Testing of life history traits of a soilborne pathogen in vitro: Do characteristics of oospores change according the strains of Aphanomyces euteiches and the host plant infected by the pathogen?

Abstract

Aphanomyces euteiches is a polyphagous, homothallic soilborne pathogen producing asexual (zoospores) and sexual (oospores) spores. Even if oospores are essential for disease development and survival, to date, no study has focused on the production rates of oospores or the quality of the offspring produced by oospores. In this study, a nonabrasive oospore extraction method from infected roots of leguminous species (pea, faba bean and vetch) was developed. This methodology includes steps of grinding and filtration. The quality of oospores (viable, dormant and dead) was assessed with tetrazolium bromide staining, and germination of oospores was tested using exudates of peas, faba bean and vetch. The average yield of the extraction method was approximately 21%. Staining revealed some differences between strains and between leguminous species. The germination percentage of oospores extracted from pea, faba bean and vetch was 25%, 62% and 70%, respectively, and a significant difference was observed according to the origin of A. euteiches‐inoculated strains. Application of exudates seems to stimulate the germination of oospores (2% for the control, 18% for pea exudates and 1% for vetch exudates). Differences observed between A. euteiches strains and leguminous species indicate that more knowledge concerning the biology of oospores is needed. This will help to better estimate evolution process of the pathogen and manage resistance and crop successions.

Pea Breeding for Resistance to Rhizospheric Pathogens

“…These effects are further aggravated through the action of other pathogenic enzymes when found in associations with root rots [ 49 ]. The root-rot-afflicted plants become dwarfed and water-stressed due to the progressive development of watery lesions and dark brown roots with cortex decay, resulting in subsequent yellowing and wilting of the upper part of the host plant [ 91 ]. After the host roots and tissues decay, spores are re-injected into the soil and some remain on the plant material debris, all serving as an inoculum awaiting another infection cycle.…”

Management strategies and distribution of Aphanomyces root rot of alfalfa (Medicago sativa), a continuing threat to forage production in the United States

“…Oospores can be visualized in susceptible root tissue under a light microscope (Figure 5). The thick‐walled oospores provide a suitable resting state to survive harsh winter conditions (Billard et al, 2019). Oospores survive for years in tissues of infected plants or in soil.…”