Radiosensitivity and early-stage morpho-physiological profiling of M1V1 sweet potato (Ipomoea batatas L.) vine cuttings to different doses of gamma irradiation: breeding for mutants with virus resistance, nutritional quality, and high yield

Abstract Background Induced mutation using physical mutagens like gamma irradiation is an efficient strategy for broadening genetic diversity in vegetatively propagated polyploid crops like sweet potato ( Ipomoea batatas L. ) , where conventional breeding is constrained by high heterozygosity and self-incompatibility. This study evaluated the radiosensitivity, morpho-physiological, nutritional, and viral disease resistance responses of first vegetative generation (M 1 V 1 ) sweet potato genotypes. The experiment was conducted at Hawassa University in a screen house using a Randomized Complete Block Design (RCBD) with 20 replications. Vine cuttings of three genotypes-Hawassa-83 (white-fleshed), Alamura (orange-fleshed), and Kabode (creamy yellow-fleshed)-were exposed to gamma radiation doses of 0, 15, 25, and 35 Gy from a 60 Co source. Radiosensitivity (LD 50 /GR 50 ) was determined via probit analysis. Agronomic traits, physiological parameters (chlorophyll fluorescence [F v /F m ], and proline content), Virus disease severity (VDS), tuber number and β-carotene content were systematically recorded across growth stages up to 150 days after planting (DAP). Results Probit analysis revealed a significant, genotype-dependent sensitivity to gamma irradiation. Alamura exhibited highest radio-tolerance (LD 50 = 39.51 Gy; GR 50 = 37.56 Gy), whereas Kabode was most sensitive (LD 50 = 32.58 Gy, GR 50 = 32.49 Gy). Significant main effects and interactions were observed between genotype and dose ( P < 0.05). Low-dose hormesis was evident in tuber production; Hawassa-83 reached peak productivity at 25 Gy (6.94 tubers; a 33% increase over the control), while Alamura peaked at 25 Gy (6.35 tubers). Notably at 25 Gy, β-carotene content in Alamura increased by 68.6% (11 mg/100 g). Viral suppression correlated directly with morpho-physiological traits; baseline VDS (3.2–3.6) dropped at 35 Gy to highly resistant scores in Alamura (1.15) and Hawassa-83 (1.37). This suppression coincided with peak proline accumulation at 25 Gy in Alamura (10.35 µmol/g) and Hawassa-83 (8.3 µmol/g) alongside high photosynthetic efficiency (F v /F m = 0.78) in Alamura, prior to severe photoinhibition at 35 Gy. Multivariate analysis (Correlation, PCA, and HCA) effectively isolated multi-trait putative mutant lines. Conclusion Gamma irradiation successfully induced valuable genotype-dependent variations and low-dose hormetic benefits in sweet potato, establishing precise selection targets. Three promising multi-trait, putative M 1 V 1 mutant clones selected from Alamura (15 and 25 Gy) and Hawassa-83 (25 Gy) cohorts-were identified with concurrent enhancements in yield, β-carotene content, and virus resistance, warranting further generational advancement to confirm trait stability.