Dissecting drivers of context dependency in plant microbiome interactions
Figure: Mean absolute growth and standard deviation per field and maize line. Significant differences between the maize lines in 35-65% of the fields and significant between-field growth differences in all five growth parameters. Global p-values for between-maize-line comparison, between-field comparison and the interaction between those two terms (F:M) are indicated on the right of every subplot using ANOVA. Differences between maize lines are indicated above the bar plots per field by using t-test, corrected for multiple testing with “false discovery rate”. Significance levels: ***p < 0.001, **p = 0.001-0.01, *p = 0.01-0.05, ‘.’p = 0.05-0.1.
MSc Cora Küttel
08/2026
Supervision: Loïc Thurre and Prof. Klaus Schlaeppi
Abstract:
Humanity is facing the challenge of maintaining ecosystem functions and crop production at the same time. Under several strategies to address this challenge, inoculation with arbuscular mycorrhizal fungi (AMF) shows promising results but suffers from context-dependency under field conditions. Native AMF are thought to play a role in the context-dependency of inoculated AMF , but knowledge on their impact on plant growth remains scarce. The recently developed AMF-resistant maize mutant castor allows to quantify the impact of native AMF on plant growth and allows insights into native AMF community composition in natural soils. This thesis aimed to quantify the contribution of native AMF to maize growth in different soils using castor and to identify the most important soil and fungal predictors for this growth contribution. Furthermore, differences in fungal community between castor and its mycorrhized counterpart WT were evaluated.
To quantify the growth contribution of native AMF to maize, castor and WT were planted in different soils under field and greenhouse conditions. Physiochemical soil analysis was conducted as well as root fungal community profiling using AMF-specific primers. Linear models were built after reducing soil and fungal parameters with random forest, lasso regression, spearman correlation and stepwise model selection.
Growth response to native AMF ranged from +1% to +91% under field conditions, and from -24% to +92% under greenhouse conditions. The final model identified phosphate as most important predictor being negatively associated with maize growth response to native AMF. Two AMF species (Entrophospora lutea and Paraglomus sp.) were associated with high maize growth response. Two other fungi (Pyxidiophora arvernensis and Cladosporium sp.) were associated with low or high maize growth response, respectively. It is suggested that the biotic mechanisms of interspecific competition and dispersal limitation might be responsible for the selection of those parameters. The results of this thesis suggest both abiotic and biotic factors as important elements influencing the contribution of native AMF to maize growth and demonstrate the importance of native AMF in the agricultural setting.
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