Chactomium spp. Are saprophytic Ascomycetes which act as plant debris cellulose destroying fungi with more than 300 species described all over world. These fungi are capable of producing many kinds of antagonistic substances and enzymes, especially cellulases, to suppress many plant pathogens and decay plant straw and municipal refuse, which leave us many aspects to be developed and applied.

Conidium germination and approssorium formation rate under eight subatratea, different agar surface with various cAMP and IBMX concentration gradients, different nutrient resource, pH value of conidial suspensison, and cultural filter of antigonistic bacteria were observed. Conidium density of its suspeusion and its pH value did not affect the appressorium formation of Magnaporthe grisea 91-11B1, high density (conidia>10 5/mL) and unsuitable pH value (>10 or <4) would significantly reduce the germination of conidia The hydrophobic substratum surfaces could enhance the appressorium formation, The starvation of nutrition and the surfaces of onion epidermis could stimulate the appressorium morphogenesis, and rich mltrition could inhlbh it, Compared with ion-free pure water,tap water could facilitate the appressorium formation, 2.5mmol/L cAMP and 8.0mmol/L IBMX, the mostly commonly used phosphodiesterase inhibitor, significantly promote apressorium formation. Conidia which collected by vibrating method were more elfective to differentiate into appressorium than those by washing method. Among 13 strains of antagonistic bacteria, three sttains, such as Xb216, Xh240 and Xh220 strongly iuhibited the germination and appressorium formation.

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Temperature sensitive mutants (ts-mutants) are godd material for studying cell division and differentiation. Two hundred and seventy-four ts-mutants of Magnaporthe grisea were induced by UV radiation. These mutants could grow at 25℃, but not at 33℃. Pathogenicity test indicated that the pathogenicity of 32 ts-mutants reduced distinctly. Under 33℃ conditions, seven of them did not germinate, 12 stopped growing after germination and no appressorium formed, nine stopped growing after appressorium formed, for mutants formed swell and bunch appressorium, then stopped growing. The ability of perithecia formation of some mutants was changed.