When a plant is infected by a pathogen, what are the plant s own resistance measures?

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 such as lignin in plants.

Callose, plant protection, etc. can protect plants from pathogenic bacteria infection, these substances can limit the spread of pathogenic bacteria, such as callosum, some have certain antibacterial activity. At the same time with salicylic acid.

The signaling pathways represented by the pathway and the jasmonic acid pathway can make the whole plant and the surrounding plants resistant and release chemicals for self-protection. A set of immune systems is present in plants.

Infection of pathogenic bacteria can be perceived. 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 intracellular R gene-dominated recognition pattern, in which pathogenic bacteria release effectors to evade or blind PTI responses to enhance pathogenicity, which are then recognized by the protein encoded by the R gene to stimulate the plant's immune response.

i.e. ETI reaction. 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.

Most fruits have a waxy layer on the surface, and the fruit is metabolized with the parent body at all times before it is picked. There are also probiotics inside the fruit.

If you cut off contact with the mother, you will spontaneously secrete a lot of abscisic acid.

Hormones promote the oxidative breakdown of fruits and provide energy for seed germination. <>

Plants have innate basic resistance to diseases, including physical, such as waxy layer, cuticle, and lignification of orifices, etc., as well as chemical, mainly broad-spectrum bactericidal substances, phenols, saponins, unsaturated lactones, and so on. These reactions have a resistant effect to all pathogenic factors. In addition, plants have evolved pathogen-mediated resistance, which is also divided into physical and chemical aspects.

Physical ones include lignification, corkification, delamination, and cell wall sedimentation, vascular bundle occlusion. Chemistry includes programmed cell death, burst of reactive oxygen species, phytoprotection, disease-related proteins, and detoxification of pathogens. <>

Fundamental factors: host plant, pathogens, environmental conditions.

Environmental conditions affect the resistance of host plants to pathogens by affecting the growth and development of host plants, and at the same time, the environment affects the pathogenicity of pathogens to host plants by affecting the growth and development of pathogens.

Plant diseases can only occur if the environmental conditions are favorable to the pathogen and not to the host plant. The pathogens have pathogenic effects on the host plant. The host plant is resistant to disease by instinctively resisting the infection of pathogens.

Plant pathogens (fungi, bacteria, viruses) are pathogens, and as long as the temperature and humidity are suitable, the pathogens will be transmitted to the plants through wind or insects.

！What are the basic causes of plant diseases, and how do these factors cause plant diseases?

The infection cycle generally includes the following links:

a) Primary infection and reinfection.

The concept of primary infection: the first infection after overwintering, after the plant begins to grow and develop, is called primary infection.

The concept of re-infestation: In the same growing season, each infestation that occurs after the initial infestation is called re-infestation.

The concept of single-course disease: In a growing season of a plant, there is only one infection process of the disease, which is called a single-course disease.

The concept of multi-course disease: In a growing season of a plant, there are multiple infection processes of the disease, which is called multi-course disease.

Note: 1 There is a close relationship between the incubation period and re-infection of plant diseases. The incubation period of the disease is short, and there is more chance of re-infection. Environmental conditions are conducive to the occurrence of diseases and shorten the incubation period, which can increase the number of re-infections.

2. For diseases with re-infection, in addition to removing the overwintering pathogens, it is an effective prevention and control measure to eradicate the disease center in time and eliminate the source of re-infection.

b) Overwintering of pathogens.

The main overwintering sites of pathogens are as follows:

1.Seedlings and other propagation material, 2Diseased plants, 3Diseased plant remains, 4Soil fertilizer.

Note: The pathogen is dormant during the overwintering period, which is the weakest link in its infection cycle, and the latent breeding site is relatively fixed and concentrated, and the overwintering place of the pathogen is identified to control or eliminate, which is a powerful measure to take the initiative in the prevention and control of plant diseases.

iii) Transmission of pathogens.

Plant diseases are transmitted in the following ways:

1.Airflow propagation, 2Rainwater propagation, 3Animal Transmission, 4Anthropogenic transmission.

It should be noted that the transmission of pathogens is the link between the various links in the infection cycle. With the help of dissemination, plant diseases can spread, spread and become prevalent.

The disease infection cycle refers to the entire process that occurs from the beginning of the previous growing season to the recurrence of a disease in the next growing season. In the whole infection cycle of the disease, the pathogen overwinters and summers, and through transmission, carries out the initial infection and re-infection, and then enters the dormant state, so that the disease can be reversed and continued in the field.

Summary. The bacteria that can infect plants and cause diseases are mainly from Pseudomonas, Xanthomonas, Agrobacterium, Corynebacterium, Owenella and Mycoplasma.

1. Which plant pathogens infect the plant body in an active invasion manner.

1. Plant pathogenic fungi.

2 Bacterial diseases of plants.

3 Viral diseases of plants.

Fungi are the main plant pathogenic microorganisms, and many fungi can cause plant diseases.

The main branches of bacteria that can infect plants and cause diseases are Pseudomonas, Xanthomonas susceptibility, Agrobacterium, Corynebacterium, Eurbridge, and Clamplasma.

There are 300 viruses known to cause plant diseases

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.

In addition to the fixed products of growth, plants also present (), which is used to defend against pests. +a direct defense + b indirect defense.

In addition to the fixed products of growth, plants also store and wither in indirect defense, which is used to defend against pests in the dust cave. 1.Physical Defense:

For example, the mesophyll cells have crystals, the leaf surface has hairs or thorns or hooks, and the stems have thorns; 2.Chemical defense: secondary metabolites, such as plant phenols, various toxic substances, and some substances that are not easily digested and utilized (lignin, wax, cellulose, etc.); 3.

Behavioral defenses: such as a decrease in the water content and nitrogen content of the plant body.

The ways in which ectomycorrhizae resist disease are multifaceted.

The main ones are the blocking effect of ectomycorrhizal fungi, the protective effect of the micro-beating biological community around mycorrhizae, and the production of secondary metabolites by mycorrhizal fungi.

In nature, the roots of healthy plants are colonized by a complex microbial community of bacteria and filamentous eukaryotes (i.e., fungi and oomycetes), the composition of which has a profound impact on plant health. Maintaining the microbial balance in the roots is very important for plants to stay healthy, however, the way plants achieve this is still largely unknown.