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ARS Home » Northeast Area » Washington, D.C. » National Arboretum » Floral and Nursery Plants Research » Research » Publications at this Location » Publication #412608
Research Project: Functional Genomics, Genetic Improvement, and Sustainable Production of Nursery Crops

Location: Floral and Nursery Plants Research

Title: Production and verification of novel Osmanthus hybrids

Author
item Alexander, Lisa
item WU, XINGBO - University Of Florida
item Gouker, Fred

Submitted to: Frontiers in Horticulture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/29/2024
Publication Date: 4/10/2024
Citation: Alexander, L.W., Wu, X., Gouker, F.E. 2024. Production and verification of novel Osmanthus hybrids. Frontiers in Horticulture. https://doi.org/10.3389/fhort.2024.1382450.
DOI: https://doi.org/10.3389/fhort.2024.1382450

Interpretive Summary: Ornamental flowering trees enjoy worldwide popularity for their impact in the landscape, and few flowering tree species boast the intense fragrance found in Osmanthus (tea olive) species. These species are used prolifically as specimen trees, hedges, and fragrant verges in USDA Hardiness zones 7 - 10 where they thrive. Further breeding improvement is necessary in Osmanthus to increase cold-hardiness and introgress the smooth leaf and upright form of O. fragrans into cultivars adapted for U.S. landscapes. USDA scientists in McMinnville, Tennessee developed new Osmanthus hybrids by making controlled and open-pollinated crosses among Osmanthus species and assigning parentage to the seedlings using molecular markers. Hybrids in this study including O. armatus × O. fortunei, O. armatus × O. heterophyllus, and O. armatus × O. fragrans are novel Osmanthus hybrids. These hybrids will be evaluated for cold-tolerance, growth, form, and ornamental potential. Evaluation of more Osmanthus accessions and subsequent hybridizations will be necessary to introgress favorable genes and generate the variation necessary to expand the genus into new markets.

Technical Abstract: Osmanthus fragrans Lour. is prized for its fragrant, cool-season blooms, smooth leaves, and compact tree form; however, the species is limited in production and use to USDA Hardiness Zones 7 and higher. Osmanthus fortunei (an O. fragrans × O. heterophyllus hybrid) displays cold-hardiness intermediate to that of its parents, suggesting that hybrid breeding can be an avenue for cold-hardiness improvement in Osmanthus. The objectives of this study were to produce, verify, and evaluate novel Osmanthus hybrids by 1) making controlled and open-pollinated crosses among Osmanthus species; 2) using SSR markers to determine parentage of cross progeny, and 3) compare flowering, leaf shape, and form of hybrids offspring with parents. Fifty-eight of 66 progenies (88%) were assigned paternity at the 95% confidence level or above and 47 progenies (71%) were assigned paternity at the 99% confidence level. Progenies in this study including O. armatus × O. fortunei, O. armatus × O. heterophyllus, and O. armatus × O. fragrans are novel Osmanthus hybrids. Open-pollinated families increased in height an average of 204% and 159% per year in the first and second growing seasons, respectively. Male flower type was significantly associated with progeny flower type ('2= 17.5, p < 0.0001) while leaf margin was not associated with cross family ('2 = 0.83, p = 0.84). Evaluation of more Osmanthus accessions and subsequent hybridizations will be necessary to introgress favorable genes and generate the variation necessary to expand the genus into new markets.