When mimosa is touched, the unfolded leaves will close, and this organism has a regular response to external stimuli, which is stressful, and the stress can also make the organism "seek benefits and avoid harm", which is a manifestation of the organism's adaptation to the environment.
All living things tend to benefit and avoid harm, but in different ways.
For plants, it naturally cannot achieve profit and avoid harm by staying away or avoiding them like animals, but it has also evolved its own complex and fine regulatory mechanisms.
In fact, seeking advantage and avoiding harm is a very broad concept, what is profit? What is harmful? Is the stakes only in the external environment? How are the stakes measured? Sometimes it seems to be a harm, but it is actually for the greater "benefit", which contains quite complex biological mechanisms.
The mimosa response is a more classic model, in fact, we can use different examples to get a rough idea of what kind of beneficial and harm-avoiding behaviors plants can do in different situations.
First, the carbon and nitrogen imbalance, how can plants seek benefits and avoid harms?
What is carbon and nitrogen balance? The aboveground part of the plant forms an overall coordination and balance through the process of photosynthesis fixing the carbon source and the underground part of the soil to obtain nutrients represented by nitrogen elements, and ultimately maintain the growth and development of the plant.
If there is an imbalance between carbon and nitrogen, such as less carbon and nitrogen, if it is an animal, it can move to a place where there is carbon and nitrogen, and "eat some carbon" or "eat some nitrogen" can restore balance. This is a figurative statement, and plants certainly can't do that.
Plants need to coordinate the exchange of information between the aboveground leaves and the underground roots, such as more carbon, less nitrogen, then the root system needs to work more.
At present, humans have discovered that light plays an important role in this. Light energy promotes the corresponding aboveground and underground root system to grow together, because the root system can not see light in the soil, so it is necessary to transmit some systematic signal from the aboveground part of the plant over a long distance to transmit the optical signal.
After a series of experiments, the researchers found that the LONG HYPOCOTYL 5 (HY5) gene is a key part of this.
The HY5 gene encodes the bZIP transcription factor protein, which remains stablely active when the leaves see light, and once it enters darkness, the protein is passivated and degraded. Under light conditions, the HY5 protein in leaves can be moved from mesophyll cells over long distances through the microtubule system to the roots, completing a series of reactions that ultimately maintain the overall carbon and nitrogen balance of the plant.
In this way, plants can adapt well to environmental changes, achieve profit and avoid harm, and maintain their normal growth and development.
Second, plants tend to benefit and avoid harm to ammonium
Plants have different components, so for different structures, they also have their own ways of seeking benefits and avoiding harms.
For example, the root system, which is the main place for the exchange of substances between plants and the outside world, that is, soil. In particular, the root crown, as the top of the root system, on the one hand, bears the responsibility of protecting the root tip, on the other hand, it also needs to perceive external signals and guide the root system to complete the pursuit of benefits and avoid harm.
Taking Arabidopsis thaliana as an example, if the roots are in a state of high ammonium, then the inhibitory effect on the lateral roots of Arabidopsis thaliana is mainly to inhibit its elongation. This inhibition is a local inhibition effect produced directly by ammonium through the root tip rather than the overall inhibition effect. Plant bodies can regulate nitrogen and carbon distribution in the body, for example, to promote the growth of roots in other non-toxic areas, ensuring normal growth of aboveground parts. This is also a kind of plant growth mode that seeks advantages and avoids harm, and it is formed by the long-term evolution of plants actively adapting to the stressed environment.
Third, how do plants from the source of honey powder seek benefits and avoid harms?
For honey powder source plants, natural enemies of insects are an unavoidable topic.
Predator insects supplement nutrition by eating pollen, nectar, etc., which has many ecological significance, such as promoting sexual maturity and prolonging life.
There are many factors that affect the nutritional supplementation behavior of natural enemy insects, which are divided into internal and external factors. From the perspective of external factors, since most predator insects have short mouthparts, the structure of flowers will have a great impact.
According to studies, both potato beetle egg oligosic wasps and ladybird stalk-bellied wasps cannot feed on nectar from cup-shaped and tubular flowers due to their head widths greater than the flower aperture, but both can eat nectar from flowers exposed to the outside. This is also a way to settle down with the evolutionary relationship and avoid the benefits and avoid the disadvantages.
Among the many plants that seek advantage and avoid harm, some mechanisms are explained, and some need to be further elaborated.