Background

Industrial nitrogen fertiliser is responsible for roughly 1.4% of global greenhouse-gas emissions and the bulk of agricultural runoff pollution. Legumes fix their own nitrogen by accommodating rhizobial bacteria inside specialised root cells (the symbiosome). Decades of work have mapped the legume host machinery that enables this accommodation; what’s been missing is a tractable strategy for transferring the minimal sufficient subset into cereals.

Objective

SYMBIOPATH identifies, builds, and tests the smallest functional module of host genes required to support intracellular bacterial accommodation in a non-legume model. The aim is not full nitrogen fixation in barley on day one — it is to find the lowest-complexity module that can be expressed, regulated, and characterised, so it can serve as a platform for layered engineering.

Aims

• Identify the minimal symbiosome biogenesis gene set in Medicago truncatula using targeted CRISPRi screens in root cortex cells.
• Build and test synthetic operons that reconstitute the minimal set in barley root cortex under root-specific promoters.
• Characterise partner-bacterium compatibility with engineered hosts using a defined set of Sinorhizobium and Mesorhizobium test strains.

The project is supported by a major research grant (2024–2029) and contributes open synthetic-biology parts to a public plant-engineering collection. All vector designs are publicly licensable.