Download Careers360 App
  • Engineering and Architecture
  • Management and Business Administration
  • Medicine and Allied Sciences
  • Law
  • Animation and Design
  • Media, Mass Communication and Journalism
  • Finance & Accounts
  • Computer Application and IT
  • Pharmacy
  • Hospitality and Tourism
  • Competition
  • School
  • Study Abroad
  • Arts, Commerce & Sciences
  • Learn
  • Online Courses and Certifications
Pollen-Pistil Interaction & Outbreeding Devices: Outbreeding Devices, Mechanism

Pollen-Pistil Interaction & Outbreeding Devices: Outbreeding Devices, Mechanism

Edited By Irshad Anwar | Updated on Jul 02, 2025 07:12 PM IST

Definition Of Pollen And Pistil

This complex series of events, called pollen-pistil interaction, gets initiated right after the pollen grains land on the stigma of a pistil; in the end, it guarantees successful fertilization. The interaction is what therefore determines compatibility and assures genetic material transfer from pollen to ovules during plant reproduction.

This is the process: recognition, adhesion, hydration, and germination of the pollen tube, and finally, the sperm cells are delivered to the ovule. One of these mechanisms is that of self-incompatibility and structural modification like heterostyly, which favours cross-pollination, thus securing genetic diversity.

Pollen-Pistil Interaction

The pollen-pistil interaction is described below-

Structure of Flower and Reproductive Organs

Description of pistil

The pistil is the female reproductive organ of a plant, comprising the stigma, the pollen-receptive area; a style, which essentially is the stalk connecting the stigma into the ovary; and the ovary itself, containing the ovules.

Description of pollen

They are the male gametophyte, which contains the male genetic material. They germinate on compatible stigmas into a pollen tube that grows down the style towards the ovary.

Mechanism of Pollen-Pistil Interaction

Pollination process

This includes both self-well and cross-pollination. The former occurs in the self-same flower, while the latter is between flowers. Mediation takes place through wind, water, or even pollinators.

Pollen adhesion to stigma

Falling on the stigma, the pollen grains get adhered to the sticky surface of the stigma.

Pollen hydration and germination

The pollen grain takes up water from the stigma and germinates to form a pollen tube.

Growth of pollen tube

The pollen tube grows chemically guided down the style into the ovary towards the ovule.

Interaction with style and ovary

The pollen tube extends through tissues of the style and finally reaches the ovule before fertilisation.

Molecular and Cellular Interactions

Role of chemical signals

The growing pollen tube towards the ovary is guided through chemical signals from the pistil.

Pollen recognition and rejection mechanisms

The stigma recognises compatible pollen for germination and incompatible pollen through various biochemical mechanisms for rejection.

Role of S-genes in self-incompatibility

The expression of the self-incompatibility phenomenon by S-genes ensures that there won't be any self-fertilisation but cross-pollination. This is achieved by rejecting the pollen from the same plant or from any other plant that has the same genotype.

Outbreeding Devices

The outbreeding devices are described below-

Definition and Importance

Explanation of outbreeding devices

These are the mechanisms which avoid self-fertilisation and achieve genetic diversity due to cross-pollination.

Importance in genetic diversity and evolution

It sustains genetic diversity within the plant population and enhances the adaptability and evolution of plants.

Types of Outbreeding Devices

Dichogamy

Temporal separation of male and female reproductive phases within the same flower avoids self-pollination.

Herkogamy

The physical separation of the anther and stigma reduces the opportunity for self-pollination of the flower.

Self-Incompatibility

The genetic mechanism that prevents the pollen from fertilising its own plant's ovules.

Dioecy and Monoecy

Dioecy refers to plants with separate male and female individuals, whereas monoecy refers to plants having separate male and female flowers on the same individual.

Heterostyly

The presence of different flowers morphs with styles and stamens of different lengths that will enhance cross-pollination.

Recommended video on "Pollen-Pistil Interaction & Outbreeding Devices"


Frequently Asked Questions (FAQs)

1. What is pollen-pistil interaction?

Pollen-pistil interaction: The interaction of pollen grains with the pistil of a flower in bringing about fertilisation and seed formation.

2. What is pollen-pistil interaction?
Pollen-pistil interaction refers to the complex series of events that occur when pollen grains land on the stigma of a flower and grow towards the ovule. This process involves recognition, adhesion, germination of the pollen grain, and growth of the pollen tube through the style to reach the ovary.
3. What are outbreeding devices in plants?

