A coordinated switch in sucrose and callose metabolism enables enhanced symplastic unloading in potato tubers

• Published in: Quantitative plant biology 2024, Vol.5, p.e4-e4, Article e4
• Main Authors: van den Herik, Bas, Bergonzi, Sara, Li, Yingji, Bachem, Christian W, Ten Tusscher, Kirsten H
• Format: Article
• Language: English
• Subjects: Callose; Efficiency; Energy metabolism; Energy storage; Gene expression; Genes; Homeostasis; Metabolism; Microscopy; Original; Phylogenetics; potato; Potatoes; Sucrose; Tubers; Unloading
• ISSN: 2632-8828; 2632-8828
• DOI: 10.1017/qpb.2024.4

One of the early changes upon tuber induction is the switch from apoplastic to symplastic unloading. Whether and how this change in unloading mode contributes to sink strength has remained unclear. In addition, developing tubers also change from energy to storage-based sucrose metabolism. Here, we investigated the coordination between changes in unloading mode and sucrose metabolism and their relative role in tuber sink strength by looking into callose and sucrose metabolism gene expression combined with a model of apoplastic and symplastic unloading. Gene expression analysis suggests that callose deposition in tubers is decreased by lower callose synthase expression. Furthermore, changes in callose and sucrose metabolism are strongly correlated, indicating a well-coordinated developmental switch. Modelling indicates that symplastic unloading is not the most efficient unloading mode per se. Instead, it is the concurrent metabolic switch that provides the physiological conditions necessary to potentiate symplastic transport and thereby enhance tuber sink strength .