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February : Of JF Kennedy, potatoes, and how pathogens adapt on new host plants

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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
DOI: 10.1126/science.1250171
  • Perspective (Botany)

Pathogen Specialization

Gitta Coaker
Department of Plant Pathology, University of California, Davis, Davis, CA 95616, USA.


Summary


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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