Arbuscular mycorrhizal fungus spores host bacteria and their biofilm efficient in nutrient biodynamics and soil-borne plant pathogen suppression

Abstract

AbstractThe combination of bacteria and arbuscular mycorrhizal fungi (AMF) would be ideal for nutrient biodvnamics in soils and protection from soil-borne plant pathogens (SBPP). During the process of plant colonization AMF interact with bacteria where spores cytoplasm and hvphae provide specific niches for certain populations of bacteria. The clarification of the relationship AMF-bacteria has great potential for sustainable agriculture. The currently research aimed to isolate and characterize bacteria. Which we have designated most probable endobacteria (MPE) from an AMF spore. Three bacterial strains were taken from about 500 spores by using a 200 &x00B5;m diameter hvpodermic needle. These bacteria were identified by DNA and morphological methods. Antagonism to SBPP (Pythium ultimum NBRC 100123, Fusarium oxyxporum f. sp. lactucae MAFF 744088, Rhizoctonia solani MAFF 237426 and Roselinia necatrix - isolated from a Japanese apricot (Prunus mume) by Dr. Norihiko Kobayashi), P solubilization, ethylene production, nitrogenase activity and stimulation of AMF hyphal growth were evaluated. Here we show that the bacteria strongly functioned on nutrient biodynamics (P solubilization and Nitrogenase activity), ethylene production, protection from SBPP and stimulation of AMF hyphal growth. In addition, fresh samples of spores and hyphae were observed and photographed with a new type of scanning electronic microscope (SEM) (FEI Co., Quanta 250FEG), where the hyphae and spores with bacterial slime could be detected. Our results demonstrated the importance of bacteria associated to AMF for the soil ecology having a substantial mpact on sustainability. More specifically, the methods of extraction by ultra-thin needle reveled species associated to AMF, probably from inside spores. Moreover, the observation of bacterial biofilm showed a physical structure that the bacteria could form surround spores and hyphae to help AMF.