| Plant can produce many pathogenesis-related protein when plant was infested by pathogen or suffering the outside intimidation, PR-3 protein in PR protein family posses chitinase activity, chitinase was closely related to plant defense reaction mechanism. Varieties of soybean with different resistance were inoculated by Phythophthora sojae, then activities of chitinase, inhibition effect on P. sojae of chitinase,β-1,3-glucanase and mixed liquid two kinds of enzyme were detected to study the correlation between chitinase activity and soybean resistant to Phytophthora root rot and partial enzyme properties. The results were obtained as follows:Chitinase activities of uninoculation soybean with different resistance have not significant difference. The contant and activity of chitinase were significantly increased after inoculated. Increase in activity of chitinase in resistant variety was faster than in susceptible variety, high activity of chitinase maintain for ages. Chitinase activity of resistant variety reached the peak at 24 hour, but middle susceptible and susceptible varieties reached the peak at 48 hour. The results suggested that chitinase can be induced by P. sojae and the relationship between chitinase activities and the resistance of soybean varieties were positive correlation. The optimal temperature and pH of the enzyme activity were 45℃and 5.0, respectively. The enzyme activity was stable under 45℃and in the pH range of 46 chitinase, chitinase activity losed rapidly over 60℃and pH 7. The chitinase activity was stimulated by Mn2+,Zn2+,Ba2+,Fe3+,Ca2+ and inhibited by Al3+,Ag+,Fe2+,K+,Mg2+,Cu2+,Hg2+.The inhibition effect of chitinase on mycelial growth, sporangia formation and spore germination of P. sojae was the weakest, second wasβ-1,3-glucanase, the strongest was mixed enzyme liquid. The results showed that the inhibition effect of chitinase on P. sojae was weak, but synergism of chitinase andβ-1,3-glucanase can enhance inhibition effect on P. sojae.
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