Effects Of Herbicides And Fungicides On The Symbiotic System Of Arbuscular Mycorrhizal Fungi And Hairy Roots

Arbuscular mycorrhizal fungi(AMF) are a kind of living fungal microorganisms, which can form symbiotic associations with more than80%of land plants. These fungi have a series of important physiological and ecological function, such as promoting nutrient uptake and improving resistance of plants. Thus they have broad application prospects in bioremediation and eco-agriculture. In this paper, we studied several factors which effected on spore germination of G.e, established a strict in vitro dual cultivation system of Glomus etunicatum (G.e) and transferred Ri T-DNA carrot hairy roots, also we used the system and investigated the effects of herbicides and fungicides on G.e spores and symbiotic system. The main results are as follows:The effects of composition and pH of the medium, secretions of host plant roots and temperature on spore germination of G.e were studied. The most appropriate medium was the MSR medium, then the most suitable PH value was6.0in the four kinds of MSR, M, water agar and LB medium. The secretions of host plant roots promoted the spore germination and the4℃treatment significantly decreased the spore germination.A strict in vitro dual cultivation system associating the transferred Ri T-DNA carrot hairy roots with G.e was established. Sterile G.e spores were inoculated with the carrot hairy roots,45days later, a large number of mycelium and mature offspring spores were appeared in the medium, and we observed that G.e spores infected the carrot hairy roots through the method of trypan blue staining. The impacts of three herbicides including glyphosate, prometryn, acetochlor and three fungicides including chlorothalonil, carbendazim, thiram on spore germination and hyphal length of G.e were investigated in three different concentrations of0.1,1,10mg/L with a strict in vitro dual cultivation method. All treatments had detrimental effcects on spore germination and hyphal growth, The toxicity of herbicides on G.e spores were glyphosate, prometryn, acetochlor in turn and the toxicity of fungicides on G.e spores were chlorothalonil, carbendazim, thiram in turn. Moreover, fungicides appeared more toxic than herbicides on spore germination and hyphal elongation.All three herbicides and all three fungicides had harmful impacts on mycorrhizal colonization, daughter spore production, the proportion of hyphae with succinate dehydrogenase as well as alkaline phosphatases activity, generally they showed a downward trend with the increasing concentrations of six pesticides besides there was a positive correlation among the four. Furthermore, we confirmed that the AM symbiotic system had the ability to improve the biomass of carrot hairy roots, reduce the accumulation of malondialdehyde in the hairy roots, ease the lipid peroxidation of hairy roots, decrease the damage degree of host plants, and thus enhance the tolerance of plants in adverse conditions.