A large percentage of microbes in nature reside in the biofilm mode of life, where they are attached to surfaces and are embedded in self-secreted polymeric matrices, in contrast to their free-floating or planktonic lifestyle. In vegetated soils, the plant root-associated microbes are nearly 100-fold higher in abundance than in soils lacking the host influence. This is mainly because plants release up to 40% of photosynthetically fixed carbon in the form of root exudates and volatile organic compounds (VOCs), thus creating a diverse chemical milieu around the roots to the region extending a few millimetres from the root surface, known as the rhizosphere.

While much is known about the beneficial properties of plant exudate constituents in soluble form, very little is known about the role of plant root VOCs (rVOCs) in assembling biofilms in soil microbiota, which may extend the beneficial sphere of host influence below ground to the scale of centimetres.

The investigation of rVOCs has led to several fundamental discoveries and innovations in methodologies to study the below- ground chemical interactions between plants and microbes. A novel airflow system was developed to direct plant root VOCs towards complex soil microbial community. These rVOCs, specifically oxylipins, shift the microbiome composition and growth dynamics of complex soil biofilms. This signalling is evolutionarily conserved from ferns to higher plants. Methyl jasmonate (MeJA) was identified as a bioactive signal of rVOCs that rapidly triggers both biofilm and microbiome changes. In contrast to the planktonic community, the resulting biofilm community provides ecological benefits to the host from a distance via growth enhancement. Despite being beyond the immediate rhizosphere, the resultant biofilms, in turn, promoted plant growth by 25–30%. Thus, the volatile host defence signal, MeJA, is co-opted for assembling host-beneficial biofilms in the soil microbiota and extending the sphere of host influence in the rhizosphere.

Based on these findings, SCELSE is developing nature-based solutions for regenerative and climate resilient agriculture in setting such as indoor or greenhouse farming. This discovery will play a role in tackling the challenge of increasing crop productivity while simultaneously reducing the environmental impact. Two major classes of agri-solutions are being developed: (1) a novel class of agrochemicals that promote soil beneficial biofilms; and (2) ecology-inspired beneficial microbial consortia that are responsive to crop signals or their derivatives and provide services of enhanced crop growth and climate resilience.

Understanding root-soil microbiome interactions to foster enhanced crop resilience and productivity.