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An endophytic fungus isolated from finger millet (Eleusine coracana) produces anti-fungal natural products.

Mousa WK, Schwan A, Davidson J, Strange P, Liu H, Zhou T, Auzanneau FI, Raizada MN - Front Microbiol (2015)

Bottom Line: We conclude that the ancient, disease-tolerant crop, finger millet, is a novel source of endophytic anti-fungal natural products.This paper suggests the value of the crops grown by subsistence farmers as sources of endophytes and their natural products.Application of these natural chemicals to solve real world problems will require further validation.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Agriculture, University of Guelph Guelph, ON, Canada ; Department of Pharmacognosy, Mansoura University Mansoura, Egypt.

ABSTRACT
Finger millet is an ancient African cereal crop, domesticated 7000 years ago in Ethiopia, reaching India at 3000 BC. Finger millet is reported to be resistant to various fungal pathogens including Fusarium sp. We hypothesized that finger millet may host beneficial endophytes (plant-colonizing microbes) that contribute to the antifungal activity. Here we report the first isolation of endophyte(s) from finger millet. Five distinct fungal species were isolated from roots and predicted taxonomically based on 18S rDNA sequencing. Extracts from three putative endophytes inhibited growth of F. graminearum and three other pathogenic Fusarium species. The most potent anti-Fusarium strain (WF4, predicted to be a Phoma sp.) was confirmed to behave as an endophyte using pathogenicity and confocal microscopy experiments. Bioassay-guided fractionation of the WF4 extract identified four anti-fungal compounds, viridicatol, tenuazonic acid, alternariol, and alternariol monomethyl ether. All the purified compounds caused dramatic breakage of F. graminearum hyphae in vitro. These compounds have not previously been reported to have anti-Fusarium activity. None of the compounds, except for tenuazonic acid, have previously been reported to be produced by Phoma. We conclude that the ancient, disease-tolerant crop, finger millet, is a novel source of endophytic anti-fungal natural products. This paper suggests the value of the crops grown by subsistence farmers as sources of endophytes and their natural products. Application of these natural chemicals to solve real world problems will require further validation.

No MeSH data available.


Related in: MedlinePlus

The effects of the purified compounds on F. graminearum in vitro using the agar disc diffusion assay and neutral red staining. (A–D) Representative pictures of the agar disc diffusion assay of the purified anti-fungal compounds, (A) viridicatol, (B) tenuazonic acid, (C) alternariol, and (D) alternariol monomethyl ether (n = 3). The inhibition of F. graminearum is shown by the clear halo around each disc soaked with the purified compound. (E) Cartoon of the experimental methodology to examine microscopic in vitro interactions between F. graminearum (pink) and each compound (orange) or the buffer control (respective compound solvent). The microscope slides were pre-coated with PDA and incubated for 24 h. F. graminearum hyphae were then stained with the vitality stain, neutral red. Shown are representative microscope slide pictures (n = 3) of the interactions of F. graminearum with: (F) viridicatol compared to (J) the buffer control; (G) tenuazonic acid compared to (K) the buffer control; (H) alternariol compared to (L) the buffer control; (I) alternariol monomethyl ether compared to (M) the buffer control. The blue arrows point to areas of apparent breakage of F. graminearum hyphae.
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Figure 7: The effects of the purified compounds on F. graminearum in vitro using the agar disc diffusion assay and neutral red staining. (A–D) Representative pictures of the agar disc diffusion assay of the purified anti-fungal compounds, (A) viridicatol, (B) tenuazonic acid, (C) alternariol, and (D) alternariol monomethyl ether (n = 3). The inhibition of F. graminearum is shown by the clear halo around each disc soaked with the purified compound. (E) Cartoon of the experimental methodology to examine microscopic in vitro interactions between F. graminearum (pink) and each compound (orange) or the buffer control (respective compound solvent). The microscope slides were pre-coated with PDA and incubated for 24 h. F. graminearum hyphae were then stained with the vitality stain, neutral red. Shown are representative microscope slide pictures (n = 3) of the interactions of F. graminearum with: (F) viridicatol compared to (J) the buffer control; (G) tenuazonic acid compared to (K) the buffer control; (H) alternariol compared to (L) the buffer control; (I) alternariol monomethyl ether compared to (M) the buffer control. The blue arrows point to areas of apparent breakage of F. graminearum hyphae.

Mentions: The putative anti-fungal compounds, viridicatol, tenuazonic acid, alternariol and alternariol-mono methyl ether were verified as having anti-F. graminearum activity by using the agar disc diffusion method (diameter of fungal inhibition zone): application of the compounds 1–4 (20 μl of 5 mg/ml) caused inhibition zones of 1.8, 2, 1.5, 1.5 mm (respectively) compared to the solvent buffer (0–0.5 mm) (Figures 7A–D), respectively.


