Plant Synthetic Biology
Key Achivements
- The world's first successful PETase expression and secretion in a plant via transient transformation.
Summary
Plant synthetic biology is about building useful genetic functions inside plants in a predictable way. For this project, our goal is to prove that PETase can be expressed and secreted in plants, laying the groundwork for tomorrow’s plastic pollution solution. However, the approach to plant synthetic biology is not as straightforward as one might think. On this page, a detailed account of how plant synthetic biology is explored will be discussed. However, information about the design process and future outlook can be found in the Engineering and Vision and Outlook Pages.
Why Agrobacterium-mediated plant transformation?
We want the plant to express PETase. Although a recent study identified the genetic sequence of PETase, we can’t simply “throw” the genes into the plant. Instead, we have to use a system of transformation called Agrobacterium-mediated plant transformation. Marc Van Montagu and Jozef Schell initially discovered this process in the 1970s. Then, in 1983, Mary-Dell Chilton's team discovered that Agrobacterium could be engineered to deliver foreign DNA to plants without causing tumors. This breakthrough led to the development of binary vector systems and revolutionized the introduction of genes into plants, making Agrobacterium a powerful tool for plant research and biotechnology (Gelvin Stanton B, 2003).
How it works:
The Agrobacterium contains a binary vector system: a helper plasmid and a disarmed Ti-plasmid.
Diagram from our Plant Synthetic Biology Workshop (Buaboocha, 2025)
In this system, the Ti plasmid delivers the transfer-DNA (tDNA) region into the plant genome via virulence (vir) genes, which act like a biological transporter. The system is binary because it contains two separate vectors, one carrying the tDNA and another carrying the vir genes.
Transient vs. Stable Transformation
Transient
Agroinfiltration proceeds by lightly wounding the abaxial leaf surface, pressing a syringe with Agrobacterium suspension against the lamina, and infiltrating until the tissue visibly wets; plants are then incubated. Because the T-DNA does not integrate, expression can be measured within a few days, which is ideal for screening promoter strength, signal peptide efficacy, and overall construct function for PETase secretion. However, this strength is also a weakness in the long run, as offspring would not inherit genetic modifications, nor do all parts of the plant contain the transformed genome.
Stable
Stable integration uses Agrobacterium co-cultivation of explants, antibiotic selection of transformed callus, and regeneration via organogenesis or somatic embryogenesis before rooting and acclimation. Since this process is performed earlier on in the plant’s life, the entire plant’s genome will be transformed, allowing inheritance.
Why do we focus on transient transformation?
Due to the simplicity and efficiency, our project prioritized transient expression, as our immediate goal is to show that PETase can be expressed and secreted in plants.
What we learnt
This project teaches two key insights about how plant synthetic biology can benefit future research by other teams:
- Alpha-Amylase 3S, a signal peptide that can secrete proteins into the matrix in plants, is highly functional, as shown by our effective PETase secretion. More information about how this is implemented and the results that it gave is available in the Contribution, Engineering and Results Pages.
- Low-concentration AGA medium must be used to grow plants for sterilized stable transformation to ensure plant growth. Furthermore, it’s going to be very beneficial to grow large quantities of plants, as many are likely to not be suitable for transformation (due to potential mold or contamination). More information about our stable transformation journey can be found in the Engineering and Experiment pages.
Acknowledgements:
Various details in this article are obtained from our Plant Synthetic Biology Workshop with Associate Professor Teerapong Buaboocha and Associate Professor Supaart Sirikantarama. Their slideshow can be found here.
Additionally, facts and figures are checked by our lab supervisor, Dr. Kittiya Tantisuwanichku.
References
- Gelvin Stanton B. (2003). Agrobacterium-Mediated Plant Transformation: The Biology behind the “GeneJockeying” Tool. Microbiology and Molecular Biology Reviews, 67(1), 16–37. https://doi.org/10.1128/mmbr.67.1.1637.2003