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Santos WB, Schettini GP, Maiorano AM, Bussiman FO, Balieiro JCC, Ferraz GC, Pereira GL, Baldassini WA, Neto ORM, Oliveira HN, Curi RA. Genome-wide scans for signatures of selection in Mangalarga Marchador horses using high-throughput SNP genotyping. BMC Genomics 2021; 22:737. [PMID: 34645387 PMCID: PMC8515666 DOI: 10.1186/s12864-021-08053-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 09/07/2021] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND The detection of signatures of selection in genomic regions provides insights into the evolutionary process, enabling discoveries regarding complex phenotypic traits. In this research, we focused on identifying genomic regions affected by different selection pressures, mainly highlighting the recent positive selection, as well as understanding the candidate genes and functional pathways associated with the signatures of selection in the Mangalarga Marchador genome. Besides, we seek to direct the discussion about genes and traits of importance in this breed, especially traits related to the type and quality of gait, temperament, conformation, and locomotor system. RESULTS Three different methods were used to search for signals of selection: Tajima's D (TD), the integrated haplotype score (iHS), and runs of homozygosity (ROH). The samples were composed of males (n = 62) and females (n = 130) that were initially chosen considering well-defined phenotypes for gait: picada (n = 86) and batida (n = 106). All horses were genotyped using a 670 k Axiom® Equine Genotyping Array (Axiom MNEC670). In total, 27, 104 (chosen), and 38 candidate genes were observed within the signatures of selection identified in TD, iHS, and ROH analyses, respectively. The genes are acting in essential biological processes. The enrichment analysis highlighted the following functions: anterior/posterior pattern for the set of genes (GLI3, HOXC9, HOXC6, HOXC5, HOXC4, HOXC13, HOXC11, and HOXC10); limb morphogenesis, skeletal system, proximal/distal pattern formation, JUN kinase activity (CCL19 and MAP3K6); and muscle stretch response (MAPK14). Other candidate genes were associated with energy metabolism, bronchodilator response, NADH regeneration, reproduction, keratinization, and the immunological system. CONCLUSIONS Our findings revealed evidence of signatures of selection in the MM breed that encompass genes acting on athletic performance, limb development, and energy to muscle activity, with the particular involvement of the HOX family genes. The genome of MM is marked by recent positive selection. However, Tajima's D and iHS results point also to the presence of balancing selection in specific regions of the genome.
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Affiliation(s)
- Wellington B Santos
- Department of Animal Science, São Paulo State University (Unesp) - FCAV, Via de Acesso Professor Paulo Donato Castelane, NN, CEP: 14884-900, Jaboticabal, SP, Brazil.
| | - Gustavo P Schettini
- Department of Animal Science, São Paulo State University (Unesp) - FCAV, Via de Acesso Professor Paulo Donato Castelane, NN, CEP: 14884-900, Jaboticabal, SP, Brazil
| | - Amanda M Maiorano
- Department of Animal Science, São Paulo State University (Unesp) - FCAV, Via de Acesso Professor Paulo Donato Castelane, NN, CEP: 14884-900, Jaboticabal, SP, Brazil
| | - Fernando O Bussiman
- Department of Animal Science, University of São Paulo (USP) - FZEA, Pirassununga, Brazil
| | - Júlio C C Balieiro
- Department of Animal Science, University of São Paulo (USP) - FZEA, Pirassununga, Brazil
| | - Guilherme C Ferraz
- Department of Animal Science, São Paulo State University (Unesp) - FCAV, Via de Acesso Professor Paulo Donato Castelane, NN, CEP: 14884-900, Jaboticabal, SP, Brazil
| | - Guilherme L Pereira
- Department of Breeding and Animal Nutrition, São Paulo State University (Unesp) - FMVZ, Botucatu, Brazil
| | - Welder Angelo Baldassini
- Department of Breeding and Animal Nutrition, São Paulo State University (Unesp) - FMVZ, Botucatu, Brazil
| | - Otávio R M Neto
- Department of Breeding and Animal Nutrition, São Paulo State University (Unesp) - FMVZ, Botucatu, Brazil
| | - Henrique N Oliveira
- Department of Animal Science, São Paulo State University (Unesp) - FCAV, Via de Acesso Professor Paulo Donato Castelane, NN, CEP: 14884-900, Jaboticabal, SP, Brazil
| | - Rogério A Curi
- Department of Breeding and Animal Nutrition, São Paulo State University (Unesp) - FMVZ, Botucatu, Brazil
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Fountain ED, Zhou LC, Karklus A, Liu QX, Meyers J, Fontanilla IKC, Rafael EF, Yu JY, Zhang Q, Zhu XL, Pei EL, Yuan YH, Banes GL. Cross-Species Application of Illumina iScan Microarrays for Cost-Effective, High-Throughput SNP Discovery. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.629252] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Microarrays can be a cost-effective alternative to high-throughput sequencing for discovering novel single-nucleotide polymorphisms (SNPs). Illumina’s iScan platform dominates the market, but their commercial microarray products are designed for model organisms. Further, the platform outputs data in a proprietary format. This cannot be easily converted to human-readable genotypes or be merged with pre-existing data. To address this, we present and validate a novel pipeline to facilitate data analysis from cross-species application of Illumina microarrays. This facilitates the generation of a compatible VCF from iScan data and the merging of this with a second VCF comprising genotypes derived from other samples and sources. Our pipeline includes a custom script, iScanVCFMerge (presented as a Python package), which we validate using iScan data from three great ape genera. We conclude that cross-species application of microarrays can be a rapid, cost-effective approach for SNP discovery in non-model organisms. Our pipeline surmounts the common challenges of integrating iScan genotypes with pre-existing data.
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Abstract
Runs of homozygosity (ROH) are chromosomal stretches that in a diploid genome appear in a homozygous state and display identical alleles at multiple contiguous loci. This study aimed to systematically compare the genomic distribution of the ROH islands among five populations of wild vs commercial chickens of both layer and broiler type. To this end, we analyzed whole genome sequences of 115 birds including white layer (WL, n = 25), brown layer (BL, n = 25), broiler line A (BRA, n = 20), broiler line B (BRB, n = 20) and Red Junglefowl (RJF, n = 25). The ROH segments varied in size markedly among populations, ranging from 0.3 to 21.83 Mb reflecting their past genealogy. White layers contained the largest portion of the genome in homozygous state with an average ROH length of 432.1 Mb (±18.7) per bird, despite carrying it in short segments (0.3-1 Mb). Population-wise inbreeding measures based on Wright's (Fis) and genomic (FROH) metrics revealed highly inbred genome of layer lines relative to the broilers and Red Junglefowl. We further revealed the ROH islands, among commercial lines overlapped with QTL related to limb development (GREM1, MEOX2), body weight (Meis2a.1, uc_338), eggshell color (GLCCI1, ICA1, UMAD1), antibody response to Newcastle virus (ROBO2), and feather pecking. Comparison of ROH landscape in sequencing resolution demonstrated that a sizable portion of genome of commercial lines segregates in homozygote state, reflecting many generations of assortative mating and intensive selection in their recent history. In contrary, wild birds carry shorter ROH segments, likely suggestive of older evolutionary events.
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