江西水稻穗腐病病原菌鉴定及生物学特性研究

Studies on the Biological Characteristics and Pathogenic Identification of Rice Spikelet Rot Disease in Jiangxi Province

水稻穗腐病(Rice spikelet rot disease)在全国都有发生,江西近年发生较重,吉泰盆地尤烈,但鲜有报道。通过采集病样,并进行疑似病原菌的分离、形态学与分子鉴定和科赫法则验证等,明确江西水稻穗腐病病原菌种类和优势种。结果表明,厚垣镰刀菌(Fusarium chlamydosporum)、细交链格孢菌(Alternaria tenuissima)、香茅弯孢菌(Curvularia cymbopogonis)和稻黑孢(Nigrospora oryzae)为病原菌。24～28℃为最适温度;镰刀菌在pH7长势良好,而其他3种最适pH为7～9。葡萄糖和淀粉为最适碳源,硝酸钾为最适氮源。采用不同方式接种后,注射发病率比喷雾高(孕穗期:29.46%>17.89%)。与孕穗期接种(喷雾:17.89%)相比,抽穗期接种(喷雾:20.35%)的发病率更高。致病率由高到低依次为:厚垣镰刀菌、香茅弯孢菌、细交链格孢和稻黑孢。对不同穗腐病发生地区的病样进行鉴定,所有地区均可检出厚垣镰刀菌和香茅弯孢菌;细交链格孢菌在井冈山市、万安县、余江县和修水县4市县检出;而稻黑孢仅在万安县和修水县检出,它是新的致病源,这对世界范围内稻穗腐病的病原认识是一个有益和新的补充;今后应该加强对稻黑孢的监控和研究。综上,厚垣镰刀菌和香茅弯孢菌是江西水稻穗腐病主要病原菌,细交链格孢菌和稻黑孢的分布具有明显区域性。

Rice spikelet rot disease(RSRD)occurrs throughout China,it has burst out heavily in Jiangxi Province in these years, especially in Jitai Basin.But few studies were reported.In this study, the pathogen and dominant species of RSRD in Jiangxi area were identified by collecting the disease samples,separating the sus pected pathogenic bacteria, identifying the morphological and molecular and the Koch rule verification.The re sults showed that,F usarium chlamydosporum,Alternaria tenuissima,Curvularia cymbopogonis and Nigrospora oryzae were pathogens.The optimum temperature for them was 24-28 ℃.The optimum pH for Fusarium chla mydosporum was pH7, while that for the other 3 was pH 7-9.Glucose and starch were the most suitable carbon sources,and potassium nitrate was the most suitable nitrogen source.The incidence of injection was higher that of spray( Booting stage: 29.46%>17.89%).Compared to inoculation in the booting stage,the incidence of heading stage was higher( Spray: 20.35%>17.89%).The ranking order of the pathogenicity rates of these four pathogens was:F. chlamydosporum>C. cymbopogonis>A. tenuissima>N.oryzae.Samples of 5 RSRD outbreaking regions were collected for identification. F. chlamydosporum and C. cymbopogonis were detected in all the regions.A. tenuissi ma was detected in Jinggangshan City, Wanan County, Yujiang County and Xiushui County.However,N .oryzae was detected in only Wanan County and Xiushui County,it was a new pathogenic source of RSRD.This is a useful and new supplement to the pathogens knowledge of the RSRD in the world,so the study and monitor of the Nigros pora oryzae should be strengthened.In conclusion,F . chlamydosporum and C. cymbopogonis were the main patho gens of RSRD in Jiangxi,the distribution of A. tenuissima and N.oryzae displayed regional characteristics.