Practice question

Clonal selection targets crops propagated vegetatively where genotype is conserved intact through mitosis without meiosis or segregation. Examples include potato propagated via tubers, sugarcane via stem cuttings, banana via suckers, sweet potato via vine cuttings, and fruit trees via grafting and budding. These species are highly heterozygous, often polyploid, and suffer severe inbreeding depression if selfed, making seed propagation undesirable and genetically unstable. Superior clone arises via natural mutation, introduction, or hybridization followed by segregation in seedling population where only best heterotic combinations survive. Once elite genotype is identified, vegetative multiplication fixes its heterozygous gene combination indefinitely, preserving epistatic and dominance interactions that cause heterosis. Selection focuses on clonal performance across locations, virus-free status, and stability. Method does not involve gamete reshuffling after initial selection, ensuring uniformity and true-to-type propagation for commercial cultivation and market consistency. Adventitious meristem formation from differentiated tissues is regulated by auxin transport PIN proteins and cytokinin signaling ARR genes, allowing dedifferentiation and shoot organogenesis that sustains clonal propagation without sexual recombination and maintains high heterozygosity essential for horticultural quality and vigor.