Phytostimulator Microorganisms

Endophytic microorganisms are those capable of colonizing and residing in plant tissues without manifesting evident symptoms of disease. This classification is based on the location in which the individuals live, not the functions they perform. Interestingly, these microorganisms can cause disease loss or not in plants, although the process of entry and colonization of plant tissues is similar to an infectious process. Thus, it is suggested that there are infectious processes that do not necessarily harm the host. For example, the colonization of microorganisms on specific host plants results in metabolic changes, despite not causing disease. Colonization of plants by endophytic microorganisms is common and not an exception. Plant phenotypes are an extension of the phenotypes of microorganisms that colonize plant tissues. These microorganisms are ubiquitous and can colonize different plant tissues, such as roots, stems, leaves, fruits, and seeds. Endophytic colonization has several effects, including plasticity, which is the response of plants to environmental conditions controlled by the expression of microbial and plant genes. Endophytic microorganisms provide several benefits to host plants, including the production of phytohormonesPhytohormones such as indole-3-acetic acid, gibberellin, cytokinins, salicylic acid, jasmonic acid, and abscisic acid. The relationship between plant-associated bacteria and the growth, development, and architecture of the roots and shoots of plants is vital due to the production of these phytohormonesPhytohormones, which act as messengers in metabolic pathways in plants. Plant colonization by endophytic microorganisms has a significant impact on host plants, influencing growth, development, root architecture, and aerial parts. The production of phytohormonesPhytohormones by endophytic bacteria plays a crucial role in these effects, contributing to responses to environmental stresses and plant-microorganism interactions. The present chapter will address the key aspects related to microorganism phytohormonePhytohormones producers and their effects on plant growth. In addition, these microorganisms can be used for sustainable production, thereby reducing costs and environmental impact.