Host status and reaction of Medicago truncatula accessions to infection by three major pathogens of pea (Pisum sativum) and alfalfa (Medicago sativa)

Abstract

Ditylenchus dipsaci, the stem nematode of alfalfa (Medicago sativa), Mycosphaerella pinodes, cause of Ascochyta blight in pea (Pisum sativum) and Aphanomyces euteiches, cause of pea root rot, result in major yield losses in French alfalfa and pea crops. These diseases are difficult to control and the partial resistances currently available are not effective enough. Medicago truncatula, the barrel medic, is the legume model for genetic studies, which should lead to the identification and characterization of new resistance genes for pathogens. We evaluated a collection of 34 accessions of M. truncatula and nine accessions from three other species (two from M. italica, six from M. littoralis and one from M. polymorpha) for resistance to these three major diseases. We developed screening tests, including standard host references, for each pathogen. Most of the accessions tested were resistant to D. dipsaci, with only three accessions classified as susceptible. A very high level of resistance to M. pinodes was observed among the accessions, none of which was susceptible to this pathogen. Conversely, a high level of variation, from resistant to susceptible accessions, was identified in response to infection by A. euteiches.

Reaction of genotypes from several species of grain and forage legumes to infection with a French pea isolate of the oomycete Aphanomyces euteiches

“…Aphanomyces root rot may cause major yield losses in conditions favourable for the disease (yield losses may reach 100% on some plots in France) and is now considered the major factor limiting pea cultivation. Resistance to this disease has been studied in pea for several years, but no resistant cultivars are yet available (Pilet et al 2005;Moussart et al 2007). The only control measure currently available consists of soil assessment and avoiding infested fields (Moussart et al 2006).…”

“…Aphanomyces euteiches has been isolated from a number of legume species: pea Levenfors et al 2003), faba bean (Salt and Delaney 1985;Lamari and Bernier 1985), vetch (Levenfors et al 2003), lentil (Lamari and Bernier 1985), alfafa (Malvick et al 1998), French bean (Salt and Delanay 1985), red clover (Tofte and Smith 1992), subterranean clover (Greenhalgh et al 1985), barrel medic (Moussart et al 2007) and several other plants (Chan and Close 1987). Isolates from different species may display some specificity for the species from which they were isolated.…”

“…Several studies have screened pea (Malvick and Percich 1999;Wicker et al 2003;Pilet-Nayel personal communication) and barrel medic (Medicago truncatula; Moussart et al 2007) genotypes for resistance to pea A. euteiches isolates. Several isolates were tested against a large pea genotype collection, but only a low level of partial resistance was found in a few genotypes.…”

Disease resistance in pea (Pisum sativum L.) types for autumn sowings in Mediterranean environments - a review

“…truncatula is already being studied to unravel resistance to a large number of pathogens, from parasitic plants (Lozano-Baena et al 2007;Fernández-Aparicio et al 2008a), bacterial pathogens (Vailleau et al 2007), nematodes (Moussart et al 2007) to fungal and oomycete pathogens (Rubiales & Moral 2004;Ellwood et al 2006;Tivoli et al 2006b;Moussart et al 2007;Prats et al 2007). The transcriptomic and proteomic approaches developed for this model legume can be used to understand the molecular components and identify candidate genes involved in M. truncatula defence against these pathogens.…”

Study the Efficiency of Survey of Certain Fungicides for the Yellow Yellow/Pseudopeziza jonesii Nannf/Medicago sativa

“…Higher effectiveness was found in the follicular preparation. The analysis of the experimental results shows that the Pseudopeziza jonesii Nannf infestation index ranges from 15.70 to 27.90% over the period of the survey (Table 2) [12][13][14][15]. …”