congresos y reuniones científicas
Phylogeny and chromosome evolution in Jaborosa (Solanaceae)
Congreso; IV Simposio Latinoamericano de Citogenética y Evolución; 2013
Institución organizadora:
Sociedade Brasileira Genética
Jaborosa is a genus of Solanaceae exclusive of southern South America. It comprises 23 species that inhabit the Andean zone from southern Peru to southernmost Patagonia, with the exception of two species, which grow in the basins of the Paraná and Uruguay rivers. The genus shows a remarkable variation in life forms and specially in floral traits (morphology, corolla colour and chemical composition of the scent). Classic cytological investigations demonstrated that Jaborosa have evolved at the diplod level, keeping 2n = 24, but developing different number of satellites and karyotype formulae. Within the phylogenetic context of the Solanaceae, Jaborosa is closely related to Nolana and Lycium, but a complete phylogeny of the genus is lacking. With the aims of clarify the phylogenetic relationships among the species of Jaborosa, and to study the evolution of different cytogenetic characters, we performed the following analyses: 1) A molecular phylogeny based on four plastid spacer regions (trnH-pbsA, trnDGUC-trnTGGU, rpl32- trnLUAG, ndhF-rpl32) and the nuclear GBSSI waxy gene 2) CMA/DAPI chromosome banding and fluorescent in situ hybridization with probes for the 18-5.8-26S and the 5S rDNA genes in mitotic chromosomes. Our results strongly supported the monophyly of the genus with two principal clades: one grouping the three species that mainly grow in eastern and western lowland areas and clearly exhibit floral traits associated with pollination by nocturnal hawkmoths, and a second clade grouping the rest of the species distributed in Patagonia steppe and the Andes Range. Regarding CMA/DAPI bands and rDNA sites, no evolutionary trend can be clearly inferred, since the number and position of these markers (on the chromosome and respect to one another) notably differed among species, suggesting they are subject of dynamic changes and evolve fastly. The combination of CMA/DAPI bands and rDNA sites showed to be useful as species/specific markers, evidencing recurrent chromosome rearrangements (e.g. duplications, deletions, transposition events). Minor sites could also have been added/deleted through non homologous unequal crossing-over. Financial support: CONICET, ANPCyT, UNC.