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From sunlight to roots: How do plants transport nutrients through the phloem?
In the plant world, phloem is a vibrant tissue responsible for the transport of soluble organic compounds produced after photosynthesis, especially sugars such as sucrose. This process is called "transport," and it allows plants to efficiently transport nutrients from the site of photosynthesis to different parts of the plant.
The name phloem comes from the ancient Greek word "phloiós", meaning bark, because in trees, phloem is the innermost layer of bark.
Structure and composition of phloem
Phloem tissue is mainly composed of duct cells, parenchyma cells and supporting cells. Vessel cells are often called "sieve tube elements" and their main function is to transport sugars within the plant. These cells lose their nucleus and many organelles as they mature and therefore rely on companion cells for most of their metabolic needs.
There are many holes at the ends of sieve tube cells, which are sieve areas formed by modified protoplasts and reinforced by polysaccharides carlos.
The role of companion cells
Companion cells are essential for the metabolic function of sieve tube members. The cytoplasm of these cells is connected to the sieve tube elements by protoplasts and usually has more ribosomes and mitochondria, which promotes their metabolic capacity.
Function and transportation of phloem
Unlike xylem, the cells in phloem are living cells specialized in transporting watery sap, which contains sugar. Sugars are quickly transferred to non-photosynthetic plant parts such as roots or storage structures such as tubers or bulbs. During spring growth, the roots are a sugar source and the growing area of the plant is the sugar sink. This multi-directional transport and periodic changes in sugar sources make phloem transport flexible.
"Through the phloem transport process, plants not only complete the cycle of nutrients, but also transmit information over long distances, showing their intelligence and adaptability."
Development and formation of phloem
The formation of phloem begins in the embryonic stage of the plant, and the development of xylem and phloem comes from the original vascular tissue. As the plant grows tremendously, secondary phloem forms as the vascular cambium thickens. The known molecular regulatory mechanisms of this process are better understood in small model plants such as Arabidopsis thaliana.
Nutritional utilization of phloem
In Finland and Scandinavia, the phloem of pine trees has been used as a food substitute for its unique flavor and long history. This phloem becomes an important source of food during times of famine and demonstrates nature's adaptability.
The impact of tree truncation
Since phloem is usually located on the outside of the xylem, if the trunk is severely peeled, water and nutrients will not be transported to the roots normally, causing the plant to die. This is also used in agriculture to promote the growth of specific fruits through ring cutting technology.
Conclusion
Phloem is not only a channel for plant nutrient transport, but also an important key to plant physiology and ecological adaptation. As research deepens, this vibrant organization will continue to reveal the wisdom and secrets of plants' survival in nature. Now that we understand these mechanisms, can we better understand plant life and their role in ecosystems?
