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Article|01 Mar 2020|OPEN
Genome-wide association studies for inflorescence type and remontancy in Hydrangea macrophylla
Xingbo Wu1 & Lisa W. Alexander2
1Oak Ridge Institute of Science and Technology, Otis L. Floyd Nursery Research Center, 472 Cadillac Lane, McMinnville, TN, USA
2U.S. Department of Agriculture, Agricultural Research Service, U.S. National Arboretum, Floral and Nursery Plants Research Unit, Otis L. Floyd Nursery Research Center, 472 Cadillac Lane, McMinnville, TN, USA

Horticulture Research 7,
Article number: 20027 (2020)
doi: 10.1038/hortres.2020.27
Views: 351

Received: 12 Aug 2019
Revised: 31 Dec 2019
Accepted: 04 Jan 2020
Published online: 01 Mar 2020


Inflorescence type and remontancy are two valuable traits in bigleaf hydrangea (Hydrangea macrophylla L.) and both are recessively inherited. Molecular marker-assisted selection (MAS) can greatly reduce the time necessary to breed cultivars with desired traits. In this study, a genome-wide association study (GWAS) using 5803 single-nucleotide polymorphisms (SNPs) was performed using a panel of 82 bigleaf hydrangea cultivars. One SNP locus (Hy_CAPS_Inflo) associated with inflorescence type was identified with general linear model (GLM) and mixed linear model (MLM) methods that explained 65.5% and 36.1% of the phenotypic variations, respectively. Twenty-three SNPs associated with remontancy were detected in GLM whereas no SNP was detected in MLM. The SNP locus (Hy_CAPS_Inflo) was converted to a cleaved amplified polymorphic sequence (CAPS) marker that showed absolute identification accuracy (100%) of inflorescence type in a validation panel consisting of eighteen H. macrophylla cultivars. The SNP was investigated in 341 F1 progenies using genotyping by sequencing (GBS) and co-segregated with inflorescence type (χ2 = 0.12; P = 0.73). The SNP was subsequently used for breeding selection using kompetitive allele specific PCR (KASP) technology. Future directions for the use of genomics and MAS in hydrangea breeding improvement are discussed. The results presented in this study provide insights for further research on understanding genetic mechanisms behind inflorescence type and remontancy in H. macrophylla. The CAPS and KASP markers developed here will be immediately useful for applying MAS to accelerate breeding improvement in hydrangea.