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Georgia Journal of Science

Article Title

FIRST CHROMOSOME NUMBER DETERMINATIONS IN UTRICULARIA FLORIDANA, THE FLORIDA YELLOW BLADDERWORT, A CARNIVOROUS AQUATIC PLANT ENDEMIC TO THE SOUTHEASTERN UNITED STATES. **

Abstract

The genus Utricularia, comprising ca. 233 species commonly known as the bladderworts, is one of three genera in the carnivorous plant family Lentibulariaceae. These plants of wet soils and aquatic habitats are known for their extreme interspecific cytological variability, particularly within Utricularia and Genlisea: genomes in Genlisea show 24-fold differences in size between species, with 1C-values ranging from 63 Mbp in G. aurea (the smallest recorded in flowering plants) to 1510 Mbp in G. hispidula, and within Utricularia chromosome numbers range from n=6-40, with lengths spanning from ultra-diminutive to "normal". The genomic variability and miniaturization exhibited in this group may be due to accelerated mutational rates in certain gene regions, thus this group of plants is of particular interest to plant geneticists. However, minute chromosome size coupled with an absence of roots and tendency to inhabit inconvenient habitats renders determination of chromosome numbers in this group difficult, such that fewer than 20% of Utricularia species have been counted. Our goal in this study is to determine for the first time chromosome numbers in U. floridana. Samples from two discrete populations from separate lakes in the Ordway-Swisher Biological Station, Putnam County, FL were cultivated in tanks under optimal growing conditions. Vegetative buds were harvested during periods of active growth, immediately pretreated with 8-hydroxyquinoline to enhance spreading of mitotic chromosomes, fixed in 3:1 ethanol-glacial acetic acid, and stored in 70% ethanol. Meristem cells were isolated from surrounding tissues, stained with aceto-orcein or DAPI, and examined via light and fluorescent microscopy. Discrete cells with well-defined chromosomes were imaged and counted. We expect to establish for the first time chromosome numbers for this interesting species, verifying our results across multiple specimens from two discrete populations.

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