Root vitality and protein homeostasis determine divergent strategies against autotoxicity in cassava cultivars

Autotoxic stress can disturb cassava (Manihot esculenta Crantz) endogenous hormones, thus hindering plant growth and development. However, the mechanisms by which cassava responds to autotoxic stress are still unknown. Hydroxyacetone, 2,4-di-tert-butylphenol, and acetic acid, previously confirmed as the main autotoxins, were applied in this study to simulate autotoxic stress on cassava using a tissue culture approach. Three genotypes, SC205, NZ199, and XX048, were used as plant materials. The allelopathic effects varied with genotype. Under autotoxicity stress, XX048 showed stronger negative allelopathy than SC205 and NZ199, with root length and biomass significantly reduced. Under identical stress conditions, SC205 and XX048 yielded 696 and 545 differentially expressed proteins (DEPs), respectively, which were functionally enriched in the catalytic/binding, metabolic, cellular, single‑organism, and stress‑defense categories. Cassava's defence responses to autotoxic stress appeared to be initiated by apoplastic glutathione, while salicylic acid served as the primary signalling hormone, modulating glutathione metabolism systemically. Protein-protein interaction network analysis revealed that under identical stress conditions, the two varieties shared conserved basal defences but diverged in their adaptive strategies, revealing fundamental molecular distinctions between the genotypes.