RNAi-based plant immunization platform for TR-4 and other fungal pathogens

Overview

This solution offers a novel approach to plant disease protection by immunizing perennial crops against fungal pathogens using RNA interference (RNAi). The technology uses a benign, naturally replicating subviral RNA vector that is engineered to instruct the plant to produce its own therapeutic small interfering RNAs (siRNAs) once introduced. A single application provides lifetime protection against targeted pathogens, with no genetic modification to the plant, no heritability to offspring, and no spread between trees. The platform is being applied to Fusarium wilt of banana (Tropical Race 4, or TR-4), one of the most devastating threats to global banana production, and has already been validated against more than a dozen deadly plant diseases.

Technical specifications

Core technology:

• A natural replicating subviral RNA vector engineered to deliver siRNA-generating sequences into the plant
• Once inside the plant, the vector continuously produces siRNAs that silence critical genes in the target pathogen
• siRNAs are designed to be highly targeted to specific pathogens, reducing collateral effects on beneficial organisms

Key advantages over conventional RNAi delivery:

• Conventional siRNA sprays or injections require weekly or monthly reapplication, making them uneconomic for long-lived crops like bananas
• The replicating vector approach enables a single application to deliver sustained, lifetime siRNA production within the plant
• The approach is non-genetically modified, working across all varieties
• Application can be delivered via shoots through the mother plant

Validation status:

• An siRNA has been developed that reduces TR-4 by over 90% in vitro
• siRNAs have successfully reduced other fungal pathogens in vivo, including Botrytis
• The vector has demonstrated compatibility with over 30 plant species, with new compatibilities being confirmed regularly

Technology readiness level

The platform is at an advanced preclinical stage with strong proof-of-concept data. The siRNA candidate against TR-4 has been validated in vitro, and the vector system has demonstrated efficacy against multiple fungal pathogens in vivo across more than 30 plant hosts. Remaining next steps include selecting the optimal siRNA sequence that can be taken up by TR-4 in vivo, targeting a critical pathogen gene, and demonstrating full compatibility with banana plants. Initial testing in banana has confirmed vector replication, but additional vectors need to be evaluated and new ones developed to achieve sufficient mobility for complete plant protection. Optimization follows a two-step process: siRNA design is refined first in vitro and then validated in the model plant Nicotiana benthamiana against the pathogen before moving to target crops.