[in Japanese]

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Fatty acid composition, particularly the proportion of oleic acid (C18:1), has recently become an important breeding objective due to its strong influence on beef palatability and health benefits. Meanwhile, advances in whole-genome sequencing technologies now enable the comprehensive detection of genetic variants across the entire genome, providing powerful resources for identifying causal polymorphisms related to complex traits. In these contexts, we performed whole-genome sequencing in Japanese Black cattle to develop novel DNA markers associated with C18:1 proportion in intramuscular fat. Eight Japanese Black cattle showing extremely high or low C18:1 value was used for whole-genome sequencing. Approximately 16 million polymorphisms were detected, and variants showing variant annotations which were expected to have effects on gene function and large allelic differences between the high and low groups were prioritized. Among 70 polymorphisms within 33 genes, a missense substitution in the dermatan sulfate epimerase-like (DSEL) gene (c.733T>A; S245T) was identified as a strong candidate variant based on the gene function involved in fatty acid metabolism. Verification of the effect of this variant in a Japanese Black cattle population (n = 606) revealed a significant association with the proportion of C18:1 (p = 0.031) and significant difference of the C18:1 proportion between its genotypes. These results indicate that DSEL is an important candidate gene influencing fatty acid composition in Japanese Black cattle and that the identified c.733T>A polymorphism may serve as a useful DNA marker for selection to improve the proportion of C18:1 in beef.

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