Studies on Fitness and Mechanism of Multiple-herbicide Resistant Echinochloa oryzicola Vasing

1997年，在加州的萨克拉门托的稻田区发现了一种对多种除草剂具有抗性的稻瘟病菌生物型。对该抗性生物型进行了研究，目的是阐明（1）它对敏感生物型的相对适合度和（2）抗性机制。1.抗性生物型的相对适合度在京都的移植田间试验中生长的个体和在萨克拉门托的各个田间生长的个体上，测量由植物产生的种子数量作为适合度的标准。抗性生物型的相对适合度在京都的移栽试验中为0.70~0.73，在萨克拉门托的实际田间调查中为0.50~0.58。2.抗性生物型对几种化学结构和作用方式不同的除草剂的抗性机制研究注意到微粒体P-450。在该项目的生化和分子分析中，发现当用除草剂处理时，抗性生物型比敏感生物型诱导更大的P-450活性，并且不止一种P-450参与除草剂抗性。

In 1997, a multiple-herbicide resistant biotype of E.oryzicola, was found at the rice paddy area of Sacramento in California. This resistant biotype was studied with objectives to elucidate (1) its relative fitness against susceptible biotype and (2) mechanism of the resistance.1.Relative fitness of the resistant biotypeThe number of seeds produced by a plant was measured as a criterion of fitness on individuals grown in a transplanted field experiment in Kyoto and on those grown at various fields of Sacramento. The relative fitness of resistant biotype ranged from 0.70 to 0.73 in the transplanted experiment of Kyoto and from 0.50 to 0.58 in the actual field survey at Sacramento.2.Mechanism of the resistanceMechanism of the resistant biotype to several herbicides that differ in chemical structure and mode of action was studied with an attention to the microsomal P-450. In biochemical and molecular analyses of this project, it was found that the resistant biotype induced larger P-450 activity than the susceptible biotype when treated with a herbicide, and that more than a species of P-450s were involved in the herbicide resistance.