Variable but Inheritable: Colchicine-Induced Polyploidy in Phaseolus vulgaris Generates Physiological Variability with Limited Inheritance

Abstract

Polyploidy is widely used in plant breeding to increase phenotypic variation and potentially improve stress-related traits; however, its effects in common bean remain poorly characterized. Here, colchicine-induced polyploidy was evaluated in Phaseolus vulgaris cv. Zorzal to determine whether tetraploid lines exhibit coordinated changes in stomatal anatomy, physiology, pigment composition, oxidative balance, and ploidy inheritance. Polyploidy was induced using different colchicine exposure regimes and confirmed by flow cytometry. Stomatal traits, gas-exchange parameters, photosynthetic pigments, oxidative stress markers, antioxidant capacity, and multivariate phenotypic relationships were subsequently analyzed in confirmed tetraploid lines. Colchicine treatments successfully generated tetraploid and mixoploid plants, although induction efficiency was highly variable among replicates. Tetraploid lines showed heterogeneous physiological responses, including increases in the photosynthetic rate and stomatal conductance in some genotypes, but no consistent reduction in stomatal pore area index. Pigment composition and antioxidant-related traits also varied among lines, without a uniform response pattern. Multivariate analyses revealed coordinated but highly divergent phenotypic profiles among tetraploid genotypes. Importantly, the induced tetraploids were not stably transmitted to the C1 generation, with a predominance of diploid progeny among the evaluated offspring. Overall, colchicine-induced polyploidization generated substantial physiological variability among independently derived tetraploid plants of P. vulgaris cv. ‘Zorzal’; however, the predominance of diploid individuals among the evaluated C1 progeny indicates limited transmission of the induced tetraploid state to the subsequent generation.