scholarly journals Evolution and diversity of the wild rice Oryza officinalis complex, across continents genome types, and ploidy levels

Author(s):  
Matt Shenton ◽  
Masaaki Kobayashi ◽  
Shin Terashima ◽  
Hajime Ohyanagi ◽  
Dario Copetti ◽  
...  

Abstract The Oryza officinalis complex is the largest species group in Oryza, with more than nine species from four continents, and is a tertiary gene pool that can be exploited in breeding programs for the improvement of cultivated rice. Most diploid and tetraploid members of this group have a C genome. Using a new reference C genome for the diploid species Oryza officinalis, and draft genomes for two other C genome diploid species O. eichingeri and O. rhizomatis, we examine the influence of transposable elements on genome structure and provide a detailed phylogeny and evolutionary history of the Oryza C genomes. The O. officinalis genome is 1.6 times larger than the A genome of cultivated O. sativa, mostly due to proliferation of Gypsy type long-terminal repeat (LTR) transposable elements, but overall syntenic relationships are maintained with other Oryza genomes (A, B and F). Draft genome assemblies of the two other C genome diploid species, O. eichingeri and O. rhizomatis, and short-read resequencing of a series of other C genome species and accessions reveal that after the divergence of the C genome progenitor, there was still a substantial degree of variation within the C genome species through proliferation and loss of both DNA and LTR transposable elements. We provide a detailed phylogeny and evolutionary history of the Oryza C genomes, and a genomic resource for the exploitation of the Oryza tertiary gene pool.

Genome ◽  
2011 ◽  
Vol 54 (12) ◽  
pp. 986-992 ◽  
Author(s):  
Huan Wang ◽  
Dongfa Sun ◽  
Genlou Sun

The phylogeny of diploid Hordeum species has been studied using both chloroplast and nuclear gene sequences. However, the studies of different nuclear datasets of Hordeum species often arrived at similar conclusions, whereas the studies of different chloroplast DNA data generally resulted in inconsistent conclusions. Although the monophyly of the genus is well supported by both morphological and molecular data, the intrageneric phylogeny is still a matter of controversy. To better understand the evolutionary history of Hordeum species, two chloroplast gene loci (trnD-trnT intergenic spacer and rps16 gene) and one nuclear marker (thioreoxin-like gene (HTL)) were used to explore the phylogeny of Hordeum species. Two obviously different types of trnD-trnT sequences were observed, with an approximately 210 base pair difference between these two types: one for American species, another for Eurasian species. The trnD-trnT data generally separated the diploid Hordeum species into Eurasian and American clades, with the exception of Hordeum marinum subsp. gussoneanum. The rps16 data also grouped most American species together and suggested that Hordeum flexuosum has a different plastid type from the remaining American species. The nuclear gene HTL data clearly divided Hordeum species into two clades: the Xu + H genome clade and the Xa + I genome clade. Within clades, H genome species were well separated from the Xu species, and the I genome species were well separated from the Xa genome species. The incongruence between chloroplast and nuclear datasets was found and discussed.


2013 ◽  
Vol 6 (1) ◽  
pp. 54 ◽  
Author(s):  
Sarah G Oliveira ◽  
Diogo C Cabral-de-Mello ◽  
Rita C Moura ◽  
Cesar Martins

2012 ◽  
Vol 5 (1) ◽  
pp. 77-86 ◽  
Author(s):  
Arnaud Le Rouzic ◽  
Thibaut Payen ◽  
Aurélie Hua-Van

2019 ◽  
Author(s):  
Xun Xu ◽  
Song Ge ◽  
Fu-min Zhang

Abstract Background: Reciprocal gene loss (RGL) of duplicate genes is an important genetic resource of reproductive isolation, which is essential for speciation. In the past decades, various RGL patterns have been revealed, but RGL process is still poorly understood. The RGL of the duplicate DOPPELGANGER1 (DPL1) and DOPPELGANGER2 (DPL2) gene can lead to BDM-type hybrid incompatibility between two rice subspecies. The evolutionary history of the duplicate genes, including their origin and mechanism of duplication as well as their evolutionary divergence after the duplication, remains unclear. In this study, we investigated the evolutionary history of the duplicate genes for gaining insights into the process of RGL.Results: We reconstructed phylogenetic relationships of DPL copies from all 15 diploid species representing six genome types of rice genus and then found that all the DPL copies from the latest diverged A- and B-genome gather into one monophyletic clade. Southern blot analysis also detected definitely two DPL copies only in A- and B-genome. High conserved collinearity can be observed between A- and B-genomic segments containing DPL1 and DPL2 respectively but not between DPL1 and DPL2 segments. Investigations of transposon elements indicated that DPL duplication is related to DNA transposons. Likelihood-based analyses with branch models showed a relaxation of selective constraint in DPL1 lineage but an enhancement in DPL2 lineage after DPL duplication. Sequence analysis also indicated that quite a few defective DPL1 can be found in 6 wild and cultivated species out of all 8 species of A-genome but only one defective DPL2 occurs in a cultivated rice subspecies. Conclusions: DPL duplication of rice originated in the recent common ancestor of A- and B-genome about 6.76 million years ago and the duplication was possibly caused by DNA transposons. The DPL1 is a redundant copy and has being in the process of pseudogenization, suggesting that artificial selection may play an important role in forming the RGL of DPLs between two rice subspecies during the domestication.


