Plasmodesmata

Definition

Plasmodesmata are microscopic channels that traverse the cell walls of plant cells, allowing for the intercellular transport of materials and the communication between adjacent cells. These structures are essential for the coordination and integration of cellular activities within the plant organism. The term 'plasmodesmata' is particularly relevant in the context of the viral life cycle, as these channels can serve as pathways for the movement and spread of plant viruses between cells.

5 Must Know Facts For Your Next Test

1. Plasmodesmata are essential for the movement of materials, including water, nutrients, and signaling molecules, between plant cells, enabling coordinated growth and development.
2. The size and permeability of plasmodesmata can be regulated by the plant, allowing for the selective transport of specific molecules or the restriction of unwanted materials, such as plant viruses.
3. Viruses can exploit the plasmodesmatal network to move from cell to cell, spreading the infection throughout the plant, a process known as cell-to-cell movement.
4. The structure of plasmodesmata includes a central rod-like structure called a desmotubule, which is continuous with the endoplasmic reticulum of the connected cells, facilitating the transport of materials.
5. The formation and modification of plasmodesmata are dynamic processes that are influenced by various environmental and developmental cues, allowing plants to adapt and respond to their changing conditions.

Review Questions

• Explain the role of plasmodesmata in the intercellular transport of materials within a plant.
  • Plasmodesmata are essential channels that traverse the cell walls of plant cells, allowing for the movement of water, nutrients, signaling molecules, and other materials between adjacent cells. This symplastic transport enables the coordination of cellular activities and the integration of the plant organism as a whole. The size and permeability of plasmodesmata can be regulated by the plant, allowing for the selective transport of specific molecules or the restriction of unwanted materials, such as plant viruses.
• Describe how viruses can exploit the plasmodesmatal network to spread within a plant.
  • Viruses can take advantage of the plasmodesmatal network to move from cell to cell, spreading the infection throughout the plant. This process, known as cell-to-cell movement, allows viruses to bypass the physical barrier of the cell wall and travel through the cytoplasmic continuity established by the plasmodesmata. The structure of plasmodesmata, which includes a central rod-like desmotubule continuous with the endoplasmic reticulum, can facilitate the transport of viral particles or viral components, enabling the virus to spread and infect new cells.
• Analyze how the dynamic nature of plasmodesmata formation and modification allows plants to adapt to their changing environmental and developmental conditions.
  • The formation and modification of plasmodesmata are not static processes, but rather are influenced by various environmental and developmental cues. This dynamic nature of plasmodesmata allows plants to adapt to their changing conditions by altering the size, permeability, and distribution of these intercellular channels. For example, plants may increase the number or size of plasmodesmata in response to environmental stresses, such as drought or pathogen attack, to facilitate the transport of signaling molecules and defense compounds between cells. Conversely, plasmodesmata may be selectively closed or restricted in certain developmental stages or in response to specific stimuli, allowing plants to control the movement of materials and regulate cellular activities as needed. This adaptability of the plasmodesmatal network is a crucial mechanism by which plants can coordinate their growth, development, and defense responses to their environment.

Related terms

Symplastic Transport: The movement of materials, such as nutrients, signaling molecules, and even viruses, through the interconnected network of plasmodesmata within a plant tissue.

Cell Wall: The rigid, protective outer layer of plant cells that provides structural support and acts as a barrier, with plasmodesmata serving as channels that penetrate this layer.

Cytoplasmic Continuity: The direct connection between the cytoplasm of adjacent plant cells, facilitated by the presence of plasmodesmata, allowing for the exchange of materials and the coordination of cellular activities.