First insights into colchicine-mediated polyploidy induction in Vaccinium floribundum Kunth

Polyploidy induction represents a promising yet challenging strategy to enhance the genetic potential of Vaccinium floribundum Kunth, an Andean crop wild relative of blueberry, with high nutritional and antioxidant value. This study explored for the first time the response of nine accessions to colchicine exposure as a preliminary step toward chromosome doubling. Axillary buds were treated with aqueous colchicine at 125 and 250 mg·L⁻¹ for 24, 48, or 96 h and subsequently cultivated in vitro. A generalized linear mixed model (GLMM) revealed that colchicine concentration was the principal determinant of explant mortality (β₁₂₅ = 4.658, β₂₅₀ = 5.037, p < 0.001), whereas exposure duration and interaction terms were non-significant (p > 0.05). Random effects captured pronounced inter-accession heterogeneity (σ² = 5.351), reflecting intrinsic variability in tolerance to colchicine toxicity. Modeled mortality increased consistently with concentration, yet certain accessions such as Enca 20 retained comparatively low mortality (< 45% across treatments) and partial regenerative competence, indicating genotype-dependent resilience. Flow cytometry confirmed that all regenerated plants remained diploid, indicating that chromosome doubling was not achieved under the tested conditions. These findings establish an empirical baseline for refining chromosome-doubling protocols through optimized concentrations and the selection of tolerant genotypes.