| In this paper, the optimal pathotoxin production factors, extraction, purification, bioassay and the characteristic of physical chemistry of the pathotoxin produced by Phytophthora sojae (Pmg.) were systematically researched. The effect of the pathotoxin on the ultrastructural organization, the activity of disease resistant enzyme and the content of phytoalexin of soybean with different resistance to Pmg were also analyzed. The main results were as follows:(1) Some optimal production factors of pathotoxin produced by Phytophthora sojae were studied.The experimental results showed that the most suitable conditions were Fries liquid medium whose pH was 6-7 under the cultural condition of static and semi-light at 25-28癈 for 10 days.(2) The best extraction way of the pathotoxin produced by Pmg was to use the weak polarity organic solvent,especially ether. The rude crystalline of the pathotoxin was gotten by continuous extraction by ether.The bio-activity of the rude pathotoxin was determined by the seedlings with cutting roots and the vitro leaves, and the former material appeared the same symptom as those with the hypocotyl inoculation and the latter material broght the small spots on it.The main component of the pathotoxin produced by Phytophthora sojae was preliminarily thought of as a kind of glycoprotein ,and the content of the protein and glucose was measured by way of anthrone-chromometry and bovin serum albumin.The optimal concentration of the pathotoxin was the dilute factor of 100(the protein content was 24.079ug/ml and the glucose content was 21.518ug/ml )chosen by soybean varieties with different resistance .This also proved that the pathotoxin was a kind of Non- Host Specitiy Toxin.The results showed that the toxin activity of protein was stronger than that of glucose after the pathotoxin was hydrolyzed by protein hydrolytic enzyme and the glucose hydrolytic enzyme.The pathotoxin was separated 5 components by silica gel thin-layer chromatography and the Rf of those were 0.23, 0.56, 0.59, 0.67 and 0.78.The virulence of the components was different and the strongest virulent component was that with RfO.78.The leaves treated by the component with RfO.78 had many spots and water immersion symptom.The order of the virulence of the components was that with Rf 0.78X).67>0.59 = 0.56>023.This indicated that the component with relatively small molecular weight had much more virulence than that with relativly big molecular weight.(3) The root ultrastructure, especially, the chondriosome of soybean varieties with different resistance treated by the pathotoxin at 72hours had distinct diversity.Most of the chondriosome in roots of susceptible variety Hefeng 25 appeared the vacuolus.,but the cell structure of resistant variety SuinonglO was relatively normal.This showed that the normal activity of the physiological biochemistry in roots of resistant variety was to accelerate the synthesize of phytoalexin and enhanced resistance ability.The leaf ultrastructure of soybean varieties with different resistance treated by the pathotoxin at 72hours had distinct diversity.The resistant variety had relatively normal leaf ultrastructure, but the susceptible ones had destroyed chondriosome and chlorophyll.(4) Treated by the pathotoxin of optimal concentration,,the resistant soybean varieties had the higher activity of PAL in roots than that in control .The activity of PALin stem was less sensitive than that in roots and the activity of PALin leaves was the lest sensitive.Although the activity of PAL in susceptible varieties was higer than that in control at some periods,the ascent of PAL activity was lower than the descent of PAL.The increase of the content of phenols in roots and stems of resistant soybean varieties was also more sensitive than that in leaves.This showed that the increase of PAL activity enhanced the production of phenols.The increase of flavonoids in leaves of resistant soybean varieties was higher than that in roots and stems.The activity of PPO in roots and the activ... |
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