A simple and reliable multi-gene transformation method for switchgrass

Area of Science:

• Plant Biotechnology
• Molecular Biology
• Bioenergy Crops

Background:

• Switchgrass (Panicum virgatum L.) is a key biomass crop for bioenergy production.
• Developing transgenic switchgrass with multiple desired traits is crucial for enhancing its utility.
• Existing transformation methods can be complex and may result in untransformed plants.

Purpose of the Study:

• To establish a simple and reliable Agrobacterium-mediated transformation method for switchgrass.
• To develop a system for introducing multiple genes of interest into switchgrass efficiently.
• To create a novel selection method to eliminate non-transgenic plants.

Main Methods:

• Construction of a MultiRound Gateway-compatible binary vector (pHKGB110) for single transformation with multiple genes.
• Optimization of Agrobacterium tumefaciens EHA101 co-cultivation and selection conditions using meropenem.
• Development of an 'herbicide dipping method' for direct selection of transformed shoots using Basta.

Main Results:

• Achieved high transformation efficiency with prolonged co-cultivation (7 days) and meropenem selection.
• The herbicide dipping method completely eliminated untransformed shoots during the rooting stage.
• Over 90% of bar-positive transformants successfully carried both introduced reporter genes (GUSPlus and gfp).

Conclusions:

• A simple, reliable Agrobacterium-mediated transformation protocol for switchgrass was successfully developed.
• The method allows for the production of numerous transgenic switchgrass plants with multiple genes without escapes.
• This technique is suitable for large-scale production of genetically modified switchgrass lines for bioenergy applications.