Esterase Polymorphism and the Analysis of Genetic Diversity and Structure in Cactus Populations Descended from Cereus peruvianus Plants Regenerated In Vitro

摘要

The genetic structure of Cereus peruvianus populations descended from cultivated plants (F₁ populations) and from plants regenerated in vitro (R₁ populations) was analyzed using α- and β-esterase isozymes in native PAGE. The estimated proportion of polymorphic loci was higher (50%) in the R₁ populations than the F₁ populations (42.85%). The mean observed (0.5599) and expected (0.5620) heterozygosity in R₁ descendents was also higher than the rates in F₁ descendents (H _o = 0.4142; H _e = 0.4977). A low level of population differentiation was detected in R₁ descendents (F _st = 0.05). In contrast, population differentiation was high in F₁ descendents (0.2583). Esterase analysis using PAGE showed that artificial selection by silvicultural management provides high genetic diversity and a large genetic basis for C. peruvianus, whereas in vitro selection from callus tissue culture involves an increase of heterozygosity levels in descendents from somaclones and a low level of interpopulational divergence.