From the archives: Plasmodesmata-regulation of function, targeting by pathogenic bacteria, and...

The organs in a multicellular organism’s body are made up of tissues formed by cells. To work together cohesively, cells must communicate. One way that cells communicate is through direct contact with other cells. The points of contact that connect adjacent cells are called intercellular junctions.

Contact-dependent signaling, as the name suggests, requires that communicating cells be in direct contact with each other. This is achieved either through receptor-ligand interactions or by specialized cytoplasmic channels that allow the flow of small molecules between cells. In animal cells, channels called gap junctions facilitate contact-dependent signaling in certain tissues, whereas, plasmodesmata perform a similar function in plants.
Gap Junctions
In animal cells, gap junctions are formed...

Plants present a rich source of nutrients for many organisms, making it a target for herbivores and infectious agents. Plants, though lacking a proper immune system, have developed an array of constitutive and inducible defenses to fend off these attacks.

Plants have rigid cell walls that are made up of cell wall polysaccharides that mediate cell-cell adhesion. The primary cell walls of plants consist of two independent and interacting polysaccharide networks: a pectin matrix that embeds the second network comprising cellulose and hemicelluloses.
Pectins are complex heteropolymers mainly composed of negatively-charged α-D-glucopyranosyl uronic acid and some neutral glycosyl residues such as α-L-rhamnopyranose, α-L-arabinofuranose,...

Plakins are large proteins with binding domains for microtubules, microfilaments, intermediate filaments, and membrane-associated protein complexes at cell junctions. Plakin functions are evolutionarily conserved and are primarily involved in organizing the different components of the cytoskeleton by crosslinking them to each other and connecting them to the cell-matrix and cell adhesion complexes. They are also known to interact with signal transducers, serve as scaffolds for signaling...

Plant growth depends on its ability to take up water and dissolved minerals from the soil. The root system of every plant is equipped with the necessary tissues to facilitate the entry of water and solutes. The plant tissues involved in the transport of water and minerals have two major compartments - the apoplast and the symplast. The apoplast includes everything outside the plasma membrane of living cells and consists of cell walls, extracellular spaces, xylem, phloem, and tracheids. The...