USING DIFFERENCES IN THE CHEMICAL-COMPOSITION OF PHYTOPATHOGENIC FUNGI AND PLANTS TO INVESTIGATE THEIR RELATIONSHIPS

Chitin, polyols, ergosterol, and specific fungal antigens are absent f rom pathogen-free cereal seedlings and the time-course of accumulation of these substances after infection allows estimation of the rate of colonization of plant tissues by phytopathogenic fungi, The level of f ungal metabolites is directly related to the degree of compatibility o f partners in the process of pathogenesis, as established in laborator y experiments on wheat plants (Triticum aestivum L.) inoculated with s tem and leaf rust (Puccinia graminis Pers. f.sp. tritici Erikss. et He nn. and Puccinia recondita Desm.) or glume blotch (Septoria nodorum Be rk.) and rice (Oryza sativa L.) seedlings inoculated with blast (Pyric ularia oryzae Br. et Cav.). Fungal metabolite content correlates with disease progress in the field under recurrent infection of plants. Bio chemical tests make it possible to estimate both the level and (with a n appropriate experimental design) type of resistance of the particula r plant cultivar. Quantitative evaluation of fungal metabolites in inf ected seedlings also allows comparison of the fungitoxity of chemical substances.