Isolation and identification of pathogenic fungi of rice brown spot

【Objective】 The isolation and identification of pathogenic fungi of rice brown spot were studied,which laid the foundation for further study of the pathogenesis of the disease and effective prevention and control.【Method】 The pathogenic fungi of rice brown spot was separated by using the conventional separation method of the fungal.The inoculation experiment was verified by Koch's postulates.The pathogen colonies of rice brown spot were identified by the morphological and molecular.【Result】 The separation of the pathogenic fungi of rice brown spot was confirmed by inoculation experiment.Its conidiophores of the pathogenic fungi of rice brown spot isolated were single,brown,not branched and their tops were geniculation.Conidia was elongated oval,spindle,pour sticks shape,straight or bent to one side,brown,the both ends of the conidia gradually narrowed,obtuse,its hilum was relatively flat,5-10 replums;The lengths of 18S rDNA and ITS sequence were respectively about 1.8 kb and 570 bp.Homdogy between the 18S rDNA of pathogen identified and one of Cochliobolus cynodontis was the highest,and their similarity was 99%;homology between the ITS of pathogen identified and one of Bipolaris oryzae was the highest,and their similarity was 99%.Cluster analysis indicated that this pathogen had the closest relation with the 18S rDNA of Bipolaris eleusines and the ITS of Bipolaris sp.【Conclusion】 The pathogenic fungus of rice brown spot was successfully isolated from the rice;The results of morphological and molecular identification were both B.oryzae.