1. Transportation: Companion cells are responsible for the loading and unloading of sugars, hormones, and other molecules into and out of the sieve elements of the phloem. They ensure that these essential substances are efficiently transported to the rest of the plant.
2. Protein synthesis: Companion cells are highly active metabolically and have a large number of ribosomes, which are responsible for protein synthesis. They produce and transport the necessary proteins required for the functional integrity of the sieve elements.
3. Metabolic support: Companion cells provide metabolic support to sieve elements by supplying them with energy and other essential nutrients. They help maintain the high metabolic activity needed for long-distance transport in the phloem.
4. Cellular communication: Companion cells are involved in cell-to-cell communication within the phloem tissue. They facilitate the coordination of phloem loading and unloading processes, as well as respond to changes in the plant's environment and regulate the flow of substances in the phloem.
5. Defense mechanism: Companion cells play a role in the defense response of plants. They produce and release secondary metabolites and defense proteins to protect the phloem tissue from pathogens and pests.
6. Rigid support: Companion cells provide structural support to the sieve elements, ensuring their stability and integrity. This support helps maintain the continuous flow of substances through the phloem.
Overall, companion cells play a crucial role in the efficient and effective functioning of the phloem tissue in plants. They support the transportation of vital substances, maintain cell-to-cell communication, provide metabolic support, participate in defense mechanisms, and contribute to the structural stability of the phloem.
Functions of companion cells
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