MCScanX: a toolkit for detection and evolutionary analysis of gene synteny and collinearity

Wang, Yupeng; Tang, Haibao; DeBarry, Jeremy D.; Tan, Xiaoxiao; Li, Jingping; Wang, Xiyin; Lee, Tae‐Ho; Jin, Huizhe; Marler, Barry S.; Guo, Hui; Kissinger, Jessica C.; Paterson, Andrew H.

doi:10.1093/nar/gkr1293

Cited by 5,080 publications

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“…Synteny between the sub-genomes and B. vulgaris was assessed by first creating pseudomolecules by concatenating scaffolds which were known to be ordered and oriented within each of the nine chromosomes. Syntenic regions between these B. vulgaris chromosomes and those of quinoa were then identified using the recommended settings of the CoGe SynMap tool 70 and visualized using MCScanX 71 and VGSC 72 . For the purposes of visualization, quinoa chromosomes CqB05, CqA08, CqB11, CqA15 and CqB16 were inverted.…”

Section: Article Researchmentioning

confidence: 99%

The genome of Chenopodium quinoa

Jarvis

Lightfoot

et al. 2017

Nature

601

706

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Quinoa (Chenopodium quinoa Willd., 2n = 4x = 36) is a highly nutritious crop that is adapted to thrive in a wide range of agroecosystems. It was presumably first domesticated more than 7,000 years ago by pre-Columbian cultures and was known as the 'mother grain' of the Incan Empire 1 . Quinoa has adapted to the high plains of the Andean Altiplano (> 3,500 m above sea level), where it has developed tolerance to several abiotic stresses [2][3][4] . Quinoa has gained international attention because of the nutritional value of its seeds, which are gluten-free, have a low glycaemic index 5 , and contain an excellent balance of essential amino acids, fibre, lipids, carbohydrates, vitamins, and minerals 6 . Quinoa has the potential to provide a highly nutritious food source that can be grown on marginal lands not currently suitable for other major crops. This potential was recognized when the United Nations declared 2013 as the International Year of Quinoa, this being one of only three times a plant has received such a designation.Despite its agronomic potential, quinoa is still an underutilized crop 7 , with relatively few active breeding programs 8 . Breeding efforts to improve the crop for important agronomic traits are needed to expand quinoa production worldwide. To accelerate the improvement of quinoa, we present here the allotetraploid quinoa genome. We demonstrate the utility of the genome sequence by identifying a gene that probably regulates the presence of seed triterpenoid saponin content. Moreover, we sequenced the genomes of additional diploid and tetraploid Chenopodium species to characterize genetic diversity within the primary germplasm pool for quinoa and to understand sub-genome evolution in quinoa. Together, these resources provide the foundation for accelerating the genetic improvement of the crop, with the objective of enhancing global food security for a growing world population. Sequencing, assembly and annotationWe sequenced and assembled the genome of the coastal Chilean quinoa accession PI 614886 (BioSample accession code SAMN04338310) using single-molecule real-time (SMRT) sequencing technology from Pacific Biosciences (PacBio) and optical and chromosome-contact maps from BioNano Genomics 9 and Dovetail Genomics 10 . The assembly contains 3,486 scaffolds, with a scaffold N50 of 3.84 Mb and 90% of the assembled genome contained in 439 scaffolds (Table 1). The total assembly size of 1.39 gigabases (Gb) is similar to the reported size estimates of the quinoa genome (1.45-1.50 Gb (refs 11,12)). To combine scaffolds into pseudomolecules, an existing linkage map from quinoa 13 was integrated with two new linkage maps. The resulting map (Extended Data Fig. 1) of 6,403 unique markers spans a total length of 2,034 centimorgans (cM) and consists of 18 linkage groups (Supplementary Table 7), corresponding to the haploid chromosome number of quinoa. Pseudomolecules (hereafter referred to as chromosomes, which are numbered according to a previously published single-nucleotide polymorphism (SNP) linkage ...

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Section: Article Researchmentioning

confidence: 99%

The genome of Chenopodium quinoa

Jarvis

Lightfoot

et al. 2017

Nature

601

706

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“…We annotated protein-coding genes by integrating evidence from RNA sequencing, ab initio predictions and comparison with UniProt. Most synteny and Ka/Ks (non-synonymous divergence/synonymous divergence) analyses were performed using the package MCScanX 29 and synteny plots were drawn using Circos 30 . alternates between a haploid phase (in which a single allele of each gene is present) and a diploid phase (in which the genes are present in two allelic versions arranged colinearly on homologous chromosomes).…”

