Biological Characteristics And Toxin Fraction Analysis Of The Sexual Hybridizing Progenies Of Setosphaeria Turcica

Northern Leaf Blight of Corn (NLBC) is a major leaf disease of corn. The causual agent is Exserohilum turcicum. Setosphaeria turcica is its sexual stage. The former reseaches indicated that the pathotoxin named HT-toxin produced by its fungal pathology was the important reason causing this disease. The Setosphaeria turcica was sexual stage of this fungal pathogen.The genetic variation of some biological characteristics including pathogenicity and toxigenicity in the ascospore cultured progenies of isolate 01-12 and 01-15 of Setosphaeria turcica was analyzed in this paper. The results revealed that the character of some progenies was significantly different from their parent isolates and sister isolates in the growth velocity and the amount of conidium. when they were cultured in the PDA medium.There were significant differences among the progenies of sexual hybridization in infection efficiency,latent period,lesion size,sporulation and fitness index. Some progenies with strong fitness index or weak fitness index emerged. Through the research we found that the progenies of sexual hybridization of this fungal pathogen have higher or lower fitness index than its parent isolates.The biological activity of progeny isolate toxins were analyzed using acupuncturing leaves in vitro manifested that they had different toxicity to corn. The lesion areas on inhomogeneous species of corn produced by the toxins of some progenies were different. This kind of toxin occupied one third of the total toxins. Other two third of the total toxin did not manifest difference among the inhomogeneous species of corn.The best isolating conditions for the toxins of the progenies had been studied using high performance liquid chromatography(HPLC). The results were as follows:50%methanol and 50% hyperpure water could be used as mobile phase to isolate the toxin of the progenies. Add acid reagent had largely effect on separating degree of the toxin. The quantity of peak was the bigest when the injection quantity was 15 uL.The experiment manifest the toxin could be isolate effectively with noacid reagent added. The peak had good separating degree in the condition. We foundthe toxin of the progenies was different they had same fractions and dissimilarfractions. The some fractions of progeny isolate toxins were same with the fractionof the toxin of their parents,some did not exist in the toxin of their parents.