Evolutionary trends in Iridaceae: new cytogenetic findings from the New World

Autor(es):Mostrar menos -

Moraes, Ana Paula ^[1] ; Souza-Chies, Tatiana T. ^{[2, 1]} ; Stiehl-Alves, Eudes M. ^[1] ; Burchardt, Paula ^[1] ; Eggers, Lilian ^[2] ; Siljak-Yakovlev, Sonja ^[3] ; Brown, Spencer C. ^{[4, 5]} ; Chauveau, Olivier ^{[3, 2]} ; Nadot, Sophie ^[3] ; Bourge, Mickael ^{[4, 5]} ; Viccini, Lyderson Facio ^[6] ; Kaltchuk-Santos, Eliane ^{[1, 7]}

Afiliação do(s) autor(es)

^[1] Univ Fed Rio Grande do Sul, Inst Biociencias, Programa Posgrad Genet & Biol Mol, Porto Alegre, RS - Brazil

^[2] Univ Estadual Sao Paulo UNESP, Inst Biociencias, Dept Bot, Botucatu, SP - Brazil

^[3] Univ Paris 11, CNRS, UMR 8079, Lab Ecol Systemat & Evolut, F-91405 Orsay - France

^[4] CNRS, UPR 2355, Inst Sci Vegetal, F-91198 Gif Sur Yvette - France

^[5] Imagif, F-91198 Gif Sur Yvette - France

^[6] Univ Fed Juiz de Fora, Inst Ciencias Biol, Dept Biol, Juiz De Fora, MG - Brazil

^[7] Univ Estadual Sao Paulo UNESP, Inst Biociencias, Dept Genet, Botucatu, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Botanical Journal of the Linnean Society; v. 177, n. 1, p. 27-49, JAN 2015.
• Citações Web of Science: 16

Resumo

With the present work, we aim to provide a better understanding of chromosome evolutionary trends among southern Brazilian species of Iridoideae. Chromosome numbers and genome sizes were determined for 21 and 22 species belonging to eight genera of Tigridieae and two genera of Trimezieae, respectively. The chromosome numbers of nine species belonging to five genera are reported here for the first time. Analyses of meiotic behaviour, tetrad normality and pollen viability in 14 species revealed regular meiosis and high meiotic indexes and pollen viability (>90%). The chromosome data obtained here and compiled from the literature were plotted onto a phylogenetic framework to identify major events of chromosome rearrangements across the phylogenetic tree of Iridoideae. Following this approach, we propose that the ancestral base chromosome number for Iridoideae is x=8 and that polyploidy and dysploidy events have occurred throughout evolution. Despite the variation in chromosome numbers observed in Tigridieae and Trimezieae, for these two tribes our data provide support for an ancestral base number of x=7, largely conserved in Tigridieae, but a polyploidy event may have occurred prior to the diversification of Trimezieae, giving rise to a base number of x(2)=14 (detected by maximum-parsimony using haploid number and maximum likelihood). In Tigridieae, polyploid cytotypes were commonly observed (2x, 4x, 6x and 8x), whereas in Trimezieae, dysploidy seems to have been the most important event. This feature is reflected in the genome size, which varied greatly among species of Iridoideae, 4.2-fold in Tigridieae and 1.5-fold in Trimezieae. Although no clear difference was observed among the genome sizes of Tigridieae and Trimezieae, an important distinction was observed between these two tribes and Sisyrinchieae, with the latter possessing the smallest genome sizes in Iridoideae.(c) 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 177, 27-49. (AU)

• Processo FAPESP: 11/22215-3 - Respostas do genoma vegetal às variações ambientais: o que as Orchidaceae têm a contar?
• Beneficiário: Ana Paula de Moraes
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores