Abstract
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 log10 0.5-2.6 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, 22-42% of the microscope fields (each 0.196 mm2) contained > or = 1 A. pullulans cell. Occupancy on a microscope field basis was greater over the midvein (47-89%) or smaller veins (49-65%) than over interveinal regions (11-21%). 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 (> or = 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.
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Claims 12
Claim · model-written summary
Direct microscopy estimated A. pullulans densities 0.5–2.6 log10 units higher than plating.
- Taxon
- apple
Malus domesticat0 - Organ / stage
- adaxial leaf surfacese0
- Interactor
- A. pullulans
Aureobasidium pullulanse0symbiont - Outcome
- Population densitiese0
- Direction
- highere0
- Value
- log10 0.5-2.6 Ue0
- Comparator
- CFU obtained by plating leaf washingse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Population densities from adaxial leaf surfaces were approximately log10 0.5-2.6 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”
t0“apple leaf surfaces”
Claim · model-written summary
Microscopic field occupancy by A. pullulans averaged 22–42% per date.
- Taxon
- appleMalus domesticat0
- Interactor
- A. pullulansAureobasidium pullulanse0symbiont
- Outcome
- mean occupancy per datee0
- Value
- 22-42%e0
- Qualifier
- each 0.196 mm2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Overall, when expressed as mean occupancy per date, 22-42% of the microscope fields (each 0.196 mm2) contained > or = 1 A. pullulans cell”
t0“apple leaf surfaces”
Claim · model-written summary
A. pullulans field occupancy was greater over the midvein than interveinal regions.
- Taxon
- appleMalus domesticat0
- Organ / stage
- midveine0
- Interactor
- A. pullulansAureobasidium pullulanse1symbionte0
- Outcome
- Occupancye0
- Direction
- greatere0
- Value
- 47-89%e0
- Qualifier
- 11-21%e0
- Comparator
- interveinal regionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Occupancy on a microscope field basis was greater over the midvein (47-89%) or smaller veins (49-65%) than over interveinal regions (11-21%)”
t0“apple leaf surfaces”
e1“Population densities from adaxial leaf surfaces were approximately log10 0.5-2.6 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”
Claim · model-written summary
A. pullulans field occupancy was greater over smaller veins than interveinal regions.
- Taxon
- appleMalus domesticat0
- Organ / stage
- smaller veinse0
- Interactor
- A. pullulansAureobasidium pullulanse1symbionte0
- Outcome
- Occupancye0
- Direction
- greatere0
- Value
- 49-65%e0
- Qualifier
- 11-21%e0
- Comparator
- interveinal regionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Occupancy on a microscope field basis was greater over the midvein (47-89%) or smaller veins (49-65%) than over interveinal regions (11-21%)”
t0“apple leaf surfaces”
e1“Population densities from adaxial leaf surfaces were approximately log10 0.5-2.6 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”
Claim · model-written summary
A. pullulans colonization intensity was significantly greater over veins than interveinal regions.
- Taxon
- appleMalus domesticat0
- Organ / stage
- veinal arease0
- Interactor
- A. pullulansAureobasidium pullulanse0symbiont
- Outcome
- Intensity of colonizatione0
- Direction
- greatere0
- Comparator
- interveinal arease0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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”
t0“apple leaf surfaces”
Claim · model-written summary
Main colonizing A. pullulans morphotypes were blastospores, swollen cells and chlamydospores.
- Taxon
- appleMalus domesticat0
- Outcome
- blastospores, swollen cells, and chlamydosporese0
Not reportedInteractor
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The primary fungal morphotypes involved in colonization were blastospores, swollen cells, and chlamydospores; only infrequently were hyphae or pseudohyphae seen”
t0“apple leaf surfaces”
Claim · model-written summary
A. pullulans hyphae and pseudohyphae were infrequently seen.
- Taxon
- appleMalus domesticat0
- Outcome
- hyphae or pseudohyphaee0
- Direction
- infrequentlye0
Not reportedInteractor
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“only infrequently were hyphae or pseudohyphae seen”
t0“apple leaf surfaces”
Claim · model-written summary
A. pullulans microcolony number increased over the growing season.
- Taxon
- appleMalus domesticat0
- Interactor
- A. pullulansAureobasidium pullulanse0symbiont
- Outcome
- Numbers of microcoloniese0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Numbers of microcolonies (> or = 10 clustered cells) and percentage of total A. pullulans cells that occurred as microcolonies increased over the growing season”
t0“apple leaf surfaces”
Claim · model-written summary
Percentage of A. pullulans cells in microcolonies increased over the growing season.
- Taxon
- appleMalus domesticat0
- Interactor
- A. pullulansAureobasidium pullulanse0symbiont
- Outcome
- percentage of total A. pullulans cells that occurred as microcoloniese0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Numbers of microcolonies (> or = 10 clustered cells) and percentage of total A. pullulans cells that occurred as microcolonies increased over the growing season”
t0“apple leaf surfaces”
Claim · model-written summary
A. pullulans microcolonies were significantly greater over veins than interveinal regions.
- Taxon
- appleMalus domesticat0
- Organ / stage
- veinal regionse0
- Interactor
- A. pullulansAureobasidium pullulanse1symbionte0
- Outcome
- microcoloniese0
- Direction
- greatere0
- Comparator
- interveinal regionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“microcolonies increased over the growing season and were significantly greater (P < 0.05) over veinal regions compared with interveinal regions”
t0“apple leaf surfaces”
e1“Population densities from adaxial leaf surfaces were approximately log10 0.5-2.6 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”
Claim · model-written summary
Naturally occurring interveinal micro-wounds were associated with locally high A. pullulans concentrations.
- Taxon
- appleMalus domesticat0
- Organ / stage
- micro-woundse0
- Interactor
- A. pullulansAureobasidium pullulanse0symbiont
- Outcome
- concentrations of A. pullulanse0
- Direction
- highe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Locally high concentrations of A. pullulans were associated with naturally occurring micro-wounds in interveinal areas”
t0“apple leaf surfaces”
Claim · model-written summary
The authors conclude that A. pullulans colonizes apple leaves mainly as single cells or groups and is highly heterogeneous.
- Taxon
- appleMalus domesticat0
- Interactor
- A. pullulansAureobasidium pullulanse0symbiont
- Outcome
- single cells and groups thereofe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A. pullulans colonizes the phylloplane predominantly as single cells and groups thereof in a highly heterogeneous fashion”
t0“apple leaf surfaces”