Abstract
Cassava (Manihot esculenta Crantz) storage roots exhibit significant variation in starch content among cultivars, yet the metabolic and molecular mechanisms governing carbon allocation between storage and structural components remain poorly understood. Here, we investigated carbon partitioning in two cassava cultivars with distinct starch phenotypes: high-starch FX01 and low-starch SC16. Using 13C isotope labeling coupled with metabolomic analysis, we traced the pathway of carbohydrates through primary and secondary metabolism. The results revealed that SC16 exhibits enhanced photosynthetic capacity and elevated soluble sugar content in storage roots, whereas FX01 demonstrates superior starch synthesis due to its efficient glucose and fructose phosphorylation. Conversely, SC16 exhibits a faster conversion of 13C-labeled ferulic acid, directing carbon flow towards lignin biosynthesis via the phenylpropanoid pathway. Further, by silencing the MeCOMT8 gene, encoding a key enzyme in ferulic acid biosynthesis, we observed a reduction in lignin content and an increase in ADP-glucose levels in the MeCOMT8-silenced cassava plants, suggesting a regulatory link between these competing pathways. Our research elucidated that the variations in carbon allocation between starch and lignin biosynthesis among different cultivars are finely orchestrated through the specific-step alteration of metabolic flux. These findings provide potential candidate targeted points and valuable insights for high-starch breeding in cassava.
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Data availability
Source data are provided with this paper. The numerical source data for Figs. 1b-j, 2c-e, 3b-h, 4, 5b-k, 6, 7, 8b-d, 8g-k, and 9 (bar graphs) are provided in Supplementary data 7. Metabolomics data are provided as supplementary data 1-6. Raw metabolomics data have been deposited to MetaboLights (https://www.ebi.ac.uk/metabolights/) with the dataset identifier MTBLS13541. Uncropped and unedited gel images for Fig. 8a are provided as Supplementary Fig. S10. All other data supporting the findings of this study are available in the paper and its supplementary information files. Any additional data are available from the corresponding author upon reasonable request.
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Acknowledgements
We greatly appreciate Professor Kun-Fang Cao’s revisions and valuable suggestions regarding the manuscript. This work was supported by NSFC (32160429), Guangxi Science and Technology Plan Project (Guike AD25069107) and Guangxi Natural Science Foundation, Guangxi, China (2021GXNSFDA196009).
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X.W.F. conceived and designed the study, and revised the manuscript. X.W.F. and Y.Z.L. supervised the project. J.J.X. and M.L. were responsible for drafting the manuscript, and performed the experiments with Z.C. P.C.Z. and K.H.L. conducted statistical analyses. S.T.D. executed the partial experiment of RT-qPCR. All authors reviewed and approved the final manuscript.
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Li, M., Xu, J., Cai, Z. et al. Variations in carbon flux allocation among cassava (Manihot esculenta) cultivars arise from balanced competition between starch accumulation and structural component development. Commun Biol (2026). https://doi.org/10.1038/s42003-026-09556-4
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DOI: https://doi.org/10.1038/s42003-026-09556-4
