Module: | Embryo, Seed, Fruit & Apomixis
Q91: Consider the following statements regarding the origin of incompatibility proteins in sporophytic self-incompatibility (SSI):
1. In sporophytic self-incompatibility, the rejection phenotype of the pollen is dictated by the diploid genotype of the parent plant that produced it.
2. The tapetum synthesizes specific recognition proteins and deposits them into the cavities of the pollen exine during maturation.
3. Upon landing on the stigma, these tapetum-derived proteins completely dissolve the stigmatic papillae to force fertilization.
Which of the above statements is/are correct?
2. The tapetum synthesizes specific recognition proteins and deposits them into the cavities of the pollen exine during maturation.
3. Upon landing on the stigma, these tapetum-derived proteins completely dissolve the stigmatic papillae to force fertilization.
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 fundamentally incorrect.
Self-incompatibility (SI) prevents inbreeding.
In Sporophytic SI (SSI), the genetic identity of the pollen is not determined by its own haploid genome, but by the diploid genome of the sporophyte (the father plant). Causally, this happens because the tapetum (a diploid maternal tissue) synthesizes specific S-allele proteins.
Before the tapetum degrades, it physically deposits these recognition proteins into the sculptured cavities of the pollen's exine.
When the pollen lands, these proteins interact with the stigma.
Statement 3 describes a physiological impossibility.
These proteins do not dissolve the stigma; instead, if they match the stigma's S-alleles, they trigger a massive biochemical rejection cascade.
The stigma actively denies hydration to the pollen, preventing germination entirely.
Self-incompatibility (SI) prevents inbreeding.
In Sporophytic SI (SSI), the genetic identity of the pollen is not determined by its own haploid genome, but by the diploid genome of the sporophyte (the father plant). Causally, this happens because the tapetum (a diploid maternal tissue) synthesizes specific S-allele proteins.
Before the tapetum degrades, it physically deposits these recognition proteins into the sculptured cavities of the pollen's exine.
When the pollen lands, these proteins interact with the stigma.
Statement 3 describes a physiological impossibility.
These proteins do not dissolve the stigma; instead, if they match the stigma's S-alleles, they trigger a massive biochemical rejection cascade.
The stigma actively denies hydration to the pollen, preventing germination entirely.