Module: | Pollination & Outbreeding Devices
Q65: Consider the following statements regarding stigmatic papillae and pollen hydration:
1. The receptive surface of the stigma is covered in specialized cells called papillae that secrete a lipid-rich proteinaceous exudate.
2. This exudate controls the critical first step of pollen-pistil interaction by regulating the osmotic gradient necessary for pollen hydration.
3. In a self-incompatible reaction, the stigmatic exudate accelerates the hydration of self-pollen to rapidly destroy it via osmotic bursting.
Which of the above statements is/are correct?
2. This exudate controls the critical first step of pollen-pistil interaction by regulating the osmotic gradient necessary for pollen hydration.
3. In a self-incompatible reaction, the stigmatic exudate accelerates the hydration of self-pollen to rapidly destroy it via osmotic bursting.
Which of the above statements is/are correct?
✅ Correct Answer: A
The correct option is A. Statements 1 and 2 are correct, whereas Statement 3 is strictly incorrect.
The stigma is not merely a passive landing pad; it is highly interactive.
Structurally, its surface contains papillae that produce an exudate rich in lipids, water, and recognition proteins.
When a pollen grain lands, it is initially dehydrated.
The causal mechanism for germination requires the pollen to absorb water from this stigmatic exudate (hydration) to activate its metabolic enzymes.
Statement 3 presents a physiological falsehood regarding incompatibility.
In sporophytic self-incompatibility (SSI), the rejection mechanism does not cause the pollen to burst.
Instead, the stigmatic papillae actively block water transfer.
The incompatible self-pollen fails to hydrate adequately, effectively paralyzing it and preventing the emergence of the pollen tube altogether.
The stigma is not merely a passive landing pad; it is highly interactive.
Structurally, its surface contains papillae that produce an exudate rich in lipids, water, and recognition proteins.
When a pollen grain lands, it is initially dehydrated.
The causal mechanism for germination requires the pollen to absorb water from this stigmatic exudate (hydration) to activate its metabolic enzymes.
Statement 3 presents a physiological falsehood regarding incompatibility.
In sporophytic self-incompatibility (SSI), the rejection mechanism does not cause the pollen to burst.
Instead, the stigmatic papillae actively block water transfer.
The incompatible self-pollen fails to hydrate adequately, effectively paralyzing it and preventing the emergence of the pollen tube altogether.