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A high-density genetic map with array-based markers facilitates structural and quantitative trait locus analyses of the common wheat genome.

ABSTRACT: The large genome and allohexaploidy of common wheat have complicated construction of a high-density genetic map. Although improvements in the throughput of next-generation sequencing (NGS) technologies have made it possible to obtain a large amount of genotyping data for an entire mapping population by direct sequencing, including hexaploid wheat, a significant number of missing data points are often apparent due to the low coverage of sequencing. In the present study, a microarray-based polymorphism detection system was developed using NGS data obtained from complexity-reduced genomic DNA of two common wheat cultivars, Chinese Spring (CS) and Mironovskaya 808. After design and selection of polymorphic probes, 13,056 new markers were added to the linkage map of a recombinant inbred mapping population between CS and Mironovskaya 808. On average, 2.49 missing data points per marker were observed in the 201 recombinant inbred lines, with a maximum of 42. Around 40% of the new markers were derived from genic regions and 11% from repetitive regions. The low number of retroelements indicated that the new polymorphic markers were mainly derived from the less repetitive region of the wheat genome. Around 25% of the mapped sequences were useful for alignment with the physical map of barley. Quantitative trait locus (QTL) analyses of 14 agronomically important traits related to flowering, spikes, and seeds demonstrated that the new high-density map showed improved QTL detection, resolution, and accuracy over the original simple sequence repeat map.

SUBMITTER: Iehisa JC

PROVIDER: S-EPMC4195500 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature

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A high-density genetic map with array-based markers facilitates structural and quantitative trait locus analyses of the common wheat genome.

Iehisa Julio Cesar Masaru JC Ohno Ryoko R Kimura Tatsuro T Enoki Hiroyuki H Nishimura Satoru S Okamoto Yuki Y Nasuda Shuhei S Takumi Shigeo S

DNA research : an international journal for rapid publication of reports on genes and genomes 20140627 5

The large genome and allohexaploidy of common wheat have complicated construction of a high-density genetic map. Although improvements in the throughput of next-generation sequencing (NGS) technologies have made it possible to obtain a large amount of genotyping data for an entire mapping population by direct sequencing, including hexaploid wheat, a significant number of missing data points are often apparent due to the low coverage of sequencing. In the present study, a microarray-based polymor ...[more]

PMID: 24972598

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Project description:A high-density consensus map is a powerful tool for gene mapping, cloning and molecular marker-assisted selection in wheat breeding. The objective of this study was to construct a high-density, single nucleotide polymorphism (SNP)-based consensus map of common wheat (Triticum aestivum L.) by integrating genetic maps from four recombinant inbred line populations. The populations were each genotyped using the wheat 90K Infinium iSelect SNP assay. A total of 29,692 SNP markers were mapped on 21 linkage groups corresponding to 21 hexaploid wheat chromosomes, covering 2,906.86 cM, with an overall marker density of 10.21 markers/cM. Compared with the previous maps based on the wheat 90K SNP chip detected 22,736 (76.6%) of the SNPs with consistent chromosomal locations, whereas 1,974 (6.7%) showed different chromosomal locations, and 4,982 (16.8%) were newly mapped. Alignment of the present consensus map and the wheat expressed sequence tags (ESTs) Chromosome Bin Map enabled assignment of 1,221 SNP markers to specific chromosome bins and 819 ESTs were integrated into the consensus map. The marker orders of the consensus map were validated based on physical positions on the wheat genome with Spearman rank correlation coefficients ranging from 0.69 (4D) to 0.97 (1A, 4B, 5B, and 6A), and were also confirmed by comparison with genetic position on the previously 40K SNP consensus map with Spearman rank correlation coefficients ranging from 0.84 (6D) to 0.99 (6A). Chromosomal rearrangements reported previously were confirmed in the present consensus map and new putative rearrangements were identified. In addition, an integrated consensus map was developed through the combination of five published maps with ours, containing 52,607 molecular markers. The consensus map described here provided a high-density SNP marker map and a reliable order of SNPs, representing a step forward in mapping and validation of chromosomal locations of SNPs on the wheat 90K array. Moreover, it can be used as a reference for quantitative trait loci (QTL) mapping to facilitate exploitation of genes and QTL in wheat breeding.

