Contrasting genome organisation: two regions of the Brassica oleracea genome compared with collinear regions of the Arabidopsis thaliana genome

Genome ◽  
2001 ◽  
Vol 44 (5) ◽  
pp. 808-817 ◽  
Author(s):  
C D Ryder ◽  
L B Smith ◽  
G R Teakle ◽  
G J King

Brassica crop species are of worldwide importance and are closely related to the model plant Arabidopsis thaliana for which the complete genome sequence has recently been established. We investigated collinearity of marker order by comparing two contrasting regions of the Brassica oleracea genome with homologous regions of A. thaliana. Although there is widespread replication of marker loci in both A. thaliana and B. oleracea, we found that a combination of genetic markers mapped in B. oleracea, including RFLPs, CAPS, and SSRs allowed comparison and interpretation of medium-scale chromosomal organisation and rearrangements. The interpretation of data was facilitated by hybridising probes onto the whole A. thaliana genome, as represented by BAC contigs. Twenty marker loci were sampled from the whole length of the shortest B. oleracea linkage group, O6, and 21 from a 30.4-cM section of the longest linkage group, O3. There is evidence of locus duplication on linkage group O6. Locus order is well conserved between a putative duplicated region of 10.5 cM and a discrete region comprising 25 cM of A. thaliana chromosome I. This was supported by evidence from seven paralogous loci, three of which were duplicated in a 30.6-cM region of linkage group O6. The pattern of locus order for the remainder of linkage group O6 and the sampled section of linkage group O3 was more complex when compared with the A. thaliana genome. Although there was some conservation of locus order between markers on linkage group O3 and approximately 9 cM of A. thaliana chromosome I, this was superimposed upon a complex pattern of additional loci that were replicated in both A. thaliana and B. oleracea. The results are discussed in the context of the ability to use collinear information to assist map-based cloning.Key words: comparative mapping, BAC, physical contig, MADS box.

2017 ◽  
Vol 107 (11) ◽  
pp. 1399-1405 ◽  
Author(s):  
Jasper R. L. Depotter ◽  
Luis Rodriguez-Moreno ◽  
Bart P. H. J. Thomma ◽  
Thomas A. Wood

Verticillium longisporum is an economically important fungal pathogen of brassicaceous crops that originated from at least three hybridization events between different Verticillium spp., leading to the hybrid lineages A1/D1, A1/D2, and A1/D3. Isolates of lineage A1/D1 generally cause stem striping on oilseed rape (Brassica napus), which has recently been reported for the first time to occur in the United Kingdom. Intriguingly, the emerging U.K. population is distinct from the north-central European stem striping population. Little is known about the pathogenicity of the newly emerged U.K. population; hence, pathogenicity tests were executed to compare British isolates to previously characterized reference strains. In addition to the model plant Arabidopsis thaliana, the pathogenicity of four British isolates was assessed on four cultivars of three Brassica crop species: oilseed rape (Quartz and Incentive), cauliflower (Clapton), and Chinese cabbage (Hilton). To this end, vascular discoloration of the roots, plant biomass accumulations, and fungal stem colonization upon isolate infection were evaluated. The British isolates appeared to be remarkably aggressive, because plant biomass was significantly affected and severe vascular discoloration was observed. The British isolates were successful stem colonizers and the extent of fungal colonization negatively correlated with plant biomass of cauliflower and Quartz oilseed rape. However, in Quartz, the fungal colonization of A1/D1 isolates was significantly lower than that of the virulent reference isolate from lineage A1/D3, PD589. Moreover, despite levels of stem colonization similar to those of A1/D1 strains, PD589 did not cause significant disease on Incentive. Thus, A1/D1 isolates, including British isolates, are aggressive oilseed rape pathogens despite limited colonization levels in comparison with a virulent A1/D3 isolate.


Genetics ◽  
2003 ◽  
Vol 164 (1) ◽  
pp. 359-372 ◽  
Author(s):  
Lewis Lukens ◽  
Fei Zou ◽  
Derek Lydiate ◽  
Isobel Parkin ◽  
Tom Osborn

Abstract Brassica oleracea is closely related to the model plant, Arabidopsis thaliana. Despite this relationship, it has been difficult to both identify the most closely related segments between the genomes and determine the degree of genome replication within B. oleracea relative to A. thaliana. These difficulties have arisen in part because both species have replicated genomes, and the criteria used to identify orthologous regions between the genomes are often ambiguous. In this report, we compare the positions of sequenced Brassica loci with a known position on a B. oleracea genetic map to the positions of their putative orthologs within the A. thaliana genome. We use explicit criteria to distinguish orthologous from paralogous loci. In addition, we develop a conservative algorithm to identify collinear loci between the genomes and a permutation test to evaluate the significance of these regions. The algorithm identified 34 significant A. thaliana regions that are collinear with >28% of the B. oleracea genetic map. These regions have a mean of 3.3 markers spanning 2.1 Mbp of the A. thaliana genome and 2.5 cM of the B. oleracea genetic map. Our findings are consistent with the hypothesis that the B. oleracea genome has been highly rearranged since divergence from A. thaliana, likely as a result of polyploidization.


2021 ◽  
Author(s):  
Bo Wang ◽  
Yanyan Jia ◽  
Peng Jia ◽  
Quanbin Dong ◽  
Xiaofei Yang ◽  
...  

