Promoção de crescimento vegetal por rizobactérias: uma revisão

Abstract

In view of the concern with environmental preservation, due to the observation that human activities can cause profound impacts, research work has led to a change from so-called conventional agriculture, which uses agrochemical products and fertilizers, to agriculture that seeks forms less harmful to the environment. Plant growth-promoting rhizobacteria (PGPR) are microorganisms that can live freely in the rhizosphere, formsymbiotic associations with plants and colonize the internal tissues of plants. Thesebacteria are known as they can enhance the growth of plants, especially the root system,which provides greater access and use of nutrients and water. Among the mechanismsresponsible for promoting plant growth by bacteria, the following are often involved: the production of indoleacetic acid - IAA through the enzyme indolepyruvatedecarboxylase in the presence of the amino acid tryptophan, where its main effect is topromote the growth of roots and stems, through the elongation of newly formed cells inthe meristems. Another mechanism is the solubilization of phosphate, through the action of organic acids and phosphatases, facilitating the conversion of insoluble forms into soluble ones, making this nutrient available to plants, being of fundamental importance due to it being the second limiting mineral for plant growth, as well as the production of diffusible antibiotics and lytic enzymes such as chitinases, providing efficient biological control of phytopathogens in nature. The objective of this review was to collect available information on the role of rhizobacteria in promoting plant growth. Bibliographical research of articles was carried out, using digital scientific databases, using key words such as: inorganic phosphate; exopolysaccharide, inoculants, biofilms, phytohormones, water stress and growth induction. At the end of reading the abstracts, the most relevant and current articles were chosen, thus fulfilling the proposed objective.