Outbreeding mechanisms: These are mechanisms which prevent self-fertilisation and hence promote cross-pollination to ensure genetic diversity.

4. What are outbreeding devices in plants?
Outbreeding devices are mechanisms that plants have evolved to promote cross-pollination and genetic diversity. These devices help prevent self-fertilization and encourage the exchange of genetic material between different individuals of the same species.
5. How does self-incompatibility work in plants?

Some genetic process prevents self-pollen from fertilising the ovule. This process promotes inter-crossing.

6. What is the difference between dichogamy and herkogamy?

In dichogamy, there is temporal separation, while in herkogamy there is spatial separation of the male and female reproductive organs.

7. Why is genetic diversity important in plants?

It plays a huge role in adaptability and population resiliency for survival against changes in the environment and fighting diseases.

8. What is the function of the stigma in pollen-pistil interactions?
The stigma plays several crucial roles in pollen-pistil interactions:
9. How does the S-RNase system contribute to self-incompatibility?
The S-RNase system is a molecular mechanism involved in gametophytic self-incompatibility. S-RNases are proteins produced by the pistil that can degrade RNA in incompatible pollen tubes, preventing their growth and fertilization. Compatible pollen tubes can inactivate or avoid these S-RNases, allowing successful fertilization.
10. How do unilateral incompatibility systems work?
Unilateral incompatibility occurs when pollen from species A can fertilize species B, but pollen from species B cannot fertilize species A. This asymmetric barrier to hybridization is often found between self-incompatible and self-compatible species. It involves complex interactions between pollen and pistil proteins and can contribute to the evolution of new species.
11. How do plants ensure genetic diversity in the absence of pollinators?
Plants can ensure genetic diversity without pollinators through several mechanisms:
12. What is the role of the extracellular matrix in pollen tube growth?
The extracellular matrix plays crucial roles in pollen tube growth:
13. How does dichogamy function as an outbreeding device?
Dichogamy is an outbreeding device where male and female reproductive organs in a flower mature at different times. This temporal separation prevents self-pollination by ensuring that pollen is not released when the stigma of the same flower is receptive, thus promoting cross-pollination.
14. What is the difference between protandry and protogyny?
Protandry and protogyny are two types of dichogamy. In protandry, the male reproductive parts (stamens) mature before the female parts (pistil), while in protogyny, the female parts mature before the male parts. Both mechanisms promote outbreeding by reducing the chances of self-pollination.
15. How does herkogamy promote outbreeding?
Herkogamy is an outbreeding device where there is a spatial separation between male and female reproductive organs within a flower. This physical distance makes it difficult for self-pollination to occur, increasing the likelihood of cross-pollination by pollinators.
16. What is self-incompatibility in plants?
Self-incompatibility is a genetic mechanism that prevents self-fertilization in many plant species. It involves the recognition and rejection of pollen from the same plant or genetically similar individuals, thus promoting outbreeding and genetic diversity.
17. Why is pollen-pistil interaction important for plant reproduction?
Pollen-pistil interaction is crucial for plant reproduction because it enables the male gametes (sperm cells) to reach the female gametes (egg cells) in the ovule. This interaction ensures successful fertilization and seed production, which are essential for the continuation of plant species.
18. What role do pollen coat proteins play in pollen-pistil interactions?
Pollen coat proteins are involved in the initial stages of pollen-pistil interaction. They help in pollen adhesion to the stigma, pollen hydration, and recognition between pollen and pistil. Some of these proteins also play a role in self-incompatibility responses.
19. How does pollen tube guidance work?
Pollen tube guidance is the process by which the growing pollen tube is directed towards the ovule. It involves chemical signals produced by the pistil and ovule, such as calcium gradients and specific proteins, which attract and guide the pollen tube through the style and into the ovary.
20. What is the significance of the pollen tube's tip growth?
The pollen tube's tip growth is crucial for its progression through the style. This highly specialized form of cellular growth allows the pollen tube to navigate through the pistil's tissues, responding to guidance cues and delivering the sperm cells to the ovule for fertilization.
21. How does gametophytic self-incompatibility work?
