Plant genetic transformation (PGT) is a process where DNA is introduced into plant cells, tissues, or organs using molecular and cellular biology methods.

Through plant genetic transformation, we can discover a gene and its function, understand traits of interest and favor breeding programs by producing novel and genetically diverse plant materials.

In a plant transformation protocol, step-by-step wet lab activities are performed to introduce the foreign DNA (exogenous DNA) and evaluate its insertion. Thus, PGT comprises:

  1. Delivery of the DNA into a single cell and
  2. Regeneration into entire fertile plants



Plant Transformation basic steps - first DNA is delivered into the plant cell. The plant is then regenerated with new genetic information

However, researchers are not always interested in developing a whole genetically transformed plant (stable transformation), instead, they may want to quickly test the expression of a foreign gene in the plant tissue (transient transformation). Furthermore, how you transfer foreign DNA into plant cells can be divided into: protoplast-mediated, biolistic-mediated, and Agrobacterium-mediated techniques.



Plant genetic transformation strategies

Stable transformation:

Depending on their goal, researchers may want to develop a stable genetically transformed plant variety to massively produce new plant materials with desirable traits for agriculture, like disease resistance.

With stable transformation, the foreign DNA is fully integrated into the host genome and expressed in later generations of the plant.

This type of plant transformation is used for longer-term research. For instance, a stable transformation project can take months, even years, to be thoroughly developed.

stable transformation diagram - foreign DNA is integrated into the host genome and expressed in later generations of the plant.



Transient transformation:

In other cases, researchers are more interested in understanding a gene or protein function. In this case, developing a whole genetically transformed plant is not necessary. Instead, a tissue portion (e.g. detached leaf) would be enough to evaluate the expression of a foreign gene.

Here, transient transformation allows temporary introduction or silencing of genes to determine their expression. Therefore, the foreign DNA is not integrated into the host cell. A transient method can also be used for gene silencing by expressing small interfering RNAs (siRNAs) and microRNAs (miRNAs) in plant tissues. In this case, a transient transformation can take days or weeks.



Table 1.1. Comparison for stable and transient transformation.


Advantages

Disadvantages

Stable transformation

  • A transgenic line can be produced
  • The target gene is inherited
  • A metabolite can be constantly expressed
  • Plants are used as biofactories
  • Months to years in the transformation process

Transient transformation

  • It is a fast method
  • It can easily be scaled up for commercial uses
  • It can be used to produce recombinant proteins
  • It can be used for the targeted silencing of genes
  • It has a highly variable transformation efficiency


Written by Adriana Gallego, PhD

References

Jones, H. D., & Sparks, C. A. (2009). Stable transformation of plants. Methods Mol Biol, 513, 111-130.

Keshavareddy, G., Kumar, A. R. V., & S. Ramu, V. (2018). Methods of Plant Transformation- A Review. International Journal of Current Microbiology and Applied Sciences, 7(07), 2656-2668.

Kikkert, J. R., Vidal, J. R., & Reisch, B. I. (2005). Stable transformation of plant cells by particle bombardment/biolistics. Methods Mol Biol, 286, 61-78.

Krenek, P., Samajova, O., Luptovciak, I., Doskocilova, A., Komis, G., & Samaj, J. (2015). Transient plant transformation mediated by Agrobacterium tumefaciens: Principles, methods and applications. Biotechnol Adv, 33(6 Pt 2), 1024-1042.

Mathur, J., & Koncz, C. (1998). PEG-Mediated Protoplast Transformation with Naked DNA. In J. Martinez-Zapater & J. Salinas (Eds.), Methods in Molecular Biology: Arabidopsis Protocols (Vol. 82). Humana Press Inc.

Shillito, R. (1999). Methods of Genetic Transformation: Electroporation and Polyethylene Glycol Treatment. In Molecular improvement of cereal crops. Springer, Dordrecht.