Project description:Key messageThis study identified a novel SNP and developed a highly efficient KASP marker for drought tolerance in wheat by genotyping NILs targeting a major QTL for drought tolerance using an SNP array and validation with commercial varieties. Common wheat (Triticum aestivum L.) is an important winter crop worldwide and a typical allopolyploid with a large and complex genome. With global warming, the environmental volatility and incidence of drought in wheat-producing areas will increase. Molecular markers for drought tolerance are urgently needed to enhance drought tolerance breeding. Here, we genotyped four near-isogenic line (NIL) pairs targeting a major QTL qDSI.4B.1 on wheat chromosome arm 4BS for drought tolerance using the 90K SNP Illumina iSelect array and discovered a single nucleotide polymorphism (SNP) (Excalibur_c100336_106) with consistent genotype-phenotype associations among all four NIL pairs and their parents. Then, we converted the SNP into a Kompetitive Allele-Specific PCR (KASP) marker, with an accuracy of 100% for the four NIL pairs and their parents and as high as 81.8% for the 44 tested wheat lines with known phenotypes collected from Australia and China. Two genes near this SNP were suggested as candidate genes for drought tolerance in wheat after checking the Chinese Spring reference genome annotation version 1.1. One gene, TraesCS4B02G085300, encodes an F-box protein reportedly related to the ABA network, a main pathway for drought tolerance, and another gene, TraesCS4B02G085400, encodes a calcineurin-like metallophos-phoesterase transmembrane protein, which participates in Ca2+-dependent phosphorylation regulatory system. Based on this work and previous research on pre-harvest sprouting, we established a quick and efficient general SQV-based approach for KASP marker development, integrating genotyping by SNP arrays (S) using NILs targeting major QTL for a specific trait (Q) and validating them with commercial varieties (V). The identified SNP and developed KASP marker could be applied to marker-assisted selection in drought breeding, and further study of the candidate genes may improve our understanding of drought tolerance in wheat.

Project description:BackgroundWalnut (Juglans regia, 2n = 32, approximately 606 Mb per 1C genome) is an economically important tree crop. Resistance to anthracnose, caused by Colletotrichum gloeosporioides, is a major objective of walnut genetic improvement in China. The recently developed specific length amplified fragment sequencing (SLAF-seq) is an efficient strategy that can obtain large numbers of markers with sufficient sequence information to construct high-density genetic maps and permits detection of quantitative trait loci (QTLs) for molecular breeding.ResultsSLAF-seq generated 161.64 M paired-end reads. 153,820 SLAF markers were obtained, of which 49,174 were polymorphic. 13,635 polymorphic markers were sorted into five segregation types and 2,577 markers of them were used to construct genetic linkage maps: 2,395 of these fell into 16 linkage groups (LGs) for the female map, 448 markers for the male map, and 2,577 markers for the integrated map. Taking into account the size of all LGs, the marker coverage was 2,664.36 cM for the female map, 1,305.58 cM for the male map, and 2,457.82 cM for the integrated map. The average intervals between two adjacent mapped markers were 1.11 cM, 2.91 cM and 0.95 cM for three maps, respectively. 'SNP_only' markers accounted for 89.25% of the markers on the integrated map. Mapping markers contained 5,043 single nucleotide polymorphisms (SNPs) loci, which corresponded to two SNP loci per SLAF marker. According to the integrated map, we used interval mapping (Logarithm of odds, LOD > 3.0) to detect our quantitative trait. One QTL was detected for anthracnose resistance. The interval of this QTL ranged from 165.51 cM to 176.33 cM on LG14, and ten markers in this interval that were above the threshold value were considered to be linked markers to the anthracnose resistance trait. The phenotypic variance explained by each marker ranged from 16.2 to 19.9%, and their LOD scores varied from 3.22 to 4.04.ConclusionsHigh-density genetic maps for walnut containing 16 LGs were constructed using the SLAF-seq method with an F1 population. One QTL for walnut anthracnose resistance was identified based on the map. The results will aid molecular marker-assisted breeding and walnut resistance genes identification.

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A high-density genetic map with array-based markers facilitates structural and quantitative trait locus analyses of the common wheat genome.

Publications

A high-density genetic map with array-based markers facilitates structural and quantitative trait locus analyses of the common wheat genome.

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