What are the main ways of plant disease resistance and defense?

The structure represented by the waxy layer on the surface of plant leaves can effectively prevent the colonization and infection of some pathogenic bacteria. This is the first defense that plants have evolved.

Secondary metabolites in plants, such as lignin, callosum, and plant protection, can protect plants from pathogenic bacteria, and these substances can limit the spread of pathogenic bacteria, such as callosum, and some have certain antibacterial activity. At the same time, the signal propagation pathways represented by the salicylic acid pathway and the jasmonic acid pathway can make the whole plant and the surrounding plants resistant and release chemicals for self-protection.

There is an immune system in the plant that can sense the infection of pathogenic bacteria. At present, it is mainly believed that there are two sets of models, one is the pathogen-related molecular model, i.e., the PAMP mode, in which the funnier induces plant immunity, that is, the PTI response; The other is the recognition mode dominated by the R gene in the cell, in which the pathogen releases effectors to avoid or blind the PTI response to enhance pathogenicity, and then is recognized by the protein encoded by the R gene to stimulate the plant's immune response, that is, the ETI response.

In the soil of plant roots, there are microbial communities, which have a symbiotic relationship with plants, and they also have a certain inhibitory effect on the infection of pathogenic bacteria. In addition, some plants have endophytes in their bodies, and these endophytes may also have a positive effect on the plant's disease resistance and defense response.

Answer]: Resistance to expansion Resistance to reinfection (to acquire disease resistance).

Analysis: Plant disease resistance refers to a kind of heritable characteristics of plants to avoid, terminate or block the invasion and expansion of pathogens, and reduce the degree of disease and loss. According to the different mechanisms of disease resistance of hand-modified host plants, they can be divided into passive disease resistance and active disease resistance.

It mainly includes the following categories: Disease avoidance, the susceptible site of the host plant avoids the large-scale invasion of pathogen carriers in space or time due to morphology, function or phenology, etc., resulting in disease avoidance; Anti-invasion, when the same amount of inoculum is exposed to the surface of the plant susceptible under the same inoculation conditions, if the number of disease sites on a certain variety is significantly less than that of other varieties, it is anti-invasion; Anti-propagation refers to the host's response to the pathogen after the pathogen invades, which is ultimately manifested as the length of the incubation period, the number of lesions, the size of the lesions, the speed of the expansion and dispersion of the lesions, and the amount of spores produced by the pathogen. Anti-damage (disease resistance), that is, although the host plant cannot inhibit or resist the invasion, expansion and reproduction of pathogens, it can resist the damage caused by pathogens to products through various physiological regulation and compensatory effects; Resistance to reinfection (to acquire disease resistance), that is, the disease resistance of plants after being pre-inoculated by various organisms or treated with chemical and physical factors.

Planting disease-resistant varieties can fundamentally solve the problem, and attention should be paid to practical problems, economic problems, ecological and environmental problems, etc.

Planting disease-resistant varieties can fundamentally solve the problem, avoid pests and viruses, and planting disease-resistant varieties is the basis of control strategies. Attention should be paid to practical problems, economic problems, ecological and environmental problems, etc., different land, different environments, the actual problems are not the same, the methods of prevention and control are also different, the prevention and control is necessary to consider economic problems, if the cost is too high, there is no need to continue.

It is of great practical significance to strengthen the research on crop disease-resistant varieties and select excellent disease-resistant varieties suitable for large-scale promotion and application, so as to improve the quantity and quality of production buckets, reduce the use of pesticides, and protect the ecological environment.

In the use of pesticides to prevent and control diseases, insects, weeds, to get the best possible control effect, but also to consider the prevention or reduction of pesticides, but also to consider the safety of people and animals, the author of this aspect of the technical key to make the following introduction. Prescribing the right medicine is the key to achieving good prevention and treatment results. Otherwise, not only the effect is poor, but also the pesticides will be wasted, the time for prevention and control will be delayed, and the loss of agricultural production will be caused.

The first thing to do is to understand whether it is a disease or a pest in the field, and what kind of disease or insect it is. Then understand the ingredients, characteristics, and uses of the purchased pesticides. For example, it is insect repellent to remove the state, Ruijinte, Lesben, avermectin, etc.; carbendazim, methyl tobuzin, fenrustin, etc. are disease prevention; In addition to saxin, acetochlor, high-efficiency cover grass energy, grass shu, Roundup and so on are weedicidal.

The scope of prevention and treatment of the agent is limited, and there is no "panacea". For example, enemy killing can control a variety of pests on cotton, but it is ineffective against cotton red spiders. Efficient grass cover to control grasses and weeds has a good effect on Mai Niang, but it cannot prevent Wang Liang from being trapped and sensitive to broad-leaved weeds.

If the drug is used incorrectly, not only can it not achieve the expected control effect, but it will even cause greater harm than diseases, insects and weeds. Therefore, it is necessary to select the appropriate pesticides according to the control object, so as to give full play to the effectiveness of the agent itself.

China's agriculture has made great progress in recent years, and in the face of different degrees of diseases, insects and weeds, the rational use of chemical pesticides is an important means to ensure a bumper agricultural harvest. Pesticide in the control of pests and diseases plays an important role in the treatment measures, with the increase of pesticide types, the resistance is gradually prominent, in the application stage not only need to do a good job in biological control, but also in accordance with the requirements of the implementation of anti-fast high drug performance is manifested in the continuous application of a pesticide in a fixed area for many years, after a period of time to use such pesticides again, the control effect declines. In order to achieve the original application effect, it is necessary to increase the dosage and concentration of pesticides.

Causes of pesticide resistance: the selective evolution of pests themselves, China's agricultural development is gradually accelerating, the types of pests are increasing, and pests have changed to varying degrees in physiology or behavior with the application of pesticides, which is the primary factor for drug resistance. The evolution of pests has a direct impact on the rational application of pesticides, and if the resistance cannot be inhibited in response to changes in the environment, it will inevitably have an impact on the rational application of pesticides.

To improve immunity, insects need to adapt to environmental changes and continuously improve their own immune function and function. The application of pesticides has changed the characteristics of its physiological structure, continuously improved the application level of pesticides, and even reduced the absorption of pesticides. Measures:

Due to the ever-changing environment, it is necessary to pay attention to the immune effect and use drugs rationally according to the specific requirements of drug resistance. Considering genetic factors and morphological differences, it is necessary to evaluate the tolerance of pesticides and improve the ability to resist drugs. After exposure to a certain dose of the agent, the disease, insect and weed pests will be poisoned or have an inhibitory effect.

Measures: According to the tolerability effect and the specific changes in the resistance of the bacteria, it is necessary to make multiple selections and select pesticides according to the resistance of the agent.