“Gene Transfer Across Taxonomic Borders” ( Seminar Synopsis)

UNIVERSITY OF AGRICULTURAL SCIENCES, BANGALORE

DEPARTMENT OF GENETICS AND PLANT BREEDING

“Gene Transfer Across Taxonomic Borders”

Gene transfer across taxonomic borders in plants refers to the movement of genetic material between organisms that are not closely related—often crossing species, genus, or even kingdom boundaries. Initially, genetic information was thought to be passed only from parent to offspring (vertical gene transfer). However, the exchange of genes between different species, especially across taxonomic lines (horizontal gene transfer), is limited by reproductive barriers.

The discovery of the Ti plasmid in Agrobacterium as a natural gene transfer agent in the 1970s saw the birth of recombinant DNA technology. This enabled scientists to cut, copy, and insert genes from one organism into another. Transgenic plants are those that carry additional, stably integrated, and expressed foreign genes from other species.

The Agrobacterium-mediated DNA transfer system is a powerful vector system used for plant transformation. However, traditional gene delivery methods often involve inserting genes into plant cells through Agrobacteria or external forces (such as gene guns or electroporation), which may result in limitations such as plant cell damage, low transformation efficiency, and DNA integration at random sites in the genome. Newer technologies, such as nanoparticle-mediated gene delivery, deliver biomolecules to intact plant cells without the need for external forces. Another innovative method, SDN-3 technology, introduces a gene construct along with a long donor DNA segment containing the desired complete transgene to be integrated at a targeted site.

An example of gene transfer across taxonomic borders is Golden Rice, which was created by transforming rice with two beta-carotene biosynthesis genes: psy (phytoene synthase) from the daffodil plant (Narcissus pseudonarcissus) and crtI (phytoene desaturase) from the soil bacterium. This combination of transgenes enables the biosynthesis of provitamin A in the rice endosperm. Since 2002, the Genetic Engineering Appraisal Committee (GEAC) in India has approved six Bt cotton events for commercial cultivation. However, GM mustard and Bt brinjal face regulatory challenges in the country.

The SCB-29 transgenic maize is a single-copy T-DNA insertion event with an intact T-DNA fragment inserted into chromosome 10. The transgenes were expressed stably in SCB-29, which provides tolerance to both glyphosate and glufosinate without significant yield drag.

Gene transfer across taxonomic borders in plants presents both significant challenges and exciting opportunities. It can lead to crops with enhanced traits like disease resistance, stress tolerance, and improved nutritional content. However, careful consideration must be given to the potential ecological and environmental consequences of these transfers, including the risk of unintended effects.

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REFERENCES

1. WENBIN, S. U., MINGYUE, X. U., YASMINA, R. AND LIMING, Y. (2023). Technological Development and Application of Plant Genetic Transformation. Int J Mol Sci., 24(13): 10646.

2. YE, X., AL-BABILI, S., KLÖTI, A., ZHANG, J., LUCCA, P., BEYER, P. AND POTRYKUS, I. (2000). Engineering the provitamin A (beta-carotene) biosynthetic pathway into (carotenoid-free) rice endosperm. Science, 287(5451): 303-305.

3. YU, X., SUN, Y., LIN, C., WANG, P., SHEN, Z. AND ZHAO, Y. (2023). Development of Transgenic Maize Tolerant to Both Glyphosate and Glufosinate. Agronomy, 13: 226.