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Host-range dynamics of Cochliobolus lunatus: from a biocontrol agent to a severe environmental threat.

Louis B, Waikhom SD, Roy P, Bhardwaj PK, Sharma CK, Singh MW, Talukdar NC - Biomed Res Int (2014)

Bottom Line: A maximum likelihood inference based on GPDH locus separated C. lunatus strains into subclusters and revealed the emergence of unclustered strains.The evolving nutritional requirement of C. lunatus in the last decade is exhibited by the invasion of vertebrates, invertebrates, dicots, and monocots.Our results contribute towards a better understanding of the host-range dynamics of C. lunatus and provide useful implications on the threat posed to the environment when C. lunatus is used as a mycoherbicide.

View Article: PubMed Central - PubMed

Affiliation: Institute of Bioresources and Sustainable Development (IBSD), Takyelpat, Imphal, Manipur 795001, India ; Department of Biotechnology, The University of Burdwan, Golapbag More, West Bengal 713104, India ; Department of Biochemistry, University of Yaoundé I, BP 812, Yaoundé, Cameroon.

ABSTRACT
We undertook an investigation to advance understanding of the host-range dynamics and biocontrol implications of Cochliobolus lunatus in the past decade. Potato (Solanum tuberosum L) farms were routinely surveyed for brown-to-black leaf spot disease caused by C. lunatus. A biphasic gene data set was assembled and databases were mined for reported hosts of C. lunatus in the last decade. The placement of five virulent strains of C. lunatus causing foliar necrosis of potato was studied with microscopic and phylogenetic tools. Analysis of morphology showed intraspecific variations in stromatic tissues among the virulent strains causing foliar necrosis of potato. A maximum likelihood inference based on GPDH locus separated C. lunatus strains into subclusters and revealed the emergence of unclustered strains. The evolving nutritional requirement of C. lunatus in the last decade is exhibited by the invasion of vertebrates, invertebrates, dicots, and monocots. Our results contribute towards a better understanding of the host-range dynamics of C. lunatus and provide useful implications on the threat posed to the environment when C. lunatus is used as a mycoherbicide.

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Light microscopic images showing morphological variations of five strains of Cochliobolus lunatus causing brown-to-black leaf spot disease of potato. (a) Strain Btl26IBSD (DDBJ accession AB859034) with no stromata, (b) strain Btl27IBSD (DDBJ accession AB859035) with no stromata, (c) Btl28IBSD (DDBJ accession AB859036) having stromatic tissue, (d) strain Btl29IBSD (DDBJ accession AB859037) having stromatic tissue, and (e) strain Btl30IBSD (DDBJ accession AB859038) having stromatic tissue. Images were acquired with Olympus DP70 camera (Olympus BX61, USA) at 1000X magnification and scale bars represent 10 μm.
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fig1: Light microscopic images showing morphological variations of five strains of Cochliobolus lunatus causing brown-to-black leaf spot disease of potato. (a) Strain Btl26IBSD (DDBJ accession AB859034) with no stromata, (b) strain Btl27IBSD (DDBJ accession AB859035) with no stromata, (c) Btl28IBSD (DDBJ accession AB859036) having stromatic tissue, (d) strain Btl29IBSD (DDBJ accession AB859037) having stromatic tissue, and (e) strain Btl30IBSD (DDBJ accession AB859038) having stromatic tissue. Images were acquired with Olympus DP70 camera (Olympus BX61, USA) at 1000X magnification and scale bars represent 10 μm.

Mentions: Basically, most Cochliobolus species have curved conidia, a broad rounded apex cell, a distinct swollen central cell, a tapering to narrowly round base cell, and 4-5 distinct septa. The five strains of Cochliobolus causing brown-to-black leaf spot disease of potato produced varied colonies and conidia (Figure 1) similar to previous studies [6, 7]. The isolates visibly produced different growth patterns (Figure 1). In one isolate Btl26IBSD (DDBJ accession AB859034), brown to whitish mycelium, reddish brown medium, and canoe five-celled conidia without stromatic tissues were observed (Figure 1(a)). In C. lunatus, the stromata are oval or ellipsoidal, 10 to 40 μm in diameter, and located beneath the ascomata. Another isolate Btl27IBSD (DDBJ accession AB859035) produced greyish-brown mycelium and cylindrical clavated fived-celled conidia void of stromatic tissue (Figure 1(b)). Isolate Btl28IBSD (DDBJ accession AB859036) profusely produced yellowish pigmented five-celled conidia, with stromatic tissue, variable shapes, and end at one cell with a thin hilium (Figure 1(c)). Isolates Btl29IBSD (DDBJ accession AB859037) and Btl30IBSD (DDBJ accession AB859038) produced greyish-brown cottony mycelium (Figures 1(d) and 1(e)). Noteworthy, isolate Btl30IBSD profusely produced dark pigments, and with each cell of the conidia bearing a distinctive oval stromata of different sizes. The exact role of stromata in pathogenicity is not known. The stromata are enclosed by a ring of melanin-like pigment, may play a role in preventing desiccation of the conidia, conserved the gene-pool, and ensure survival under adverse conditions. As shown (Figure 1), morphological characters revealed significant intraspecific variations.


