Chemical communication in the rhizosphere of plants (CHEMCOMRHIZO)

In CHEMCOMRHIZO we study the use by plants of metabolites to communicate with other organisms in their rhizosphere.
CHEMCOMRHIZO is divided into two main categories of rhizosphere signaling molecules: strigolactones and nematode hatching stimulants. Within these main parts we are looking at biosynthesis and perception.
An exciting example of rhizosphere signalling molecules are the strigolactones. These are used by the friends of plants, the arbuscular mycorrhizal fungi as well as other members of the root microbiome, for host detection but also by their enemies, root parasitic plants. Furthermore, they have an endogenous signalling function, as a plant hormone that regulates shoot branching and root architecture. I postulated that this dual positive and negative signalling role of the strigolactones is the result of a paradigm: enemies of plants recruit molecules that are essential to the plant as cues.

This paradigm has two important implications: 1) other plant-produced signalling molecules known to be abused by plant enemies likely have another, beneficial essential function in plants and 2) the involvement of multiple, positive and negative, biological functions exerts a selective pressure on these signalling molecules that results in the evolution of diversity in structure and biological specificity. For the strigolactones we are investigating implication 2): what is the biological relevance of the large structural diversity in the strigolactones. For implication 1) we are studying the nematode hatching stimulants. We address this using an innovative approach in a new area for the group by setting out to discover a new signalling role for plant parasitic cyst nematode hatching stimulants, with the microbiome being a plausible candidate. We do that by elucidating their biosynthesis and looking at the consequences of knocking out their production. In addition, also for the hatching stimulants we study how biological specificity is mediated by the creation of structural diversity and the concomitant changes in perception, in nematodes.

Together, the work should shed light on the significance of structural diversity in signalling molecules and the co-evolution of perception and could result in the discovery of a new class of signalling molecules in plants, perhaps signaling the microbiome. It may also provide the basis for biotechnological and agronomical applications to optimise colonisation by AM fungi and other microbiome members or to control plant development, and prevent parasitation by root parasitic plants and cyst nematodes

CHEMCOMRHIZO is divided into the following work packages:

WP 1. The chemistry of rhizosphere signalling
WP 2. Structural diversity in strigolactones
WP 2.1 Identification and characterisation of missing enzymes
WP 2.2 Specificity in strigolactone rhizosphere signalling
WP 3. Characterisation of hatching stimulant biosynthesis and function
WP 3.1 Identification and characterisation of hatching stimulant biosynthetic enzymes
WP 3.2 In planta signalling: effect of hatching stimulants on host physiology
WP 3.3 Ex planta signalling: hatching stimulant rhizosphere signalling
WP 4. Perception of rhizosphere signaling

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