Dataset Information

Chromosome identification and reconstruction of evolutionary rearrangements in Brachypodium distachyon, B. stacei and B. hybridum.

ABSTRACT:

Background and aims

The Brachypodium genus represents a useful model system to study grass genome organization. Palaeogenomic analyses (e.g. Murat F, Armero A, Pont C, Klopp C, Salse J. 2017. Reconstructing the genome of the most recent common ancestor of flowering plants. Nature Genetics49: 490-496) have identified polyploidization and dysploidy as the prime mechanisms driving the diversity of plant karyotypes and nested chromosome fusions (NCFs) crucial for shaping grass chromosomes. This study compares the karyotype structure and evolution in B. distachyon (genome Bd), B. stacei (genome Bs) and in their putative allotetraploid B. hybridum (genomes BdBs).

Methods

Brachypodium chromosomes were measured and identified using multicolour fluorescence in situ hybridization (mcFISH). For higher resolution, comparative chromosome barcoding was developed using sets of low-repeat, physically mapped B. distachyon-derived bacterial artificial chromosome (BAC) clones.

Key results

All species had rather small chromosomes, and essentially all in the Bs genome were morphometrically indistinguishable. Seven BACs combined with two rDNA-based probes provided unambiguous and reproducible chromosome discrimination. Comparative chromosome barcoding revealed NCFs that contributed to the reduction in the x = 12 chromosome number that has been suggested for the intermediate ancestral grass karyotype. Chromosome Bd3 derives from two NCFs of three ancestral chromosomes (Os2, Os8, Os10). Chromosome Bs6 shows an ancient Os8/Os10 NCF, whilst Bs4 represents Os2 only. Chromosome Bd4 originated from a descending dysploidy that involves two NCFs of Os12, Os9 and Os11. The specific distribution of BACs along Bs9 and Bs5, in both B. stacei and B. hybridum, suggests a Bs genome-specific Robertsonian rearrangement.

Conclusions

mcFISH-based karyotyping identifies all chromosomes in Brachypodium annuals. Comparative chromosome barcoding reveals rearrangements responsible for the diverse organization of Bd and Bs genomes and provides new data regarding karyotype evolution since the split of the two diploids. The fact that no chromosome rearrangements were observed in B. hybridum compared with the karyotypes of its phylogenetic ancestors suggests prolonged genome stasis after the formation of the allotetraploid.

SUBMITTER: Lusinska J

PROVIDER: S-EPMC6110338 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature

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Publications

Chromosome identification and reconstruction of evolutionary rearrangements in Brachypodium distachyon, B. stacei and B. hybridum.

Lusinska Joanna J Majka Joanna J Betekhtin Alexander A Susek Karolina K Wolny Elzbieta E Hasterok Robert R

Annals of botany 20180801 3

<h4>Background and aims</h4>The Brachypodium genus represents a useful model system to study grass genome organization. Palaeogenomic analyses (e.g. Murat F, Armero A, Pont C, Klopp C, Salse J. 2017. Reconstructing the genome of the most recent common ancestor of flowering plants. Nature Genetics49: 490-496) have identified polyploidization and dysploidy as the prime mechanisms driving the diversity of plant karyotypes and nested chromosome fusions (NCFs) crucial for shaping grass chromosomes. T ...[more]

PMID: 29893795

Similar Datasets

Project description:Background and aimsMorphological traits in combination with metabolite fingerprinting were used to investigate inter- and intraspecies diversity within the model annual grasses Brachypodium distachyon, Brachypodium stacei and Brachypodium hybridum .MethodsPhenotypic variation of 15 morphological characters and 2219 nominal mass ( m / z ) signals generated using flow infusion electrospray ionization-mass spectrometry (FIE-MS) were evaluated in individuals from a total of 174 wild populations and six inbred lines, and 12 lines, of the three species, respectively. Basic statistics and multivariate principal component analysis and discriminant analysis were used to differentiate inter- and intraspecific variability of the two types of variable, and their association was assayed with the rcorr function.Key resultsBasic statistics and analysis of variance detected eight phenotypic characters [(stomata) leaf guard cell length, pollen grain length, (plant) height, second leaf width, inflorescence length, number of spikelets per inflorescence, lemma length, awn length] and 434 tentatively annotated metabolite signals that significantly discriminated the three species. Three phenotypic traits (pollen grain length, spikelet length, number of flowers per inflorescence) might be genetically fixed. The three species showed different metabolomic profiles. Discriminant analysis significantly discriminated the three taxa with both morphometric and metabolome traits and the intraspecific phenotypic diversity within B. distachyon and B. stacei . The populations of B. hybridum were considerably less differentiated.ConclusionsHighly explanatory metabolite signals together with morphological characters revealed concordant patterns of differentiation of the three taxa. Intraspecific phenotypic diversity was observed between northern and southern Iberian populations of B. distachyon and between eastern Mediterranean/south-western Asian and western Mediterranean populations of B. stacei . Significant association was found for pollen grain length and lemma length and ten and six metabolomic signals, respectively. These results would guide the selection of new germplasm lines of the three model grasses in ongoing genome-wide association studies.

Dataset Information

Chromosome identification and reconstruction of evolutionary rearrangements in Brachypodium distachyon, B. stacei and B. hybridum.

Background and aims

Methods

Key results

Conclusions

Publications

Chromosome identification and reconstruction of evolutionary rearrangements in Brachypodium distachyon, B. stacei and B. hybridum.

Similar Datasets

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