Dicistronic binary vector system-A versatile tool for gene expression studies in cell cultures and plants

Area of Science:

• Plant molecular biology
• Genetic engineering
• Biotechnology

Background:

• Monitoring gene expression in plants is crucial for understanding gene function and developing improved crop varieties.
• Traditional methods can be complex and time-consuming.
• Dicistronic vectors offer a potential solution for simultaneous gene expression and monitoring.

Purpose of the Study:

• To develop and validate novel dicistronic binary vector constructs for Agrobacterium-mediated gene transfer in plants.
• To establish a system for monitoring target gene translational expression using a co-translated reporter gene.
• To assess the utility of this system for physiological studies, specifically salt tolerance.

Main Methods:

• Construction of dicistronic binary vectors based on pGreenII, incorporating a reporter gene (luciferase) linked via an internal ribosome entry site (IRES) to a target gene.
• Validation using a mannopine synthase promoter (p-MAS) fused to a beta-glucuronidase (gus) gene and a firefly luciferase (luc) gene.
• Testing of different IRES elements, with tobamo IRES showing highest activity in transient expression.
• Replacement of the gus gene with a sodium antiporter gene (Atnhx1) for salt tolerance studies.
• Comparative analysis of transgenic tobacco cell cultures and pea plants (Pisum sativum L.) for salt tolerance.

Main Results:

• The developed dicistronic vectors successfully enabled translational expression monitoring of target genes in plants.
• The tobamo IRES element demonstrated the highest activity among tested IRES elements for transient expression.
• Transgenic tobacco cell cultures and pea plants expressing the Atnhx1 gene exhibited improved salt tolerance compared to wild-type counterparts.
• A direct correlation was observed between luciferase gene expression (luminescence) and increased sodium chloride tolerance.

Conclusions:

• Dicistronic binary vectors provide an effective tool for monitoring gene expression and facilitating physiological studies in plants.
• The tobamo IRES element is a highly active component for co-translational expression systems in plants.
• This technology holds promise for developing crops with enhanced stress tolerance, such as improved salt tolerance.