The Chemotaxis Of Arbuscular Mycorrhizal To Rhizobia

Arbusular mycorrhizal (AM) fungi are obligately biotrophic organisms. About 80% of plants from all phyla of land plants are hosts of AM fungi. AM fungi improve plant growth through their ability to increase plant uptake of P and other nutrients.AM fungal spore germination and length of germ tube were affected by minerals, pH,temperature, humidity, photoperiod and secretory products of host roots. The symbiosis formed by arbuscular mycorrhizal fungi, rhizobia and legumes is a special association in plant-microbe symbiosis. The developmental switches in the AM fungi and rhizobia are triggered by signals secreted from host, AM fungi and rhizobia which induce changes in differential hyphal branching, appressorium formation, root colonization , arbuscular development and the form of root nodule. During the process of direct or indirect action, the chemotaxis that is known as the first step of symbiosis between host and rhizobia is a dominance for rhizobia.In this paper, through the study on Amorpha fruticosa in different treatment, include non-innoculation (AM-+Rh-), mon-innoculation AM fungi (AM+), mon-innoculation rizobia (Rh+), and dipl-innoculation (AM++Rh+), the effect of height of plant, length of root and fresh weight induced by AM fungi and rhizobia were tested, the infection sequence of rhizobia and the infection rates of AM under different treatments and the chemotaxis between Apigenin and rhizobia, AM fungi and Rhizobia had been determined. The results suggested that the height of plant, length of root and fresh weight under AM++Rh+ are better than AM+ are. The infection of rhizobia under AM++Rh+ is more quickly than AM+ is. The infection rate of AM fungi under AM++Rh+ is higher than AM+ is. The chemotaxis between Apigenin and rhizobia under the inoculation conditions of AM-+Rh-, AM+ and AM++Rh+ in 25℃,28℃,31℃showed that there exsited negative chemotaxis. There were some signals between AMF and rhizobia and there exsited auxoaction in coordination during the formation of symbiosis. The chemotaxis between the root-exudates and rhizobia under the inoculation conditions of AM-+Rh-, AM+ and AM++Rh+ in 25℃,28℃,31℃showed that the surrounding conditions (temperature) in rhizosphere have some effects on the regulation of incipient identification signals in the tri-symbiosis of AMF-host- rhizobia.