FecXBar a Novel BMP15 mutation responsible for prolificacy and female sterility in Tunisian Barbarine Sheep

Narjess Lassoued,Sonia Bedhiaf-Romdhani,Ahmed Rejeb,Mohamed Aouina,Zohra Benkhlil,Stephane Fabre,Mourad Rekik,Florent Woloszyn

doi:10.1186/s12863-017-0510-x

Abstract

BackgroundNaturally occurring mutations in growth and differentiation factor 9 (GDF9) or bone morphogenetic protein 15 (BMP15) genes are associated with increased ovulation rate (OR) and litter size (LS) but also sterility. Observing the Tunisian Barbarine ewes of the “W” flock selected for improved prolificacy, we found prolific and infertile ewes with streaky ovaries. Blood genomic DNA was extracted from a subset of low-ovulating, prolific and infertile ewes of the “W” flock, and the entire coding sequences of GDF9 and BMP15 were sequenced.ResultsWe evidenced a novel polymorphism in the exon 1 of the BMP15 gene associated with increased prolificacy and sterility. This novel mutation called FecXBar is a composite polymorphism associating a single nucleotide substitution (c.301G > T), a 3 bp deletion (c.302_304delCTA) and a C insertion (c.310insC) in the ovine BMP15 cDNA leading to a frame shift at protein position 101. Calculated in the “W” flock, the FecXBar allele increased OR by 0.7 ova and LS by 0.3 lambs (p = 0.08). As for already identified mutations, homozygous females carrying FecXBar exhibited streaky ovaries with a blockade at the primary stage of folliculogenesis as shown by histochemistry.ConclusionsOur investigation demonstrates a new mutation in the BMP15 gene providing a valuable genetic tool to control fecundity in Tunisian Barbarine, usable for diffusion program into conventional flocks looking for prolificacy improvement.

Highlights

Occurring mutations in growth and differentiation factor 9 (GDF9) or bone morphogenetic protein 15 (BMP15) genes are associated with increased ovulation rate (OR) and litter size (LS) and sterility
BMP15 and GDF9 sequence analysis Following laparoscopic observation of Tunisian Barbarine ewes of the “W” flock selected for increased LS, ewes were classified in 3 phenotypic groups regarding OR: low-ovulating (n = 7), high-ovulating (n = 11) and “streaky-bearing ovaries” females (n = 7)
Our results evidenced a new mutation in ovine BMP15 gene affecting the prolificacy and fertility of Barbarine ewes in the “W” flock selected for increased prolificacy

Summary

Introduction

Occurring mutations in growth and differentiation factor 9 (GDF9) or bone morphogenetic protein 15 (BMP15) genes are associated with increased ovulation rate (OR) and litter size (LS) and sterility. Sheep husbandry is a main pillar of the red meat value chain in Tunisia and several breeding programs are being implemented to sustain genetic improvement of sheep meat production retaining traits as diverse as meat quality, growth rate, environmental adaptation and prolificacy [1]. Considering the latter trait, most of the sheep breeds and strains in Tunisia are low prolific. Numerous studies in sheep identified point mutations in genes of the bone morphogenetic protein (BMP) family of growth factors associated to increased prolificacy and to sterility [6] resembling the phenotypes observed in the Barbarine “W” flock. Up to now, 6 different mutations were evidenced in the bone morphogenetic protein 15 (BMP15) gene and 3 mutations in the growth and differentiation factor 9

Methods

Results

Discussion

Conclusion