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Phylogeography and modes of reproduction in diploid and tetraploid halophytes of Limonium species (Plumbaginaceae): evidence for a pattern of geographical parthenogenesis
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Resumo(s)
Background and Aims The genus Limonium (Plumbaginaceae) has long been recognized to have sexual and
apomictic (asexual seed formation) modes of reproduction. This study aimed to elucidate phylogeographical patterns
and modes of reproduction in diploid and tetraploid Limonium species, namely three putative sexual diploid
species with morphological affinities (L. nydeggeri, L. ovalifolium, L. lanceolatum) and three related, probably apomict
tetraploid species (L. binervosum, L. dodartii, L. multiflorum).
Methods cpDNA diversity and differentiation between natural populations of the species were investigated using
two chloroplast sequence regions (trnL intron and trnL–trnF intergenic spacer). Floral heteromorphies, ovule
cytoembryological analyses and pollination and crossing tests were performed in representative species of each
ploidy group, namely diploid L. ovalifolium and tetraploid L. multiflorum, using plants from greenhouse collections.
Key Results and Conclusions Genetic analyses showed that diploid species have a higher haplotype diversity
and a higher number of unique (endemic) haplotypes than tetraploid species. Network analysis revealed correlations
between cpDNA haplotype distribution and ploidy groups, species groups and geographical origin, and haplotype
sharing within and among species with distinct ploidy levels. Reproductive biology analyses showed that diploid
L. ovalifolium mainly forms meiotically reduced tetrasporic embryo sacs of Gagea ova, Adoxa and Drusa types.
Limonium multiflorum, however, has only unreduced, diplosporic (apomictic) embryo sacs of Rudbeckia type, and
autonomous apomictic development seems to occur. Taken together, the findings provide evidence of a pattern of
‘geographical parthenogenesis’ in which quaternary climatic oscillations appear to be involved in the geographical
patterns of coastal diploid and tetraploid Limonium species
Descrição
Palavras-chave
apomixis cytoplasmic markers cpDNA female gametophyte development floral biology geographical parthenogenesis Limonium phylogeography polyploidy reproductive methods
Contexto Educativo
Citação
Annals of Botany 117: 37–50, 2016
Editora
Oxford University Press