Cell Plate vs. Phragmoplast

Attribute	Cell Plate	Phragmoplast
Definition	The structure formed during cytokinesis in plant cells, which eventually develops into the cell wall.	A specialized microtubule structure that forms during cytokinesis in plant cells and guides the deposition of new cell wall material.
Formation	Forms from Golgi vesicles that fuse together at the equatorial plane of the dividing cell.	Forms from pre-prophase band microtubules that reorganize into a dense array at the equatorial plane of the dividing cell.
Components	Primarily composed of Golgi vesicles, microtubules, and cell wall materials.	Primarily composed of microtubules, actin filaments, and vesicles carrying cell wall materials.
Function	Facilitates the separation of daughter cells by forming a new cell wall between them.	Guides the deposition of new cell wall material, ensuring proper cell division and formation of daughter cells.
Occurrence	Found in plant cells during cytokinesis.	Found in plant cells during cytokinesis.
Species	Present in all plant species.	Present in all plant species.

Introduction

Cell division is a fundamental process in the growth and development of all living organisms. In plants, cell division involves the formation of a new cell wall, which is crucial for maintaining the structural integrity of the plant. Two important structures involved in cell wall formation are the cell plate and the phragmoplast. While both structures play a role in cytokinesis, they differ in their formation, composition, and function. This article aims to compare the attributes of the cell plate and phragmoplast, shedding light on their similarities and differences.

Cell Plate

The cell plate is a structure that forms during cytokinesis in plant cells. It is responsible for the synthesis and deposition of new cell wall material, ultimately leading to the separation of the two daughter cells. The formation of the cell plate begins during late telophase, when vesicles derived from the Golgi apparatus accumulate at the equatorial region of the dividing cell. These vesicles fuse together, forming a tubular network known as the phragmosome.

As the phragmosome expands, it gradually transforms into the cell plate. The cell plate grows outward from the center of the dividing cell, guided by the microtubules of the phragmoplast. The microtubules serve as tracks for the movement of Golgi-derived vesicles, which transport cell wall components such as cellulose and pectin to the expanding cell plate. The deposition of these components leads to the formation of a new cell wall between the daughter cells.

The cell plate is composed of several layers, including the primary cell wall, middle lamella, and secondary cell wall. The primary cell wall is the first layer to be deposited and provides initial structural support to the developing cell plate. The middle lamella, composed of pectin, acts as a cementing layer between adjacent cell plates. Finally, the secondary cell wall is formed on top of the primary cell wall, providing additional strength and rigidity to the cell plate.

Once the cell plate is fully formed, it fuses with the existing cell wall, completing the process of cytokinesis. The daughter cells are then separated, each surrounded by its own cell wall. The cell plate also plays a role in cell expansion and growth, as it contributes to the overall size and shape of the plant.

Phragmoplast

The phragmoplast is a microtubule-based structure that forms during late telophase and cytokinesis in plant cells. It serves as a scaffold for the deposition of vesicles and the assembly of the cell plate. Unlike the cell plate, which is a visible structure, the phragmoplast is not directly involved in cell wall formation but plays a crucial role in guiding the expansion and positioning of the cell plate.

The phragmoplast forms between the two sets of daughter chromosomes, extending from the spindle poles towards the equatorial region of the dividing cell. It consists of overlapping microtubules, which provide structural support and serve as tracks for the movement of Golgi-derived vesicles. These vesicles carry cell wall components to the expanding cell plate, contributing to its growth and development.

As the phragmoplast expands, it pushes the daughter nuclei towards the opposite poles of the dividing cell. This movement ensures the proper positioning of the daughter cells and the formation of a new cell wall between them. The phragmoplast also plays a role in the orientation of cell division, as it helps determine the plane of cytokinesis and the subsequent arrangement of daughter cells.

Once the cell plate is fully formed, the phragmoplast disassembles, and the microtubules are depolymerized. This marks the completion of cytokinesis and the separation of the daughter cells. The remnants of the phragmoplast can sometimes be observed as a ring-like structure at the center of the newly formed cell wall.

Comparison

While the cell plate and phragmoplast are both involved in cytokinesis and cell wall formation in plant cells, they differ in several aspects. Firstly, the cell plate is a visible structure that forms from the fusion of Golgi-derived vesicles, while the phragmoplast is a microtubule-based scaffold that guides the expansion of the cell plate.

Secondly, the cell plate is composed of multiple layers, including the primary cell wall, middle lamella, and secondary cell wall, whereas the phragmoplast does not have a defined composition and is primarily composed of microtubules.

Thirdly, the cell plate is directly involved in the synthesis and deposition of new cell wall material, while the phragmoplast serves as a guiding structure for the movement of Golgi-derived vesicles and the assembly of the cell plate.

Lastly, the cell plate fuses with the existing cell wall, completing the process of cytokinesis, while the phragmoplast disassembles once the cell plate is fully formed.

Conclusion

In conclusion, the cell plate and phragmoplast are two important structures involved in cytokinesis and cell wall formation in plant cells. While the cell plate is responsible for the synthesis and deposition of new cell wall material, the phragmoplast serves as a scaffold for the expansion and positioning of the cell plate. Despite their differences, both structures play crucial roles in maintaining the structural integrity of plant cells and contribute to the growth and development of plants.