Fighting plant

  Compared with the hurried human world, the life of plants seems calm and peaceful, but this is only the surface of the matter. The greedy appetite of pests puts plants at risk, and they must fight back to save their lives.
  The fact is also true. Plants are not victims without the ability to parry. They have evolved powerful defense capabilities-producing special defense compounds. These compounds can act as “poisons”, and can also inform their companions of the imminent danger and appeal to allies for help.
  However, all these defensive measures come at a price and consume the energy that plants would otherwise use for growth and repair. In order to preserve energy, plants must choose the way and timing of using “chemical weapons”. Here are five strategies for plants to fight back pests while protecting themselves.
  Warned
  to avoid wasting energy, the plant is not all the time in the synthesis of “chemical weapons”, but only when the real danger coming to begin production. Once pests bite the leaves of plants, the leaves release chemical volatiles to send alarms, telling other parts of the plant and neighboring plants to start defense.
  Certain plants produce jasmonic acid when they are injured. Jasmonic acid can break down JAZ protein, and JAZ protein is used to inhibit the production of protective toxic compounds in plants. The decomposition of JAZ protein by jasmonic acid makes plants’ genes for producing toxic compounds full of energy, and accelerates the production of defensive weapons needed by plants.
  Many species live in symbiosis with fungi in the soil. Fungi penetrate the surface of plant roots to take up carbon elements, and at the same time help plants obtain nutrients such as nitrogen and phosphorus that they depend on for survival. The fungus connects the surrounding areas into one piece through filament-like hyphae, forming a huge underground network. Some plants will use this underground network to communicate with each other and warn of impending danger.
  The experimenter put the aphid on the bean plant and wrapped the plant with a polyethylene bag to prevent it from spreading the alarm through the air. At this time, other legumes that have established contact with the fungi under the soil surface begin to release defensive compounds, and legumes that are not in the same fungal community have no response. It can be seen that the fungus has played the role of the “biological Internet”, transmitting important information from one plant to another.
  Request reinforcements
  plants also secrete volatile, can attract natural enemies of substances to protect themselves.
  When European corn is attacked by caterpillars, corn plants will release volatile β-caryophyllene to attract parasitic wasps. The parasitic wasp lays eggs in the caterpillar, which slows the caterpillar’s ​​feeding rate. After a few weeks, the eggs of the parasitic wasp hatch and the caterpillars die. European corn can also release β-caryophyllene underground to resist rootworm attacks. These volatile substances spread through the pores of the soil, telling the natural enemy of the rootworm: “The food is ready, come and have a nice meal!”
  But sometimes, such a move will also attract uninvited guests. Some corn varieties grown in the United States have lost the ability to produce β-caryophyllene and become helpless when attacked by pests. When the researchers repaired the genes of these corns to allow them to regain this ability, they found that the roots of these corns were infected with pathogenic fungi. These fungi also seem to be attracted by β-caryophyllene. This presents a problem for corn: Either succumb to the fungus to keep its allied parasitic wasps, or fend for themselves under the attack of pests.
  Set traps
  if we can lure the enemy into a trap carefully arranged, why the use of arms? The molecules of cruciferous plants store the harmless compound glucosinolates, separated from the glucosidase in the body by only a thin cell wall. When pests bite this barrier, the two substances will mix together and a chemical reaction will occur, producing toxic gases to enclose the pests. It is this reaction that makes cruciferous plants have a special bitter taste and antioxidant properties.
  Only when these traps work, plants will use resources to promote this defense. When biting pests such as caterpillars activate the trap, the devastating consequences will stimulate plants to accelerate the production of glucosinolates. However, when aphid-like sucking pests suck plant juice through needle-like mouthparts, they will not trigger the trap. In this case, plants will not use their own resources to make weapons.
  Espionage
  Some plants already know the “code” used by enemies to communicate with each other, and can make good use of it to send false information. For example, when aphids are attacked, they will release the pheromone β-farnesene to warn nearby aphids of danger and run away. Plants often release β-farnesene when they are attacked by aphids in an attempt to imitate the alarm and scare them away. However, not all β-farnesene will work.
  In most cases, plants will release pheromone at a uniform rate as a chemical weapon, but aphids have adapted and are not affected by this. However, wild potatoes can change this pattern to make it more effective: it stores pheromone at the end of the tiny hairs on the leaf. When the aphid falls on the leaf, its feet will be stuck to the sticky leaf surface; when the aphid struggles hard, the end of the leaf villi will be destroyed and a large amount of pheromone will be released. This subtly mimics the rhythmic alarm of aphids.
  Emergency self-help
  in the battle with the pests, the plants must wound care. The “green leaf volatiles” produced by plants can act as antibiotics to protect the injured tissues of plants from infection by bacteria and fungi, and at the same time inform surrounding plants. These volatiles are the “grass scent” we smell when we just trim the lawn.
  Traumatic acid (also known as “callus”) produced by injured plants can stimulate cells to accelerate division to close the wound. Its effect is equivalent to that of animal blood clotting in the wound. These reactions are produced within a few minutes after being attacked by pests. Plants must constantly allocate their own resources to balance self-defense and self-repair.
  Plants and insects have been fighting for generations, and the two sides constantly change their strategies in an effort to overwhelm the other. For example, insects have begun to evolve antidote against plant “chemical weapons”, they can neutralize toxins, and even use these toxins. Naturally, plants are not to be outdone and continue to create new weapons. The war between plants and insects is an arms race: both sides do their best to keep their territory.