Module: | Pollination & Outbreeding Devices
Q54: Consider the following statements regarding the chemotropic guidance of the pollen tube:
1. The growth of the pollen tube through the stylar tissue toward the ovary is strictly guided by specific chemotactic gradients.
2. The filiform apparatus of the synergids secretes chemical complexes, highly rich in calcium, boron, and inositol, to attract the tube.
3. During this journey, the pollen tube exclusively grows intracellularly, penetrating directly through the cytoplasm of every stylar cell it encounters.
Which of the above statements is/are correct?
2. The filiform apparatus of the synergids secretes chemical complexes, highly rich in calcium, boron, and inositol, to attract the tube.
3. During this journey, the pollen tube exclusively grows intracellularly, penetrating directly through the cytoplasm of every stylar cell it encounters.
Which of the above statements is/are correct?
✅ Correct Answer: A
The correct option is A. Statements 1 and 2 are correct, while Statement 3 is a physiological distractor.
Pollen tube growth is a masterpiece of targeted navigation (chemotropism). Once the pollen germinates, the tube must traverse the style.
The primary chemical attractants are secreted by the filiform apparatus located in the synergids at the micropyle.
These secretions form a gradient heavily dependent on a Calcium-Boron-Inositol complex, which causally directs the tube's apical growth machinery.
Statement 3 is incorrect regarding the cellular pathway.
In a solid style, the pollen tube does not pierce and destroy every cell it meets (intracellular growth). Instead, it secretes pectinase enzymes that dissolve the middle lamella, allowing the tube to grow intercellularly, sliding through the spaces between the stylar cells, until it reaches the ovarian cavity.
Pollen tube growth is a masterpiece of targeted navigation (chemotropism). Once the pollen germinates, the tube must traverse the style.
The primary chemical attractants are secreted by the filiform apparatus located in the synergids at the micropyle.
These secretions form a gradient heavily dependent on a Calcium-Boron-Inositol complex, which causally directs the tube's apical growth machinery.
Statement 3 is incorrect regarding the cellular pathway.
In a solid style, the pollen tube does not pierce and destroy every cell it meets (intracellular growth). Instead, it secretes pectinase enzymes that dissolve the middle lamella, allowing the tube to grow intercellularly, sliding through the spaces between the stylar cells, until it reaches the ovarian cavity.