Determination of proper gamma radiation dose in mutation breeding of M×M60 (Prunus mahaleb × P. avium) concerning dwarfness induction

Abstract

This study evaluates the effects of acute and chronic γ-ray irradiation on M × M60 cherry rootstock to optimize mutation breeding for dwarfing traits. To determine the median lethal dose (LD₅₀), median growth reduction dose (GR₅₀), and associated LD_25,75, GR₂₅,₇₅ values, we exposed in vitro shoot cultures of M × M60 cherry rootstock to varying doses of γ-ray radiation (10, 20, 30, 40, 50, or 60 Gy). Lethal dose was estimated (with R² > 0.92) 23.54 Gy for LD₂₅, 38.64 Gy for LD₅₀, and 53.38 Gy for LD₇₅, respectively. Despite the stimulatory impacts of low dose (10 Gy) irradiation on shoot number (SN) in M₁V₁ and rooting traits in M₁V₄ generations, the recorded values for these traits were hampered with increasing γ-ray doses, as well. According to the radio-sensitivity analysis based on SL, HSL, LN and FW, GR₂₅ (11.49–17.79 Gy), GR₅₀ (26.26–31.15 Gy), and GR₇₅ (41.03–45.38Gy) were obtained. Results also indicated the effectiveness of γ-ray irradiation on stem length and internode distance reduction of the two-year-old acclimatized mutants in greenhouse conditions from respective 63.60 cm and 2.20 cm in the control to 20.52 cm and 0.98 cm in the irradiated mutants with 50 Gy. The results of this study demonstrate the potential of in vitro mutagenesis as a promising tools for developing M × M60 cherry rootstocks with reduced vigor, which could have significant benefits for orchard management.