Diversification and geographical distribution of Psidium (Myrtaceae) species with distinct ploidy levels

Abstract

Polyploidy (diploid to octoploid) was evidenced from seven Psidium species, besides the outcomes of the whole-genome duplication about the nuclear DNA content, DNA sequence, and distribution. The previous studies have reported the occurrence of polyploid species in Psidium, all deriving from the basic chromosome number x = 11, which is conserved in Myrtaceae. Here, we aimed to assess the ploidy levels of seven Psidium species and to investigate the genomic outcomes of this karyotype change. Data on chromosome number, ploidy level, nuclear DNA content, and DNA sequence (SSR markers) were sought, quantified, and compared to geographical distribution of the studied Psidium species. A euploid series based on x = 11 was evidenced, with diploid, tetraploid, hexaploid, and octoploid species. These species also differed regarding at least one of the other analyzed traits, especially the hexaploids and the octoploid in relation to the others. Diploid species show restricted geographical distribution in the Atlantic Forest, differently from the polyploid species, which occur in several biomes in Brazil. Ploidy level of the Psidium species is related with the nuclear genome size and both seems to be related with species’ geographical distribution. Besides polyploidy, the genetic changes associated with numerical chromosome shift shown in this study, which increases the knowledge about the diversification and distribution of Psidium species.