Inhibition of Fusarium oxysporum f-sp. dianthi in the non-VAM species Dianthus caryophyllus by co-culture with Tagetes patula companion plants colonized by Glomus intraradices

Abstract

The effect of the mycorrhizal fungus Glomus intraradices on disease development caused by Fusarium oxysporum f.sp. dianthi in the nonmycorrhizal species Dianthus caryophyllus was studied by co-culture of carnation plants with the mycorrhizal species Tagetes patula. Presence of VAM T. patula plants more than doubled the survival of D. caryophyllus, significantly reduced the disease symptoms, and decreased F. o. dianthi propagules by 4:1 in soil. Non-VAM T. patula plants had no effect. Dianthus caryophyllus shoot biomass was reduced by F. o. dianthi in non-VAM controls but was not affected in presence of G. intraradices. Glomus intraradices alone has no effect on T. patula or D. caryophyllus shoot biomass. Dianthus caryophyllus mineral shoot content was not modified by G. intraradices. In absence of T. patula, G. intraradices did not colonize D. caryophyllus, whereas in its presence, 14–20% of the carnation root length contained abundant vesicles and hypha but very rarely arbuscules. The presence of G. intraradices clearly reduced the disease caused by F. o. dianthi in D. caryophyllus. Reduction in disease severity was associated with reduced F. o. dianthi propagule number in the substrate and was clearly unrelated to plant nutrition. Our results may be explained either by the induction of D. caryophyllus disease resistance mechanisms by the mycorrhizal fungus or by direct or indirect microbial interactions in the soil. Key words: vesicular–arbuscular mycorrhizae, marigolds, carnation, disease, biocontrol.

Priming Plant Defence Against Pathogens by Arbuscular Mycorrhizal Fungi

“…However, there are reports on biocontrol of pathogens in non-AM species by co-culture with mycorrhizal plants. Whether this effect is related to induced resistance or to microbial interactions in the soil remains to be elucidated (St-Arnaud et al 1997) .…”

Arbuscular mycorrhizal fungi in field crop production: Potential and new direction

“…Numerous researchers report AMF-related changes in the quality of the soil microbial community (Marschner and Baumann 2003) and variation in the size of specific microbial populations (St-Arnaud et al 1997;Amora-Lazcano et al 1998;Andrade et al 1998a, b;Edwards et al 1998;Filion et al 1999;Green et al 1999), but no general trend for an AMF effect on soil microorganisms emerges, most likely due to the complexity and wide biodiversity of the soil environment.…”

“…Breeding techniques involving the selection of genotypes in soil containing selected AMF strains may lead to the development of cultivar/inoculant packages for low-input crop production. In light of the large body of literature reporting the biocontrol effect of AMF (Dehne 1982;St-Arnaud et al 1995), it appears that this approach might be particularly interesting for the production of pesticide-free food crops, at a time where food safety has become a priority in Canada and elsewhere. Plant breeding, however, is a business driven by the requests of the industry.…”

Mycorrhizal status of selected herbaceous plants in Molinia meadows of Folusz, near Szubin (Poland)

“…In the literature, reports have been contradictory concerning the mycorrhizal status of species that belong to the genus Dianthus. For example, D. caryophyllus, D. gratianopolitanus, and D. plumarius were listed as nonmycorrhizal plants (Harley & Harley 1987a, b, 1990St-Arnaud et al 1997;Zubek et al 2008); however, D. caryophyllus was reported to develop AM associations with a variety of AM fungi in greenhouse conditions (Kerur & Lakshman 2009). According to Harley & Harley (1987a, b, 1990, D. deltoides is nonmycorrhizal.…”