Abstract Detail

Pteridology

Wheatley, Kayla [1], Pelosi, Jessie [2], Hornych, Ondřej [3], Zumwalde, Bethany [1], Sessa, Emily [1].

Cytology of the invasive climbing fern Lygodium japonicum in Florida.

Lygodium japonicum (Lygodiaceae) is a vining fern native to eastern Asia and introduced to North America as early as the 1880s. As a highly invasive fern, L. japonicum has colonized much of the southeastern United States. In its native range, chromosome counts of L. japonicum have suggested both diploid (n=29), and tetraploid (n=58) cytotypes. The success of L. japonicum as an invasive species could be due to polyploidy since multiple genomes may mask deleterious alleles, increase genetic diversity in the form of fixed heterozygosity, alter morphology, increase ecological tolerance, and/or cause niche differentiation. In this study, we aimed to determine the ploidy of L. japonicum in the state of Florida with flow cytometry, spore size measurements, and chromosome counts. A total of 35 L. japonicum individuals were collected from 10 populations throughout its range in Florida. A total of 17 samples were analyzed via DAPI staining to test whether samples differ in their ploidy level and to estimate AT base percentage. Furthermore, absolute genome size was calculated for three samples analyzed using PI stain. Spores were obtained from fertile L. japonicum samples (14 of 35); additionally, spores from diploid L. microphyllum (n=30) were collected from Loxahatchee National Wildlife Refuge for comparison. These spores were fixed to slides, photographed, and measured at 400x magnification. Preliminary results from the flow cytometry suggest low variation in AT content in sampled individuals suggesting that samples had similar genome sizes throughout the populations sampled. The genome size of three samples (representing three distinct populations) was on average 1C = 13.89 +/- 0.2 pg. The sample of L. japonicum from which we obtained an absolute genome size and measured spore size had larger spores compared to the diploid spores of L. microphyllum (average spore length: L. japonicum = 84.0 um; L. microphyllum= 62.8 um; average spore width: L. japoniucm = 65.9 um; L. microphyllum = 54.3 um). In the remaining fertile samples, however, L. japonicum spore lengths and widths showed high variation, with some individuals having spores around the same size as the diploid L. microphyllum spores. Chromosome counts are currently in progress. These preliminary data might suggest the presence of two cytotypes of L. japonicum in Florida (diploid and tetraploid), although further spore measurements and additional flow cytometry data are needed.

1 - University of Florida, Biology, 521 Bartram Hall, Gainesville, FL, 32611, USA
2 - University Of Florida, Biology, 521 Bartram Hall PO Box 118525, Gainesville, FL, 32611, United States
3 - Buzulucká 323, Kutna Hora, 270 01, Czech Republic

Keywords:
genome size
cytology
fern
Invasive
chromosome counts.

Presentation Type: Poster
Number: PPT003
Abstract ID:356
Candidate for Awards:None