Factors affecting PEG-mediated stable transformation of maize protoplasts

Area of Science:

• Plant Biotechnology
• Molecular Biology
• Genetics

Background:

• Maize (Zea mays) genetic transformation is crucial for crop improvement.
• Polyethylene glycol (PEG)-mediated transformation of maize protoplasts offers a potential route for efficient gene delivery.

Purpose of the Study:

• To investigate and optimize factors affecting stable transformation and co-transformation frequencies in maize protoplasts using PEG-mediated DNA uptake.
• To establish a simple, inexpensive, and effective protocol for generating large numbers of transformed maize cell lines.

Main Methods:

• Investigated the impact of protoplast plating conditions, pre-treatment buffer composition, PEG concentration, and DNA concentration on transformation efficiency.
• Evaluated the role of carrier DNA and DNA linearization on transformation outcomes.
• Assessed co-transformation efficiency of an unlinked marker gene (hygromycin phosphotransferase) by varying nonselected:selected DNA ratios.

Main Results:

• Protoplast plating conditions, buffer composition, PEG, and DNA concentrations significantly influenced transformation frequencies.
• Carrier DNA was not beneficial for circular plasmid DNA transformation.
• Co-transformation efficiency increased with higher nonselected:selected DNA ratios, reaching 65% at a 100:1 ratio.
• Up to 300 transformed calli per million protoplasts were recovered under optimal conditions.

Conclusions:

• The optimized PEG-mediated transformation protocol is effective for generating substantial numbers of stably transformed and co-transformed maize cell lines.
• This method provides a valuable tool for maize research requiring high-throughput transformation.
• The findings contribute to advancing genetic engineering techniques in maize.