Which one of the following is commonly used as a selection marker for developing transgenic plants?
Which one of the following is commonly used as a selection marker for developing transgenic plants?
Select an option to attempt
Correct Answer: Option D
Explanation
Selectable marker for plant transformation — hygromycin resistance:In plant transformation (Agrobacterium-mediated or biolistic), a SELECTABLE MARKER gene is needed to identify successfully transformed cells/shoots.Hygromycin resistance gene (hpt, hygromycin phosphotransferase):• Encodes an enzyme that inactivates hygromycin B (an aminoglycoside antibiotic that inhibits translation in both prokaryotes and eukaryotes).• Transformed cells expressing hpt survive on hygromycin-containing selection medium.• Non-transformed cells die → only transformed cells grow into callus and then plants.Distractors:• GFP: A REPORTER gene (shows where expression occurs via green fluorescence), NOT a selectable marker — it doesn't confer any growth advantage on selective medium.• Other selectable markers include: nptII (neomycin/kanamycin resistance), bar (bialaphos resistance), PMI (phosphomannose isomerase, positive selection on mannose medium).Answer: Hygromycin phosphotransferase (hpt) gene confers antibiotic resistance for positive selection of transformed plants.