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ARS Home » Northeast Area » Washington, D.C. » National Arboretum » Floral and Nursery Plants Research » Research » Publications at this Location » Publication #230572
Title: SSR Marker Analysis of Genetic Relationships within Hydrangea paniculata

Author
item Reed, Sandra
item Rinehart, Timothy - Tim

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/7/2008
Publication Date: 2/20/2009
Citation: Reed, S.M., Rinehart, T.A. 2009. SSR Marker Analysis of Genetic Relationships within Hydrangea paniculata. HortScience. 44(1):27-31.

Interpretive Summary: Approximately 50 cultivars of Hydrangea paniculata, which is also known as panicle hydrangea, have been introduced to the trade. A few originated in Japan and have been in cultivation for over 100 years. Others were developed through breeding efforts in Europe and have only been introduced to the U.S. during the past 10 to 15 years. In addition to named cultivars, a few wild-collected H. paniculata accessions are available in the U.S. The objective of this study was to use molecular markers to evaluate genetic relationships within H. paniculata. Three cultivars (Boskoop, Compact Grandiflora and Webb) were either identical to or sports of the popular cultivar Grandiflora. The name ‘Pee Wee’ appears to have been applied to two morphologically distinct compact forms of H. paniculata, one of which seems to be a sport of ‘Tardiva’ whereas the other is likely derived from ‘Grandiflora’. No close genetic similarity was observed among several cultivars from a long-term Belgium breeding program, even though many had one parent in common. Early-flowering cultivars were genetically distinct from those that flower in mid-summer. Two wild-collected accessions from Taiwan were genetically similar, but were distinctly different from the Japanese cultivars and selections. This study identified potentially unexploited sources of germplasm within H. paniculata and revealed relationships between existing cultivars of this popular shrub. This information should of value when selecting parents for breeding programs.

Technical Abstract: Genetic diversity studies using 26 simple-sequence repeat (SSR) markers were conducted with 36 taxa of Hydrangea paniculata Sieb. The SSR loci were highly variable among the taxa, producing a mean of 5.8 alleles per locus. Three cultivars (Boskoop, Compact Grandiflora and Webb) were either identical to or sports of the popular cultivar Grandiflora. The name ‘Pee Wee’ appears to have been applied to two phenotypically different compact forms of H. paniculata, one of which seems to be a sport of ‘Tardiva’ whereas the other is likely derived from ‘Grandiflora’. No close genetic similarity was observed among several cultivars from a long-term Belgium breeding program, even though many had one parent in common. Early-flowering taxa clustered separately from taxa that flower in mid-summer, but close genetic relationships were not observed among early-flowering cultivars. Two taxa from Taiwan were genetically similar, but were distinctly different from the Japanese taxa. These, along with the early-flowering taxa and a new collection from Japan, may represent unexploited sources of germplasm for improvement of H. paniculata.