers for respiratory sucrose loss.

内源代谢主要导致收获后甜菜根中蔗糖含量和加工质量的损失。然而，负责此代谢及其转录调控的基因却鲜为人知。为了识别参与收获后甜菜根代谢及其转录调控的基因和代谢途径，本研究对收获时及在5°C和12°C条件下储存12天、40天和120天的甜菜根转录组和代谢组进行了分析，并确定了与储存时间或温度相关的基因表达和代谢物浓度变化。在储存过程中，8656个基因，即所有表达基因的34%，以及225种代谢物，即检测到的代谢物的59%，其表达或浓度发生了改变，这表明储存的根中存在广泛的转录和代谢变化。这些基因和代谢物参与了广泛的细胞和分子功能，其中碳水化合物代谢是归类基因和代谢物数量最多的功能。由于呼吸作用在收获后代谢中起着核心作用，并且是甜菜根中蔗糖损失的主要原因，因此识别了参与和与呼吸作用相关的基因和代谢物。在储存过程中，75个参与呼吸作用的基因表现出差异表达，包括两个与呼吸速率高度相关的双向糖转运蛋白SWEET17基因。加权基因共表达网络分析识别出1896个与呼吸速率呈正相关的额外基因，并预测丙酮酸激酶基因是呼吸速率的中心调节因子或生物标志物。总的来说，这些结果揭示了储存甜菜根中发生的广泛而多样的生理和代谢变化，并确定了具有作为呼吸蔗糖损失调节因子或生物标志物潜在作用的基因。