| Summary: | Mycotoxigenic fungal pathogens <i>Fusarium</i> and <i>Alternaria</i> are a leading cause of loss in cereal production. On wheat-ears, they are confronted by bacterial antagonists such as pseudomonads. Studies on these groups’ interactions often neglect the infection process’s temporal aspects and the associated priority effects. In the present study, the focus was on how the first colonizer affects the subsequent ones. In a climate chamber experiment, wheat-ears were successively inoculated with two different strains (<i>Alternaria tenuissima At</i>625, <i>Fusarium graminearum Fg</i>23, or <i>Pseudomonas simiae Ps</i>9). Over three weeks, microbial abundances and mycotoxin concentrations were analyzed and visualized via Self Organizing Maps with Sammon Mapping (SOM-SM). All three strains revealed different characteristics and strategies to deal with co-inoculation: <i>Fg</i>23, as the first colonizer, suppressed the establishment of <i>At</i>625 and <i>Ps</i>9. Nevertheless, primary inoculation of <i>At</i>625 reduced all of the <i>Fusarium</i> toxins and stopped <i>Ps</i>9 from establishing. <i>Ps</i>9 showed priority effects in delaying and blocking the production of the fungal mycotoxins. The SOM-SM analysis visualized the competitive strengths: <i>Fg</i>23 ranked first, <i>At</i>625 second, <i>Ps</i>9 third. Our findings of species-specific priority effects in a natural environment and the role of the mycotoxins involved are relevant for developing biocontrol strategies.
|
|---|