Identifying inoculation methods for screening of resistance to Fusarium langsethiae in selected oat varieties

Abstract

F. langsethiae is reported as the main producer of HT-2+T-2 toxins in Norwegian oats (Hofgaard et al., 2016). This investigation aimed to identify whether ranking of oat varieties according to the content of HT-2+T-2 toxins in grains from F. langsethiae inoculated plants differs from the ranking of cultivars according to deoxynivalenol (DON) in F. graminearum inoculated plants. Also, developing a method for screening of resistance to F. langsethiae/ F. graminearum in oats and ranking selected oats varieties according to the content of F. langsethiae/ F. graminearum DNA and mycotoxins produced by these fungus (HT-2 +T-2/ DON) in grains harvested from F. langsethiae/ F. graminearum inoculated plants. In the course of three experiments, three oats varieties (Vinger, Odal, Belinda) were inoculated by injecting or spraying F. langsethiae/ F. graminearum spore suspension into the flag leaf sheath at late boot stage (GS45) or flag leaf sheath opening (GS47). Plants were also inoculated by spraying a F. langsethiae spore suspension at late boot stage (GS45), middle of heading (GS55) and full flowering (GS65). Grain samples from plants that were spray inoculated with a F. langsethiae spore suspension at full flowering or middle of the heading, contained high levels of F. langsethiae DNA and HT-2+T-2, while only low levels of HT-2 and T-2 were detected in oats that were inoculated at late boot stage or at flag leaf sheath opening. A significantly higher content of F. langsethiae DNA was detected in the grains harvested from F. langsethiae inoculated Belinda than from Odal, whereas Vinger contained the least content of F. langsethiae DNA. The grains harvested from F. langsethiae inoculated Belinda also contained more of HT-2+T-2 than Odal, whereas Vinger contained the least content of HT-2+T-2, however this difference was not significant between varieties. Inoculation by spraying or injecting with F. graminearum spore suspension at flag leaf sheath opening or late boot stage were found to significantly increase the content of F. graminearum DNA and DON in comparison to non-inoculated plants in selected oats varieties. The grains harvested from Belinda contained higher amount of F. graminearum DNA and DON than Odal and Vinger, whereas Vinger contained the least content of F. graminearum DNA and DON, however the differences were not significant between varieties. Inoculation by spraying with a F. langsethiae spore suspension at full flowering and middle of heading found to be the best method for inoculation of plants with F. langsethiae. Belinda was the most susceptible variety to both F. langsethiae and F. graminearum between the tested oat varieties, while Vinger showed better resistance to both of the Fusarium species than Odal and Belinda. Vinger also had less of HT-2+T-2 toxins than Odal and Belinda, while the content of DON was less in Vinger and Odal compared to Belinda, whereas Belinda contained highest levels of HT-2+T-2 and DON.