SNP g.1007A>G within the porcine DNAL 4 gene affects sperm motility traits and percentage of midpiece abnormalities

Contents The flagellar beating of a spermatozoa's axoneme is caused by the varying activation and inactivation of dynein molecules. Dynein, axonemal, light chain 4 ( DNAL 4 ) is a functional candidate gene for sperm motility as it encodes a small subunit of the dyneins. We resequenced the porcine DNAL 4 using three artificial insemination ( AI ) boars each with high (>68%) or low (<60%) motility, and detected 23 SNP . These were then genotyped for 82 AI boars. Using spermatological records, significantly negative genetic correlations between ejaculate volume ( VOL ) and the further spermatological parameters concentration ( CONC ) ( r  = −.43), motility of undiluted semen ( MOTUD ) ( r  = −.09), motility after 24 h ( MOT 1) ( r  = −.17) and after 48 hr ( MOT 2) ( r  = −.23) were estimated. Significantly positive correlations existed between CONC and MOT 1 ( r  = .07) as well as MOT 2 ( r  = .10), between MOTUD and MOT 1 ( r  = .33), between MOTUD and MOT 2 ( r  = .36), and finally between MOT 1 and MOT 2 ( r  = .70). Significantly negatively correlated were all motility traits with the parameters abnormal acrosome ( AA ) ( MOTUD r  = −.06; MOT 1 r  = −.08, and MOT 2 r  = −.1) and presence of cytoplasmic droplet ( CD ) ( MOTUD r  = −.07; MOT 1 r  = −.08; MOT 2 r  = −.07). Association analyses (single marker regression model; SMR ) propose that SNP g.1007A>G, located in the second intron, reduces motility significantly ( MOTUD ‐4.59%; MOT 1 ‐10.33%; MOT 2 ‐19.37%). According to the dominant‐recessive model ( DRM ), genotype AA is always superior compared to genotypes AG and GG (i.e. MOTUD 67.67%, 64.16% and 53.91%; MOT 1 54.17%, 43.75% and 28.44%; MOT 2 44.12%, 24.91% and 4.97%). The average effect of gene substitution (g.1007A>G) on abnormal midpiece ( AM ) was 0.71%, the genotypic values—as expressed by LS means—were 0.1 ( AA ) and 0.81 ( AG ).