| Salvia (Danshen in Chinese, Salvia miltiorrhiza Bge.), commonly known as Huoxuegen(which means herb root for activating blood), was perennial herb in Lamiaceae and was used its dry fleshy root as medicine, and was also recognized as the preferred drug for the treatment of cardiovascular diseases worldwide. Under artificial cultivation conditions, due to the low diversity and low abundance of biological communities in the ecological environment of herbal field, Salvia root rot was increasing year by year, which resulting in low herbs yields and poor quality. After the infection of arbuscular mycorrhizal (AM) fungi in plant, mycorhiza was formed, and arbuscular mycorrhizal was common symbiosis in nature. Arbuscular mycorrhiza played important roles in improving crop nutrient absorption, expanding the scope of root absorption, promoting growth, and improving plant's abilities of disease resistance.The author first isolated and identified pathogenic bacteriaes caused Salvia root diseases, investigated physiological and biochemical effects of these pathogenic bacteriaes on Salvia, identified the main pathogens cause of Salvia root disease, then screened AM fungi. Based on these studyes, th author also finished futher researches the effects and mechanismes of AM fungi on resistance to Salvia root diseases via the application of molecular biological, physiological and biochemical methods. The main results are as follows:1. Select typical pathogens strains in Salvia roots from cultivating bases in Laiwu Shandong and Anguo Hebei, after separation, cultivation, purification and pathogenicity testing of pathogenic bacteriaes, the bacteriaes were identified by morphological and molecular techniques, and they were Verticillium dahlia (VD) in Verticillium, and transformed Plectosphaerella cucumerina (PC) of Fusarium oxysporum in Fusarium.2. Under greenhouse conditions, Salvia root was infected by pathogenic bacteriaes, then four key enzymic activities related to corp's disease resistanc were significantly increased, and these four enzymes were:polyphenol oxidase (PPO), phenylalnine ammonialyase (PAL), peroxidase (POD) and superoxidase (SOD), relative expression levels of pathogenesis-related protein gene PR10and defense gene PDF2.1were also significantly increased. And PC group were significantly higher than VD group, indicating that Salvia seedlings were more sensitive to Fusarium oxysporum. At the same time, seen from the statistics of the incidence rate of PC was significantly higher than VD group, indicating that PC were more pathogenical to Salvia seedling. Therefore, in following experiments Fusarium oxysporum was selected as a pathogen. This experiment showed that the pathogen could lead to a series of physiological and biochemical reactions in plant, phytoalexins produced and accumulated variety of different enzymes activity and production of pathogenesis-related protein, which made bases for follow-up screening of resistant bacterial flora and mechanism of anti-disease resistance.3. There were many kinds of AM fungi species, in order to select the species which could significantly enhanced Salvia disease resistance, this paper examined the impact of three AM fungal species isolated from Salvia plants on Salvia growth and active ingredient content. The results showed that inoculation with AM fungi can promote the elements absorption of Salvia in Cu, Zn, Mn, Fe and Mg, Ga and K, inprove dry weight of underground part of the ground, the underground part of the number of branches, root length, leaf net photosynthetic rate, transpiration rate, and inporve stomatal conductance. After inoculation with AM fungi, chlorophyll content and soluble sugar contents were significantly higher than those without inoculation, AM mycorrhizal processing could promote the accumulation of water-soluble chemical composition in Salvia leaf and root, such as rosmarinic acid and salvianolic acid B, and also promote the accumulation of fat-soluble chemical compositions in Salvia root, such as Tanshinone I, Tanshinone IIA, dihydro tanshinone, and miltionone, which could improve the quality of herbal materials. And vaccination G.versiforme showed most obvious effect, so G.versiforme was selecte to study disease-resistant and mechnism in Salvia root.,4. By the above experimental study, chosen Fusarium oxysporum pathogenic to process Salvia seedling, and selected G.versiforme on disease prevention and control, so as to explore the mechanismes of AM fungi enhance disease resistance ability of Salvia root. The experimental results showed that the inoculated mycorrhizal fungi G.versiforme treatment significantly reduced the incidence of Salvia miltiorrhiza. After infection of pathogenic bacteriaes, plant growth weakened, chlorophyll content reduced, chitin and protein content decreased, but G.versiforme treatment could significantly ease negative effects caused by pathogens, chlorophyll content increased, chitinase activity and protein content improved. G.versiforme treatment also significantly increased the content of soluble sugar in leaves, and increased activities of defense enzyme β-1,3glucanase and phenylalanine aminotransferase.In summary, AM fungi could enhance Salvia anti-disease ability in Salvia root, its mechanims might include impoving plant mineral nutirtion status, promoting Salvia growth, enchancing photosynthesis, inporving transformation and accumulation of soluble sugars, enhancing defensive enzyme activity, imporving disease resistant related-gene PR gene and PDF gene expression, these researches provided theory basis for application of beneficial microbes, mycorrhizal fungi to make biological control of diseases. |
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