in some cases they assist penetration, in other cases they have an attack function,

in others they are real determinants of pathogenicity.

After initial contact, the pathogen produces enzymes that serve to dissolve these

components to continue its penetration. In addition to these enzymes, it has ability to create

toxins that kill cells and reduce their response and reactivity, which are needed

especially to necrotrophs to kill cells for their nutrition. In some soft rots

we will have bacteria that produce peptoglycid enzymes, which dissolve the peptic lamella that holds

the cells together.

Lytic enzymes

They come into play in the degradation of the apoplast: cuticle, cell wall and lamella

median are the main barriers to the advance of pathogens towards the symplast. The names of the

enzymes have the suffix -ase preceded by the substrate they degrade.

EPICUTICULAR WAXES: in granular or rod form, generally penetrated thanks to

mechanical effort;

CUTIN: (long-chain fatty acids, intersected with each other linked by ester bonds, 16/18 atoms

of C) major component of the cuticle, infiltrated with waxes towards the outside, with pectin and

cellulose inwards; polyester of long-chain fatty acids (C16-C18) linked together by

foreign bonds;

CUTINASE: enzymes that degrade cutin

67)What function do lytic enzymes perform in the infectious process?

Lytic enzymes play a key role in the infectious process of some organisms, in

especially bacteria and viruses. These enzymes are capable of destroying or weakening the walls

cells of the host organisms, thus allowing them to penetrate inside the host cells

or to escape from the infected cell. Lytic enzymes are critical tools used by

infectious organisms to overcome protective barriers of host cells in the process

infectious, thus facilitating their spread and replication. Fungi and oomycetes, to penetrate the

wall, degrade pectins with pectinolytic enzymes; mushrooms are able to modify the pH

of the tissue to promote the action of lytic enzymes, for example through the secretion of acids

organic to lower the pH or the release of ammonia to raise the pH.

One of the best-known examples of fungi that use lytic enzymes to penetrate the apoplast of

plants is the genus of phytopathogenic fungi called Colletotrichum. These mushrooms are

responsible for diseases commonly known as anthracosis, which affect a wide range

of plants, including trees, shrubs and agricultural crops. The Colletotrichum infection process

involves the production of lytic enzymes, such as pectinases,cellularases and proteases, which act on

plant cell wall and allow the fungus to penetrate the apoplast. The apoplast is the

extracellular space between plant cell walls and plays an important role in

intercellular communication, nutrient transport and response to infections. Lytic enzymes

produced by Colletotrichum act on the degradation of the wall components

cell of the plant, such as pectin and cellulose, thus facilitating the entry of the fungus into the

plant cells. Once inside plant cells, the fungus can cause damage,

multiply and spread through plant tissue.

Lytic enzymes

They come into play in the degradation of the apoplast: cuticle, cell wall and lamella

median are the main barriers to the advance of pathogens towards the symplast. The names of the

enzymes have the suffix -ase preceded by the substrate they degrade.

68)What types of lytic enzymes important in the infectious process do you know?

In phytoinfectious processes, several lytic enzymes play a key role in allowing the

pathogens to penetrate the defensive barriers of plants. Some of the important lytic enzymes


1. Pectinases: These enzymes are responsible for the degradation of pectin, a

main component of the plant cell wall. Pectinase makes the wall

cell less cohesive, thus facilitating the penetration of the pathogen.

2. Cellulase: Cellulase enzymes act on cellulose, which is an important component

of plant cell walls. Their action weakens the cell wall, allowing

for the pathogen to penetrate more easily.

3. Hemolysins: Some pathogens produce hemolysins, enzymes that destroy membranes

cells, facilitating the lysis of host cells and the release of the pathogen.

4. Proteases: Proteolytic enzymes degrade proteins present in cell walls and moles

plant tissues. This action favors the penetration of the pathogen through the

cell wall.

5. Glycosylidases: These enzymes act on the degradation of sugars bound to proteins and

to cell membranes, facilitating the passage of the pathogen through barriers

sugars of plant cells.

6. Lipases: Some pathogens produce lipases, which degrade lipids present in membranes

mobile phones. This can help weaken the membranes and promote entry of the


69)What is the substrate of pectolytic enzymes and which pathogens produce them?

