Sexual Reproduction in Flowering Plants

Study Notes

Sexual Reproduction in Flowering Plants

Pollen tubes grow through stigma and style to reach the ovary.
Pollen grains can be either two-celled or three-celled at release.
The two-celled pollen consists of a vegetative cell and a generative cell; the generative cell divides to form two male gametes.
For three-celled pollen, the pollen tube carries two male gametes directly.
Upon reaching the ovary, the pollen tube enters the ovule through the micropyle, targeting one synergid.
The filiform apparatus guides the pollen tube at the micropylar end of the synergid.
Pollen-pistil interaction encompasses the recognition of pollen and the regulation of pollen tube growth, crucial for successful fertilization.
Knowledge of pollen-pistil interactions can aid plant breeders in creating desired hybrids, even in cases of incompatible pollinations.

Studying Pollen Germination

To observe pollen germination, use pollen from flowers such as pea, chickpea, Crotalaria, balsam, and Vinca.
Dust pollen on a glass slide with a sugar solution and examine under a microscope after 15-30 minutes.
Pollen tubes should be visible emerging from the pollen grains, indicating successful germination.

Artificial Hybridization

Plant breeders cross different species and genera to enhance desirable traits for superior crop varieties.
Emasculation prevents contamination of the stigma by unwanted pollen; this involves removing anthers from flower buds before they release pollen.
After emasculation, flowers are bagged to protect the stigma from external pollen sources.
When the stigma becomes receptive, mature pollen from the desired male parent is applied, and the flower is then rebagged.
If the female parent produces unisexual flowers, emasculation is unnecessary; instead, female flower buds are bagged pre-opening for controlled pollination.
The steps ensure that only selected pollen contributes to fertilization, aiding in the development of specific hybrid crops.

Description

Explore the fascinating process of sexual reproduction in flowering plants. This quiz covers key concepts such as the growth of the pollen tube, the roles of vegetative and generative cells, and the mechanisms involved in successful fertilization. Test your understanding of how these processes contribute to plant reproduction.