A Sensitive Assay for Rapid Detection and Quantification ofAphanomyces euteichesin Soil

Abstract

Aphanomyces euteiches is a widespread oomycete pathogen causing root rot in a wide range of leguminous crops. Losses can reach up to 100% for pea culture and there is currently no registered pesticide for its control. Crop management remains the most efficient tool to control root rot, and avoidance of infested soil seems to be the optimal solution. A test was developed to identify fields suitable for pea crops, consisting of the determination of the inoculum potential of soil using baiting plants. A new rapid, specific, and sensitive molecular method is described allowing the quantification of less than 10 oospores per gram of soil. This challenge is achieved by a real-time polymerase chain reaction procedure targeting internal transcribed spacer 1 from the ribosomal DNA operons. A preliminary study based on typical soils from northwestern France demonstrated that the A. euteiches oospore density in soil is related to the inoculum potential. Furthermore, this method has proved sensitive enough to accurately study the influence of biotic factors that may govern the actual emergence of root rot.

Detection of interactions between the pea root rot pathogens Aphanomyces euteiches and Fusarium spp. using a multiplex qPCR assay

“…Aphanomyces euteiches is the most damaging root pathogen of pea and alfalfa, but will also infect a number of other cultivated and wild legume species (Vandemark et al ., ; Gaulin et al ., ). This oomycete has a broad geographical range that includes Europe, Japan, Australia, New Zealand and North America (Gangneux et al ., ). Oospores are highly resilient to drought and temperature fluctuations, and can remain viable in soil for up to a decade (Gaulin et al ., ).…”

“…In the presence of root exudates, oospores germinate, form sporangia and release motile zoospores that encyst on root tissue. Infection can occur at any stage of plant growth (Gaulin et al ., ; Gangneux et al ., ). Fusarium is a large genus of fungi with a global distribution (Ma et al ., ).…”

“…Assays can be multiplexed in order to detect multiple pathogen species within a single reaction, increasing efficiency and allowing the use of host DNA as an endogenous control (Schena et al ., ). qPCR assays have been developed to quantify A. euteiches in alfalfa roots (Vandemark et al ., ) and soil (Sauvage et al ., ; Gangneux et al ., ). Multiplex qPCR has been used to quantify seven Fusarium spp.…”

Detection and Quantification of Pythium tracheiphilum in Soil by Multiplex Real-Time qPCR

“…The detection limit for the P. tracheiphilum multiplexed qPCR assay was established as 10 oospores/g of dry soil, with coefficients of variation less than 2%. In comparison, the detection limit was determined to be between 1 and 50 oospores/g of soil (depending on soil clay content) for Aphanomyces cochlioides (Almquist et al 2016), 10 oospores/g of soil for A. euteiches (Gangneux et al 2014), and 20 oospores/g of soil for Phytophthora infestans (Hussain et al 2005).…”

Beheersing van bodempathogenen via bodemgezondheidsmaatregelen : Een overzicht van de beschikbare kennis voor een selectie van akkerbouwgewassen met hun bijbehorende bodemziekten

“…In Zweden reduceerde gele mosterd (Sinapis alba) als groenbemester wortelrot veroorzaakt door A. euteiches sterk, mits de mosterd zich goed ontwikkelde (hoge N-dosis) (Hossain et al, 2015). Een biotoets voor het vaststellen van een bodembesmetting is beschreven en wordt toegepast in Frankrijk (Gangneux et al, 2014), maar ook in België en Oostenrijk wordt een standaard biotoets door conservenindustrie toegepast (Clarkson et al, 2014), maar die is voor de praktijk in Nederland vooralsnog niet beschikbaar.…”