Pectolytic enzymes act on pectin, a component of the plant cell wall. There

pectin is a complex substance made up of polymer chains of galacturonic acids.

This polysaccharide is present in the cell wall of plants and plays a key role

in the structure and cohesion of the cell wall.

Pathogens that produce pectolytic enzymes are often associated with plant diseases, in

particularly to diseases involving cell wall degradation. One of the kinds of

Pathogens known to produce pectolytic enzymes is Erwinia, a genus of bacteria

phytopathogens. For example, Erwinia carotovora and Erwinia chrysanthemi are two species of

disease-associated bacteria that cause pectin degradation in host plants.

These bacteria can cause diseases such as “soft rot” in which the plant tissue

it is decomposed due to the action of enzymes, including pectolytic ones. This process of

decomposition of the cell wall facilitates the penetration of the pathogen and the subsequent one

development of the infection.

It is important to note that even some phytopathogenic fungi, such as those of the genus

Colletotrichum mentioned above, can produce pectolytic enzymes as part

of their enzymatic arsenal to weaken the plant cell wall and facilitate

the infection.

PECTIC SUBSTANCES: major components of the median lamella, they constitute the

“intercellular cement” that holds cells together to form tissues; they also form part

of the primary wall; they are chains of galacturonan + side chains of


Pectolytic enzymes (pectinases): of different types depending on the direction they catalyze;

The substrate of these enzymes are pectic substances

very important in soft rot;

present in the median lamella, and which are produced for example by Pectobacterium ssp.,

but also by some types of mushrooms. They are very important in soft rots and come

used by the genus Erwinia spp which causes tissue maceration and liquefaction.

70) How can the production of pectolytic enzymes by a bacterium be evaluated


The evaluation of the production of pectolytic enzymes by a phytopathogenic bacterium can

be carried out using various laboratory techniques. Here are some of the methodologies


1. Enzyme activity: Direct measurement of enzyme activity can be

performed using specific pectin substrates and monitoring the rate of

degradation. This analysis may involve the quantification of the products of

degradation of pectin or the use of colorimetric indicators.

2. Zone of degradation on culture media: The phytopathogenic bacteria they produce

Pectolytic enzymes can create zones of pectin degradation on culture media

containing pectin as substrate. These areas can be highlighted via

the addition of specific reagents or through staining techniques.

3. Gel analysis: Gel electrophoresis can be used to separate and visualize the

pectolytic enzymes produced by the bacterium. In this case, the presence and activity of

Enzymes can be detected using zymograms, which are gels containing pectin

where electrophoresis is performed.

4. PCR and genetic analysis: Analysis at the genetic level can be used for

identify the genes involved in the production of pectolytic enzymes. The presence of specific

genes or gene clusters associated with such enzymes can be confirmed using the

polymerase chain reaction (PCR) technique or other analytical techniques


5. Infection experiments on plants: Evaluation of the aggressiveness of the bacterium

phytopathogen on host plants can provide clues to the production of pectolytic enzymes.

Observation of specific symptoms, such as necrosis and tissue degradation, can

be related to the activity of these enzymes.

Using a combination of these techniques can provide a comprehensive assessment of

production of pectolytic enzymes by a phytopathogenic bacterium.

71) Does lignin represent an easily or difficultly degradable substrate?

Lignin represents a difficult-to-degrade substrate. Lignin is a component

fundamental part of plant cell walls and plays a key role in the provision of

rigidity and mechanical resistance to plants. It consists of a three-dimensional matrix

complex of phenolic polymers. Its degradation requires the coordinated action of enzymes

ligninolytics, known as lignases or ligninase peroxidases, which can break chemical bonds

complexes present in lignin.

Lignin-degrading enzymes are mainly produced by soil bacteria, fungi

decomposers and other organisms specialized in the degradation of organic matter

complex. However, lignin degradation is a relatively slow process and

complex due to its robust and resistant chemical structure. This is important to point out

that lignin degradation is not typical of many disease-causing phytopathogens in plants

plant. Indeed, many pathogens avoid and prefer complete degradation of lignin

focus on the breakdown of other cell wall components, such as cellulose and

hematocellulose, to access