A new molecular mechanism supports that blue-greenish egg color evolved independently across chicken breeds

Refine localizations of functional variants affecting eggshell color of Lueyang black-boned chicken in the SLCO1B3

“…There was no significant difference of activities among the other 4 constructs ( Figure 6 ). We detected higher activities on the Hap4 of the −1,639/+18 construct than Hap13 in previous study ( Chen and Wang, 2022 ). Here, the activity difference was reproducible although it did not achieve statistical significance ( Figure 6 ).…”

“…LBC can also lay blue-green eggs. We detected a strong positive correlation between levels of SLCO1B3 expression in shell gland of LBC and eggshell biliverdin content, but did not find the EAV-HP insertion in the LBC ( Chen and Wang, 2022 ). The findings imply that SLCO1B3 remains to be a candidate gene affecting eggshell color of LBC, but functions through a new molecular mechanism.…”

“…The 5′ upstream region of genes is of importance in determining the pattern and level of expression of genes. We found that a promoter haplotype (Hap4) was associated not only with the blue egg of LBC, but with high promoter activities ( Chen and Wang, 2022 ). This study expected to define the core promoter of SLCO1B3 and to identify functional variants in the upstream region by association analysis and 5′-deleted reporter assay.…”

“…Our previous studies found that 2 haplotypes at the upstream 1.6-kb (Chr1: 65165648-65167304) region of SLCO1B3 were significantly associated with blue (Hap4) and brown (Hap13) eggs of LBC ( Chen and Wang, 2022 ). In this study, five 5′-deleted fragments were amplified from each of 2 birds that are homozygous for Hap4 and Hap13 using one common 3′ primer and five 5′-nested PCR primers ( Table S3 ).…”

“…Lueyang black-boned chicken ( LBC ) is an indigenous breed from Shaanxi province of China. Differing from commercial laying hens that lay uniform color eggs, LBC lays colorful eggs ranging from light brown, brown, greenish-brown, light green to olive green, implying that QTLs controlling eggshell color are segregating in the population ( Chen and Wang, 2022 ). Variable colors provide an opportunity for mapping QTLs, although it is unfavorable to sale of eggs.…”