TY - JOUR

T1 - Production of light-coloured, low heat-absorbing Holstein Friesian cattle by precise embryo-mediated genome editing

AU - Wei, Jingwei

AU - Brophy, Brigid

AU - Cole, Sally Ann

AU - Leath, Shane

AU - Oback, Björn

AU - Boch, Jens

AU - Wells, David N.

AU - Laible, Götz

N1 - Funding Information: The authors would like to thank members of the Animal Biotech team and farm staff for their support. We are grateful for funding of this study by AgResearch, CRV Ltd, Livestock Improvement Corporation and the Ministry of Business, Innovation and Employment.

PY - 2023/9/22

Y1 - 2023/9/22

N2 - Context. Genome editing enables the introduction of beneficial sequence variants into the genomes of animals with high genetic merit in a single generation. This can be achieved by introducing variants into primary cells followed by producing a live animal from these cells by somatic cell nuclear transfer cloning. The latter step is associated with low efficiencies and developmental problems due to incorrect reprogramming of the donor cells, causing animal welfare concerns. Direct editing of fertilised one-cell embryos could circumvent this issue and might better integrate with genetic improvement strategies implemented by the industry. Methods. In vitro fertilised zygotes were injected with TALEN editors and repair template to introduce a known coat colour dilution mutation in the PMEL gene. Embryo biopsies of injected embryos were screened by polymerase chain reaction and sequencing for intended biallelic edits before transferring verified embryos into recipients for development to term. Calves were genotyped and their coats scanned with visible and hyperspectral cameras to assess thermal energy absorption. Key results. Multiple non-mosaic calves with precision edited genotypes were produced, including calves from high genetic merit parents. Compared to controls, the edited calves showed a strong coat colour dilution which was associated with lower thermal energy absorbance. Conclusions. Although biopsy screening was not absolutely accurate, non-mosaic, precisely edited calves can be readily produced by embryo-mediated editing. The lighter coat colouring caused by the PMEL mutation can lower radiative heat gain which might help to reduce heat stress. Implications. The study validates putative causative sequence variants to rapidly adapt grazing cattle to changing environmental conditions.

AB - Context. Genome editing enables the introduction of beneficial sequence variants into the genomes of animals with high genetic merit in a single generation. This can be achieved by introducing variants into primary cells followed by producing a live animal from these cells by somatic cell nuclear transfer cloning. The latter step is associated with low efficiencies and developmental problems due to incorrect reprogramming of the donor cells, causing animal welfare concerns. Direct editing of fertilised one-cell embryos could circumvent this issue and might better integrate with genetic improvement strategies implemented by the industry. Methods. In vitro fertilised zygotes were injected with TALEN editors and repair template to introduce a known coat colour dilution mutation in the PMEL gene. Embryo biopsies of injected embryos were screened by polymerase chain reaction and sequencing for intended biallelic edits before transferring verified embryos into recipients for development to term. Calves were genotyped and their coats scanned with visible and hyperspectral cameras to assess thermal energy absorption. Key results. Multiple non-mosaic calves with precision edited genotypes were produced, including calves from high genetic merit parents. Compared to controls, the edited calves showed a strong coat colour dilution which was associated with lower thermal energy absorbance. Conclusions. Although biopsy screening was not absolutely accurate, non-mosaic, precisely edited calves can be readily produced by embryo-mediated editing. The lighter coat colouring caused by the PMEL mutation can lower radiative heat gain which might help to reduce heat stress. Implications. The study validates putative causative sequence variants to rapidly adapt grazing cattle to changing environmental conditions.

KW - cattle

KW - coat color dilution

KW - embryo-mediated

KW - genome editing

KW - heat stress

KW - homology-directed repair

KW - microinjection

KW - P. Leu18del

KW - PMEL

KW - pre-melanosome protein 17

KW - TALEN

UR - http://www.scopus.com/inward/record.url?scp=85179642582&partnerID=8YFLogxK

U2 - 10.1071/RD23163

DO - 10.1071/RD23163

M3 - Review article

C2 - 38064192

AN - SCOPUS:85179642582

VL - 36

SP - 112

EP - 123

JO - Reproduction, Fertility and Development

JF - Reproduction, Fertility and Development

SN - 1031-3613

IS - 2

ER -