Abstract:Attempted with lesion types to assess the quantitative resistances of wheat to HLB and utilizing drip-inoculating of conidiospores (Bipolaris sorokiniana) suspension solution on the excised leaf in petri dish and using electron microscopy, we examined the changing of lesion types on the detached leaf segment of wheat and its related species and cellular ultrastructure in both resistant and susceptible genera. The results indicated that the lesion types on wheat leaf at same growth stage caused by the fungi were related only to their own genetic resistance of the wheat genotypes. Two kinds of lesion types in the test materials were found: wheat reaction types of the lesion were altering with time, differed in leaf arrangement and varieties, with the cellular structure and function at 14.3％ intact, 28.6％ changed, 57.1％ lost in the diseased cells, respectively; wheat related species, which were not altering with time, existed variation only in species or genera as well as a few in leaf arrangement, with the same percentage of 33.3％ for cellular structure and function intact, changed and lost. Organelles altered in the diseased cells both for wheat and its related species were observed.