Studies On Biology And Physiology Characters Of The Rhizoctonia Solani Resistant To Jinggangmycin

Rice sheath blight is an increasing concern for rice production, Crop losses may range from slight to heavy each year.The disease is caused by Rhizoctonia solani. This fungus was mainly controled by Jinggangmycin as chmical agent in China for more than 30 years, but very little was known about studies of resistance of R.solani to Jinggangmycin.In this article the Jinggangmycin was used for inducing fungicide resistance, the R.solani strains which resisted to the Jinggangmycin were systematic studiedIn lab the Jinggangmycin resistance strain Jgm^r was gained through inducement and got a virulence formulation as y=1.1396x + 3.7839, EC₅₀=11.6766 μg/mL, 95% cofidence limits from 10.4595 to 13.0356 μg/mL.The fungicide resistance index of Jgm^r increased by 36.77. It's demonstrated in biological experiments that Jgm^r is less sensitive than normal ones, mostly manifested by that lower mycelium growth rate, less growing quantity. But the growing of strains nearly the same if under indigent medium. Pathological experiments showed that:the disesase index of Jgm^r was 56.0, while 18.5 was caused by sensitive strain Jgm^s . Even after 10 generations growing in free Jinggangmycin medium, the Jinggangmycin resistance ability of Jgm^r preserved.In transmission electron microscopy, the configuration and the cell structure of Jgm^r changed. Abnormality of Jgm^r turned out earlier than Jgm^s, it shrinked or expanded anomalously, the protoplasm of mycelium manifolded and the cell organs cleared up. But them could not tell the nucleolus differences of all strains under Jinggangmycin medium or free Jinggangmycin medium.Physiological experiments showed that: the crude metabolites of Jgm^s and Jgm^r caused electrolyte leak from the cells of the rice young caudex, the damnification as high as 39.61% was caused by Jgm^s, 15.68% was caused by Jgm^r. Comparing to the only sensitivity to higher dextrose osmotic pressure, Jgm^r was sensitive to higher or lower dextrose osmotic pressure. The conductions of Jgm^s and Jgm^r were ascending in PS medium containing Jinggangmycin in 0¹20mins, which demonstrated that Jinggangmycin do impact soluble...