G1 point mutation in growth differentiation factor 9 gene affects litter size in Sudanese desert sheep

Amani Z Abdelgadir; Lutfi M A Musa; Khaleel I Jawasreh; Aubai O Saleem; Faisal El-Hag; Mohamed-Khair A Ahmed

doi:10.14202/vetworld.2021.104-112

G1 point mutation in growth differentiation factor 9 gene affects litter size in Sudanese desert sheep

Vet World. 2021 Jan;14(1):104-112. doi: 10.14202/vetworld.2021.104-112. Epub 2021 Jan 13.

Authors

Amani Z Abdelgadir¹, Lutfi M A Musa^{2

3}, Khaleel I Jawasreh⁴, Aubai O Saleem⁵, Faisal El-Hag⁶, Mohamed-Khair A Ahmed²

Affiliations

¹ Department of Animal Production, Faculty of Agriculture, Omdurman Islamic University, Sudan.
² Department of Animal Breeding and Genetics, Faculty of Animal Production, University of Khartoum, Sudan.
³ Arab Center for Studies of Arid Zones and Dry Land, The League of Arab states, Syria.
⁴ Department of Animal Productions, Faculty of Agriculture - Jordan University of Science and Technology, Jordan.
⁵ Department of Bioinformatics, Africa City of technology, Sudan.
⁶ Arid Land Research Center (ALRC), Tottori University, 1390 Hamasaka, Tottori 680-0001, Japan.

Abstract

Background and aim: Sudanese desert sheep encompass different sheep breeds named according to the different Sudanese tribes that rear them such as the Dubasi, Shugor, and Watish sheep. The objectives of this study were to screen for G1 point mutation in the polymorphic growth differentiation factor 9 (GDF9) gene, investigate its association with litter size, and construct the phylogeny of the different tribal breeds that belong to the Sudanese Desert sheep tribal types.

Materials and methods: Genomic DNA was extracted from whole blood of three tribal Desert sheep breeds (Dubasi, Watish, and Shugor) using the guanidine chloride method. Polymerase chain reaction-restriction fragment length polymorphism with HhaI restriction enzyme and sequencing techniques was used for genotyping the GDF9 locus for possible mutations associated with litter size in the three desert sheep tribal types.

Results: G1 mutation in GDF9 caused the replacement of Arginine by Histidine at residue 87. The wild type allele (A) had the highest frequency, whereas the mutant type allele (a) had the lowest in all the sequenced subtypes. The genotype frequencies of the wild type ewes (AA) were higher than the heterozygous (Aa) and the mutant type (aa) frequencies in the three studied desert sheep types. No significant differences were found in the allele frequency between the three tribal types. Litter size was significantly influenced by the genotypes of GDF9 gene, parities, and subtypes (p≤0.01, 0.01, and 0.05, respectively). In the Watish sheep type, heterozygous sheep in their second parity recorded the highest litter size. Sequence alignment of GDF9 gene samples with the database entry indicated that all three tribal types were similar and identical to the reference sequence. The phylogenetic tree revealed that Shugor is the common ancestor of the studied types and Watish is more closely related to Shugor than Dubasi. This result mi ght partly explain the lower reproductive performance of Dubasi compared to Watish and Shugor.

Conclusion: The presence of one copy of GDF9 gene increased litter size in the studied Sudanese Desert sheep. This locus may be used as a biomarker for litter size improvement through genotypic selection and allele or gene introgression.

Keywords: Sudanese sheep; common ancestor; growth differentiation factor 9 gene; similarity and identity.