Interactions between pea root‐inhabiting fungi examined using signature fatty acids

Abstract

Summary• Interactions are investigated between the arbuscular mycorrhizal fungus, Glomus mosseae , and the root pathogen, Aphanomyces euteiches , on pea ( Pisum sativum ) roots, as arbuscular mycorrhiza are known to suppress a broad range of root pathogens.• Phospholipid (PLFA) and neutral lipid (NLFA) fatty acids were used as indicators of biomass and energy reserves, respectively, of A. euteiches and G. mosseae in inoculated roots of pot-grown pea seedlings.• Symbiosis between pea and G. mosseae had no effect on the severity of disease caused by A. euteiches , which decreased pea shoot and root dry weight. However, the presence of G. mosseae in pea roots reduced both biomass and energy reserves of A. euteiches , indicated by a reduction in PLFA 14 : 0 and both NLFAs 14 : 0 and 14 : 1 ω 9. Similarly, a reduction in PLFA and NLFA 16 : 1 ω 5 indicated reduced biomass and energy reserves of G. mosseae in A. euteiches -infected roots.• Signature fatty acids can be used to quantify biomass and energy reserves of G. mosseae and A. euteiches simultaneously, in pea root; this appears to be a promising method for studying interactions between arbuscular mycorrhizal fungi and root pathogens in planta .

Interactions between indigenous arbuscular mycorrhizal fungi and Aphanomyces euteiches in field-grown pea

“…Interactions between AMF and A. euteiches also studied in experiments under controlled conditions resulted in a reduction in disease severity (Kjøller and Rosendahl 1996;Bødker et al 1998) and oospore production by the pathogen (Rosendahl 1985;Bødker et al 1998;Larsen and Bødker 2001).…”

Cover crops to increase soil microbial diversity and mitigate decline in perennial agriculture. A review

“…Because generalist pathogens may not be as affected by the diversity of a plant community per se and are common in some perennial systems, e.g., "Cylindrocarpon" in apple (Mazzola and Manici 2012), avocado (Vitale et al 2012), and grape (Úrbez-Torres et al 2014), the ability of a cover crop to encourage beneficial microbes might be paramount to avoiding crop decline if these pathogens are prevalent. Microbial antagonists such as AM fungi, diseaseprotective fungi, e.g., Trichoderma spp., and diseasesuppressive bacteria, e.g., pseudomonads, are instrumental in preventing soil-borne disease whether through competition for resources or niche space (Larsen and Bodker 2001), direct antibiosis (Haas and Defago 2005), or by induction of plant systemic resistance (Pozo et al 2002). Entomopathogenic fungi provide protection from soil-dwelling insect pests, outbreaks of which are another form of negative feedback in these systems.…”

Combined Effect of Arbuscular Mycorrhiza, <i>Rhizobium</i> and <i>Sclerotium rolfsii</i> on Grass Pea (<i>Lathyrus sativus</i>)

“…Arbuscular mycorrhizal colonization may also protect host roots, especially under nutrient limitation (Graham, 2001). Larsen and Bodker (2001) found that arbuscular mycorrhizal fungi played positive role in the areas of disease suppression. In a recent study, the presence of arbuscular mycorrhiza in pea roots is known to reduce the disease and the effect on a pathogen was measured by recording the enzymatic activity of the pathogen under influence of the AM fungus (Kjøller and Rosendahl, 1996).…”