- Department of Crop Production Ecology, Swedish University of Agricultural Sciences
Kolseth, Anna-Karin; Persson, Paula
Focusing on F. graminearum, results from two studies on inter species interactions of Fusarium will be discussed. The two studies have different inoculation strategies, one using inoculated sterilized kernels placed at sowing depth as inoculum, and the other using spray inoculation of dissolved conidia on the panicle, at flowering stage. Both studies were performed in growth chambers with oat as a host but they differed considering the choice of Fusarium species studied. The first study, with inoculum at sowing depth used F. graminearum, F. culmorum and F. langsethiae as models, while the spray inoculation study focused on F. graminearum, F. avenaceum and F. langsethiae. In both studies Fusarium inoculations were performed with both single species and different combinations of species mixtures. Infection development in both studies was quantified using real-time PCR. When placing inoculum at sowing depth, following the development of fungal infection over time, F. culmorum was detected earlier during plant development compared to F. graminearum in roots, stem bases and first nodes (DC 60). At a later stage (DC 90), F. graminearum had caught up, but the two species did show a different colonization pattern. While a large proportion of sampled plants had detectable F. culmorum DNA in roots, stem bases and first nodes (23 of 50 plants inoculated with F. culmorum), no infection of this species was found in the panicles. In comparison, F. graminearum was found in roots, stem bases and first nodes in only 3 of 38 plants inoculated with F. graminearum. It had on the other hand spread and contaminated pots with other inoculation treatments, and was found in almost all panicles in the growth chamber irrespective of inoculation treatment. Infection of F. langsethiae was not detectable using real-time PCR in any sampled material in any growth stage. Pots inoculated with F. langsethiae at sowing depth showed a lower cross contamination of F. graminearum in roots, stem bases and first nodes compared to the control pots, but no difference was found in F. graminearum panicle infections, comparing uninoculated control pots with F. langsethiae inoculated pots. Applying inoculum directly to the panicle using spray inoculation, following the development of the infection over 2 weeks (sampling 2, 6, 10 and 14 days after inoculation), reveals an effect of the two other species on F. graminearum. When F. graminearum was co-inoculated with either F. avenaceum or F. langsethiae or both, F. graminearum did show a lower infection rate at all time-points compared to when it was inoculated singly. Results imply that F. graminearum has a preference for air dispersal entering the plant in to the panicle. Results also imply that this species is poor at interference competition in planta. Recent outbreaks of F. graminearum in Scandinavia may be explained by an optimal seasonal climate, but can the dispersal pattern of F. graminearum also be of importance? By being good at dispersal it may be the first one to establish on the host, and thereby gain a competitive advantage over other Fusarium species.
2012, Volume: 8, number: 10, pages: 33
Publisher: Nordic Asssociation of Agricultural Scientists
NBFS Nordic Baltic Fusarium Seminar 2012