68. Which one of the following can be used as a selection marker for developing transgenicplants?
(a)□­galactosidase
(b) □­glucoronidase
(c) Green fluorescent protein
(d) Hygromycin phosphotransferase

Understanding Selection Markers in Transgenic Plant Development

When developing transgenic plants, it’s crucial to determine which plant cells have successfully integrated foreign DNA. To do this, scientists use selection markers, which help distinguish transformed cells from non-transformed ones.

Correct Answer:

(d) Hygromycin phosphotransferase

What Is a Selection Marker?

A selection marker is a gene introduced into a plant alongside the gene of interest. It enables the transformed cells to survive under conditions that kill untransformed cells. This is usually done through antibiotic or herbicide resistance.

Why Hygromycin Phosphotransferase Is Effective

Hygromycin phosphotransferase (HPT) confers resistance to hygromycin B, a potent antibiotic that inhibits protein synthesis. Here’s how it works:

• HPT detoxifies hygromycin, allowing only the transformed cells to survive.

• It is widely used in plant transformation protocols due to its reliability and high selection efficiency.

• Hygromycin is effective in a broad range of plant species.

Why Not the Other Options?

Let’s briefly examine the incorrect choices:

• (a) β-galactosidase: A reporter gene, not a selection marker. It is used to monitor gene expression, not select for transformed cells.

• (b) β-glucuronidase (GUS): Also a reporter gene, used to visualize promoter activity but doesn’t confer resistance.

• (c) Green fluorescent protein (GFP): A visual marker, great for imaging but not used for antibiotic or herbicide resistance selection.

Summary

In transgenic plant research, hygromycin phosphotransferase is a trusted and efficient selection marker. It ensures only genetically modified cells thrive under selective pressure, streamlining the identification process for successful transformations.