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Biological control of the cucurbit powdery mildew pathogen Podosphaera xanthii by means of the epiphytic fungus Pseudozyma aphidis and parasitism as a mode of action.

Gafni A, Calderon CE, Harris R, Buxdorf K, Dafa-Berger A, Zeilinger-Reichert E, Levy M - Front Plant Sci (2015)

Bottom Line: We identified a unique, biologically active isolate of the epiphytic yeast Pseudozyma aphidis that is capable of inhibiting Botrytis cinerea via a dual mode of action, namely induced resistance and antibiosis.We also show that crude extract of P. aphidis metabolites can inhibit P. xanthii spore germination in planta.Our results suggest that in addition to its antibiosis as mode of action, P. aphidis may also act as an ectoparasite on P. xanthii.

View Article: PubMed Central - PubMed

Affiliation: Plant Pathology and Microbiology, Hebrew University of Jerusalem Jerusalem, Israel.

ABSTRACT
Epiphytic yeasts, which colonize plant surfaces, may possess activity that can be harnessed to help plants defend themselves against various pathogens. Due to their unique characteristics, epiphytic yeasts belonging to the genus Pseudozyma hold great potential for use as biocontrol agents. We identified a unique, biologically active isolate of the epiphytic yeast Pseudozyma aphidis that is capable of inhibiting Botrytis cinerea via a dual mode of action, namely induced resistance and antibiosis. Here, we show that strain L12 of P. aphidis can reduce the severity of powdery mildew caused by Podosphaera xanthii on cucumber plants with an efficacy of 75%. Confocal and scanning electron microscopy analyses demonstrated P. aphidis proliferation on infected tissue and its production of long hyphae that parasitize the powdery mildew hyphae and spores as an ectoparasite. We also show that crude extract of P. aphidis metabolites can inhibit P. xanthii spore germination in planta. Our results suggest that in addition to its antibiosis as mode of action, P. aphidis may also act as an ectoparasite on P. xanthii. These results indicate that P. aphidis strain L12 has the potential to control powdery mildew.

No MeSH data available.


Related in: MedlinePlus

Imaging of P. aphidis proliferation on infected cucumber cotyledons. Fluorescence microscopy analysis of cucumber cotyledons treated with GFP-tagged P. aphidis(A) followed by successive inoculation (3 days after P. aphidis treatment) with P. xanthii(B) or treated with water and inoculated with P. xanthii(C). Images were recorded 5 days after inoculation P. xanthii. Shown are representative pictures taken of one cotyledon out of 5 from each treatment in one representative experiment. The entire experiment was performed three times with similar results.
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Figure 1: Imaging of P. aphidis proliferation on infected cucumber cotyledons. Fluorescence microscopy analysis of cucumber cotyledons treated with GFP-tagged P. aphidis(A) followed by successive inoculation (3 days after P. aphidis treatment) with P. xanthii(B) or treated with water and inoculated with P. xanthii(C). Images were recorded 5 days after inoculation P. xanthii. Shown are representative pictures taken of one cotyledon out of 5 from each treatment in one representative experiment. The entire experiment was performed three times with similar results.

Mentions: We first demonstrated the ability of P. aphidis to maintain a stable population on cucumber (C. sativus) seedlings. Specifically, we treated 10-day-old seedlings with a P. aphidis suspension and monitored the number of CFU appearing over a period of 21 days post-inoculation. The size of the P. aphidis remained stable for 18-days on plants maintained under controlled conditions (Supplementary Figure 2). Foliar application of P. aphidis (108 cells/ml) to cucumber plants did not result in any symptoms of pathogenicity or phytotoxicity, such as chlorosis. Furthermore, following application of GFP-expressing P. aphidis (Supplementary Figure 1) to healthy cucumber cotyledons, we observed minor spreading of the green fluorescence cells throughout the cotyledons (Figure 1A). When P. aphidis-treated cucumber cotyledons were then inoculated with P. xanthii, a stronger, denser and more uniform green fluorescent signal was observed in the inoculated area (Figure 1B), indicating the close association of P. aphidis with P. xanthii.


