[Efficient Agrobacterium-mediated transformation of soybean]

Area of Science:

• Plant Biotechnology
• Molecular Biology
• Agricultural Science

Background:

• Soybean [Glycine max (L.) Merr] transformation is crucial for crop improvement.
• Agrobacterium tumefaciens-mediated transformation is a primary method for soybean genetic engineering.
• Enhancing transformation efficiency is key to developing improved soybean cultivars.

Purpose of the Study:

• To optimize Agrobacterium tumefaciens-mediated transformation of soybean embryonic tips.
• To identify factors influencing transformation efficiency, including bacterial strain, incubation, and co-cultivation conditions.
• To generate transgenic soybean plants expressing insect resistance genes.

Main Methods:

• Evaluated hypervirulent Agrobacterium tumefaciens strains (KYRT1, EHA105, LBA4404).
• Optimized incubation time and bacterial suspension concentration (A600=0.5 for 20 h).
• Determined optimal co-cultivation conditions: acidic medium (pH 5.4), 22°C, dark, 5 days, with resting and step-by-step selection cultures.

Main Results:

• The hypervirulent strain KYRT1 demonstrated superior transformation capability.
• Optimized conditions significantly improved transformation efficiency.
• Transgenic soybean plants expressing cryIA(c) and Pinellia ternata agglutinins (pta) genes were successfully generated across seven cultivars.
• Transformation frequency ranged from 4.29% to 18.0%, with approximately 70% of transgenic plants being fertile.
• PCR and Southern analyses confirmed stable integration of insect resistance genes.

Conclusions:

• Optimized Agrobacterium tumefaciens transformation protocols significantly enhance soybean genetic engineering.
• The developed method yields fertile transgenic soybean plants with stable insect resistance gene integration.
• This research provides a robust platform for developing insect-resistant soybean varieties.