Here, we report a high-quality (HQ) and almost complete genome assembly with a single gap and quality value (QV) larger than 60 of the model plant Arabidopsis thaliana ecotype Columbia (Col-0), generated using combination of Oxford Nanopore Technology (ONT) ultra-long reads, high fidelity (HiFi) reads and Hi-C data. The total genome assembly size is 133,877,291 bp (chr1: 32,659,241 bp, chr2: 22,712,559 bp, chr3: 26,161,332 bp, chr4: 22,250,686 bp and chr5: 30,093,473 bp), and introduces 14.73 Mb (96% belong to centromere) novel sequences compared to TAIR10.1 reference genome. All five chromosomes of our HQ assembly are highly accurate with QV larger than 60, ranging from QV62 to QV68, which is significantly higher than TAIR10.1 referecne (44-51) and a recent published genome (41-43). We have completely resolved chr3 and chr5 from telomere-to-telomere. For chr2 and chr4, we have completely resolved apart from the nucleolar organizing regions, which are composed of highly long-repetitive DNA fragments. It has been reported that the length of centromere 1 is about 9 Mb and it is hard to assembly since tens of thousands of CEN180 satellite repeats. Based on the cutting-edge sequencing data, we assembled about 4Mb continuous sequence of centromere 1. We found different identity patterns across five centromeres, and all centromeres were significantly enriched with CENH3 ChIP-seq signals, confirming the accuracy of the assembly. We obtained four clusters of CEN180 repeats, and found CENH3 presented a strong preference for a cluster 3. Moreover, we observed hypomethylation patterns in CENH3 enriched regions. This high-quality assembly genome will be a valuable reference to assist us in the understanding of global pattern of centromeric polymorphism, genetic and epigenetic in naturally inbred lines of Arabidopsis thaliana.


Genome ◽  
1998 ◽  
Vol 41 (1) ◽  
pp. 62-69 ◽  
Author(s):  
A C Cavell ◽  
D J Lydiate ◽  
IAP Parkin ◽  
C Dean ◽  
M Trick

Arabidopsis thaliana (the model dicotyledonous plant) is closely related to Brassica crop species. Genome collinearity, or conservation of marker order, between Brassica napus (oilseed rape) and A. thaliana was assessed over a 7.5-Mbp region of the long arm of A. thaliana chromosome 4, equivalent to 30 cM. Estimates of copy number indicated that sequences present in a single copy in the haploid genome of A. thaliana (n = 5) were present in 2-8 copies in the haploid genome of B. napus (n = 19), while sequences present in multiple copies in A. thaliana were present in over 10 copies in B. napus. Genetic mapping in B. napus of DNA markers derived from a segment of A. thaliana chromosome 4 revealed duplicated homologous segments in the B. napus genome. Physical mapping in A. thaliana of homologues of Brassica clones derived from these regions confirmed the identity of six duplicated segments with substantial homology to the 7.5-Mbp region of chromosome 4 in A. thaliana. These six duplicated Brassica regions (on average 22cM in length) are collinear, except that two of the six copies contain the same large internal inversion. These results have encouraging implications for the feasibility of shuttling between the physical map of A. thaliana and genetic maps of Brassica species, for identifying candidate genes and for map based gene cloning in Brassica crops.


Inventions ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 52
Author(s):  
Rajan Kapoor ◽  
Aniruddha Datta ◽  
Michael Thomson

Conventional breeding approaches that focus on yield under highly favorable nutrient conditions have resulted in reduced genetic and trait diversity in crops. Under the growing threat from climate change, the mining of novel genes in more resilient varieties can help dramatically improve trait improvement efforts. In this work, we propose the use of the joint graphical lasso for discovering genes responsible for desired phenotypic traits. We prove its efficiency by using gene expression data for wild type and delayed flowering mutants for the model plant. Arabidopsis thaliana shows that it recovers the mutation causing genes LNK1 and LNK2. Some novel interactions of these genes were also predicted. Observing the network level changes between two phenotypes can also help develop meaningful biological hypotheses regarding the novel functions of these genes. Now that this data analysis strategy has been validated in a model plant, it can be extended to crop plants to help identify the key genes for beneficial traits for crop improvement.


Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1804
Author(s):  
Izabela Perkowska ◽  
Joanna Siwinska ◽  
Alexandre Olry ◽  
Jérémy Grosjean ◽  
Alain Hehn ◽  
...  

Coumarins are phytochemicals occurring in the plant kingdom, which biosynthesis is induced under various stress factors. They belong to the wide class of specialized metabolites well known for their beneficial properties. Due to their high and wide biological activities, coumarins are important not only for the survival of plants in changing environmental conditions, but are of great importance in the pharmaceutical industry and are an active source for drug development. The identification of coumarins from natural sources has been reported for different plant species including a model plant Arabidopsis thaliana. In our previous work, we demonstrated a presence of naturally occurring intraspecies variation in the concentrations of scopoletin and its glycoside, scopolin, the major coumarins accumulating in Arabidopsis roots. Here, we expanded this work by examining a larger group of 28 Arabidopsis natural populations (called accessions) and by extracting and analysing coumarins from two different types of tissues–roots and leaves. In the current work, by quantifying the coumarin content in plant extracts with ultra-high-performance liquid chromatography coupled with a mass spectrometry analysis (UHPLC-MS), we detected a significant natural variation in the content of simple coumarins like scopoletin, umbelliferone and esculetin together with their glycosides: scopolin, skimmin and esculin, respectively. Increasing our knowledge of coumarin accumulation in Arabidopsis natural populations, might be beneficial for the future discovery of physiological mechanisms of action of various alleles involved in their biosynthesis. A better understanding of biosynthetic pathways of biologically active compounds is the prerequisite step in undertaking a metabolic engineering research.


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