A canker disease of Florida torreya (Torreya taxifolia) has been implicated in the decline of this critically endangered species in its native range of northern Florida and southeastern Georgia. In surveys of eight Florida torreya sites, cankers were present on all dead trees and 71 to 100% of living trees, suggesting that a fungal pathogen might be the causal agent. To identify the causal agent, nuclear ribosomal internal transcribed spacer region (ITS rDNA) sequences were determined for 115 fungi isolated from cankers on 46 symptomatic trees sampled at three sites in northern Florida. BLASTn searches of the GenBank nucleotide database, using the ITS rDNA sequences as the query, indicated that a novel Fusarium species designated Fsp-1 might be the etiological agent. Molecular phylogenetic analyses of partial translation elongation factor 1-alpha (EF-1) and RNA polymerase second largest subunit (RPB2) gene sequences indicate that Fsp-1 represents a novel species representing one of the earliest divergences within the Gibberella clade of Fusarium. Results of pathogenicity experiments established that the four isolates of Fsp-1 tested could induce canker symptoms on cultivated Florida torreya in a growth chamber. Koch's postulates were completed by the recovery and identification of Fsp-1 from cankers of the inoculated plants.
Helonias bullata, commonly known as swamp pink, is a perennial rhizomatous herb native to the eastern coast of the United States that is found mainly in forested wetlands, swamps, and mountain bogs. Habitat destruction has caused H. bullata to become rare, and it is federally listed as threatened. Protocols were developed for in vitro germination, shoot micropropagation, shoot establishment in soil, and seed cryopreservation that will assist in the safeguarding and conservation of dwindling natural populations. Seeds were germinated in vitro on plant growth regulator (PGR)-free 1/3-strength Murashige and Skoog (MS) medium after seed sterilization in H 2 O 2 and used for establishment of shoot cultures. Shoot multiplication and elongation occurred on 1/3-strength MS medium containing 0.25-1 mg/l kinetin or 1-2 mg/l trans-zeatin followed by growth on PGR-free medium. All shoots (100%) rooted when planted directly into potting media. Rapid-immersion seed cryopreservation resulted in statistically significant increases in germination in vitro or in potting mix compared to control treatments. H. bullata seeds share characteristics of both orthodox and recalcitrant seeds including rapid loss of viability over time, survival at 5°C, and survival after cryopreservation. Therefore, they are most accurately classified as intermediate-type seed.
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