A scalable approach to inoculate plant viral vectors into plant tissue using non-pathogenic transgenic galls

Authors: Deblasio, Stacy; GAO, FENG - Consultant; PANG, ZHIQIAN - Consultant; IGWE, DAVID - Cornell University; SULLIVAN, SAMANTHA - Oak Ridge Institute For Science And Education (ORISE); WANG, YU-HUI - Cornell University; Pitino, Marco; CORADETTI, SAMUEL - Cornell University; SIMON, ANNE - University Of Maryland; Heck, Michelle

Submitted to: biorRxiv
Publication Type: Pre-print Publication
Publication Acceptance Date: 1/30/2026
Publication Date: N/A
Citation: N/A

Interpretive Summary: Huanglongbing (HLB), also known as citrus greening disease, is the most serious threat to citrus production worldwide. The disease reduces tree health, fruit yield, and fruit quality, and there is currently no cure. Although new biological treatments are being developed, a major barrier to their success is how to deliver these therapies effectively and economically into mature citrus trees. Benign plant viruses are being explored as a new way to deliver treatments that suppress disease or improve plant health. However, delivering these viral therapies into perennial crops such as citrus and grape remains a major challenge, limiting their commercial potential. In this study, we tested whether a new delivery approach, referred to as symbiont technology, could be used to introduce a small plant virus into plants. Symbionts are non-damaging biofactories that form naturally on plant stems and remain connected to the plant’s internal transport system. We demonstrated that symbiont technology can reliably deliver a small plant virus throughout both model plants and citrus trees, including trees already infected with the HLB pathogen. In contrast, conventional delivery methods failed to establish consistent virus movement. This work shows that symbiont technology provides a practical and scalable way to deliver biological therapies into woody perennial crops, overcoming a key barrier to the development of next-generation disease management tools for citrus and other high-value tree crops.

Technical Abstract: Vascular plant pathogens transmitted by insects inflict devastating economic losses on crops worldwide. By obstructing and usurping the natural flow of nutrients, plant infection by these pathogens drastically reduces yields, vigor and productivity. Treating fruit-bearing trees against persistent vascular pathogens poses a unique challenge, as systemic delivery of therapeutics must navigate the compartmentalized architecture of the tree’s vascular system under changing environmental conditions without disrupting fruit production or long-term tree health. Plant viruses have gained traction as a novel approach to deliver therapies to crop plants, including fruit trees, but delivery of viral vectors to orchards at scale remains a significant challenge. We tested whether transgenic galls can be used to systemically infect plants with a plant virus infectious clone. We combined the plant growth regulator gene cassette from Agrobacterium tumefaciens strain C58 with the wild-type strain of citrus yellow vein associated virus-1 (CY1) on a single plasmid within the T-DNA for plant cell transformation. Using EHA105, a disarmed strain of A. tumefaciens, we inoculated stems with these gall-forming plasmids and initiated systemic CY1 infection in citrus and Arabidopsis thaliana over three independent experiments. We provide proof-of-concept that transgenic galls, referred to as symbionts, can launch the systemic infection of CY1 in economically important and model plants. Symbiont delivery of therapeutic viral vectors is theoretically scalable from inoculation of mother trees within the nursery to millions of trees in the field and may be a valuable tool for the commercial delivery of therapeutic plant viral vectors.