Key message

An integrative comparative transcriptomic approach on six sugar beet varieties showing different amount of sucrose loss during storage revealed genotype-specific main driver genes and pathways characterizing storability.

Abstract

Sugar beet is next to sugar cane one of the most important sugar crops accounting for about 15% of the sucrose produced worldwide. Since its processing is increasingly centralized, storage of beet roots over an extended time has become necessary. Sucrose loss during storage is a major concern for the sugar industry because the accumulation of invert sugar and byproducts severely affect sucrose manufacturing. This loss is mainly due to ongoing respiration, but changes in cell wall composition and pathogen infestation also contribute. While some varieties can cope better during storage, the underlying molecular mechanisms are currently undiscovered. We applied integrative transcriptomics on six varieties exhibiting different levels of sucrose loss during storage. Already prior to storage, well storable varieties were characterized by a higher number of parenchyma cells, a smaller cell area, and a thinner periderm. Supporting these findings, transcriptomics identified changes in genes involved in cell wall modifications. After 13 weeks of storage, over 900 differentially expressed genes were detected between well and badly storable varieties, mainly in the category of defense response but also in carbohydrate metabolism and the phenylpropanoid pathway. These findings were confirmed by gene co-expression network analysis where hub genes were identified as main drivers of invert sugar accumulation and sucrose loss. Our data provide insight into transcriptional changes in sugar beet roots during storage resulting in the characterization of key pathways and hub genes that might be further used as markers to improve pathogen resistance and storage properties.

中文翻译：

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整合转录组学揭示了基因型对甜菜贮藏性的影响。

关键信息

对六种甜菜品种的综合比较转录组学方法显示出储存期间不同量的蔗糖损失，揭示了基因型特异性的主要驱动基因和表征储存性的途径。

抽象的

甜菜是仅次于甘蔗的最重要的糖料作物之一，约占全球蔗糖产量的 15%。由于甜菜根的加工越来越集中，因此有必要长时间储存​​甜菜根。储存过程中的蔗糖损失是制糖业的一个主要问题，因为转化糖和副产品的积累会严重影响蔗糖的生产。这种损失主要是由于持续的呼吸作用，但细胞壁组成和病原体侵染的变化也有影响。虽然有些品种在储存期间可以更好地应对，但目前尚未发现潜在的分子机制。我们对在储存过程中表现出不同程度的蔗糖损失的六个品种应用了整合转录组学。已经在存储之前，耐贮藏品种的特点是实质细胞数量较多，细胞面积较小，周皮较薄。支持这些发现，转录组学确定了参与细胞壁修饰的基因的变化。储存 13 周后，在储存良好和储存不良的品种之间检测到 900 多个差异表达基因，主要在防御反应类别中，但在碳水化合物代谢和苯丙烷途径方面也有。这些发现通过基因共表达网络分析得到证实，其中枢纽基因被确定为转化糖积累和蔗糖损失的主要驱动因素。