Background and aims

The root surface of a plant usually exceeds the leaf area and is constantly exposed to a variety of soil-borne microorganisms. Root pathogens and pests as well as belowground interactions with beneficial microbes can significantly influence a plants' performance. Unfortunately the analysis of these interactions is often limited because of the arduous task of accessing roots growing in soil. Here we present a soil-free root observation system (SF-ROBS) designed to grow maize (Zea mays) plants and to study root interactions with either beneficial or pathogenic microbes.

Methods

The SF-ROBS consists of pouches lined with wet filter paper supplying nutrient solution.

Results

The aspect of maize grown in the SF-ROBS was similar to soil-grown maize; the plant growth was similar for the shoot but different for the roots (biomass and length increased in the SF-ROBS). SF-ROBS-grown roots were successfully inoculated with the hemi-biotrophic maize fungal pathogen Colletotrichum graminicola and the beneficial rhizobacteria Pseudomonas putida KT2440. Thus the SF-ROBS is a system suitable to study two major belowground phenomena namely root fungal defense reactions and interactions of roots with beneficial soil-borne bacteria.

Conclusions

This system contributes to a better understanding of belowground plant microbe interactions in maize and most likely also in other crops.