College of Resources and Environmental Sciences, China Agricultural University, Beijing, China.
Pest Manag Sci. 2010 Sep;66(9):1018-24. doi: 10.1002/ps.1976.
One promising area of rice disease management is the potential of exploiting biological control agents. Rice seedling rot disease caused by soil-borne pathogenic fungi has become a dominant disease problem because of greater use of direct seeding. Rice hull has been potentially used to control paddy weeds, but little information is available on rice disease. This study was conducted to investigate the relationships between disease incidence and soil amended with tricin-releasing rice hull, and to assess fungicidal activity of tricin and its synthesised aurone isomer, with an attempt to develop an allelochemical-based fungicide against rice seedling rot disease.
Tricin was detected in all hulls of 12 rice cultivars tested, but its contents in rice hulls varied greatly with the cultivar and genotype. Tricin in rice hulls was released into the soil once amended. Disease incidence was significantly reduced by soil amended with rice hull. Tricin-rich rice hull amendment greatly suppressed soil-borne pathogenic fungi Fusarium oxysporum Schlecht. and Rhizoctonia solani Kühn which cause rice seedling rot disease. In attempting to obtain enough tricin for further experiments, the aurone isomer (5,7,4'-trihydroxy-3',5'-dimethoxyaurone) of tricin rather than tricin itself was unexpectedly synthesised. This aurone isomer had much stronger fungicidal activity on both F. oxysporum and R. solani than tricin itself.
Soil amended with tricin-rich rice hull was associated with reduced risk of developing seedling rot disease. The tricin isomer, aurone, is more effective against rice seedling rot disease than tricin itself, making it an ideal lead compound for new fungicide discovery.
利用生物防治剂是水稻病害管理的一个有前景的领域。由于直接播种的使用越来越多，由土壤传播的病原菌引起的水稻烂秧病已成为主要病害问题。稻壳已被潜在地用于控制稻田杂草，但关于水稻病害的信息很少。本研究旨在调查添加释放麦角固醇的稻壳对病害发生率的影响，并评估麦角固醇及其合成的噢哢类异黄酮的杀菌活性，试图开发一种基于化感物质的杀菌剂来防治水稻烂秧病。
在所测试的 12 个水稻品种的所有稻壳中都检测到了麦角固醇，但它在稻壳中的含量因品种和基因型而异。添加稻壳到土壤中后，麦角固醇会释放到土壤中。土壤中添加稻壳可显著降低病害发生率。富含麦角固醇的稻壳添加物可极大地抑制引起水稻烂秧病的土壤病原菌尖孢镰刀菌和立枯丝核菌。在试图获得足够的麦角固醇用于进一步实验时，令人意外的是，获得了麦角固醇的噢哢类异黄酮（5,7,4'-三羟基-3',5'-二甲氧基噢哢）而不是麦角固醇本身。该噢哢类异黄酮对尖孢镰刀菌和立枯丝核菌的杀菌活性都比麦角固醇本身强得多。
添加富含麦角固醇的稻壳的土壤与降低烂秧病发病风险有关。噢哢类异黄酮，作为麦角固醇的异构体，比麦角固醇本身更有效地防治水稻烂秧病，使其成为新杀菌剂发现的理想先导化合物。
