Abstract:

The control of plant rust is very difficult and its biological control focuses on the study of mycoparasites. Previous studies showed that P. kenyana PG52 and T. koningii 8662 had strong parasitic effects on aeciospores of Aecidium wenshanense and Cronartium ribicola, however, the mechanism of mycoparasitism is unclear. Two kinds of toxins, identified as 3-nitro propionic acid and citric acid, were isolated from two mycoparasites using bioassay-guided method for the first time and they had a lethal effect on aeciospores.The cell membrane permeability of aeciospores was changed by two kinds of toxins and aeciospores were significantly smaller comparedwith the control. Aeciospores were confirmed dead by Trypan blue staining. After treatment by 10 μg/ mL 3-nitro propionic acid and 100 μg/ mL citric acid for 1 h, the fatality rate of aeciospores reached 50% by Trypan blue staining. When the mass concentration of citric acid was more than 500 μg/ mL, fatality rate reached 90%. Also 500 μg/ mL citric acid had a lethal effect on aeciospores of Aecidium pourthiaea, teliospores of Sterostratum corticioides and urediospores of Uromyces trifolii. The above results laid a foundation for mycoparasitism clarification and indicated a good biopesticide application prospect.

Key words: mycoparasite, toxin, isolation and identification, plant rust, biopesticide