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It seems like a simple process: Do you know how plants precisely control fruit drop?
The falling process of plants seems simple, but it is actually full of biological mysteries. When we see leaves falling quietly in the park in autumn, or fruits naturally falling off branches at the right time, there are multiple regulatory mechanisms behind it. The process of falling is called "detachment", which not only involves the plants' adaptation to the environment, but also shows their intelligent survival strategy.
Abscission is the shedding of parts of an organism, a process that is essential for plant growth and reproduction.
Detachment function
Plants shed their leaves for several reasons: first, to discard parts that are no longer needed, such as leaves that fall in autumn or flowers that wither after being pollinated. Secondly, shedding is also part of plant reproduction, spreading seeds and promoting reproduction by releasing fruits. In fact, the falling of unripe fruits is the plant's way of protecting its own resources and reducing its demand for nutrients.
Especially in many plants, if the leaves are damaged, the detachment process can help the plants retain water or improve photosynthetic efficiency. Such intelligent regulation enables plants to adjust flexibly when facing various environmental challenges.
The process of disengagement
The detachment process can generally be divided into three main steps: nutrient recovery, protective layer formation, and separation. Each step is unique and may vary depending on the plant species.
Nutrient Recovery
During the nutrient recycling process, plants will degrade chlorophyll and extract most of the nutrients. Nitrogen is usually a bottleneck for plant growth, but when fall comes, the nitrogen is recycled and flows to other tissues of the plant. This is why leaves change color in the fall, as the chlorophyll dies down, the carotenoids in the leaves reveal beautiful hues of yellow and orange.
Protective layer formation
Below the detached area, the cells begin to divide, forming a layer of cork cells; this layer prevents water loss. During the detachment process, cells that access this layer are injected with specific substances that further strengthen the plant's protective barrier, ensuring that the plant remains intact and can repair itself quickly after parts fall off.
Separation
This step may be performed in a variety of ways, but all separations occur in the disengagement zone. In some cases, the cells secrete an enzyme that self-digests the cell wall, forcing the cells apart and causing the leaves or other plant parts to fall off. Another way is through water absorption. When cells absorb a large amount of water, they swell and burst, causing the plant organs to fall off.
Isolation is not only a form of self-defense for plants, but is also an important part of the interaction between species in an ecosystem.
Mechanism of disengagement
During the detachment process, plants rely on multiple mechanisms for control, including structural, chemical, and hormonal regulation.
Construction mechanism
For example, in deciduous trees, the basal abscission zone is a separation zone made up of cells with weak walls, the cells in between swell in autumn and tear the weak walls of the upper layers, allowing the leaves to fall easily.
The role of hormones
Traditionally, researchers have believed that abscisic acid is the primary hormone that promotes abscission. But later studies found that the plant hormones auxin and ethylene played a more critical role. The reduction of auxin makes the detached area sensitive to ethylene, and when ethylene is present, it activates specific cell wall degrading enzymes, thereby promoting the detachment process.
By integrating these feedback mechanisms, plants can not only manage resources effectively, but also maintain stable growth and development amid environmental changes. As our understanding of the separation process deepens, our understanding of the laws of plant life becomes richer and more detailed.
Have you ever thought about how much wisdom and laws of survival are hidden behind these tiny biological processes?
