Parasitic plant-mediated gene delivery system for non-transgenic host plant modification

Overview

This research proposes a novel gene delivery system that uses transgenic Cuscuta (dodder), a parasitic plant, to introduce genes of interest into host plants without requiring direct genetic transformation of the host. The approach exploits the natural ability of Cuscuta to exchange molecules, including DNA, RNA, and proteins, with its host plants. By engineering Cuscuta to express and export a target gene, the system could deliver genetic material into multiple host plant species simultaneously, bypassing the species-specific and labor-intensive transformation protocols traditionally required for each crop.

The technology has potential applications in agricultural biotechnology, including conferring traits such as herbicide resistance (e.g., glyphosate tolerance via EPSPS gene delivery), pest resistance, and stress tolerance across diverse plant species. It could also serve as a tool for functional genomics studies, enabling researchers to test gene functions in multiple hosts without generating individual transgenic lines.

Technical specifications

Key features:

• Parasite-based delivery vector: Utilizes Cuscuta, a parasitic plant with a broad host range, as a living delivery system for transgenes
• Natural molecular exchange: Leverages documented protein and mRNA trafficking between Cuscuta and host plants, with hundreds of Cuscuta proteins shown to travel into and persist in host seeds
• Enhanced mobility: Incorporates tRNA-like structure (TLS) fusions to increase gene mobility between organisms, based on demonstrated enhanced movement of non-mobile genes when fused to this structure
• Multi-species delivery: A single transgenic Cuscuta line could potentially deliver genes to multiple host species at once, eliminating the need for species-specific transformation protocols
• Agrobacterium-mediated transformation: Initial transformation efforts use Agrobacterium strains EHA105 and MSU440, with ongoing optimization of growth hormone combinations and co-cultivation conditions

Research basis:

The proposal builds on prior work demonstrating that Cuscuta proteins can be exchanged, transported, and stored in host plant seeds, and that gene mobility between organisms is significantly enhanced when tRNA-like structures are fused to non-mobile genes.

Technology readiness level

The technology is currently at an early research stage (TRL 2–3). The Park lab at the University of Missouri has established Agrobacterium-mediated transformation protocols for Cuscuta and confirmed stable transformation in Cuscuta callus tissue, with GFP/GUS reporter expression maintained for more than eight weeks. However, transformation efficiency remains low and requires further optimization of hormone compositions, co-cultivation conditions, and callus induction processes.

Future validation steps include screening additional growth hormone combinations, testing various co-cultivation conditions, transforming candidate genes such as EPSPS, tracking gene movement into host plants, evaluating host growth under glyphosate treatment, and assessing transgene inheritance through host seed germination under selective conditions. Successful completion of these steps would advance the technology toward functional validation and potential field application.