**1. Introduction**

Given the ongoing increase in the world's population and the depletion of food resources, our society currently needs a sustainable supply of agricultural productivity that poses no environmental risks [1]. Plants are constantly affected by abiotic stresses, such as drought, salinity, cold, heat, and nutrient deficiencies, as well as biotic stress, including pathogens and pests. In addition to climatic changes that greatly affect soil fertility, virulence of pests and diseases, and plant-producing biomass and seeds [2]. In nature, the interaction continues between biotic stress and plants, causing dynamic changes in their activities and composition under changing environmental conditions. Beneficial microorganisms play an effective role in maintaining the balance of this interaction in a way that is in the interest of the plant at the expense of biotic stress. Furthermore, plants can more effectively withstand abiotic stress, enhance nutrient uptake and utilization, and increase photosynthetic activity by virtue of the mechanisms carried out by beneficial microorganisms, which leads to higher yield [3].

 Beneficial microorganisms can act as biopesticides by attacking phytopathogens directly and limiting their population by competition for space, nutrients, and the production of antimicrobial compounds [ 4 ]. Furthermore, beneficial microorganisms can induce plants to pre-activate the defensive responses controlled by plant hormones in order to combat infections more rapidly and successfully. This is referred to as systemic acquired resistance [ 5 ]. Among beneficial microorganisms are cyanobacteria. Cyanobacteria are photosynthetic prokaryotic organisms, extremely varied groups that can be found in practically all of the world's ecosystems.

 Cyanobacteria occur in unicellular, colonial, or multicellular filamentous forms. They are considered a subset of the bacterial kingdom. This subset is responsible for a significant amount of N 2 fixation, reduction of the level of CO 2 , solubilization of phosphate, and the production of plant growth regulators by releasing phytohormones, polypeptides, amino acids, polysaccharides, and siderophores [ 6 ]. Cyanobacteria are composed of numerous organic inclusion units capable of carrying out a wide range of specialized functions, which give cyanobacteria their unique tasks and applications in sustainable agriculture [ 7 ]. The components that make up the structure of cyanobacteria are light-harvesting antennae, phycobilisomes, polyphosphate bodies, cyanophycin granules, polyhydroxyalkanoate granules, carboxysomes, lipid bodies, thylakoids, DNA-containing areas, and ribosomes [ 8 ] ( **Figure 1** ) . Cyanobacteria have chlorophylla, which engages it in oxygenic photosynthesis, carotenoids that protect chlorophyll-a from oxidative degradation, and specific pigments called phycobilins that are bound to water-soluble proteins [ 9 ]. Flagella are not present in cyanobacteria [ 10 ].

 Some kinds of cyanobacteria contain specialized cells called heterocytes and akinetes that are morphologically distinct from vegetative cells. The position, amount, and distribution of heterocytes and akinetes are significant morphological characteristics of cyanobacteria species and genera. Heterocytes are specialized cells that allow nitrogenase to fix atmospheric nitrogen by reducing it to ammonium, a process known as diazotrophy [ 11 ]. Akinetes contain granules of glycogen and cyanophycin but no polyphosphate granules and have a multilayered cell wall [ 9 ].
