Flagella-driven chemotaxis towards exudate components is an important trait for tomato root colonization by Pseudomonas fluorescens

被引:387
作者
de Weert, S
Vermeiren, H
Mulders, IHM
Kuiper, I
Hendrickx, N
Bloemberg, GV
Vanderleyden, J
De Mot, R
Lugtenberg, BJJ
机构
[1] Leiden Univ, Inst Mol Plant Sci, NL-2333 AL Leiden, Netherlands
[2] Catholic Univ Louvain, Ctr Microbial & Plant Genet, B-3001 Heverlee, Belgium
关键词
D O I
10.1094/MPMI.2002.15.11.1173
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Motility is a major trait for competitive tomato root-tip colonization by Pseudomonas fluorescens. To test the hypothesis that this role of motility is based on chemotaxis toward exudate components, cheA mutants that were defective in flagella-driven chemotaxis but retained motility were constructed in four P fluorescens strains. After inoculation of seedlings with a 1:1 mixture of wild-type and nonmotile mutants all mutants had a strongly reduced competitive root colonizing ability after 7 days of plant growth, both in a gnotobiotic sand system as well as in non-sterile potting soil. The differences were significant on all root parts and increased from root base to root tip. Significant differences at the root tip could already be detected after 2 to 3 days. These experiments show that chemotaxis is an important competitive colonization trait. The best competitive root-tip colonizer, strain WCS365, was tested for chemotaxis toward tomato root exudate and its major identified components. A chemotactic response was detected toward root exudate, some organic acids, and some amino acids from this exudate but not toward its sugars. Comparison of the minimal concentrations required for a chemotactic response with concentrations estimated for exudates suggested that malic acid and citric acid are among major chemo-attractants for P. fluorescens WCS365 cells in the tomato rhizosphere.
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页码:1173 / 1180
页数:8
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