*2.3.1 Stimulating the systemic resistance of plants against plant pathogens by bio-agents*

The plant can resist a "pathogen" or several pathogens through structural or biochemical defenses that help the plant to inhibit the pathogen. The plant defense mechanisms are a result of the activity of the gense resistance genes responsible for plant defenses [47].

Many different biological factors have been used in the resistance of pathogens, especially viral pathogens [48]. The first knowledge of induced resistance was recorded in 1933 by Chester, and the first to use this term was Ross in 1961 who inoculated the lower leaf of tobacco plants sensitive to (TMV) Tobacco Mosaic Virus and this induced resistance in the upper leaves against TMV [49].

Induced resistance is the resistance that is based on the structural and chemical defenses that are induced after inoculation with an unsatisfactory or pathogen incompatible with the plant host, so this type of resistance develops systemically as a response to the presence and settlement of PGPR bacteria. This resistance shows specialization in stimulating resistance.

Induced Systemic Resistance (ISR), unlike Systemic Acquired Resistance (SAR), is not related to the expression genes of the pathogen-related proteins of the acquired resistance. The induced resistance is either local or systemic and the meaning of resistance. Localization is the resistance that occurs by entering the pathogen into the tissues of the plant and thus results in the production of phytotoxins, as well as the grouping of two lignins so that they lead to strengthening the walls of the cells and difficult to penetrate by the pathogen or because it leads to the death and destruction of plant cells and their dehydration, which is called the hypersensitivity reaction (HR), GM plants in which the CP protein coat accumulates from the tobacco mosaic virus TMV are resistant to infection with TMV.

Resistance by the CP gene has been demonstrated against CMVCMV, clover mosaic virus AMV, potato virus PVX, tobacco streak virus, and other viruses [50].

Many theories have been developed to explain the stimulation of plant growth and resistance by these factors, and the most common is the secretion of antibiotics and the production of compounds that compete with chemical elements needed by the pathogen in its development, as well as stimulating resistance genes with these materials and editing the work of the operator genes by disengaging them from the repressor protein molecule. It is reflected in the manufacture of anti-virus materials that may be proteins, including enzymes linked to the virus and that prevent the release of DNA [51, 52].

It was found that *Pseudomonas fluorescens* and *Rhizobacteria leguminosarum* induced systemic resistance in plants against BYMV [53] tested the possibility of stimulating pepper plant resistance against PMMOV.

Defensive gene products that include peroxidase enzyme (po) and polyphenol oxidase (ppo), which are concerned with the combination of lignin and phenaline ammonialase (pal) as they have an important role in the manufacture of phenols, phytotoxins and other defense enzymes that include pathogen-related proteins (pr), for example b1,3\_glucanases (pr2 family), chitinase and the lipase enzyme (pr3 family), which causes the decomposition of the fungal cell walls and thus the complete analysis of the cell when a fungal infection occurs that works to dissolve the lipoprotein envelope of the virus if the infection is an enveloped virus [54].

Several researchers have discussed the possibility of inducing cucumber and tomato plants to be resistant to CMV(CMV) as well as tomato mottle virus (TOMOV) using isolates from *P. fluorescence, P. putida* and *Bacillus pumils* [52]. The application of *P. fluorescence* induced SR in cucumber against CMV.

Phylum: Cyanobacteria Order: Spirulinalies Family: Spirulinaceae Genus: *Spirulina* Species: *Platensis*

*DOI: http://dx.doi.org/10.5772/intechopen.96587*

essential role to improve plant growth [69].

inhibit the multiplication of many viruses.

and mitigation of salinity damage.

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been mentioned [63].

Algae are ancient discovered organisms that date back to fossils about 305 billion years ago [62]. Its importance for health and the prevention of various diseases has

*The Activity of New Bio-Agent to Control* Cucumovirus Cucumber Mosaic Virus *(CMV)*

Spirulina is a bluish green algae that has a filamentous and spiral shape and its taxonomic position is unique because it combines Autorrphic [64], which is common in eukaryotic cells as well as bacteria and has high nutritional value, for example, vitamins B1, B2, and A [65]. The chemical composition is from proteins 55–70%, carbohydrates 15–25%, essential fatty acids 18%, minerals, vitamins, dyes, for example carotenoids and chlorophyll [60]. It was recently classified as one of the rare edible bacteria due to its low concentration of purine [66]. *S. platensis* is widely used as a nutritional supplement for human health, as well as animal feed, and its importance lies due to its high protein content of 60–70% and its high concentration of essential amino acids, fatty acids, minerals, vitamins and antioxidants [66, 67]. Blinkova et al. [68] showed that Sulfolipid extracted from *S. platensis* inhibits the activity of HIV and also consists of many amino acids and sugars and is considered essential compounds in addition to the micro and macro elements that have the

Blue-green algae are highly efficient in producing a wide range of antibiotics that have a direct effect in inhibiting the growth of pathogenic bacteria. The anti-bacterial effect of marine algae is not limited to bacteria but also has an anti-viral effect [70]. Green algae have a high efficiency to produce a group of antibiotics and have a direct effect in inhibiting the growth of pathogenic bacteria P.sp., which is resistant to antibiotics. It is also considered one of the most important organisms due to its wide range and bioactivity including: This effect on viruses is inhibitory [71]. The results obtained by Buter and Hunter [72] have supported the addition of extracts consisting of seaweed to improve the growth and productivity of the plant, and that the process of foliar spraying through these extracts has led to an increase in vegetative and productive growth and the reason is to provide essential nutrients that the root cannot provide. Mishima [73] showed that *S. platensis* has the ability to

Spenille and others [74] indicated that algae have significant effects as they increase the resistance of plants against disease, when added to the plant, and it is one of the most important organic sources used in plant production. The anti-effect of marine algae does not depend on the bacterium only, as it has an anti-viral effect [70]. Algae are important biological groups due to their wide range and biological effect, including the inhibitory effect against viruses [71]. The treatment of pepper plants with *S. platensis* had a positive effect in reducing the severity of ToMV mosaic

virus, by reducing the phenotypic symptoms, the activity of the peroxidase

enzyme, and the increase in leaf area, plant height, chlorophyll percentage, and dry weight of the shoots [75]. The United Nations Food and Agriculture Organization (FAO) as well as the independent governmental organization, www.iimsam.erg [76], recommended and emphasized the necessity of using SP as a basic and main tool to combat malnutrition in the world as well as to help achieve sustainable development. In India, some villages were working on the use of blue-green algae to improve the quality of saline soil in Samphar in Rajasthan, it is dried and used as fertilizer for crops such as wheat and barley. Gupta et al. [77] used some types of blue-green algae (*Arthrospira subsalsa & Spirulina Platensis*) with bio-fertilization
