玉米小斑病菌C小种毒素的分离、纯化及其植物病理反应

ISOLATION AND PURIFICATION OF A C-TOXIN COMPLEX FROM BIFOLARIS MAYDIS RACE C AND ITS PATHOLOGICAL REACTIONS

魏建昆等证实在中国存在玉米小斑病C小种[1]。本文通过凝胶柱层析(Sephadex G-25)和硅胶层析(Silica gel)将C毒素(HMC-toxin)分为四种亚毒素,毒素Ⅰ和毒素Ⅲ(占全部毒素管数的75%)主要侵染T、C、S、N四种同核异质玉米中的C胞质叶片,使之产生严重萎蔫,为专化性毒素,但少数管号内的毒素对T、S有轻微的伤害,而且毒素Ⅰ内少量对N也有影响,毒素Ⅱ(占10%)只轻微地侵染N细胞质,毒素Ⅳ(占15%)除了对S无影响外,对T、C、N三种细胞质均有一定的危害。由此可见,C毒素是一具有生物活性的混合体,其中以侵染C胞质的毒素为优势毒素,同时存在少量对T、S、N三种细胞质毒力较弱的毒素。对T、C、S、N四种同核体(Homocaryons)玉米人工接种C小种所出现的叶片抗性反应,从本实验获得了一定的解释。

A toxin complex from Bipolaris maydis race C was extracted and purified. The leaf wilting spot test was used as a bioassay to assess the activity of the toxin.The purified toxin complex, designated C-toxin, was chromatographed on Sephadex G-25. Of the 50 fractions, numbers 40-45 were bioactive. These fractions were combined and chromatographed on a silica gel column, From the 45 fractions collected, those from 11-19, 23-24, 27-29 and 32-34 were biologically active. Fractions of each group were combined and designated as C-toxin Ⅰ,Ⅱ,Ⅲ and Ⅳ respectively. They were each tested on maize of T,S, N and C cytoplasm. Toxin 1 showed specificity to C cytoplasm, although it was also slightly toxin to T, S and N cytoplasm.Toxin Ⅱ was specific for N cytoplasm only. Toxic Ⅲ reacted like toxin Ⅰ, but also had some toxicity for T and S cytoplasm. Toxin Ⅵ was toxic to all cytoplasm types except cms-S. These results show that C toxin has a complex cheical nature with a dominant component which causes the leaves of the C-variant to wilt. Additionally, however, it contains components with limited toxicity to T,S and N cytoplasm. These data explain the earlier observations that in leaves from C,T, S and N variants after inoculation with the race C pathogen, the most severe reaction was observed with variant C,while some wilting also occured on leaves of the other variants.