The proteinaceous substance involved in sporophytic incompatibility and stored in the exine is derived from

Options

A. Tapetum
B. Microspore
C. Anther locule
D. Stigmatic papillae

Answer

### Step-by-Step Solution:

1. **Understanding Sporophytic Incompatibility**:
- Sporophytic incompatibility is a genetic mechanism that prevents the fertilization of incompatible pollen grains. It works by inhibiting the germination of pollen on the stigma or preventing the growth of the pollen tube.

2. **Identifying the Proteinaceous Substance**:
- The question asks about a proteinaceous substance involved in this incompatibility that is stored in the exine of pollen grains. The exine is the outer layer of the pollen grain.

3. **Analyzing the Options**:
- The options given are:
- A) Tapetum
- B) Microspore
- C) Anther locule
- D) Stigmatic papilla

4. **Examining Each Option**:
- **Tapetum**: This is the innermost layer of the microsporangia (anther) and is crucial for nourishing developing pollen grains. It also provides precursors for the pollen coat, which is involved in sporophytic incompatibility.
- **Microspore**: These are the units that develop into pollen grains but do not directly relate to the proteinaceous substance involved in incompatibility.
- **Anther locule**: This is simply the chamber that contains pollen grains and does not produce the proteinaceous substance.
- **Stigmatic papilla**: These are the cells on the stigma that receive pollen but do not produce the proteinaceous substance.

5. **Conclusion**:
- Based on the analysis, the correct answer is **A) Tapetum** because it is the source of the proteinaceous substance that plays a role in sporophytic incompatibility and is stored in the exine of pollen grains.