Oral Paper

         Symbioses: Plant, Animal, and Microbe Interactions

Legacy effects of precipitation and land use impact maize growth and microbiome assembly under drought stress

Presenting Author
Joel Swift
Description
As climates change, plants and their associated microbiomes must contend with water limitation and increased frequency of drought. Natural precipitation gradients provide an opportunity to assess the legacy effects of precipitation on soil microbiomes and how these microbiomes influence the performance of future generations of plants. We collected six soil microbiomes across an east-west precipitation gradient in Kansas, which spans the temperate Great Plains region. Soil microbiomes encompassed two land use types, agricultural fields with conventional management practices and native prairies. Seedlings of two Zea Mays (maize) genotypes were inoculated with each soil microbiome in a factorial drought experiment, assessing maize phenotypic and root-associated microbiome responses (bacteria and fungi) to drought stress. Changes in maize resource allocation were apparent, with droughted plants exhibiting decreased shoot mass accumulation rates and greater root mass relative to shoot mass. Restructuring of the bacterial root-associated microbiome was also apparent, with depletion observed in Pseudomonadota and enrichment in Actinomycetota, while the fungal root-associated microbiome was largely unaffected by drought. We detected a legacy effect of historical precipitation exposure on soil microbiomes’ interactions with plant hosts during drought treatment, but only among prairie soils. Whereby maize growth under drought was maximized when seedlings were inoculated with prairie soil microbiomes from historically wetter soils. Our results demonstrate links between soil microbiomes and plant performance under drought and provide a foundation to further dissect plant-microbiome interactions towards improving drought tolerance in maize.