Abstract
BackgroundMeiotic recombination plays an important role in reproduction and evolution. The individual global recombination rate (GRR), measured as the number of crossovers (CO) per gametes, is a complex trait that has been shown to be heritable. The sex chromosomes play an important role in reproduction and fertility related traits. Therefore, variants present on the X-chromosome might have a high contribution to the genetic variation of GRR that is related to meiosis and to reproduction.ResultsWe herein used genotyping data from 58,474 New Zealand dairy cattle to estimate the contribution of the X-chromosome to male and female GRR levels. Based on the pedigree-based relationships, we first estimated that the X-chromosome accounted for 30% of the total additive genetic variance for male GRR. This percentage was equal to 19.9% when the estimation relied on a SNP-BLUP approach assuming each SNP has a small contribution. We then carried out a haplotype-based association study to map X-linked QTL, and subsequently fine-mapped the identified QTL with imputed sequence variants. With this approach we identified three QTL with large effect accounting for 7.7% of the additive genetic variance of male GRR. The associated effects were equal to + 0.79, − 1.16 and + 1.18 CO for the alternate alleles. In females, the estimated contribution of the X-chromosome to GRR was null and no significant association with X-linked loci was found. Interestingly, two of the male GRR QTL were associated with candidate genes preferentially expressed in testis, in agreement with a male-specific effect. Finally, the most significant QTL was associated with PPP4R3C, further supporting the important role of protein phosphatase in double-strand break repair by homologous recombination.ConclusionsOur study illustrates the important role the X-chromosome can have on traits such as individual recombination rate, associated with testis in males. We also show that contribution of the X-chromosome to such a trait might be sex dependent.
Highlights
Recombination is a fundamental biological and evolutionary process
Genetic studies have demonstrated that individual variation in global recombination rate (GRR), measured as the number of crossovers (CO) per gametes, is heritable in human [13], cattle [8, 9, 14], sheep [10, 15] and Drosophila [16]
The permanent environmental contribution was more impacted, decreasing from 3.8 to 1.0% suggesting that this effect could capture the X-chromosome effect when not included in the model
Summary
Recombination is a fundamental biological and evolutionary process. It creates genetic diversity among gametes and offspring by shuffling paternally and maternallyKadri et al BMC Genomics (2022) 23:114 recombination rate (RR) has been measured in the homogametic sex in many species [3,4,5,6,7], the opposite has been observed in cattle [8, 9] and sheep [10]. Recombination is a fundamental biological and evolutionary process It creates genetic diversity among gametes and offspring by shuffling paternally and maternally. Genetic studies have demonstrated that individual variation in global recombination rate (GRR), measured as the number of crossovers (CO) per gametes, is heritable in human [13], cattle [8, 9, 14], sheep [10, 15] and Drosophila [16]. The individual global recombination rate (GRR), measured as the number of crossovers (CO) per gametes, is a complex trait that has been shown to be heritable. The sex chromosomes play an important role in reproduction and fertility related traits. There‐ fore, variants present on the X-chromosome might have a high contribution to the genetic variation of GRR that is related to meiosis and to reproduction
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