Host-range dynamics of Cochliobolus lunatus: from a biocontrol agent to a severe environmental threat.

Louis B, Waikhom SD, Roy P, Bhardwaj PK, Sharma CK, Singh MW, Talukdar NC - Biomed Res Int (2014)

Light microscopic images showing morphological variations of five strains of Cochliobolus lunatus causing brown-to-black leaf spot disease of potato. (a) Strain Btl26IBSD (DDBJ accession AB859034) with no stromata, (b) strain Btl27IBSD (DDBJ accession AB859035) with no stromata, (c) Btl28IBSD (DDBJ accession AB859036) having stromatic tissue, (d) strain Btl29IBSD (DDBJ accession AB859037) having stromatic tissue, and (e) strain Btl30IBSD (DDBJ accession AB859038) having stromatic tissue. Images were acquired with Olympus DP70 camera (Olympus BX61, USA) at 1000X magnification and scale bars represent 10 μm.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4060766&req=5

fig1: Light microscopic images showing morphological variations of five strains of Cochliobolus lunatus causing brown-to-black leaf spot disease of potato. (a) Strain Btl26IBSD (DDBJ accession AB859034) with no stromata, (b) strain Btl27IBSD (DDBJ accession AB859035) with no stromata, (c) Btl28IBSD (DDBJ accession AB859036) having stromatic tissue, (d) strain Btl29IBSD (DDBJ accession AB859037) having stromatic tissue, and (e) strain Btl30IBSD (DDBJ accession AB859038) having stromatic tissue. Images were acquired with Olympus DP70 camera (Olympus BX61, USA) at 1000X magnification and scale bars represent 10 μm.
Mentions: Basically, most Cochliobolus species have curved conidia, a broad rounded apex cell, a distinct swollen central cell, a tapering to narrowly round base cell, and 4-5 distinct septa. The five strains of Cochliobolus causing brown-to-black leaf spot disease of potato produced varied colonies and conidia (Figure 1) similar to previous studies [6, 7]. The isolates visibly produced different growth patterns (Figure 1). In one isolate Btl26IBSD (DDBJ accession AB859034), brown to whitish mycelium, reddish brown medium, and canoe five-celled conidia without stromatic tissues were observed (Figure 1(a)). In C. lunatus, the stromata are oval or ellipsoidal, 10 to 40 μm in diameter, and located beneath the ascomata. Another isolate Btl27IBSD (DDBJ accession AB859035) produced greyish-brown mycelium and cylindrical clavated fived-celled conidia void of stromatic tissue (Figure 1(b)). Isolate Btl28IBSD (DDBJ accession AB859036) profusely produced yellowish pigmented five-celled conidia, with stromatic tissue, variable shapes, and end at one cell with a thin hilium (Figure 1(c)). Isolates Btl29IBSD (DDBJ accession AB859037) and Btl30IBSD (DDBJ accession AB859038) produced greyish-brown cottony mycelium (Figures 1(d) and 1(e)). Noteworthy, isolate Btl30IBSD profusely produced dark pigments, and with each cell of the conidia bearing a distinctive oval stromata of different sizes. The exact role of stromata in pathogenicity is not known. The stromata are enclosed by a ring of melanin-like pigment, may play a role in preventing desiccation of the conidia, conserved the gene-pool, and ensure survival under adverse conditions. As shown (Figure 1), morphological characters revealed significant intraspecific variations.

Bottom Line: A maximum likelihood inference based on GPDH locus separated C. lunatus strains into subclusters and revealed the emergence of unclustered strains.The evolving nutritional requirement of C. lunatus in the last decade is exhibited by the invasion of vertebrates, invertebrates, dicots, and monocots.Our results contribute towards a better understanding of the host-range dynamics of C. lunatus and provide useful implications on the threat posed to the environment when C. lunatus is used as a mycoherbicide.

View Article: PubMed Central - PubMed

Affiliation: Institute of Bioresources and Sustainable Development (IBSD), Takyelpat, Imphal, Manipur 795001, India ; Department of Biotechnology, The University of Burdwan, Golapbag More, West Bengal 713104, India ; Department of Biochemistry, University of Yaoundé I, BP 812, Yaoundé, Cameroon.

ABSTRACT
We undertook an investigation to advance understanding of the host-range dynamics and biocontrol implications of Cochliobolus lunatus in the past decade. Potato (Solanum tuberosum L) farms were routinely surveyed for brown-to-black leaf spot disease caused by C. lunatus. A biphasic gene data set was assembled and databases were mined for reported hosts of C. lunatus in the last decade. The placement of five virulent strains of C. lunatus causing foliar necrosis of potato was studied with microscopic and phylogenetic tools. Analysis of morphology showed intraspecific variations in stromatic tissues among the virulent strains causing foliar necrosis of potato. A maximum likelihood inference based on GPDH locus separated C. lunatus strains into subclusters and revealed the emergence of unclustered strains. The evolving nutritional requirement of C. lunatus in the last decade is exhibited by the invasion of vertebrates, invertebrates, dicots, and monocots. Our results contribute towards a better understanding of the host-range dynamics of C. lunatus and provide useful implications on the threat posed to the environment when C. lunatus is used as a mycoherbicide.

Show MeSH
Related in: MedlinePlus