Bioremediation of Soil pollutants by Plant-Microbe Symbiotic System

1)利用植物-微生物共生系统对土壤中PCNB及其衍生物的生物降解对土壤微生物降解PCNB的能力进行了筛选，PCNB是一种用于控制芸苔属物种根肿病的杀真菌剂，及其衍生物。唐菖蒲假单胞菌（PseudomonasgladioliM-2196）是葱属植物根部的一种共生菌，是将五氯苯甲醚代谢为五氯苯甲醚的微生物之一。被孢霉15-4是芸苔属植物根上的真菌共生体，M-2196-Allium spp.和15-4-芸苔属（Brassica spp.）共生模型表明，土壤中的多氯硝基苯可有效降解为五氯苯甲醚和五氯三苯并对甲氧胺。从叶绿素鞘氨醇单胞菌（Sphingomonaschloropheolica）中克隆了一个编码五氯酚降解酶的基因（pcpB），并将其转化植物共生菌唐菖蒲P. gladioliM-2196和镰刀菌F4。转化后的微生物-植物共生系统能有效降解土壤中的PCP。2）利用植物-微生物共生体系研究植物对土壤重金属的富集作用不同植物对土壤重金属的富集能力不同。土壤类型、植物共生微生物等环境因素对富集有影响，如土壤类型、植物共生微生物、土壤微生物等。例如，镰刀菌T3能促进番茄对铯和锶的吸收。3）共生菌的分子进化分析研究了植物共生菌的遗传转化策略，并通过限制性内切酶介导整合（REMI）法获得了共生缺陷突变体。从植物共生镰刀菌中鉴定出一个可能与共生有关的基因，并对植物共生微生物的进化进行了分子分析。

1) Biodegradation of PCNB and its Derivatives in Soil by Plant-Microbe Symbiotic SystemRhizosphere microorganisms were subjected to screening for ability to degrade PCNB, a fungicide used to control clubroot disease of Brassica spp., and its derivatives. Pseudomonas gladioli M-2196, one of those microbes that metabolize PCNB to PCA, was a symbiont on the root of Allium spp. Mortierella sp. 15-4, a fungal symbiont on the root of Brassica spp., could degrade PCNB into PCTA.The M-2196-Allium spp. and 15-4-Brassica spp. symbiotic models showed effective degradation of PCNB in soil into PCA and PCTA, respectively. A gene(pcpB)encoding a PCP degrading enzyme was cloned from Sphingomonas chloropheolica and used to transform P.gladioli M-2196 and Fusarium sp. F4, both of which are plant symbionts. The transformed microbe-plant symbiotic systems could degrade PCP in soil effectively. We also found out the biocontrol ability in Phoma glomerara on clubroot and suggested that the effect was due to epoxydon produced by the fungus.2) Accumulation of Metals by Plant from Soil using Plant-Microbe Symbiotic SystemSeveral plant species showed different ability in accumulating metals from soil. Environmental factors, such as soil types and plant-symbiotic microbes gave effects on the accumulation, i. e., Fusarium sp. T3 increased the uptake of Cs and Sr by tomato.3) Molecular-Evolutional Analysis on SymbiosisStrategies for transformation of plant-symbiotic microbes were examined and symbiosis-deficient mutants were obtained by restriction enzyme mediated integration (REMI)method. A gene that might have a sole in symbiosis was identified from plant-symbiotic Fusarium sp. Futher, molecular analysis was performed on the evolution of plantsymbiotic microbes.