August
2002
, Volume
15
, Number
8
Pages
790
-
798
Authors
P.
van West
,
B. M.
Morris
,
B.
Reid
,
A. A.
Appiah
,
M. C.
Osborne
,
T. A.
Campbell
,
S. J.
Shepherd
,
and
N. A. R.
Gow
Affiliations
Department of Molecular and Cell Biology, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, U.K.
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RelatedArticle
Accepted 17 April 2002.
Abstract
Plant roots generate electrical currents and associated electrical fields as a consequence of electrogenic ion transport at the root surface. Here we demonstrate that the attraction of swimming zoospores of oomycete plant pathogens to plant roots is mediated in part by electrotaxis in natural root-generated electric fields. The zones of accumulation of anode- or cathode-seeking zoospores adjacent to intact and wounded root surfaces correlated with their in vitro electrotactic behavior. Manipulation of the root electrical field was reflected in changes in the pattern of zoospore accumulation and imposed focal electrical fields were capable of overriding endogenous signals at the root surface. The overall pattern of zoospore accumulation around roots was not affected by the presence of amino acids at concentrations expected within the rhizosphere, although higher concentrations induced encystment and reduced root targeting. The data suggest that electrical signals can augment or override chemical ones in mediating short-range tactic responses of oomycete zoospores at root surfaces.
JnArticleKeywords
Additional keywords:
chemotaxis
,
Phytophthora
,
Pythium
.
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ArticleCopyright
© 2002 The American Phytopathological Society