A rapid and efficient Agrobacterium-mediated transient transformation system in grape berries

Area of Science:

• Plant Biotechnology
• Molecular Biology
• Fruit Science

Background:

• Grape berry transformation is challenging due to high cell turgor pressure, hindering Agrobacterium penetration.
• A rapid transient transformation system is essential for efficient gene function assessment in grapes.

Purpose of the Study:

• To develop a rapid and efficient Agrobacterium-mediated transient transformation methodology for grape berries.
• To identify optimal injection methods, grape genotypes, and developmental stages for grape berry transformation.

Main Methods:

• Evaluated two injection methods (punch and direct injection) using the β-glucuronidase (GUS) reporter gene.
• Tested six grape cultivars ('Hanxiangmi', 'Moldova', 'Zijixin', 'Jumeigui', 'Shine-Muscat', 'A17') for transformation efficiency.
• Assessed GUS activity at different time points and developmental stages (WAFB) post-injection.

Main Results:

• Direct injection was simpler and more convenient than punch injection, with no significant difference in transformation.
• 'Jumeigui', 'Shine-Muscat', and 'A17' showed high fruit integrity (>80%) and successful GUS expression.
• Optimal GUS activity was observed in 'Jumeigui' berries at 7-8 weeks after full blooming (WAFB).
• Over-expression of VvMYB44 accelerated anthocyanin accumulation and fruit coloring, confirming system efficacy.

Conclusions:

• Established a reliable Agrobacterium-mediated transient transformation system for grape berries.
• Identified 'Jumeigui', 'Shine-Muscat', and 'A17' as suitable cultivars and direct injection as the preferred method.
• The developed system is efficient for rapid elucidation of gene function in grape berries.