Collaborative Research: TR-Tech-PGR / PlantSynBio: Intragenic genome engineering for the next generation of improved plants

About This Grant

For many years, new crop varieties with improved traits like grain yield and disease resistance were developed through conventional plant breeding programs. In recent years, successful transgenic efforts were adopted to add beneficial DNA from other species into plants for research and/or crop improvement, leading to increased agricultural productivity in the United States. For example, most row crops, such as soybean and corn, possess beneficial transgenic DNA that makes them resistant to insect pests and/or herbicide spray, thereby vastly improving the crop yield for food and feedstock security. Developing and releasing transgenic crops requires a large amount of time, effort, and costs, in addition to going through safety trials and deregulation processes. This causes an almost decade-long lag between scoping the challenge to improve a crop trait and making it ready for adoption by farmers. Therefore, to accelerate crop improvement by conventional plant breeding-based approaches and avoid regulatory and social/global-level reluctance to adopt transgenic crops due to the presence of foreign DNA in a genetically modified crop plant, the team proposes an intragenic approach by adjusting, combining and transferring the desired DNA element sourced from the same plant species for improving crop traits. This intragenic approach faces significantly less regulatory burden, avoids consumer reluctance and will deliver faster technology transfer from the laboratory to the field. The research develops new biotechnology that will impact the bioeconomy and improve production of critical food crops. Transposable Elements (TEs) are mobile DNA fragments that naturally reshuffle parts of the genomes. Researchers have developed genetic tools to control the TE activity, insertion site, cargo size (user-defined sequences delivered by the TE), and the timing of TE insertion. Such genome engineering delivers a cargo DNA responsible for improving traits, e.g. disease resistance, by inserting it at a targeted position in the plant genome but flanked by TE sequences. However, such engineering leads to the insertion at one to many off-target sites in the genome. Often, these insertions tend to undergo silencing or become non-functional after a few generations. Such transgenic approaches have sourced TEs from another species. To avoid the transgenic approach, the project team proposed a new intragenic technology based on TEs sourced from the same plant species and engineered to deliver large custom cargo DNA also sourced from the same species. They also proposed to improve precise insertion at a desired location in the genome without additional off-target insertions. This new technology, called Transposase-Assisted Homology-Independent Targeted Insertion (TAHITI), will be experimented on rice plants. The team will examine the rate of targeted insertion and the off-target rates and selectively regulate the activity of the related endogenous TEs. They also plan to identify active TEs in the economically important crops maize and soybean for future adoption of intragenic approaches in these crops. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.