Chromosome studies in species of Eugenia, Myrciaria and Plinia (Myrtaceae) from south-eastern Brazil

Abstract

The chromosome numbers of Brazilian species of Myrtaceae were reassessed in the context of chromosomal evolution in fleshy-fruited Myrteae. The chromosome numbers of 14 species of Eugenia, three of Myrciaria and two of Plinia were determined, 14 of which had not been published before. In Eugenia, a diploid state (2n = 22) was found in nine species, polyploid (2n = 33 or 2n = 44) in three species, and both diploid and polyploid cytotypes in another three species. The percentage of Eugenia species with a known chromosome number increased from 19 to 31 species, 22.6% of which were polyploid (3 triploid, 1 tetraploid and 3 hexaploid) and a further 16.1% either dysploid from the triploid level or had both diploid and polyploid races, giving a total of 38.7% in which polyploidy is recorded. In Myrciaria (3 species) and Plinia (2 species), the chromosome number was 2n = 22, with no polyploidy known in these genera. The results reinforce the previous indications that polyploidy is of great importance in the evolution of fleshy-fruited Myrteae.