Investigation of the interactions between plants and biocontrol bacteria and their impact on soil suppressiveness

Pathogens in soil cause enormous yield losses in agricultural systems and are also important affectors of natural plant communities. Some agricultural as well as grassland soils are resistant against root pathogens (suppressive soils), which is mainly due to the presence of specific bacteria (biocontrol bacteria). Biocontrol bacteria among them streptomycetes, Bacillus spp. and pseudomonads produce exometabolites (e.g. HCN, DAPG, PRN) antagonistic to soil-borne plant pathogens and thus present a high potential for the protection of plants against diseases. Soil biota is strongly influenced by the host plant. Plants allocate a considerable amount of resources into root exudates and thereby create a unique environment for microorganisms living in the soil surrounding plant roots. Natural ecosystems are highly diverse and varying compositions of root exudates occurring in diverse plant communities alter the abundance, composition and activity of soil microorganisms. Diverse plant communities are more productive and sustainable than monocultures and furthermore more resistant against fungal pathogen attacks. In a recent study we demonstrated a positive relationship between plant diversity and the abundance of bacteria antagonistic to soil-borne plant pathogens. Diverse plant communities therefore may sustain a more diverse microbial community protecting them against soil-borne pathogens whereas low diverse plant communities likely lack such natural protection. Accordingly, interrelationships between plants and beneficial microorganisms need closer consideration in order to understand the functioning of ecosystems and to manage agricultural systems in an environmentally friendly and sustainable way.


Publications:

• Latz, E., Eisenhauer, N., Rall, B.C., Allan, E., Roscher, C., Scheu, S., Jousset, A. (2012): Plant diversity improves protection against soil-borne pathogens by fostering antagonistic bacterial communities. Journal of Ecology, doi: 10.1111/j.1365-2745.2011.01940.x