Chemicals Mixed To Prevent Rice From Seed-borne Fungi And Bacteria Disease And The Biodegradation Research Of PAHs

Plants suffer from both biotic and abiotic stress. Magnaporthe oryzae, Gibberella fujikuroi, Xanthomonas oryzae pv.oryzae, and Xanthomonas oryzae pv. oryzicola are the main rice pathogen that cause fungi and bacteria disease, which bring enormouse economic losses. Polycyclic Aromatic Hydrocarbons (PAHs), the most prevalent and persistent pollutants in the environment, could affect the germination and growth of plants and verified in many references. It is vital to control rice main fungi and bacteria disease and put efforts on bioremediation microbes. This research forcus on both the rice seed chemicals treatment to protect rice from pathogen affected and studies on bioremediation microbes to get possibilities to remove PAHs pollutions. The main results are as below:1) Seed treatment with chemicals mixture research. Tebuconazole and prochloraz are chemicals that registered as fungicide, and thiediazole copper were used to kill bacteria. To well protect seeds from both fungi and bacteria disease, a mixture proportion of tebuconazole and thiediazole copper or prochloraz and thiediazole copper to prevent rice from seed-borne bacteria and fungi disease were conducted. Tebuconazole and thiediazole cooper mixed as9:1is the optimum proportion as seed treatment, which could well protect rice seeds from both fungi and bacteria. Also prochloraz and thiediazole copper mixed as7:3could protect rice seeds from both fungi and bacteria infection. Two patents were granted by the China patent office for the two chemicals mixture used for seed treatment, which gave techonoly supports for controlling rice seed-borne bacteria and fungi disease.2) Identification and classification of fluorene-degradation species Novosphingobium fluoreni sp. nov. HLJ-RS18T.We isolated a bacteria strain HLJ-RS18from Sanjiang rice variety of Heilongjiang Province of China, which could degrade fluorene (three rings of polycyclic aromatic hydrocarbons/PAH). Further analysis of16S rRNA, genotypic characterization, chemotaxonomic results and phenotypic analysis indicated that HLJ-RS18T represents a novel species in the genus Novosphingobium. Therefore, we propose the species Novosphingobium fluoreni sp. nov. with HLJ-RS18T (=DSM27568=ACCC19180) as the type strain. HLJ-RS18T showed no effect on the germination of four rice varieties provided. There was no interaction of strain HLJ-RS181with Magnaporthe oryzae YN08-1, Gibberella fujikuroi US01, Xanthomonas oryzae pv.oryzae PXO99, and Xanthomonas oryzae pv. oryzicola RS105.HLJ-RS18T is a new potential bioremediation strain that could be used in the PAHs degradation.3) Multiple degradation pathways of phenanthrene by Stenotrophomonas maltophilia strain C6. Stenotrophomonas maltophilia C6was isolated by our cooperation lab, and strain C6could completely degrade phenanthrene through14days. To further well understanding the phenanthrene pathway, we isolated and identified22metabolites from the culture periodically. Finally we proposed the phenanthrene pathway by strain Stenotrophomonas maltophilia C6. Stenotrophomonas maltophilia C6could degrade phenanthrene starting from1,2-,3,4-,9,10-C position and following with ortho and meta cleavage. The concentration analysis of upper metabolites from1,2-,3,4-,9,10-C pathway, respectively, showed strain Stenotrophomonas maltophilia C6degrade phenanthrene mainly through3,4-C pathway. This is the first study of detailed phenanthrene metabolic pathways by Stenotrophomonas maltophilia. Stenotrophomonas maltophilia C6is also a potential biomediation bacteria that could contribute to the remove of phenanthrene with clearly proposed degradation pathway.