Estudos cromossomaticos em especies de Myrtaceae Juss. no sudeste do Brasil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

Myrtaceae is one of the most representative families in southeast Brazilian vegetational formations (savanna, ?campos rupestres?, atlantic forest and deciduos forest). Given the great number of species, morphological similarities between species and occurrence in varied habitats, the family presents many taxonomic problems. Chromosomic studies in Neotropical species of Myrtaceae (Myrtoideae) are still scarce. Most of the previously accomplished studies documented Australian and African species (Leptospermoideae and Chamelaucioideae). In the Myrtoideae, it is known that poliploidy is frequent, in opposition to the remainder of the family, where disploid species predominate. These studies aimed to: 1) contribute to the chromosomic knowledge of the family, by means of the chromosomic numbers determination; 2) supply subsidies for towards the circunscription and delimitation of the species; 3) evaluate the importance of poliploidy in the evolution of the group and 4) derive inferences on the reproductive processes of the some species. The constancy of the diploid number 2n=22 (with exception of poliploids) and the small chromosome size complicated the use of the karyotypic data as subsidies to taxonomy of the Myrtaceae family. The occurrence of n=11 and 2n=22 in all species of the genera analized, doesn t clarify taxonomic doubts, such as the unification or separation of genera like Myrcia, Marlierea and Gomidesia and Myrciaria and Plinia. Poliploidy occurrence in different genera, amongst diploid species, has no value as a taxonomic character at the generic level. It was possible to verify the occurrence of chromosomic races (cytotypes), differentiated by ploidy level in several species. We observed the high frequence of poliploidy (20%), in opposite of the disploidy variations. No abnormality in the meiotic process was verified, indicating regularity of the sexual reproduction process

ASSUNTO(S)

cromossomos poliploide myrtaceae

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