| In this dissertation, heredity, variation and pathogenicity differentiation of Curvularia lunata in maize leaf spot were firstly studied from interaction between plant and pathogen. Pathogenicity and physiological differentiations of this pathogen were investigated systemically in the four ways including isoenzyme analysis, identification on differential hosts, RAPD analysis and artificial mutation.By screening the prominent maize inbred-lines and the widely-planted cultivars in China, author established differential host system made up by a series of inbred -lines including Shenl35, 78599-1, Mol7, Ji477, C8605, E28, 7922 and Huangzao4 to detect physiological differentiation of Curvularia lunata , 8 maize inbred - lines involved in the differential system ,sourced from the four prominent inbred systems and with basic hereditary character of the popularized germplasm in China.The identification system is important and useful in monitoring pathogenic variation of this pathogen.8 maize inbred - lines were able to group the pathogen isolates from diseased maize leaf collected in the major maize - grown areas into 6 physiological types in which there were type A with high pathogenicity, type B and C with moderate pathogenicity, type D, E and F with weak pathogenicity. The type A isolates were originated in northern maize - grown areas, including Liaoning, Hebei, provinces and Beijing, where maize Curvularia leaf spot usually occurs severely. The result showed that the occurrence or break-out of this disease was positively related to the high pathogenicity of the pathogen,such as type A. The types B, C and D also had wide distribution, covering major maize grown region, even though their pathogenicities were not very high; Type E was only found in Dandong in Liaoning province, its pathogenicity was weak, and significantly different from type D; Type F only consisted of the albinism isolates which were confirmed as the mutants of the pathogen wild isolates, and currently...
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