Variabilidade Isoenzimática em Populações Naturais de Espinheira-Santa Maytenus aquifolia Mart. e M. ilicifolia Mart. ex Reiss e suas Implicações para o Manejo da Conservação

Brazilian medicinal plant species form a very heterogeneous group, which has been very little studied, especially concerning its genetic diversity. There is a growing interest in those species, due to the perspectives of their exploration Through cultivation or sustainable management. Two tree species, called 'espinheira-santa Maytenus aquifolia Mart. and M. ilicifolia Mart ex Reiss are traditionally used in Brazil and contain active principles the efficacy of which has been proved. Most of the leaf material obtained from those species is still collected from wilderness areas. There is a need to understand its ecological and genetic features in order to establish sound measures of conservation and management of their habitats. In this paper the isozymic diversity of five natural populations of Maytenus aquifolia and one of M. ilicifolia are investigated. Some of the genetic diversity indices and the variation in allele frequencies were obtained. Ten isozymic loci were assayed, while eight were polimorphic for at least one population (Pgi1, Pgi2. Prx1, 6-Pgdh2, Mdh1. Mdh2. Acp1. Lap1. X Est1). A total of 32 alleles was found, 31 of which occurred in the populations of M. aquifolia while 22 occurred in the M. ilicifolia population. Polimorphism was from 40% to 70%, and the number of alleles per locus varied between 1.60 to 2.70 in Caetetus and Saibadela, respectively, both extreme populations in terms of the amount of variability. The observed heterozigosity varied between 0.10 to 0.21 in Caetetus and Saibadela, the gene diversity (H) varying between 0.20 and 0.33 in the same conditions. M. ilicifolia population seemed to be philogenetically very close to M. aquifolia, since they share the majority of the alleles. Populations appear to differ significantly in their allele frequencies, there being detected several alleles peculiar to a single population. Because of that, it is suggested that it would be more advisable to conserve a larger number of populations instead of more individuals coming from a smaller number of populations, in order to conserve the genetic diversity for future generations of those species.