Question

Which treatment is preferred to develop fertile dihaploid plants generated from pollen culture?

• A. ABA treatment
• B. NAA treatment
• C. Trifluralin treatment
• D. DEPC treatment

Hint:

To make a sterile Haploid into a fertile Dihaploid, you need a "doubler." If you don't see Colchicine, look for Trifluralin or Oryzalin.

Answer 1

The Correct Option is C

Concept: Plants regenerated from pollen (androgenesis) are haploid ($n$), meaning they have only one set of chromosomes. Because they cannot undergo normal meiosis, they are sterile. To make them fertile, their chromosome number must be doubled to create a "dihaploid" ($2n$).

Step 1: The Mechanism of Doubling.
Chromosome doubling requires a "spindle inhibitor"—a chemical that allows DNA replication to occur but prevents the cell from actually dividing. This results in a cell with twice the original number of chromosomes.

Step 2: Identifying Trifluralin.
While Colchicine is the most famous doubling agent, it is highly toxic and expensive. Trifluralin (3) is an alternative dinitroaniline herbicide that also acts as a powerful anti-microtubule agent. In modern plant breeding, it is often preferred for doubling the chromosomes of haploids because it is effective at lower concentrations and is less toxic to the plant tissues than colchicine.

Step 3: Eliminating Others.
ABA and NAA are growth regulators (hormones), and DEPC is a chemical used in molecular biology to inactivate RNase enzymes; none of these can double chromosomes.