Isolation and characterization of microsatellite markers for Passiflora contracta.

Passiflora contracta Vitta (Passifloraceae) is an endemic species of the Atlantic Rainforest, one of the most species-rich ecoregions in the world, although extremely endangered. We have developed an enriched microsatellite library in order to fine-scale studies of the genetic structure of P. contracta. Twelve pairs of microsatellite primers were designed, and seven loci were successfully amplified and characterized by genotyping two wild populations of P. contracta. All seven loci were polymorphic, with an average number of alleles found being 4.8 and 5 per population. The cross-species transferability was tested using sister species Passiflora ovalis Vell. Ex Roemer. The development of these markers will contribute to the studies of population genetics in P. contracta as well as future studies concerning diversity patterns in the Atlantic Rainforest, and may also help to establish strategies for the conservation of this species.

Isolation, characterization, and cross-amplification of microsatellite markers for the Petunia integrifolia (Solanaceae) complex.

PREMISE OF THE STUDY: Microsatellite markers were developed for Petunia integrifolia subsp. depauperata with an intent to clarify taxonomic questions on the P. integrifolia complex, and to identify a purple-flowered parent of P. hybrida. METHODS AND RESULTS: We characterized 11 microsatellite loci by screening primers developed using an SSR-enriched library. Genotyping of two populations resulted in eight polymorphic loci. Cross-species transferability was tested for other members of the P. integrifolia complex. CONCLUSIONS: The development of these markers may contribute to population genetics studies in Petunia, and cross-amplification among related species could be a useful tool for research on hybridization and introgression.

Diversification of plant species in a subtropical region of eastern South American highlands: a phylogeographic perspective on native Petunia (Solanaceae).

In the Southern and Southeastern Brazilian highlands, a clade of seven species of Petunia that are endemic to the region (P. altiplana, P. bonjardinensis, P. guarapuavensis, P. mantiqueirensis, P. reitzii, P. saxicola and P. scheideana) exists in association with grassland formations. These formations are isolated in high-altitude regions, being surrounded by forested areas, and experienced contraction-expansion cycles associated with the glacial cycles of the Pleistocene. To understand the evolutionary history of this group, the divergence of which is probably linked to these past shifts in habitat, we analysed the sequences of the plastidial intergenic spacers trnH-psbA and trnS-trnG from populations throughout the known distributions of all seven species. The common ancestor of this highland clade started to differentiate ∼0.9 million years (Myr) ago, which corresponds to a high diversification rate of 2.06 species per Myr in the intervening period. The high level of haplotype sharing among several species in the clade and the absence of reciprocal monophyly suggest the persistence of ancestral polymorphisms during speciation events and/or past hybridization, because no hybrid was found. Four of the five species displayed very low genetic diversity and possessed either one or two haplotypes, which is consistent with long-term isolation in restricted areas. The three more diverse species displayed significant population structure, and P. altiplana showed a clear signs of population growth during the last glacial period. These results suggest that diversification occurred as a result of expansion of the ancestral species of the clade during glacial periods followed by fragmentation and isolation during retraction in interglacial periods.