Is the dioecy in Myrsine (Primulaceae) defined by sex chromosomes?

• Autor(a) principal: Silva, Paulo Marcos Amaral
• Data de Publicação: 2015
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/7853
• topic: Cytogenetic; Flow cytometry; Sex chromosomes; Sex determinat; Citogenética; Citometria de fluxo; Cromossomos sexuais; Sexo - Causa e determinação; Melhoramento Vegetal; 631.523

The dioecy occurs in 6% of the angiosperms, including all the Myrsine species (Primulaceae) that show male and female individuals distinguishable based in sexual organs and morphology of sepals and petals. The sexual system fixed in this genus, was the motivation in research if the existence of sexual chromosomes culminate in dioecy for Myrsine. Employing tissue culture, flow cytometry and cytogenetic tools, the aimed this study was characterize the karyotype of Myrsine coriacea (Sw.) R.Br. ex Roem & Schult., Myrsine umbellata Mart., Myrsine guianensis (Aubl.) Kuntze and Myrsine parvifolia A.DC. From leaves of male and female individuals collected in the field and leaves and roots of unknown sex obtained of in vitro culture, were found mean values of DNA content statistically identical. These data were attributed to the presence of secondary metabolites reported for the genus. However, an intraspecific variation was observed in cytogenetic analysis in the four Myrsine species. Slides exhibited metaphases with 2n = 45 and 2n = 46 chromosomes in different individuals. These results were observed consistently from different times of exposition to anti-mitotic agent and distinct treatments of enzymatic maceration. Thus, the chromosome number variation found, associated with the sexual system well defined, can be concerning to the sexual chromosomes in Myrsine genus. These data suggest a chromosomal system of sex 9 determination with multiple X and/or Y described in some plant species. The system ZW also is possible, as well as X0 or Z0, systems still not reported in vegetal groups. The present work provided the first data about the nuclear DNA content by flow cytometry in Myrsine and supplied cytogenetics evidences that indicate the existence of sexual chromosomes.