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Abstract Detail

Population Genetics

Mendes-Rodrigues, Clesnan [1], Marinho, Rafaela [2], Balao, Francisco [3], Ortiz, Pedro Luis [3], Yamagishi, Júlia [1], Bonetti, Ana Maria [2], Oliveira, Paulo Eugenio [4].

Ploidy, genome size and breeding mosaics of Eriotheca (Malvaceae-Bombacoideae) in the Brazilian Cerrados.

The recent reorganization of the Angiosperm taxonomy and phylogeny has renewed interest in the diversification of flowering plants. Genome organization and polyploidization seem to have played a central role in this process and most Angiosperms are to a certain extent polyploids. Whole genome duplications seem to be linked to the origin of larger groups but polyploidy seems also to be involved in the speciation process. Since polyploidy is also related to changes in breeding systems, changes in chromosome number can lead to increased isolation of species/populations but can also produce reproductive mosaics. Breeding system mosaics are common in many plant groups, usually with self compatible and self incompatible, or even sexual and asexual populations within a species. Polyploidy is present in some species of Cerrado, the Neotropical savanna region in Central Brazil, and it has been linked to apomixis in some taxa. Eriotheca gracilipes and Eriotheca pubescens are common tree species in this region, and present cytotypes that form reproductive mosaics. Hexaploid individuals (2n = 6x = 276) are polyembryonic and apomictic, while tetraploid and diploid individuals (2n = 2x = 92, 2n = 4x = 184) are sexual and monoembryonic. We studied here how ploidy differences have affected genome size, and pollen and stomata morphological features of the species. We are using these features to help map distribution and understand the origin of these cytotypes and of the Eriotheca species as a whole. We collected seeds from individuals with previously defined ploidy levels from four different populations in a 400 kilometer radius in Central Brazil. We also collected floral buds and leaves from individuals in the same populations. Seeds were germinated and seedlings were used for flow cytometry analyses. Pollen from pre-anthesis floral buds and stomata from fully expanded leaves were measured. All features were clearly related to ploidy levels in both species. Genome size estimates indicated a common 1Cx genome size for the species and that higher levels are result of neopolyploidy events. Neopolyploidy events seem to have led to proportionally larger pollen grains and stomatal cells, which can be easily used to identify different cytotypes. We are still mapping other populations and figuring out how to relate the distribution of cytotypes with paleoclimatic changes and expanding/retracting Cerrado plant formations. (FAPEMIG, CNPq e CAPES)

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1 - Universidade Federal de Uberlandia, Instituto de Biologia, Uberlandia, MG, 38405-320, Brazil
2 - Universidade Federal de Uberlandia, Instituto de Genética e Bioquímica, Uberlândia, MG, 38405-320, Brazil
3 - Universidad de Sevilla, Departamento de Biologia Vegetal y Ecologia, Sevilla, 41012, Spain
4 - Universidade Federal De Uberlandia, Instituto De Biologia, Campus Umuarama Bl. 2D, Uberlandia, N/A, 38400-902, Brazil

genome size
plant mating systems.

Presentation Type: Oral Paper:Papers for Topics
Session: 71
Location: Salon 6/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 4:45 PM
Number: 71013
Abstract ID:328
Candidate for Awards:None

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