Molecular Plant Pathology - Pathogen Profiles
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Cladosporium fulvum (syn. Passalora
fulva), a highly specialized plant pathogen as a model for functional
studies on plant pathogenic Mycosphaerellaceae
BART P. H. J. THOMMA1, PEDRO W. CROUS2 and PIERRE J.
G. M. DE WIT1
1 Laboratory of Phytopathology, Wageningen University,
Binnenhaven 5, 6709 PD Wageningen, The Netherlands
2 Centraalbureau voor Schimmelcultures, PO Box 85167, 3508 AD
Utrecht, The Netherlands
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Taxonomy:
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Cladosporium fulvum is an asexual fungus for which no sexual stage
is currently known. Molecular data, however, support C. fulvum as a
member of the Mycosphaerellaceae, clustering with other taxa having Mycosphaerella
teleomorphs. C. fulvum has recently been placed in the anamorph
genus Passalora as P. fulva. Its taxonomic disposition is
supported by its DNA phylogeny, as well as the distinct scars on its
conidial hila, which are typical of Passalora, and unlike Cladosporium
s.s., which has teleomorphs that reside in Davidiella, and not Mycosphaerella.
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| Host range and disease symptoms: |
The presently known sole host of C. fulvum is tomato (members of
the genusLycopersicon). C. fulvum is mainly a foliar
pathogen. Disease symptoms are most obvious on the abaxial side of the
leaf and include patches of white mould that turn brown upon sporulation.
Due to stomatal clogging, curling of leaves and wilting can occur, leading
to defoliation. |
| C. fulvum as a model pathogen: |
The interaction between C. fulvum and tomato is governed by a
gene-for-gene relationship. A total of eight Avr and Ecp
genes, and for four of these also the corresponding plant Cf genes,
have been cloned. Obtaining conclusive evidence for gene-for-gene
relationships is complicated by the poor availability of genetic tools for
most Mycosphaerellaceae plant interactions. Newly developed tools,
including Agrobacterium-mediated transformation and RNAi, added to
the genome sequence of its host tomato, which will be available within a
few years, render C. fulvum attractive as a model species for plant
pathogenic Mycosphaerellaceae. |
| Useful websites: |
http://www.sgn.cornell.edu/help/about/index.html
http://cogeme.ex.ac.uk |
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(A) Adaxial side of a tomato leaf (MoneyMaker Cf-0) 18 days
after inoculation with a compatible race of C. fulvum. Distinctive
yellow spots can be seen as a result of dead palisade parenchyma cells.
(B) Abaxial side of a tomato leaf (MoneyMaker Cf-0) 18 days after
inoculation with a compatible race of C. fulvum. White mould can be
seen developing into light brown patches where sporulation takes place.
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