Benefits Associated with the Interaction of Endophytic Bacteria and Plants

ABSTRACT The endophytic bacteria belong to a larger group of microorganisms that have their life-cycle partly or entirely inside the plant and are located in intra and inter-cellular spaces or in the vascular tissue. These bacteria can be found colonizing aerial parts or roots. This review aims to analyze the colonization strategies of endophytic bacteria through interaction with plants, as well as to highlight the metabolic influence of these organisms in plant tissues, which result in physiological and biochemical changes. Depending on the different mechanisms used internally to colonize a plant, these microorganisms are called obligate, facultative, or passive endophytes. Phytostimulation, biofertilization and biological control are mechanisms that result in the development of the plant through the production of plant hormones, bioavailability of nutrients and antagonistic action to phytopathogens, respectively. The association between endophytic bacteria and plants features important benefits such as significant increases in growth, plant biomass, length of roots, dry matter production, and grain yield. Studies show that there is a great diversity of endophytic bacteria colonizing plant structures that result in several benefits to the host plant.

Biodegradação dos herbicidas imazetapir e imazapique em solo rizosférico de seis espécies vegetais / Biodegradation of the herbicides imazethapyr and imazapic in rhizosphere soil of six plant species

A fitoestimulação é uma das técnicas de fitorremediação que pode ser utilizada para a redução da concentração dos herbicidas no solo. Para tanto é necessário a seleção de plantas que estimulem a atividade dos microrganismos degradadores da rizosfera. O objetivo deste trabalho foi avaliar a biodegradação de cinco doses do herbicida composto pela mistura formulada de imazetapir+imazapique (75 + 25 g e.a. L-1) em solo rizosférico proveniente de seis espécies vegetais com potencial para a fitoestimulação. A biodegradação do herbicida nas doses de 0, 250, 500, 1.000 e 4.000mL ha-1 no solo rizosférico de Canavalia ensiformis, Glycine max, Lolium multiflorum, Lotus corniculatus, Stizolobium aterrimum, Vicia sativa e no solo sem cultivo foi avaliada através da quantificação da produção de C-CO2 do solo e da degradação do herbicida no solo por cromatografia líquida acoplada à espectrometria de massa. A produção de C-CO2 do solo após a contaminação com a mistura de imazetapir+imazapique foi maior nos solos rizosféricos das seis espécies vegetais se comparado ao solo não cultivado. O solo rizosférico de Stizolobium aterrimum apresentou a maior degradação do herbicida imazetapir nas maiores doses avaliadas, sendo uma espécie promissora para a fitoestimulação.

Phytostimulation is a technique of phytoremediation that can be used to reduce the concentration of herbicides in the soil. It is necessary to select plants that stimulate the activity of the rizosphere degrading microorganism. The aim of this study was to evaluate the activity of the biodegradation of the herbicide compound formulated mixture of imazethapyr + imazapic (75 + and 25 g L-1) in rhizosphere soil from six plant species with potential for phytostimulation. Biodegradation of the herbicide in the rhizosphere soil of Canavalia ensiformis, Glycine max, Lolium multiflorum, Lotus corniculatus, Stizolobium aterrimum and Vicia sativa, and a control (soil without plant) was evaluated at doses of 0, 250, 500, 1.000 and 4.000mL 1 ha, by quantifying the production of C-CO2 of the soil and the degradation of the herbicide from the soil by liquid chromatography coupled to mass spectrometry. The production of C-CO2 of the soil after the contamination with the mixture imazethapyr + imazapic was higher in the rhizosphere soil of the six plant species when compared to soil not cultivated. The rhizospheric soil from Stizolobium aterrimum shouwed the highest degradation of the herbicide imazetapyr on the highest doses evaluated, being a promising specie for phytostimulation.