The occurrence of fusarium merismoides var. chlamydosporale (tuberculariaceae) in Rankin County, Mississippi.

This report documents the first occurrence of the fungus Fusarium merismoides var. chlamydosporale (Tuberculariaceae; Ascomycota) in Mississippi. The presence of this fungus was first observed in a rural area of Rankin County, Mississippi (Section 9, Township 3N, Range 5E) in March 2000, as a very wet, brilliant orange mass growing on a wild grape vine ( Vitis sp.; Vitaceae). The fungus re-appeared on the same vine in March 2001, and March 2002, lasting for approximately 3 weeks at each occurrence. It was also found growing on a second host, ironwood (Ostrya virginiana; Betulaceae), in March 2001, and March 2002.

Samples were collected from both hosts during 2001 and 2002 and isolated to single colony (based on morphology and color) on minimal media plates (1% glucose, potassium chloride, nitrate salts, trace elements, 1.8% agar; Kafer, 1977). Bright orange material from the field isolates and from the laboratory subcultures were placed into 10 mM potassium phosphate, pH 7.4, and observed by Differential Interference Contrast microscopy using a Leica DMLB microscope. Colony color and morphological structures identified from lab and field isolates from both years were identical. Micrographs and cultures were sent to Dr. Kerry O'Donnell, USDA, Agricultural Research Service, for assistance in identification of structures. Figure lA shows a mature conidium and figure lB shows a chlamydospore. The presence of canoe-shaped conidia and chlamydospores are characteristic for members of the genus Fusarium (Nirenberg and O'Donnell, 1998).

The genus Fusarium is large and morphologically diverse (Nirenberg and O'Donnell, 1998), and members of the genus are difficult to classify by morphological characteristics alone. The most reliable taxonomic placements of isolates are obtained by amplification and sequencing of the nuclear small subunit rDNA and mitochondrial rRNA as described in White et al. (1990). Samples were sent to the laboratories of Dr. Meredith Blackwell (Louisiana State University) and Dr. Charles Mims (University of Georgia) for sequencing, and the sequences were subsequently sent to Dr. David Geiser (Pennsylvania State University) for comparison against a Fusarium database. An extensive database of Fusarium sequences is maintained by Dr. Geiser.

The sequences obtained were found to be 100% identical to those of Fusarium merismoides var. chiamydosporale, as described by O'Donnell (1992). This strain was first isolated from an ironwood tree (Ostrya virginiana) in Madison, Wisconsin, described by Wollenweber (1916-1935); the second was from rotting rhizome of Asparagus officianalis collected in Germany in 1968 and described by Gerlach and Nirenberg (1982). Thus, identification of this new isolate by morphologic and genetic means as Fusarium merismo ides var. chiamydosporale represents only the third documented isolation of this strain world-wide, and the first in the southern United States.

LITERATURE CITED

Gerlach, W. and Nirenberg, H. 1982. The Genus Fusarium--a Pictorial Atlas. Kommissionverlag Paul Parey, Berlin. 406 pp.

Kafer, E. 1977. Meiotic and mitotic recombination in Aspergillus and its chromosomal aberrations. Adv. Genet. 19:33-131.

Nirenberg, H.I., and O'Donnell, K. 1998. New Fusarium species and combinations within the Gibberella fujikuroi species complex. Mycologia, 90: 434-458.

O'Donnell, K. 1992. Fusarium and its near relatives. Pages 225-233 in D.R. Reynolds and J.W. Taylor, eds. The Fungal Holomorph: Mitotic, Meiotic and Pleomorphic Speciation in Fungal Systematics. CAB International.

White, T.J., Bruns, T., Lee, S., and Taylor, J. 1990. Amplification and direct sequencing of fungal ribosomal RNA genes for phylogentics. Pages 315-322 in M.A. Innis, D.H. Gelfand, J.J. Sninsky, and T.J. White, eds. PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego.

Wollenweber, H. W. 1916-1935. Fusaria autographice delineata. Selbstverlag, Berlin, 1200 Tafeln.

George H. Dukes, Jr. (1), Gerald M. McGuire (2), II, Dionne Jackson1, and Sarah Lea McGuire (1,3)

(1.) Millsaps College Department of Biology, Jackson, MS 39210,

(2.) University of Mississippi Medical Center, Jackson, MS 39216

(3.) Author for correspondence ([e-mail])