Strigolactones as Regulators of the Rhizosphere Microbiome


Plants depend - especially if nutrients are limited - on interactions with microbial symbionts in the rhizosphere. Here we investigate how plants take influence on their associated microbiome in response to the availability of phosphorus in soil.
Strigolactones (SLs) are newly discovered plant hormones that regulate plant morphology. In addition, to the endogenous hormone function, SLs are secreted from the roots to the surrounding soil, where SLs act as signalling compounds and initiate the colonization of plant roots by arbuscular mycorrhizal fungi (AMF). AMF are beneficial soil fungi that form symbiotic associations with plant roots and often enhance the growth of the host plant. SLs exudation is especially pronounced under phosphorus (P) limiting conditions (i.e., when plants rely most on AMF for P uptake) and presents a mechanism how plants can attract AMF. However, plant roots not only associate with AMF, but interact with a wide range of other microbes. These other microbes - bacteria and fungi - collectively function as a microbiome and also contribute to plant growth and health.

Until now, the effects of SLs on microbial communities associating with plant roots have not been investigated. This project addresses a number of crucial issues concerning the significance of SLs as regulators of the rhizosphere microbiome:

  • We investigate the effects of SLs on the assembly of the rhizosphere microbiome in a range of plant species and using Petunia lines that vary in SLs exudation levels.
  • Since AMF - an important player in rhizosphere microbiome - are highly sensitive to the abundance of P in soil, we examine the rhizosphere microbial communities also along a P gradient. We investigate the dynamic changes of Petunia rhizomicrobial communities, including AMF, in response to the P levels in soil.

This project is innovative because it places the role of SLs in a community context and investigates how SLs modulate the rhizosphere microbiome as a function of the availability of phosphorus in the soil environment. This project will deliver basic knowledge on how plants manipulate their associated microbiome in response to the availability of phosphorus in soil and, is therefore important for the development of low-input sustainable agricultural systems.

This project is funded by the Swiss State Secretariat for Education, Research and Innovation (SERI) and part of the COST Action FA1206 "Strigolactones: biological roles and applications" and involves close collaboration with Prof. Didier Reinhardt (University of Fribourg, Switzerland) and Dr. Lorenzo Borghi and Prof. Enrico Martinoia (University of Zurich, Switzerland).