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Do cereal Fusarium species need each other? - Discussion on microbial interactions in the field

Persson, Paula; Kolseth, Anna-Karin

Abstract

More than fifteen Fusarium spp. have been identified associated with cereal plant material. Experience has shown that in most cases more than one species are present in a sample simultaneously. Another observation is that specific Fusarium species appear together frequently. Implications and questions of the within Fusarium species interactions and the interactions with other pathogens and saprophytes will be discussed. At our department a two-year cropping system field experiment has been performed studying a co-inoculation with the cereal pathogens Fusarium culmorum and Bipolaris sorokinia. The pathogens were introduced as fungal inoculum on barley kernels (autoclaved kernels inoculated with pure culture, incubated three weeks) at the sowing time for five different preceding crops (barley, wheat, wheat undersown with red clover, oat and pea) grown before a malting barley crop. The trial was repeated once and the results showed that both pathogens were able to grow side by side in the preceding crop and were both successfully transferred to the following barley crop. In cool and wet growing conditions equal number of barley plants showed to be infected with the two pathogens, independent of preceding crop. In a dryer and warmer season F. culmorum was the weaker pathogen and a significantly lower amount of plants were infected compared to B. sorokiniana. In the dryer climate the infection rate for B. sorokiniana in the malting barley was significantly higher grown after the preceding crops barley and wheat, compared with the other preceding crops. To study inter Fusarium species biology and to test the hypothesis that the minor cereal pathogen Fusarium langsethiae are dependent on other Fusarium spp for a successful infection a growth chamber experiment was carried out. Different levels of humidity were used in order to study development and interactions between Fusarium culmorum, Fusarium graminearum and Fusarium langsethiae on oat. Environmental conditions were based on weather from years with high levels of DON and HT-2/T-2 and on scenarios for future climate change, resulting in two different climatic treatments; warm/dry (max temp 22°C/min 55% RH) and warm/humid (max temp 22°C/min 70% RH). Inoculum of the different Fusarium species was used in monoculture or in different polycultures, but no more than two species were mixed. Inoculum was placed at sowing depth in the pots and sampling was performed at regular intervals, every two weeks after emergence of the oat plants, throughout the growth. Analysis of samples from roots, stem base, first node and kernels using quantitative real-time PCR is ongoing and the first results from this experiment will be presented and discussed.

Published in

Bioforsk Fokus
2010, Volume: 5, number: 7, pages: 26
Title: NBFS 2010 : Nordic Baltic Fusarium Seminar (NBFS), Ski, Norway, 23-25 November 2010 : book of abstracts
ISBN: 978-82-17-00709-8
Publisher: Bioforsk