Abstract: 【OBJECTIVE】Elucidation of the effects of MAPK signal pathway on the HT-toxin production and biological activity of Setosphaeria turcica, will facilitate the mechanism study of the fungal pathogenicity;【METHOD】The specific MAPK signal pathway inhibitor, U0126, is used to study the regulation of MAPK pathway on HT-toxin production and activity;【RESULTS】The composition and quantity of HT-toxin fractions extracted from isolate 01-23 are significantly altered after treated with 1-20 μmol/L U0126. The production or quantity of some fractions is inhibited and there are some new fractions are induced. The biological activities of HT-toxin on susceptible corn inbred lines, B37 and B37Ht1, are significantly inhibited in isolate 01-23 after treated with 1-20 μmol/L U0126. The inhibition is stronger on B37 than on B37Ht1. The inhibition increases from 1 μmol/L to 20 μmol/L U0126 treatments, but there is no significant difference between the 10 μmol/L and 20 μmol/L U0126 treatments, indicating that U0126 can not completely inhibit the biological activity of HT-toxin;【CONCLUSION】HT-toxin production and biological activity on susceptible corn leaves are regulated by MAPK signal transduction pathway, but the mechanism of HT-toxin production and biological activity in S. turcica is complex and infected by other unknown factors.

Key words: Setosphaeria turcica, MAPK, HT-toxin, U0126