An endophytic fungus isolated from finger millet (Eleusine coracana) produces anti-fungal natural products.

Mousa WK, Schwan A, Davidson J, Strange P, Liu H, Zhou T, Auzanneau FI, Raizada MN - Front Microbiol (2015)

The effects of the purified compounds on F. graminearum in vitro using the agar disc diffusion assay and neutral red staining. (A–D) Representative pictures of the agar disc diffusion assay of the purified anti-fungal compounds, (A) viridicatol, (B) tenuazonic acid, (C) alternariol, and (D) alternariol monomethyl ether (n = 3). The inhibition of F. graminearum is shown by the clear halo around each disc soaked with the purified compound. (E) Cartoon of the experimental methodology to examine microscopic in vitro interactions between F. graminearum (pink) and each compound (orange) or the buffer control (respective compound solvent). The microscope slides were pre-coated with PDA and incubated for 24 h. F. graminearum hyphae were then stained with the vitality stain, neutral red. Shown are representative microscope slide pictures (n = 3) of the interactions of F. graminearum with: (F) viridicatol compared to (J) the buffer control; (G) tenuazonic acid compared to (K) the buffer control; (H) alternariol compared to (L) the buffer control; (I) alternariol monomethyl ether compared to (M) the buffer control. The blue arrows point to areas of apparent breakage of F. graminearum hyphae.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4612689&req=5

Figure 7: The effects of the purified compounds on F. graminearum in vitro using the agar disc diffusion assay and neutral red staining. (A–D) Representative pictures of the agar disc diffusion assay of the purified anti-fungal compounds, (A) viridicatol, (B) tenuazonic acid, (C) alternariol, and (D) alternariol monomethyl ether (n = 3). The inhibition of F. graminearum is shown by the clear halo around each disc soaked with the purified compound. (E) Cartoon of the experimental methodology to examine microscopic in vitro interactions between F. graminearum (pink) and each compound (orange) or the buffer control (respective compound solvent). The microscope slides were pre-coated with PDA and incubated for 24 h. F. graminearum hyphae were then stained with the vitality stain, neutral red. Shown are representative microscope slide pictures (n = 3) of the interactions of F. graminearum with: (F) viridicatol compared to (J) the buffer control; (G) tenuazonic acid compared to (K) the buffer control; (H) alternariol compared to (L) the buffer control; (I) alternariol monomethyl ether compared to (M) the buffer control. The blue arrows point to areas of apparent breakage of F. graminearum hyphae.
Mentions: The putative anti-fungal compounds, viridicatol, tenuazonic acid, alternariol and alternariol-mono methyl ether were verified as having anti-F. graminearum activity by using the agar disc diffusion method (diameter of fungal inhibition zone): application of the compounds 1–4 (20 μl of 5 mg/ml) caused inhibition zones of 1.8, 2, 1.5, 1.5 mm (respectively) compared to the solvent buffer (0–0.5 mm) (Figures 7A–D), respectively.

Bottom Line: We conclude that the ancient, disease-tolerant crop, finger millet, is a novel source of endophytic anti-fungal natural products.This paper suggests the value of the crops grown by subsistence farmers as sources of endophytes and their natural products.Application of these natural chemicals to solve real world problems will require further validation.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Agriculture, University of Guelph Guelph, ON, Canada ; Department of Pharmacognosy, Mansoura University Mansoura, Egypt.

ABSTRACT
Finger millet is an ancient African cereal crop, domesticated 7000 years ago in Ethiopia, reaching India at 3000 BC. Finger millet is reported to be resistant to various fungal pathogens including Fusarium sp. We hypothesized that finger millet may host beneficial endophytes (plant-colonizing microbes) that contribute to the antifungal activity. Here we report the first isolation of endophyte(s) from finger millet. Five distinct fungal species were isolated from roots and predicted taxonomically based on 18S rDNA sequencing. Extracts from three putative endophytes inhibited growth of F. graminearum and three other pathogenic Fusarium species. The most potent anti-Fusarium strain (WF4, predicted to be a Phoma sp.) was confirmed to behave as an endophyte using pathogenicity and confocal microscopy experiments. Bioassay-guided fractionation of the WF4 extract identified four anti-fungal compounds, viridicatol, tenuazonic acid, alternariol, and alternariol monomethyl ether. All the purified compounds caused dramatic breakage of F. graminearum hyphae in vitro. These compounds have not previously been reported to have anti-Fusarium activity. None of the compounds, except for tenuazonic acid, have previously been reported to be produced by Phoma. We conclude that the ancient, disease-tolerant crop, finger millet, is a novel source of endophytic anti-fungal natural products. This paper suggests the value of the crops grown by subsistence farmers as sources of endophytes and their natural products. Application of these natural chemicals to solve real world problems will require further validation.

No MeSH data available.


Related in: MedlinePlus