10th U6+ Consortium of African Universities International Conference

Gamma irradiation is a powerful mutagenic tool in plant breeding, capable of inducing a stable, broad spectrum of DNA variation and chromosomal alterations. Flow cytometry (FCM), the gold standard for nuclear DNA quantification, enables rapid detection of irradiation-induced genomic shifts. This study evaluated the cytogenomic effects of gamma irradiation on three cassava (Manihot esculenta Crantz) genotypes (CAS-1, CAS-2, CAS-3) using doses of 0–30 Gy in a factorial design. Nuclear DNA content was estimated relative to Zea mays cv. CE-777 and statistical analyses were performed using Welch ANOVA and Games–Howell post hoc tests. Distinct genotype-specific responses emerged: CAS-1 remained stable across all treatments (≤0.5% variation); CAS-2 showed modest DNA reductions at 15–25 Gy (−0.8 to −1.6%); and CAS-3 exhibited a pronounced increase at 15 Gy (+4.5%), accompanied by endoreplication peaks (2C–32C) indicative of irradiation-induced polyploidization. Welch ANOVA confirmed highly significant genotype × dose interactions (η² = 0.989), and clustering analyses separated irradiated CAS-3 nuclei into a distinct group. These findings demonstrate cassava’s genomic plasticity under mutagenic stress: CAS-1 is stable, CAS-2 is vulnerable to DNA loss, and CAS-3 is prone to expansion and altered cell cycle regulation. The study underscores the utility of FCM for detecting subtle genomic shifts and provides actionable insights for tailored gamma irradiation strategies in cassava improvement. This approach can accelerate breeding pipelines aimed at enhancing diversity and durable resistance to viral diseases, such as cassava brown streak disease.