Am Fungi Spores Germination And Construction Of Astragalua Sinicus L. Transformed Roots Dual Cultures With Am Fungi

Arbuscular mycorrhiza (AM) is widely distributed in nature, symbiotic associations with the roots of more than 80% of land plants, which facilitates plant mineral nutrient uptake and enhances tolerance of environmental stress and plant diseases. The fungi contribute to maintenance of plant diversity and ecosystem.Because of obligate biotroph, AM fungi are incapable of completing their life cycle without host roots. So in vitro culture of AM fungi is the key technology, focal point and hot spot for research, which we have explored for more than forty years.The aim of the present work is to evaluate effect of different medium, heavy metal and other environmental factors on spore germination, hyphal growth of AM fungi, and construct of Astragalua sinicus L. transformed roots dual cultures with AM fungi of Glomus intraradices, Gigaspora margarita, Gigaspora rosea. The dual culture system is an ideal method for the research on morphology, physiology, interaction of rhizospheric organism (PGPR, pathogenic bacteria, and edlworm), classification system of AM fungi, providing purified AM fungi material. With this system we can study signal recognition and symbiotic mechanism between AM fungi and leguminous plant. Also it provides some pretense for the construction of triple system of AM fungi- leguminous plant-rhizobia.The main results were as follows:Spores can germinate on the medium of water-agar, MSR, M, MS. The water-agar medium was the most feasible medium for spore germination. Heavy metal, Zn2+ and La3+ inhibited the germination and hyphal growth at high concentration and increased the germination and hyphal growth for both isolates compared to control (without metal) at low concentration.The soybeans treated by scarified were transformed by Agrobacterium rhizogenes k599, thus transformed roots of soybeans were generated. However, they can't grow on the low ion concentration medium, so soybeans transformed roots dual culture with AM fungi was not established.The epicotyl of Astragalua sinicus L. was transformed by Agrobacterium rhizogenes k599. We studied the influence of different Km concentration on inductivity of transformed roots, and found a fit Km concentration (40μg/ml) would increase inductivity of transformed roots, whereas an over high Km concentration (60 inhibited inductivity of transformed roots. On the medium of MSR, the establishment of Astragalua sinicus L. transformed roots dual cultures with Gig.margarita, Gig.rosea, Glomus intraradices were tried and they turned out. But Gig.rosea did not generate new spores. One reason would be that after penetration growth of extraradical mycelium had a delaying phase and the reproductive phase in Gigaspore seems to be linked with a critical extraradical mycelium biomass and Auxiculary cells quantity.