AUTHOR=Alexander Lisa , Wu Xingbo , Gouker Fred 

TITLE=Production and verification of novel Osmanthus hybrids

JOURNAL=Frontiers in Horticulture

VOLUME=3

YEAR=2024

URL=https://www.frontiersin.org/journals/horticulture/articles/10.3389/fhort.2024.1382450

DOI=10.3389/fhort.2024.1382450

ISSN=2813-3595

ABSTRACT=<p><italic>Osmanthus fragrans</italic> 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. Increasing the total amount of genetic variability available for evaluation, selection, and breeding is foundational to the development of novel <italic>Osmanthus</italic> cultivars with increased cold-hardiness and improved ornamental characteristics such as high rooting rates, faster growth, fragrant flowers, and an evergreen or semi-evergreen habit. Hybridization among <italic>Osmanthus</italic> species should generate novel phenotypes and allow trait introgression among populations and breeding lines. The objectives of this study were to produce, verify, and evaluate <italic>Osmanthus</italic> hybrids by making controlled and open-pollinated crosses among <italic>Osmanthus</italic> species, using SSR markers to determine parentage of cross progeny, and comparing 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. Novel <italic>Osmanthus</italic> hybrids were produced including <italic>O. armatus</italic> × <italic>O. fortunei</italic>, <italic>O. armatus</italic> × <italic>O. heterophyllus</italic>, and <italic>O. armatus</italic> × <italic>O. fragrans</italic>. 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 (χ<sup>2</sup> = 17.5, p &lt; 0.0001) while leaf margin was not associated with cross family (χ<sup>2</sup> = 0.83, p = 0.84). Evaluation of more <italic>Osmanthus</italic> accessions and subsequent hybridizations will be necessary to introgress favorable genes and generate the variation necessary to expand the genus into new markets.</p>