Population biology ofAureobasidium pullulanson apple leaf surfaces
| Autor: | Russell N. Spear, Erik V. Nordheim, John H. Andrews |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
Immunology
Oligonucleotides General Medicine Fungus Population biology Biology biology.organism_classification Applied Microbiology and Biotechnology Microbiology Population density Plant Leaves Aureobasidium pullulans Ascomycota Malus Botany Genetics Colonization Molecular Biology In Situ Hybridization Fluorescence |
| Zdroj: | Canadian Journal of Microbiology. 48:500-513 |
| ISSN: | 1480-3275 0008-4166 |
| DOI: | 10.1139/w02-044 |
| Popis: | Colonization of apple leaves by the yeast-like fungus Aureobasidium pullulans was studied in the field on eight dates over 2 years. Population densities from adaxial leaf surfaces were approximately log100.52.6 U higher when enumerated directly along line transects as microscopic counts of A. pullulans cells specifically identified by fluorescence in situ hybridization (FISH) than indirectly as CFU obtained by plating leaf washings from comparable surfaces onto nutrient media. Site-specific mapping of the leaf landscape colonized by A. pullulans was facilitated by use of geographic information system (GIS) software. Colonization was plotted and analyzed both qualitatively (as occupancy) and quantitatively (as density). Overall, when expressed as mean occupancy per date, 2242% of the microscope fields (each 0.196 mm2) contained [Formula: see text]1 A. pullulans cell. Occupancy on a microscope field basis was greater over the midvein (4789%) or smaller veins (4965%) than over interveinal regions (1121%). Intensity of colonization, whether expressed as percentage of total A. pullulans cells associated with a particular leaf feature or as cell density per unit area, was also significantly greater (P < 0.05) over the veinal areas compared with the interveinal areas. The primary fungal morphotypes involved in colonization were blastospores, swollen cells, and chlamydospores; only infrequently were hyphae or pseudohyphae seen. Numbers of microcolonies ([Formula: see text]10 clustered cells) and percentage of total A. pullulans cells that occurred as microcolonies increased over the growing season and were significantly greater (P < 0.05) over veinal regions compared with interveinal regions. Locally high concentrations of A. pullulans were associated with naturally occurring micro-wounds in interveinal areas. We conclude that A. pullulans colonizes the phylloplane predominantly as single cells and groups thereof in a highly heterogeneous fashion and that sites exist that are relatively conducive (veins; wounds) or nonconducive (unwounded interveinal areas) for epiphytic fungal growth.Key words: phylloplane, yeast, phyllosphere, Aureobasidium, colonization. |
| Databáze: | OpenAIRE |
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