5 February, 2014
Of JF Kennedy, potatoes, and how pathogens adapt on new host plants
Fungal pathogens (and similar, non-fungal ones like Phytophthora)
are known to sometimes ''jump'' from their host plant to new hosts. This
often happens after introductions of the pathogen into new
environments, or reversely, the introduction of foreign plant species to
the native environment of the pathogen. We know that the pathogens
often evolve and adapt to become ''better'' or more aggressive pathogens
of the new host plant.
One of the oldest and best studied examples of plant pathogens is
Phytophthora infestans, which caused the potato famine in Ireland (see http://en.wikipedia.org/wiki/Great_Famine_(Ireland
). This famine changed world history in that millions of
Irish emigrated to the USA, including the great grandfather of JF
Kennedy (see http://en.wikipedia.org/wiki/Patrick_Kennedy_(1823%E2%80%931858
). If it thus wasn't for Phytophthora, Kennedy wouldn't have been
president of the USA, and the USA would have been a very different place
without the impact of the Irish immigrants!
Anyway, Phytophthora infestans continues to serve as a model for
plant pathogenic studies and in today's Science there are a Perspective
(below) and a research paper (Dong et al 2014, attached), elucidating
some of the nitty gritty detail as to HOW pathogens adapt on their new
hosts. In FABI we have some research groups looking at the mechanisms
involved in host specificity and overcoming disease resistance in
forestry and other crops such as avocado. Understanding these mechanisms
will enable us to breed more resistant crops in future.
Science 31 January 2014:
Vol. 343 no. 6170 pp. 496-497
Gitta Coaker Department of Plant Pathology, University of California, Davis, Davis, CA 95616, USA.
Plants can be attacked by a vast range of pathogen classes, causing substantial agricultural losses. The Phytophthora
(meaning "plant killer") genus is a particularly destructive pathogen
that causes root and stem base decay in a wide range of plants. Phytophthora infestans, which precipitated the Irish potato famine, originated in Central Mexico and is closely related to other Phytophthora species with distinct host ranges (1, 2).
Pathogen effectors that are secreted during infection play a key role
in disease biology, but effector-induced adaptation to new hosts is an
understudied topic. On page 552 of this issue, Dong et al. investigate how Phytophthora effector proteins evolve the ability to specialize on new hosts (see the figure) (3). (Continue reading in Coaker 2013, attached).
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