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ARS Home » Southeast Area » Stoneville, Mississippi » Genomics and Bioinformatics Research » Research » Publications at this Location » Publication #401816
Research Project: Applied Agricultural Genomics and Bioinformatics Research

Location: Genomics and Bioinformatics Research

Title: Two haplotype-resolved genomes reveal important flower traits in bigleaf hydrangea (Hydrangea macrophylla) and insights into Asterid evolution

Author
item WU, XINGBO - University Of Florida
item Simpson, Sheron
item YOUNGBLOOD, RAMEY - Mississippi State University
item Scheffler, Brian
item Alexander, Lisa
item Hulse-Kemp, Amanda

Submitted to: Horticulture Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/7/2023
Publication Date: 11/9/2023
Citation: Wu, X., Simpson, S.A., Youngblood, R., Scheffler, B.E., Alexander, L.W., Hulse-Kemp, A.M. 2023. Whole genome sequencing reveals genes implicated with important flower traits in bigleaf hydrangea (Hydrangea macrophylla). Horticulture Research. https://doi.org/10.1093/hr/uhad217.
DOI: https://doi.org/10.1093/hr/uhad217

Interpretive Summary: Obtaining the DNA blueprint for the popular ornamental plant, big leaf Hydrangea, has been a challenge. In this study, we were able to develop the first, complete DNA blueprint for not only one cultivar, but two cultivars of big leaf Hydrangea. These two plants differ in important flowering traits like the structure of the flower (inflorescence), color, and flower petal quantity (double or single). These differences, along with a genetic mapping population, allowed us to identify and verify the genetic loci responsible for these two important flower traits. We were able to also confirm and validate previous work associated with these traits. We have developed tools to allow plant breeders to use the genetic information to selectively pick which flower type plants to move forward in their breeding programs as desired.

Technical Abstract: Bigleaf hydrangea (Hydrangea macrophylla) is one of the most valuable ornamental plants in the nursery trade, yet few genomic resources were developed for this crop. Such resources are needed to understand genetic mechanisms for ornamentally important traits and are critical for implementing modern plant breeding techniques. Two high-quality reference genomes of hydrangea cultivars Veitchii and Endless Summer were assembled using PacBio long read sequencing. The ‘Veitchii’ genome is 2.21 Gb consisting of 6790 contigs with contig N50 of 708.6 Kbp, which was further scaffolded into 18 pseudochromosomes (96.4% of the assembled genome). The ‘Endless Summer’ genome is 2.22 Gb consisting of 396 contigs with contig N50 of 22.8 Mbp, which was also scaffolded into 18 pseudochromosomes (98.6% of the assembled genome). An F1 population with 341 hybrids between ’Veitchii’ and ‘Endless Summer’ was used for linkage mapping of the inflorescence shape trait using genotyping by sequencing. A linkage map comprising eighteen linkage groups was constructed with 2468 single nucleotide polymorphisms (SNPs). By mapping highly selective markers associated with the inflorescence trait to both reference genomes, CYP78A5 located on chromosome 4 was identified to be the candidate gene for determining inflorescence shape. Furthermore, a novel gene, BAM3 located on chromosome 17, was identified as a candidate gene responsible for double flower, another important trait in hydrangea. The genome resources and the candidate genes presented here will help researchers and breeders determine genetic mechanisms driving flowering characteristics and floral development to develop high-value hydrangea cultivars for the nursery industry and the public.