Tagged: dysploidy


Brachypodium

Karyotype structure and evolution in Brachypodium annuals

The Brachypodium (Poacea) genus is a useful model system for studying grass genome organisation. Its key representative B. distachyon is well characterised at the cytogenetic and genomic level, unlike other Brachypodium species such as B. stacei and B. hybridum. Using comparative chromosome mapping with B. distachyon-originated BAC-based probes, Lusinska et al. identify individual chromosomes of B. stacei and B. hybridum. They also demonstrate various and complex rearrangements including nested chromosome fusions and Robertsonian rearrangements, which shaped the B. stacei and B. hybridum karyotypes in terms of their chromosome number and structure.

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Flowers and fruits of the Andean peppers.

Phylogeny of chili peppers and wild relatives

Sweet and hot chili peppers and their wild relatives (Capsicum spp., Solanaceae) are native to the tropical and temperate Americas. Despite their worldwide importance, Capsicum taxonomy and phylogeny have been only partially analysed to date. Carrizo García et al. explore the phylogenetic relationships between nearly all Capsicum species and analyse the evolution of key characters and the geographic diversification of the genus. The most comprehensive scheme of Capsicum interspecific relationships is presented, giving new insights about species affinities and the geographic origin of the genus.

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Maximum likelihood inference of chromosome numbers

Maximum likelihood inference of chromosome numbers

Botanists interested in changes in chromosome number have often relied on inferring a basic number, x, but this has been done without consistent (reproducible) reference to species’ relationships and frequencies of particular numbers in a group. Cusimano et al.  reconstruct ancestral numbers in the large monocot family Araceae using likelihood models that treat polyploidy, chromosome fusion and chromosome fission as events with particular probabilities. The results show that chromosome fusion is common, whereas polyploidization is mostly restricted to recent Araceae groups, and suggest that the algebraic approach to the calculation of x may not be reliable, at least when applied to...

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