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

Abstract

This is the first reported study of the interactions between indigenous arbuscular mycorrhizal fungi (AMF) and Aphanomyces euteiches in pea under field conditions. A. euteiches was applied to the soil by adding oospores produced in vitro. Attempts were made to create a non-mycorrhizal control by incorporating carbendazim (Derosal Fl) in the topsoil before sowing. However, all carbendazim-treated plants showed approximately 20% root colonisation with AMF. Pea plants not treated with carbendazim showed a wide variation in AMF colonisation of 35-70% at the full flowering stage. In these control plots, root length infected with oospores of A. euteiches and colonisation by AMF were negatively correlated. Application of carbendazim increased the percent root length infected with oospores by 50-70%, depending on inoculum density of A. euteiches. Despite the lower levels of AMF colonisation in these treated plots, a negative correlation with oospore-containing root length was still observed. No correlation was found between AMF colonisation and disease severity, disease incidence or pathogen enzymatic activity (glucose-6-phosphate dehydrogenase). Thus, AMF do not seem to influence the vegetative stage of pathogen development during which cortical root rotting takes place, but rather the reproductive stage when oospores are produced. The results of this study underline the importance of field experiments for validating the significance of mycorrhizal fungi for plant health.

Bioprotection and alternative fertilisation of petunia using mycorrhiza in a soilless production system

“…Such negative effects on AM fungal development have been observed before in the interaction between pea and Aphanomyces euteiches where also no correlation between mycorrhiza colonisation levels and mycorrhiza-induced resistance was observed (Bodker et al 2002). The present results showed that the induced resistance associated with bioprotection was specific for G. mosseae.…”

Trade-Offs in Arbuscular Mycorrhizal Symbiosis: Disease Resistance, Growth Responses and Perspectives for Crop Breeding

“…However, although this may contribute, it seems unlikely to be the sole factor involved because AM colonization is not necessarily correlated with nutrient uptake [2,47,58,59]. It has also been suggested that AM-induced reduction in root pathogens is due to direct competition for root space and resources [79]. However, in split-compartment experiments, AM-colonized tomato plants exhibited lower root infection by Phytophthora parasitica Dastur both locally and in non-AM compartments [80], contradicting the suggestion that root resistance is due to direct competition.…”

“…AMF may also have potential for phytoremediation [36][37][38]; however, this review focusses on approaches that could be taken by crop breeding rather that adding AMF to soil. [4,[60][61][62][63][64][65][66] Water acquisition [67,68] Zinc acquisition [5,6] Drought tolerance [67,68] Salinity tolerance [29,[69][70][71] Reduced arsenic toxicity [72,73] Reduced sulphur starvation [74,75] Reduced phosphate toxicity [76] Reduced assimilation of adverse heavy metals [19,36,77] Disease resistance Increased resistance to root [31,[78][79][80] and foliar [81][82][83][84][85] pathogens Reduced arbuscular mycorrhizal colonization in mlo mutants [86] Jasmonic acid production [87][88][89][90] Components required for AM colonization used by pathogens, Golovinomyces cichoracerum (DC.) V.P.…”

Are field populations of arbuscular mycorrhizal fungi able to suppress the transmission of seed-borne Bipolaris sorokiniana to aerial plant parts?

“…asparagi in asparagus (Asparagus officinalis) (Matsubara et al, 2001) and root necroses due to Rhizoctonia solani in cowpea (Vigna unguiculata) (Abdel-Fattah and Shabana, 2002). Under field conditions, AM fungi were found to suppress the production of oospores but not the vegetative stage of Aphanomyces euteiches in pea, although the symptoms of the disease were not affected (Bødker et al, 2002).…”