Improvement of acidic soils by aluminium (Al)-resistant fungi and molecular mechanism of Al-resistance

1)从茶园分离得到的紫青霉f -13能中和日本东北地区酸性土壤的酸性，促进植被的萌发和生长。效率维持了几年。在日本的另一个地方，正在进行另一项实验，显示出类似的改善。本研究将P. chrysogenum IFO4626的耐铝紫外突变体的两个候选耐铝基因引入烟草，命名为to。以2型种子为试验材料，通过萌发和生长检测其耐铝能力的提高，但未发现阳性结果。我们将尝试其他候选基因和其他生长条件。3)对泰国不同地点土壤的DDGE分析表明，酸性土壤中可检测到的微生物区系少于正常土壤。土壤提取液在酸性条件下保存时，正常土壤中微生物区系的种类有所减少，但在酸性土壤中没有变化，说明酸性土壤中只存在耐铝和耐酸菌群，真菌对铝和酸的耐受性优于细菌。4)对静冈县茶田不同地点土壤的DGGE分析表明，土壤ph值对土壤微生物区系的影响较大。在pH4下，氮肥降低了土壤pH值，细菌/真菌比升高。在施氮肥的犁沟土壤中发现了特有的真菌。5)分析了粘红酵母IFO1125新铝耐受性的机制。随着铝浓度的增加，耐受性也相应增加。增加的抗性细胞增加了线粒体及其DNA。铝离子增加了产生活性氧的线粒体的膜电位，导致细胞色素氧化酶降低，从而导致铝中毒。线粒体数量的增加及其DNA的增加是对细胞色素氧化酶减少引起的呼吸能力降低的补偿。6)有3个基因参与了粘菌对铝的耐受。漆酶可能与铁摄取有关，铁摄取在Al存在时升高。亚砷酸盐易位atp酶与维持膜完整性，特别是线粒体功能有关。Ca^<2+>/钙调素依赖性蛋白激酶可能通过Ca^<2+>/钙调素依赖性信号通路参与Al耐受。少

1) We showed that Penicillium janthinellum F-13isolated from tea field could neutralize acidity of acidic soils in Tohoku Area of Japan and promoted germination and growth of vegitation. Efficiency was maintained for a few years. Another experimental execution of works are on going in another site in Japan, showing the similar improvement. In general, the strain is expected to improve vegitation in acidic soils of Japan.2) We introduced two candidate Al-tolerant genes of Al-tolerant UV-mutant derived from P. chrysogenum IFO4626 into Nicotiana tabacum, designating this as TO. Using T2seeds, increase of Al-tolerance was examined by germination and growth, but no positive results have not been detected. We will try another candidate genes and another growth conditions.3) DDGE analyses of soils collected from different sites in Thailand suggested that less microbial flora were detectable in acidic soils than in normal soil. When soil extracts were kept under acidic conditions, variety of m … More icrobial flora of regular soil was simplified, but no change was found with acidic soils, suggesting that only tolerant flora to Al and acidity exist in acidic soil and fungi are more tolerant to Al and acidity than bacteria.4) DGGE analyses of domestic soils collected from different sites in tea fields of Shizuoka Prefecture showed that microbial flora were greatly influenced by soil pHs. Nitrogen fertilizer reduced soil pH and bacteria/fungi ratio increased under pH4. Characteristic fungi were detected in furrow soils where nitrogen fertilizers are given..5) The mechanism of novel Al tolerance found in Rhodotorula glutinis IFO1125 was analyzed. Increased tolerance was obtained accordingly to increased Al concentrations. Increased resistat cells had increased mitochondria and their DNA. Al ion increased membrane potential of mitochondria producing active oxygen species caused by lowered cytochrome oxidase and resulting in Al toxicity. The increment of mitochondrial numbers and their DNA is concluded to be a conpensation for lowered respiration ability caused by decrement of cytochrome oxidase.6) Involvent of three genes were suggested in Al tolerance of R. glutinis. Laccase is possibly related to iron uptake, which is elevated in the presence of Al. Arsenite-translocating ATPase is relevant to maintaining membrane integrity, especially mitochondrial function. Ca^<2+>/calmodulin-dependent protein kinase is suggested to be involved in Al tolerance through Ca^<2+>/calmodulin-dependent signaling pathway. Less