In gametophytic self-incompatibility, the pollen grain's compatibility is determined by its own haploid genotype. If the pollen's S-allele matches one of the pistil's S-alleles, the pollen tube's growth is inhibited, preventing self-fertilization.
22. What is the difference between gametophytic and sporophytic self-incompatibility?
In gametophytic self-incompatibility, the pollen's own genotype determines its compatibility, while in sporophytic self-incompatibility, the pollen's compatibility is determined by the genotype of its parent plant (sporophyte). Sporophytic systems can lead to more complex incompatibility patterns.
23. Why is heterostyly considered an outbreeding device?
Heterostyly is an outbreeding device where flowers of the same species have different arrangements of stamens and styles. This morphological variation promotes cross-pollination between flowers with complementary structures, as pollinators are more likely to transfer pollen between compatible flower types.
24. What are the three main types of heterostyly?
The three main types of heterostyly are:
25. How do plants prevent inbreeding depression?
Plants prevent inbreeding depression through various outbreeding devices, including:
26. What is the role of calcium in pollen tube growth?
Calcium plays a crucial role in pollen tube growth. It forms a concentration gradient at the tip of the growing pollen tube, regulating cell wall expansion, vesicle fusion, and cytoskeleton organization. Calcium also acts as a second messenger in signaling pathways that guide the pollen tube's direction.
27. How do plants balance the need for outbreeding with the assurance of reproduction?
Plants balance outbreeding and reproductive assurance through various strategies:
28. How do environmental factors affect pollen-pistil interactions?
Environmental factors can significantly impact pollen-pistil interactions:
29. What is the role of arabinogalactan proteins (AGPs) in pollen-pistil interactions?
Arabinogalactan proteins (AGPs) are involved in various aspects of pollen-pistil interactions:
30. How do plants regulate the number of pollen tubes that enter the ovary?
Plants regulate the number of pollen tubes entering the ovary through several mechanisms:
31. What is the significance of interspecific incompatibility in plants?
Interspecific incompatibility is important for maintaining species boundaries in plants. It prevents hybridization between different species by:
32. What role do pistil-expressed small RNAs play in pollen-pistil interactions?
Pistil-expressed small RNAs are involved in various aspects of pollen-pistil interactions:
33. How do plants prevent multiple pollen tubes from entering a single ovule?
Plants prevent multiple pollen tubes from entering a single ovule through several mechanisms:
34. What is the significance of pollen-pistil interactions in plant breeding and crop improvement?
Pollen-pistil interactions are significant in plant breeding and crop improvement for several reasons:
35. How do plants regulate the speed of pollen tube growth?
Plants regulate pollen tube growth speed through various mechanisms:
36. What is the role of reactive oxygen species (ROS) in pollen-pistil interactions?
Reactive oxygen species (ROS) play multiple roles in pollen-pistil interactions:
37. How do plants maintain pollen viability during the journey from anther to stigma?
Plants maintain pollen viability through several adaptations:
38. What is the significance of the pollen tube's cell wall composition?
The pollen tube's cell wall composition is significant because:
39. How do plants regulate the timing of pollen release and stigma receptivity?
Plants regulate the timing of pollen release and stigma receptivity through:
40. What role do glycoproteins play in pollen-pistil interactions?
Glycoproteins are crucial in pollen-pistil interactions:
41. How do plants balance the energy costs of producing pollen with the need for successful fertilization?
Plants balance energy costs and fertilization success through various strategies:
42. What is the role of the transmitting tissue in pollen tube growth?
The transmitting tissue in the style plays several important roles in pollen tube growth:

Also Read

Apomixis - An Overview, Types

07 Jul'25 10:48 AM

Artificial Pollination: Introduction, Types, Methods, Advantages

07 Jul'25 10:28 AM

Events in the Germination of Pollen Grains: Definition, Meaning, Formation

06 Jul'25 03:44 PM

Embryogeny in Monocots: Structure, Differences, Examples

06 Jul'25 11:55 AM

Seed: Definition, Meaning, Form, Function, Dispersal, Germination

06 Jul'25 11:43 AM

Fruit and Seed Formation Without Fertilization: Formation and Development

02 Jul'25 07:13 PM

Dicotyledonous and Monocotyledonous Seeds: Structure, Differences, Examples

02 Jul'25 07:13 PM

Seed Formation and Seed Dispersal: Structure, Function and Importance

02 Jul'25 07:13 PM

Significance of Seeds and Fruits Formation: Structure, Function, Importance

02 Jul'25 07:13 PM

Fruits - Formation, Parts and Types of Fruits: Definition, Classification, Examples, & Facts

02 Jul'25 07:13 PM

Articles

Back to top