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Genetics and Molecular Biology |
2Laboratory of Ecology and Genetics, Graduate School of Environmental Earth Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan; 3Mukogaoka, Ebetsu-city, Hokkaido 067-0075, Japan
ABSTRACT
Abandonment of sexual reproduction is a well-known characteristic in aquatic plants, while the causes, levels, and consequences of sterility are often unknown. Utricularia australis f. australis (Lentibulariaceae) is a free-floating, sterile bladderwort distributed widely in temperate and tropical regions. Experimental crosses in cultivated conditions, AFLP analysis, and cpDNA haplotypes of natural populations clearly demonstrated that U. australis f. australis originates from the asymmetric hybridization between two parental taxa: U. australis f. tenuicaulis (mostly as female) and U. macrorhiza (mostly as male). No post-F1 hybrids were detected using the additive patterns of AFLP bands combined with the observation of extensive sterility in U. australis f. australis. Recurrent hybridizations and subsequent perpetuation by asexual reproduction were demonstrated by the unique, but monomorphic, AFLP genotypes observed in each U. australis f. australis population. Hybrids and parental species did not coexist, implying the superiority of the hybrid U. australis f. australis in certain environmental conditions. It remains unclear whether populations of U. australis f. australis are maintained by colonizing propagules or as relicts of past hybridization events.
Key Words: AFLP asymmetric crossability clonal reproduction cpDNA haplotypes F1 dominance free-floating aquatic plant hybrid sterility hybrid vigor
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Y. KAMEYAMA and M. OHARA Genetic Structure in Aquatic Bladderworts: Clonal Propagation and Hybrid Perpetuation Ann. Bot., November 1, 2006; 98(5): 1017 - 1024. [Abstract] [Full Text] [PDF] |
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