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Open Access Research article

Loss of compatibility might explain resistance of the Arabidopsis thaliana accession Te-0 to Golovinomyces cichoracearum

Georgina Fabro and María Elena Alvarez*

Author Affiliations

Centro de Investigaciones en Química Biológica de Córdoba CIQUIBIC, UNC-CONICET, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad Universitaria, Córdoba, X5000HUA, Argentina

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BMC Plant Biology 2012, 12:143  doi:10.1186/1471-2229-12-143

Published: 11 August 2012

Abstract

Background

The establishment of compatibility between plants and pathogens requires compliance with various conditions, such as recognition of the right host, suppression of defence mechanisms, and maintenance of an environment allowing pathogen reproduction. To date, most of the plant factors required to sustain compatibility remain unknown, with the few best characterized being those interfering with defence responses. A suitable system to study host compatibility factors is the interaction between Arabidopsis thaliana and the powdery mildew (PM) Golovinomyces cichoracearum. As an obligate biotrophic pathogen, this fungus must establish compatibility in order to perpetuate. In turn, A. thaliana displays natural variation for susceptibility to this invader, with some accessions showing full susceptibility (Col-0), and others monogenic dominant resistance (Kas-1). Interestingly, Te-0, among other accessions, displays recessive partial resistance to this PM.

Results

In this study, we characterized the interaction of G. cichoracearum with Te-0 plants to investigate the basis of this plant resistance. We found that Te-0´s incompatibility was not associated with hyper-activation of host inducible defences. Te-0 plants allowed germination of conidia and development of functional haustoria, but could not support the formation of mature conidiophores. Using a suppressive subtractive hybridization technique, we identified plant genes showing differential expression between resistant Te-0 and susceptible Col-0 plants at the fungal pre-conidiation stage.

Conclusions

Te-0 resistance is likely caused by loss of host compatibility and not by stimulation of inducible defences. Conidiophores formation is the main constraint for completion of fungal life cycle in Te-0 plants. The system here described allowed the identification of genes proposed as markers for susceptibility to this PM.

Keywords:
A. thaliana; G. cichoracearum; Compatibility factors; Powdery mildews; Conidiophore maturation; Loss of susceptibility; Haustorial staining; Haustorial imaging