title: Interspecific hybridization among cultivars of hardy Hibiscus species section Muenchhusia.
abstract: Rose mallows belong to the Muenchhusia section of the Hibiscus genus. They represent a small group of cold tolerant North American plants and are popular ornamentals mainly because of their abundant, large and colorful flowers. Due to their geographical origin they are well suited for garden use in temperate regions worldwide. The aim of the study was to investigate hybridization barriers in crosses among cultivars of Hibiscus species from the Muenchhusia section: H. coccineus, H. laevis and H. moscheutos. Crossing barriers were identified as both pre- and post-zygotic. The analysis of pollen tube growth revealed inhibition of pollen tubes and their abnormal growth. In specific crosses the fertilization success was low. The pre-fertilization barriers did not cause a complete reproductive isolation between the hybridization partners. In relation to post-fertilization barriers, the occurrence of hybrid incompatibilities such as unviability, chlorosis, necrosis, stunted growth and albinism were the main drawback in production of hybrids. The appearance of symptoms of hybrid incompatibilities was dependent upon specific parental plants. The obtained progeny had intermediate leaf morphology and flower morphology compared to parental plants. Hybridity state was verified by morphological analysis and RAPD markers. Based on the overall plant morphology, 472 hybrid progenies were obtained.
authors.affiliation: Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen , Højbakkegård Allé 9-13, DK-2630 Taastrup , Denmark.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Kuligowska
authors.affiliation: Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen , Højbakkegård Allé 9-13, DK-2630 Taastrup , Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Lütken
authors.affiliation: AgroTech A/S, Institute for Agri Technology and Food Innovation , Højbakkegård Allé 21, DK-2630 Taastrup , Denmark.
authors.forename: Brian
authors.initials: B
authors.lastname: Christensen
authors.affiliation: Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen , Højbakkegård Allé 9-13, DK-2630 Taastrup , Denmark.
authors.forename: Renate
authors.initials: R
authors.lastname: Müller
keywords: albinism; hybrid incompatibility; hybrid inviability; pollen tube; post-fertilization barrier; pre-fertilization barrier