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The Miraculous Self-Repair of Plants: Why Do Leaves Fall Off in Autumn?
Every autumn, the leaves of many trees will be covered with golden or fiery red coats, and then quietly fall from the trees. This phenomenon is not only beautiful, but also a smart act of plant self-healing. The shedding of leaves is called abscission, and this process is a survival strategy used by plants to cope with environmental changes.
Detachment is a self-regulatory mechanism used by plants to protect their growth and flourishing when faced with adverse environmental conditions.
Detachment function
Plants undergo detachment for a variety of reasons. First, detachment occurs when a tree's leaves become no longer necessary or to protect its own survival and resources before winter sets in. For deciduous plants, this is especially important during the cold winter months, as it saves energy and reduces water loss. In addition to seasonal shedding, plants may also choose to shed leaves that are affected by damage or disease to protect the remaining leaves.
The process of detachment
Detachment is not static and involves three main steps: resorption, formation of a protective layer, and detachment.
Reabsorption
During this stage, plants extract most of their nutrients by degrading chlorophyll. Nitrogen is an important element that plants need, and it is this process that causes leaves to change color in the fall, becoming bright yellow or orange.
Formation of protective layer
The cells associated with the detached area divide and form a layer of stomatal cells, at which point a waterproof material is injected to protect the detached area of the plant. This layer of protection acts as a protective net for the plant, helping it maintain a stable internal environment after the leaves fall off.
Separation
Separation can occur in a variety of ways, usually in the breakaway zone. The cells secrete enzymes that break down the cell walls, eventually causing the leaves or other plant parts to fall off.
The mechanism of detachment
The exact mechanisms of detachment vary among thousands of plant species, but changes in structure, lack of chlorophyll, chemicals, and hormones are key factors.
Structural factors
In deciduous trees, the detachment zone located at the base of the petiole is composed of thin-walled cells. When the temperature becomes low and the photo synthesis ability decreases, the detachment reaction begins.
Chemical Signal
Plants produce reactive oxygen species when they experience stress (such as pest infestations and extreme climate). The production of these chemicals can disrupt the balance within cells and lead to organelle dysfunction. This process also prompts the plant to adjust its physiological response to facilitate the necessary disengagement behavior.
Hormonal effects
Early research suggested that dissociation acid was the primary hormone driving detachment, but it is now known that its primary function is not that. Instead, the phytohormones auxin and ethylene play key roles in detachment signaling, and they interact to regulate gene expression in the detachment zone.
The wisdom of nature
Detachment behavior is not only related to survival, many plants actually perform selective detachment to avoid pests and diseases. Some studies have shown that when plants are infested by pests, they will actively break away from their leaves to reduce the population of pests, which also demonstrates the autonomous defense capabilities of plants in nature.
Conclusion
Autumn leaves sway on the trees, and their falling off actually hides a complex and magical plant self-healing mechanism. In this process, plants intelligently choose how to protect themselves and keep growing. Such changes make us think, in the face of the ever-changing environment, can we also learn some coping methods from the self-repair of plants?
