PURIFICATION AND CHARACTERIZATION OF TOXINS FROM WHEAT ISOLATES OF Drechslera tritici-repentis, Bipolaris bicolor, AND Bipolaris sorokiniana

E. E. BACH(1), H. KIMATI(2)

(1)Center of Biotechnology, Instituto Biológico, (2)Department of Phytopathology, Escola Superior de Agricultura “Luiz de Queiroz”, University of São Paulo – USP, State of São Paulo, Brazil.

ABSTRACT. Low molecular weight metabolites produced by Bipolaris bicolor, Bipolaris sorokiniana, and Drechslera tritici-repentis are considered to be toxins that facilitate disease in wheat cultivars. Several such toxins were isolated from these fungi. Electrophoresis demonstrated bands of proteins that reduced shoot inhibition in susceptible plants but not in resistant plants. Chlorophyll content was reduced during the first 10 hours of light in the susceptible plants and after 18 hours in the resistant plants. The enzyme beta-1,3-glucanase increased in the resistant plants after treatment with toxins, but in the susceptible plants this enzyme decreased compared to the control. This suggests that the toxin was a protein and the susceptible plants needed other mechanisms for induced resistance.

KEY WORDS: toxin, wheat pathogens, protein toxin.

CORRESPONDENCE TO:

E. E. BACH – Centro de Biotecnologia, Instituto Biológico, Caixa Postal 12898, CEP 04010-970, São Paulo, Brasil.