Biological control of the cucurbit powdery mildew pathogen Podosphaera xanthii by means of the epiphytic fungus Pseudozyma aphidis and parasitism as a mode of action.

Gafni A, Calderon CE, Harris R, Buxdorf K, Dafa-Berger A, Zeilinger-Reichert E, Levy M - Front Plant Sci (2015)

Imaging of P. aphidis proliferation on infected cucumber cotyledons. Fluorescence microscopy analysis of cucumber cotyledons treated with GFP-tagged P. aphidis(A) followed by successive inoculation (3 days after P. aphidis treatment) with P. xanthii(B) or treated with water and inoculated with P. xanthii(C). Images were recorded 5 days after inoculation P. xanthii. Shown are representative pictures taken of one cotyledon out of 5 from each treatment in one representative experiment. The entire experiment was performed three times with similar results.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4356082&req=5

Figure 1: Imaging of P. aphidis proliferation on infected cucumber cotyledons. Fluorescence microscopy analysis of cucumber cotyledons treated with GFP-tagged P. aphidis(A) followed by successive inoculation (3 days after P. aphidis treatment) with P. xanthii(B) or treated with water and inoculated with P. xanthii(C). Images were recorded 5 days after inoculation P. xanthii. Shown are representative pictures taken of one cotyledon out of 5 from each treatment in one representative experiment. The entire experiment was performed three times with similar results.
Mentions: We first demonstrated the ability of P. aphidis to maintain a stable population on cucumber (C. sativus) seedlings. Specifically, we treated 10-day-old seedlings with a P. aphidis suspension and monitored the number of CFU appearing over a period of 21 days post-inoculation. The size of the P. aphidis remained stable for 18-days on plants maintained under controlled conditions (Supplementary Figure 2). Foliar application of P. aphidis (108 cells/ml) to cucumber plants did not result in any symptoms of pathogenicity or phytotoxicity, such as chlorosis. Furthermore, following application of GFP-expressing P. aphidis (Supplementary Figure 1) to healthy cucumber cotyledons, we observed minor spreading of the green fluorescence cells throughout the cotyledons (Figure 1A). When P. aphidis-treated cucumber cotyledons were then inoculated with P. xanthii, a stronger, denser and more uniform green fluorescent signal was observed in the inoculated area (Figure 1B), indicating the close association of P. aphidis with P. xanthii.

Bottom Line: We identified a unique, biologically active isolate of the epiphytic yeast Pseudozyma aphidis that is capable of inhibiting Botrytis cinerea via a dual mode of action, namely induced resistance and antibiosis.We also show that crude extract of P. aphidis metabolites can inhibit P. xanthii spore germination in planta.Our results suggest that in addition to its antibiosis as mode of action, P. aphidis may also act as an ectoparasite on P. xanthii.

View Article: PubMed Central - PubMed

Affiliation: Plant Pathology and Microbiology, Hebrew University of Jerusalem Jerusalem, Israel.

ABSTRACT
Epiphytic yeasts, which colonize plant surfaces, may possess activity that can be harnessed to help plants defend themselves against various pathogens. Due to their unique characteristics, epiphytic yeasts belonging to the genus Pseudozyma hold great potential for use as biocontrol agents. We identified a unique, biologically active isolate of the epiphytic yeast Pseudozyma aphidis that is capable of inhibiting Botrytis cinerea via a dual mode of action, namely induced resistance and antibiosis. Here, we show that strain L12 of P. aphidis can reduce the severity of powdery mildew caused by Podosphaera xanthii on cucumber plants with an efficacy of 75%. Confocal and scanning electron microscopy analyses demonstrated P. aphidis proliferation on infected tissue and its production of long hyphae that parasitize the powdery mildew hyphae and spores as an ectoparasite. We also show that crude extract of P. aphidis metabolites can inhibit P. xanthii spore germination in planta. Our results suggest that in addition to its antibiosis as mode of action, P. aphidis may also act as an ectoparasite on P. xanthii. These results indicate that P. aphidis strain L12 has the potential to control powdery mildew.

No MeSH data available.


Related in: MedlinePlus