Novel agrobacterium strains for enhanced in planta plant transformation

Overview

This research initiative seeks to discover and characterize novel Agrobacterium strains that can transform plants directly in tissue (in planta) without the need for traditional tissue culture. Current transformation tools using the standard C58 strain are effective at delivering genes but tend to produce galls or undifferentiated callus tissue, leaving researchers with "trapped" transgenic material that is difficult to regenerate into whole plants. By systematically screening a diverse collection of Agrobacterium strains, this project aims to identify strains whose T-DNA (the segment of DNA transferred into the plant) carries hormone biosynthesis genes that promote shoot development, enabling regeneration of fertile transgenic plants.

The work builds on a previously identified "shooty" strain (82.139) that demonstrated the ability to induce shoots near gall tissue. Success would expand the toolkit available for crop improvement, particularly for dicot plant species (broadleaf plants such as soybean, tomato, and cotton) that are important to agriculture.

Technical specifications

Research approach:

• Screen 143 diverse Agrobacterium strains sourced from the Chang laboratory at Oregon State University, selected based on phylogenetic characterization to prioritize strains most likely to carry useful T-DNA variants
• Test each strain on Kalanchoe (a model succulent plant used as a test organism) under greenhouse conditions to evaluate their ability to induce both galls and shoots
• Compare the hormone biosynthesis genes (cytokinin and auxin) carried in each strain's T-DNA, as these plant hormones control cell division and shoot formation
• Employ machine vision and automated phenotyping (observing and measuring physical traits) to score and analyze transformation outcomes, adapting an existing pipeline previously developed for plant trait analysis
• Document and statistically analyze the relationship between strain phylogeny (evolutionary relationships), T-DNA content, and transformation phenotypes

Key innovation:

The project moves beyond the single-strain paradigm by leveraging the natural diversity of Agrobacterium genomes to find strains with optimized hormone gene combinations for shoot regeneration.

Technology readiness level

This research is at an early discovery stage (TRL 2–3). Preliminary work has shown that the T-DNA from a known shooty strain can induce shoots near galls both in vitro (in laboratory culture) and in vivo (in living plants), though at low frequency. The current project represents a systematic expansion of this proof-of-concept into a broader strain screen. Future stages will require optimization of identified strains, validation in target crop species, and development of domesticated strain backgrounds suitable for broader research and commercial use. Partnerships with industry or other research institutions could accelerate validation in commercially relevant crops.