Colchicine-Induced Polyploidy in Edible Cactus [Opuntia ficus-indica (L.) Mill.]: Impact on Biological Traits and Bioactive Compound Accumulation

Opuntia ficus-indica (OFI) is a cactus species of considerable economic importance in agriculture and various nutritional applications. We aimed to establish a feasible method for polyploid induction in OFI using colchicine treatment, as well as to identify and characterize the resulting polyploid plants. Diploid cladodes were treated with 0.5% and 1.0% colchicine for 24 or 48 h to induce polyploidization. The results demonstrated that colchicine concentration and exposure duration influenced tetraploid induction, leading to statistically significant differences (p < 0.05) in cladode size, shoot proliferation, and stomatal guard cell length and density. Higher concentrations of colchicine resulted in larger cladode dimensions and expanded guard cell sizes, along with increased shoot sprouting. In contrast, prolonged exposure durations caused reduced cladode dimensions and lower plant survival rates. Among the tested treatments, 1.0% colchicine for 48 h produced pronounced morphological responses, including increased cladode growth and reduced spine-to-spineless phenotype, although this treatment was also associated with reduced plant survival. Furthermore, induced tetraploid plants exhibited treatment-dependent increases in bioactive compounds and antioxidant activities. Specifically, 0.5% colchicine for 24 h yielded the highest total flavonoid content and antioxidant capacities (DPPH and FRAP), whereas 1.0% colchicine for 48 h significantly enhanced total phenolic content compared to control plants. Overall, the results indicate that colchicine-induced polyploidization can generate OFI variants with altered morphological characteristics and treatment-dependent bioactive profiles, providing potential breeding material for further evaluation.