Relation between pigment intensity and penetrating ability in appressoria of Colletotrichum lagenarium

Mutant 8004 of Colletotrichum lagenarium formed slightly pigmented appressoria. The appressoria germinated laterally on glass slides, but could penetrate nitrocellulose membranes. The slightly pigmented appressoria of the albino mutant 79215 were observed to behave in a similar manner when treated with 100 μM scytalone. The appressorial pigmentation of mutant 8004 was increased by the application of scytalone, and mature appressorial pigmentation, indistinguishable from that of the parent strain 104-T, was observed when appressoria were treated with 100 μM scytalone, a lower concentration than that needed for mature pigmentation of the albino mutant. The sensitivity to tricyclazole of appressorial pigmentation of mutant 8004 was higher than that of the parent strain 104-T. These results suggest that, although melanin biosynthesis is essential for appressorial penetration, slight pigmentation is sufficient.

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Localization of melanin in appressoria of Colletotrichum lagenarium

Canadian Journal of Microbiology ◽

10.1139/m86-054 ◽

1986 ◽

Vol 32 (3) ◽

pp. 280-282 ◽

Cited By ~ 21

Author(s):

Y. Kubo ◽

I. Furusawa

Keyword(s):

Microscopic Observation ◽

Parent Strain ◽

Electron Microscopic Observation ◽

Dense Layer ◽

Electron Microscopic ◽

Colletotrichum Lagenarium ◽

Albino Mutant ◽

Thin Electron

The location of melanin in appressoria of Colletotrichum lagenarium was determined by ultrastructural comparison of the parent strain 104-T, an albino mutant 79215, and an albino mutant 79215 treated with scytalone, a melanin precursor in this fungus. Melanin in appressoria of the parent strain 104-T and that of albino mutant 79215 treated with scytalone was located external to the plasmalemma as a smooth, thin, electron-dense layer. A comparable layer was not observed in appressoria of the albino mutant 79215 without scytalone. Electron microscopic observation of a median section of pigmented appressoria of albino mutant 79215 treated with scytalone indicated that the melanized layer extended over the appressoria with the exception of the pore which provides an opening for the emergence of the infection peg.

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Inhibitory effect of aflastatin A on melanin biosynthesis by Colletotrichum lagenarium

Microbiology ◽

10.1099/00221287-147-9-2623 ◽

2001 ◽

Vol 147 (9) ◽

pp. 2623-2628 ◽

Cited By ~ 14

Author(s):

Susumu Okamoto ◽

Masaru Sakurada ◽

Yasuyuki Kubo ◽

Gento Tsuji ◽

Isao Fujii ◽

...

Keyword(s):

Inhibitory Effect ◽

Colletotrichum Lagenarium ◽

Melanin Biosynthesis

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Behavior of colorless appressoria in an albino mutant of Colletotrichum lagenarium

Canadian Journal of Microbiology ◽

10.1139/m82-180 ◽

1982 ◽

Vol 28 (11) ◽

pp. 1210-1213 ◽

Cited By ~ 17

Author(s):

K. Suzuki ◽

Y. Kubo ◽

I. Furusawa ◽

N. Ishida ◽

M. Yamamoto

Keyword(s):

Nuclear Division ◽

Temperature Sensitive ◽

Colletotrichum Lagenarium ◽

Albino Mutant ◽

And Migration ◽

Appressoria Formation

Spores of an albino mutant of Colletotrichum lagenarium formed colorless appressoria. The appressoria germinated laterally and formed secondary appressoria after further incubation. Appressorial formation was accompanied by nuclear division and migration of the spore contents into the primary appressorium. When the primary appressorium was mature, the nucleus in the spore had disappeared and the spore appeared empty. Similar phenomena were observed in the formation of secondary appressoria from primary appressoria. Formation of both primary and secondary appressoria was temperature sensitive. When spores were incubated in the presence of cycloheximide after 1 h of incubation, formation of primary and secondary appressoria was not affected. Secondary appressoria pigmented by addition of 3,4-dihydroxyphenylalanine could penetrate nitrocellulose membranes.

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Temporal Transcriptional Pattern of Three Melanin Biosynthesis Genes, PKS1, SCD1, and THR1, in Appressorium-Differentiating and Nondifferentiating Conidia of Colletotrichum lagenarium.

Applied and Environmental Microbiology ◽

10.1128/aem.63.1.351-354.1997 ◽

1997 ◽

Vol 63 (1) ◽

pp. 351-354 ◽

Cited By ~ 35

Author(s):

Y Takano ◽

Y Kubo ◽

I Kuroda ◽

I Furusawa

Keyword(s):

Colletotrichum Lagenarium ◽

Melanin Biosynthesis ◽

Transcriptional Pattern

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Multiple Contributions of Peroxisomal Metabolic Function to Fungal Pathogenicity in Colletotrichum lagenarium

Applied and Environmental Microbiology ◽

10.1128/aem.00988-06 ◽

2006 ◽

Vol 72 (9) ◽

pp. 6345-6354 ◽

Cited By ~ 60

Author(s):

Makoto Asakura ◽

Tetsuro Okuno ◽

Yoshitaka Takano

Keyword(s):

Host Plant ◽

Isocitrate Lyase ◽

Glyoxylate Cycle ◽

Acetate Metabolism ◽

Colletotrichum Lagenarium ◽

Melanin Biosynthesis ◽

Fungal Pathogenicity ◽

Peroxisomal Targeting ◽

The Glyoxylate Cycle ◽

Host Invasion

ABSTRACT In Colletotrichum lagenarium, which is the causal agent of cucumber anthracnose, PEX6 is required for peroxisome biogenesis and appressorium-mediated infection. To verify the roles of peroxisome-associated metabolism in fungal pathogenicity, we isolated and functionally characterized ICL1 of C. lagenarium, which encodes isocitrate lyase involved in the glyoxylate cycle in peroxisomes. The icl1 mutants failed to utilize fatty acids and acetate for growth. Although Icl1 has no typical peroxisomal targeting signals, expression analysis of the GFP-Icl1 fusion protein indicated that Icl1 localizes in peroxisomes. These results indicate that the glyoxylate cycle that occurs inside the peroxisome is required for fatty acid and acetate metabolism for growth. Importantly, in contrast with the pex6 mutants that form nonmelanized appressoria, the icl1 mutants formed appressoria that were highly pigmented with melanin, suggesting that the glyoxylate cycle is not essential for melanin biosynthesis in appressoria. However, the icl1 mutants exhibited a severe reduction in virulence. Appressoria of the icl1 mutants failed to develop penetration hyphae in the host plant, suggesting that ICL1 is involved in host invasion. The addition of glucose partially restored virulence of the icl1 mutant. Heat shock treatment of the host plant also enabled the icl1 mutants to develop lesions, implying that the infection defect of the icl1 mutant is associated with plant defense. Together with the requirement of PEX6 for appressorial melanization, our findings suggest that peroxisomal metabolic pathways play functional roles in appressorial melanization and subsequent host invasion steps, and the latter step requires the glyoxylate cycle.

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