Phytophthora infestans enters the genomics era
Paul R. J. Birch and Stephen C. Whisson
Unit of Mycology, Bacteriology and Nematology, Division of Pathology,
Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK
Phytophthora infestans, cause of late-blight, is the most
devastating disease of potato world-wide. Recent years have seen a
dramatic intensification in molecular biological studies of P. infestans,
including the development of novel tools for transformation and gene
silencing and the resources for genetical, transcriptional and physical
mapping of the genome. This review will focus on the increasing efforts to
use these resources to discover the genetic bases of pathogenicity,
avirulence and host-specificity.
Phytophthora infestans (Mont.) de Bary—Kingdom Chromista, Phylum
Oomycota, Order Peronosporales, Family Peronosporaceae,
Genus Phytophthora, of which it is the type species.
||Infects a wide range of solanaceous
species. Economically important hosts are potato, tomato, eggplant and
some other South American hosts (tree tomato and pear melon) on which it
causes late blight.
||Infected foliage is initially
yellow, becomes water soaked and eventually blackens. Leaf symptoms
comprise purple-black or brown-black lesions at the leaf tip, later
spreading across the leaf to the stem. Whitish masses of sporangia develop
on the underside of the leaf. Tubers become infected later in the season
and, in the early stages, consist of slightly brown or purple blotches on
the skin. In damp soils the tuber decays rapidly before harvest. Tuber
infection is quickly followed by secondary fungal or bacterial infection
known as ‘wet rot’.
|Useful web site:
Natural infection by P. infestans of a plot
containing susceptible potato cultivar Bintje (A & B). Early symptoms
of infection can be seen in the centre of the plot (A), followed by
massive devastation of the plant foliage 10 days later (B).
Aerial hyphae growing from the underside of a
susceptible leaf (C) develop sporangiophores which produce sporangia (D)
in the later stages of infection.
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