Deciphering the Mechanisms of Cassava Response to Continuous Cropping and Drought Stress via Multi-Omics Integration

Continuous cropping (CC) and drought are major constraints on cassava production in China, though their individual and combined stress mechanisms remain unclear. A pot experiment employing a 2 × 2 × 3 factorial design was established to evaluate cassava performance under continuous cropping and drought stress. Compared to drought, CC more severely increased rhizosphere soil organic acid content, reduced pH, and diminished bacterial diversity and richness, thereby inducing negative allelopathic effects on cassava. The relative abundance of Chloroflexi and norank_c__AD3 was increased under CC treatment, a shift that potentially exacerbates soil microecological imbalance. CC-induced soil stress triggers jasmonic acid and salicylic acid accumulation, as well as MAPK-mediated defense pathways in cassava roots. Yet, this sustained immune activation incurs a heavy metabolic cost, ultimately compromising plant growth and yield. These findings offer novel insights into the mechanisms underlying cassava CC obstacles and identify potential targets for enhancing stress resilience.