Quantification of root fungi using signature fatty acids

Both deleterious (pathogenic) and beneficial (mycorrhizal) fungi inhabit plant roots with strong impact on plant growth and health. Various methods have been used to quantify these fungi, such as indirect measurements of plant parameters, disease index, staining techniques and serological/genetic/biochemical markers. The objective of this work is to evaluate the possibility of using signature fatty acids to quantify root-inhabiting fungi in planta and in soil. Different fatty acid-based methods can be used to quantify fungi. Phospholid fatty acids (PLFA) can be used for biomass estimation and neutral lipid fatty acids (NLFA) for estimation of fungal energy reserves and the NLFA/PLFA ratio can give information on the physiological status of the fungus. It is quite laborious to make PLFA and NLFA analyses; so whole cell fatty acid (WCFA) analyses, which are much faster, can be used as a faster alternative to give information of root infection intensity. Signature fatty acids have been used to quantify arbuscular mycorrhizal fungi (16:1ω5) and the pea root pathogen Aphanomyces euteiches (14:1ω9). Recently, we have further used arachadonic acid (20:4) to estimate root infection intensity of the plasmodiophorids Plasmodiophora brassica, causing club root in cabbage and Spongospora subterranea, the vector of mop top potato virus. Specificity of the various signature fatty acids of root-inhabiting fungi are discussed in relation to quantifying these fungi in both controlled greenhouse pot experiments and in the field. Furthermore, the possibility of using signature fatty acids to estimate soil inoculum potential of root-inhabiting fungi are discussed

Selection for resistance against root pathogens in a pea composite cross

The possibility of improving resistance in pea against the root pathogen Aphanomyces euteiches using composite cross as a breeding and selection method was examined. In order to maintain acceptable agricultural features and high yield 6 out of the 8 parental varieties in the present composite-cross were commercially grown varieties. Populations of the composite cross were grown up to five generations with selection pressure in soil heavily infested with pea root pathogens or without selection pressure on soil free of pea root pathogens. Yield of populations of the F9 and F10 generations of the composite cross grown with selection pressure was on average 35% higher than that of the population obtained without selection pressure as well as the average yield of the 8 parentals of the composite cross, which were of similar magnitude. In healthy soil the yield was overall higher than in the pathogen-infested soil, but yield did not differ between the populations from the composite cross with and without selection pressure, which were also similar to the average yield of the 8 different parentals. Recombinant inbred lines (RILs) randomly selected from the F10 population with selection pressure developed 23% less root rot than the corresponding F10 population without selection pressure, when grown in field soil heavily infested with pea root pathogens. Surprisingly, greenhouse pot experiments with pure cultures of the pea root pathogen A. euteiches resulted in higher root disease, in RILs from populations with selection pressure than from corresponding RILs without selection pressure. Problems related to greenhouse screening for resistance is discussed as well as the possibilities of using composite cross as a method to improve resistance against root diseases in grain legumes

Specificity of soil-borne pathogens on grain legumes

Specificity of soil-borne legume pathogens on pea, lupin and faba bean is currently investigated in fields where grain legumes are intensively cultivated. The study has so far lead to the following conclusions -Legume host-pathogen interactions demonstrate specificity of pathogen populations particularly in pea and lupin. -A. euteiches rot root was specified to pea in Denmark as root rot symptoms and oospores of the pathogen never were observed in roots of faba bean and lupin -F. oxysporum followed by F. solani were most frequently isolated from plant roots in plots highly infested by lupin pathogens -F. avenaceum was most frequently isolated from plant roots in plots highly infested by pea pathogens -Pathogenicity tests showed F. solani followed by F. avenaceum to be the most pathogenic Fusarium species on pea while F. avenaceum was the most destructive pathogen on faba bean. In contrast F. avenaceum was non-pathogenic on lupin

Mind the gap!

Mange unge oplever, at overgangen fra gymnasium til videregående uddannelse stiller nye krav til deres studievaner. Samtidig skifter læringsmiljøet fra det lærerstyrede gymnasium til de videregående uddannelsers krav om øget selvstændighed. Hvordan tackler vi overgangen i forhold til udvikling af informationskompetence? Hvad har de studerende med? Og hvordan forholder vi os som undervisere til deres forudsætninger? Interview med 3.G’ere giver svar på nogle af spørgsmålene

Stort potentiale for Open Access i professionshøjskolerne

En ny kortlægning af mulighederne for Open Access til artikler publiceret af professionshøjskolernes medarbejdere i danske og nordiske tidsskrifter viser, at der kan opnås fuldtekstadgang til over 75 % af artiklerne. Cirka halvdelen af tidsskrifterne tillader imidlertid ikke Open Access eller mangler viden om fænomenet