2006 ◽  
Vol 14 (8) ◽  
pp. 831-844 ◽  
Author(s):  
Gerhard Menzel ◽  
Daryna Dechyeva ◽  
Heiko Keller ◽  
Cornelia Lange ◽  
Heinz Himmelbauer ◽  
...  

1968 ◽  
Vol 10 (1) ◽  
pp. 112-118 ◽  
Author(s):  
T. K. Koshy

From a karyotype analysis of Poa annua (2n = 28) two large chromosomes, I and II, and one small chromosome, XIV, as well as three chromosome groups containing two, four and five chromosomes have been identified. From a comparison of the karyotype of Poa annua with that published of Poa exilis (2n = 14) and Poa supina (2n = 14), doubt is cast on the theory that Poa annua is an allotetraploid of the two latter diploid species. The three chromosomes of Poa annua that could be identified with certainty existed in homologous pairs, indicating that the species could have originated from Poa exilis or Poa supina and one other hitherto unidentified species. It is suggested that further work on the karyotype of diploid species might reveal further useful information on the evolutionary history of the species.


Genome ◽  
2012 ◽  
Vol 55 (11) ◽  
pp. 735-753 ◽  
Author(s):  
K.K. Nkongolo ◽  
M. Mehes-Smith

The family Pinaceae is made up mostly of diploid species (2n = 24). Systematization of karyotype analysis was developed to make comparison of intra- and interspecific karyotypes among the Pinaceae more accurate and reliable. Considering all parameters, the genera Pseudotsuga and Pseudolarix have the “most derived” (or advanced) and asymmetric karyotypes in the Pinaceae, followed by Larix, Picea, Abies, and Cedrus. The genus Pinus was the “least derived” (or ancestral) of all the genera of the Pinaceae analyzed. Differences in karyotype formulae and asymmetry indices were found among species within the same genera, suggesting that structural changes may have contributed to the diversification of the genus. This review is a detailed analysis of comparative karyotyping based on similar parameters, including numeric data and cytogenetic information. Telomeric sequence repeats and rDNA distribution in the Pinaceae were surveyed. The role of transposition in rDNA chromosome distribution is analyzed. Cytogenetic implications of hybridization between related species are reported. Likewise, the relationships between molecular phylogenetic and karyotype evolution is discussed in light of several reports. Within many genera, chromosomal organization was conserved despite independent molecular divergence and adaptation through the evolutionary history of the species of the Pinaceae.


Genome ◽  
1988 ◽  
Vol 30 (5) ◽  
pp. 627-632 ◽  
Author(s):  
A. Fominaya ◽  
C. Vega ◽  
E. Ferrer

Giemsa C-banding was used to identify individual somatic chromosomes in eight diploid species of Avena. Two patterns of heterochromatin distribution were found. The chromosomes of five A genome species (A. strigosa, A. hirtula, A. longiglumis, A. damascena, and A. canariensis) possessed mainly telomeric bands, whereas those from three C genome species (A. clauda, A. pilosa, and A. ventricosa) were characterized by higher chromatin condensation and several intercalary heterochromatin bands. The divergent evolution between the two groups is confirmed after C-banding. The unique C-banding patterns of several chromosomes in each species will be a useful tool for the study of meiotic behaviour in interspecific hybrids among Avena spp.Key words: C-banding, Avena, heterochromatin.


2018 ◽  
Author(s):  
Gökçe Aköz ◽  
Magnus Nordborg

AbstractBackgroundWhole-genome duplications (WGD) have dominated the evolutionary history of plants. One consequence of WGD is a dramatic restructuring of the genome as it undergoes diploidization, a process under which deletions and rearrangements of various sizes scramble the genetic material, leading to a repacking of the genome and eventual return to diploidy. Here, we investigate the history of WGD in the columbine genus Aquilegia, a basal eudicot, and use it to illuminate the origins of the core eudicots.ResultsWithin-genome synteny confirms that columbines are ancient tetraploids, and comparison with the grape genome reveals that this tetraploidy appears to be shared with the core eudicots. Thus, the ancient gamma hexaploidy found in all core eudicots must have involved a two-step process: first tetraploidy in the ancestry of all eudicots, then hexaploidy in the ancestry of core eudicots. Furthermore, the precise pattern of synteny sharing suggests that the latter involved allopolyploidization, and that core eudicots thus have a hybrid origin.ConclusionsNovel analyses of synteny sharing together with the well-preserved structure of the columbine genome reveal that the gamma hexaploidy at the root of core eudicots is likely a result of hybridization between a tetraploid and a diploid species.


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