Development of agricultural materials with super microbial activities

由于农用化学品造成了严重的环境问题，利用微生物控制植物病害在21世纪将是非常重要的。我们分离了大约1000个荧光假单胞菌，并筛选出了与弯曲草根亲和性最高的菌株。最后，我们得到荧光假单胞菌菌株HP72。将该菌株施用于弯曲草上，棕斑病得到完全控制。RAPD PCR可分离出该菌株的特异性DNA片段，FIA-PCR可对该菌株进行田间枚举。该菌株对海湾草坪真菌病害有较好的防治效果。该菌株在高尔夫球场土壤中存活时间长，占总荧光假单胞菌的比例高。然而，该菌株在高于33℃的温度下不生长，因此，在夏季，荧光假单胞菌的数量和占总荧光假单胞菌的比例下降。然而，更多的离子在秋天自动恢复。在田间试验中，当HP72菌群较高时，真菌病害基本得到完全控制。从液体培养基中纯化出一种抗真菌化学物质，鉴定为Phl。然后，我们试图揭示疾病控制的原因。我们制造了四个不产生任何琼脂培养基的突变体。检测了4个突变体的疾病控制活性。4个突变体虽不能产生抗真菌化学物质，但均能控制褐斑病。然后对4个菌株进行了植物促生活性测定。4个突变体均表现出促进植物生长的活性。因此，植物促生活性对病害防治的作用比抗真菌化学制剂的作用更重要。在其他植物中检测了菌株HP72的存活率。该菌株在茄子和番茄根部迅速消失。该菌株在大麦和小麦的根上存活时间较长，但在4 ~ 5周后消失，认为其对植物根的亲和力仅限于弯曲的草。作为本研究的第二个主题，我们专注于AM真菌。我们利用分子生物学方法揭示了AM真菌在土壤和植物中的多样性，并正在从各种系统发育谱系中筛选超级AM真菌。少

Plant disease control by microorganisms will be very important in 21st century because agricultural chemicals are causing serious environmental problems. We isolated approximately one thousands of fluorescent Pseudomonads, and selected strains which showed the most highest affinity to the root of bent grass. Finally, we got Pseudomonas fluorescens strain HP72. When this strain was applied on the bent grass, the brown patch disease was completely countrolled. By the RAPD PCR we could isolate DNA fragment very specific to this strain, and we could enumerate the strain in the fields by the FIA-PCR method. The strain was very effective to control fungal diseases of gulf course turf. The strain can survive very long periods in the soil of golf course and ratio to the total fluorescent pseudomonas was very high. However, the strain do not grow at higher temperature than 33℃, and therefore, in summer the population and ratio to the total fluorescent pseudomonas came down. However, the populat … More ion recovers automatically in autumn. In the field experiment, when the population of HP72 was high, the fungal diseases were almost completely controlled. An antifungal chemical was purified from the liquid culture and identified as Phl. Then, we tried to reveal what causes disease control. We made four mutants which do not produce Phl out any kinds of agar media. Disease controlling activity was examined for the four mutants. In spite of inability of producing antifungal chemical, the four mutants could control the brown patch disease. Then, plant growth promoting activity was examined for the four strains. The four mutants showed plant growth promoting activity. Therefore, the plant growth promoting activity is more important for disease control that the antifungal chenical production. The survival of the strain HP72 was tested for other plants. The strain disappeared very quickly on the roots of egg plant and tomato. The strain survived longer on the roots of barley and wheat, but finally disappeared after four to five weeks, The affinity of plant roots of HP72 is considered to be restricted to bent grass. As second subject of this study, we focused on AM fungi. We revealed the diversity of AM fungi in soils and plants by molectular biological methods, and we are selecting super AM fungi from the various kinds of phylogenetic lineages. Less