Recurrent Origin and Different Lineages of Ploidy in Solanum elaeagnifolium

CHIARINI, F.; SCALDAFERRO, M.; ACOSTA, M. C.

Foz do Iguaçu

Congreso; 21st International Chromosome Conference; 2016

Polyploidy has played a major role in the evolution of many eukaryotes. Up to know, most polyploid species studied, both plant and animal, have been recurrently formed from different progenitor populations. Solanum elaeagnifolium (Solanaceae) is a weedy species which invades several areas around the world, being North America its probable center of origin. It exhibits an euploid series (2x, 4x and 6x) for populations growing spontaneously in Argentina, while only diploids were found in the rest of the world. In Argentina the distribution pattern of S. elaeagnifolium ploidy is probably a response to environmental conditions, although historical factors have not been considered to date. Phylogeographic studies could make a significant contribution interpreting the origin and timing of polyploidy. Here, we wonder if polyploidy has multiple origins from diploid populations in S. elaeagnifolium. Chromosome counts and sequencing of two chloroplast non-coding regions were carried out in individuals from 18 populations of the species along the entire range of Argentina and from other countries. The haplotype network configuration resulted in two main lineages that were not geographically structured. One group comprises all hexaploid populations studied and some tetraploid samples apparently derived from hexaploids. The other group includes the diploid populations (embracing those from probable center of origin) and its derivate tetraploids. According to these results we concluded that in S. elaeagnifolium, tetraploids have been formed recurrently (from diploid or hexaploid progenitors), although is noticeable that hexaploids have had a different and older origin, considering the high number of mutational steps found between the two lineages.