ABSTRACT Aphanomyces root rot (ARR), caused by Aphanomyces euteiches , is a major constraint in pea ( Pisum sativum ) production. This study aimed to improve molecular detection of A. euteiches in soil samples, evaluate the susceptibility of selected legume species, and assess their influence on soil inoculum levels. Twenty‐four soil samples were analysed in bioassay 1, which was performed in two batches, using susceptible pea cv. Linnea to determine disease severity index (DSI). DNA analyses employed droplet digital PCR (ddPCR) and quantitative real‐time PCR (qPCR). Susceptibility of 14 legume species was examined by artificial inoculation, and the influence of five species on ARR in a subsequent pea crop was tested in naturally infested field soil. The number of gene copies g −1 soil differed significantly among soil samples. Soil analysis by ddPCR allowed detection of A. euteiches at a level < 10 gene copies g −1 soil, demonstrating high sensitivity. In bioassay 1, batch 2, DSI correlated significantly with A. euteiches gene copies g −1 soil quantified by ddPCR and qPCR. Visual assessment and ddPCR showed that lentil ( Lens culinaris ) and fodder vetch ( Vicia villosa ) were highly susceptible, whereas birdsfoot trefoil ( Lotus corniculatus ), sainfoin ( Onobrychis viciifolia ) and Persian clover ( Trifolium resupinatum ) were not susceptible to A. euteiches infection. Pea plants grown after fodder vetch had significantly higher DSI and number of A . euteiches gene copies. These findings underscore the importance of molecular soil analysis and knowledge of legume species susceptibility for effective ARR management.
Omer et al. (Tue,) studied this question.