Authors:
Prof. Mika Tarkka | Helmholtz - Centre for Environmental Research - UFZ | Germany
Dr. Maxime Phalempin | Helmholtz - Centre for Environmental Research - UFZ | Germany
Eva Lippold | Helmholtz - Centre for Environmental Research - UFZ | Germany
Dr. Marie-Lara Bouffaud | Helmholtz - Centre for Environmental Research - UFZ | Germany
Dr. Steffen Schlüter | Helmholtz - Centre for Environmental Research - UFZ | Germany
Prof. Doris Vetterlein | Helmholtz - Centre for Environmental Research - UFZ | Germany
Henrike Würsig | Helmholtz - Centre for Environmental Research - UFZ
Plant roots sense and respond to changes in the soil environment and, conversely, contribute to the organisation of the rhizosphere through chemical, mechanical and biotic interactions. Plant root gene expression profiling and amplicon sequencing can be used to assess how the plant adjusts its gene expression in response to the environment, genotype and processes in the rhizosphere. It also gives information on how plant beneficial microorganisms respond to changes in root-soil interactions. Our previous work has shown that substrate induces major changes in root gene expression patterns that affect gene functions related to immunity, stress, growth and water uptake, but also the diversity and abundance of ACC deaminase-carrying (ACCD) plant beneficial microorganisms. To further this knowledge, we investigated how soil compaction and different degree of root-soil contact affects the maize root and the associated rhizosphere microorganisms. In a soil compaction experiment, mechanical resistance was subtly varied for the same loam substrate by applying two different bulk densities and growing wild type maize. We observed changes in root anatomy and gene expression as well as in the diversity of ACCD microorganisms. To deepen our knowledge of substrate-related changes, we investigated how different degrees of root-soil contact affect the same variables. Three different grain size distributions were used for this purpose: sand, loam and coarse loam, i.e. loam where the fine fraction was removed. Further information on the relative importance of plant anatomy was obtained by comparing wild type maize and the root hair elongation mutant rth3 in their respective responses. We will report on changes in gene expression of maize roots and ACCD diversity of the maize rhizosphere. The results obtained do form a fundamental basis for the interpretation of changes in the root and ACCD microorganism diversity due to altered soil properties.