Section: Methods Summarymentioning

confidence: 99%

Genomic evidence for ameiotic evolution in the bdelloid rotifer Adineta vaga

Flot

Hespeels

et al. 2013

Nature

362

624

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Loss of sexual reproduction is considered an evolutionary dead end for metazoans, but bdelloid rotifers challenge this view as they appear to have persisted asexually for millions of years 1 . Neither male sex organs nor meiosis have ever been observed in these microscopic animals: oocytes are formed through mitotic divisions, with no reduction of chromosome number and no indication of chromosome pairing 2 . However, current evidence does not exclude that they may engage in sex on rare, cryptic occasions. Here we report the genome of a bdelloid rotifer, Adineta vaga (Davis, 1873) 3 , and show that its structure is incompatible with conventional meiosis. At gene scale, the genome of A. vaga is tetraploid and comprises both anciently duplicated segments and less divergent allelic regions. However, in contrast to sexual species, the allelic regions are rearranged and sometimes even found on the same chromosome. Such structure does not allow meiotic pairing; instead, we find abundant evidence of gene conversion, which may limit the accumulation of deleterious mutations in the absence of meiosis. Gene families involved in resistance to oxidation, carbohydrate metabolism and defence against transposons are significantly expanded, which may explain why transposable elements cover only 3% of the assembled sequence. Furthermore, 8% of the genes are likely to be of non-metazoan origin and were probably acquired horizontally. This apparent convergence between bdelloids and prokaryotes sheds new light on the evolutionary significance of sex.With more than 460 described species 4 , bdelloid rotifers ( Fig. 1) represent the highest metazoan taxonomic rank in which males, hermaphrodites and meiosis are unknown. Such persistence and diversification of an ameiotic clade of animals are in contradiction with the supposed long-term disadvantages of asexuality, making bdelloids an 'evolutionary scandal' 5 . Another unusual feature of bdelloid rotifers is their extreme resistance to desiccation at any stage of their life cycle 6 , enabling these microscopic animals to dwell in ephemeral freshwater habitats such as mosses, lichens and forest litter; this ability is presumably the source of their extreme resistance to ionizing radiation 7 .We assembled the genome of a clonal A. vaga lineage into separate haplotypes with a N 50 of 260 kilobases (kb) (that is, half of the assembly was composed of fragments longer than 260 kb). Assembly size was 218 megabases (Mb) but 26 Mb of the sequence had twice the average sequencing coverage, suggesting that some nearly identical regions were not resolved during assembly ( Supplementary Fig. 3); hence, the total genome size is likely to be 244 Mb, which corresponds to the estimate obtained independently using fluorometry (Supplementary Note C2). Annotation of the complete assembly (including all haplotypes) yielded 49,300 genes. Intragenomic sequence comparisons revealed numerous homologous blocks with conserved gene order (colinear regions). For each such block we computed the per-site synonymous d...

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“…For a protein sequence, the best five non-self hits in each target genome that met an E-value threshold of 0.00001 were reported. Whole-genome BLASTP results and the genome annotation file were used to compute collinear blocks for all possible pairs of chromosomes using MCScan software 68 . A region with at least 5 syntenic genes and no more than 15 gapped genes was called a syntenic block.…”

Section: Syntenic Comparisonmentioning

confidence: 99%

Genomic adaptation to polyphagy and insecticides in a major East Asian noctuid pest

et al. 2017

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The tobacco cutworm, Spodoptera litura, is among the most widespread and destructive agricultural pests, feeding on over 100 crops throughout tropical and subtropical Asia. By genome sequencing, physical mapping and transcriptome analysis, we found that the gene families encoding receptors for bitter or toxic substances and detoxification enzymes, such as cytochrome P450, carboxylesterase and glutathione-S-transferase, were massively expanded in this polyphagous species, enabling its extraordinary ability to detect and detoxify many plant secondary compounds. Larval exposure to insecticidal toxins induced expression of detoxification genes, and knockdown of representative genes using short interfering RNA (siRNA) reduced larval survival, consistent with their contribution to the insect’s natural pesticide tolerance. A population genetics study indicated that this species expanded throughout southeast Asia by migrating along a South India–South China–Japan axis, adapting to wide-ranging ecological conditions with diverse host plants and insecticides, surviving and adapting with the aid of its expanded detoxification systems. The findings of this study will enable the development of new pest management strategies for the control of major agricultural pests such as S. litura.

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MCScanX: a toolkit for detection and evolutionary analysis of gene synteny and collinearity

Cited by 5,080 publications

References 74 publications

The genome of Chenopodium quinoa

The genome of Chenopodium quinoa

Genomic evidence for ameiotic evolution in the bdelloid rotifer Adineta vaga

Genomic adaptation to polyphagy and insecticides in a major East Asian noctuid pest

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