Roles of hydrolytic enzymes in inducible defense responses of rice against fungal pathogens
1994
Wichitra Jutidamrongphan (Prince of Songkla Univ. (Thailand). Faculty of Science. Dept. of Biochemistry)
Hydrolytic enzyme gene expression induced by fungal infection or elicitor treatment at transcriptional and translational levels has been studied. The investigation of the accumulation of transcripts of both chitinase and glucanase genes at various times after treatment with fungal elicitors revealed a differential induction. A high molecular weight fungal wall elicitor was shown to be the strongest elicitor among various types of fungal elicitors obtained from rice blast and leaf scald fungi. The mRNAs of both beta 1,3-glucanase and basic chitinase were rapidly induced within half an hour and reached a maximum in 1.5 hours in the elicitor treated rice cell suspension. Whereas the slower accumulation of the mRNAs has been shown in the infected whole leaves started from 2 hours to reach a maximum at 12 hours after inoculation. There was no induction of a mRNA of acidic chitinase in the elicitor treated cells and it was shown to already exist in normal plants. The accumulation of the hydrolytic enzymes during pathogen attack has been assayed. Beta 1,3-glucanases and chitinases showed higher activities in the infected leaves than those of non infected controls within 3 days after inoculation to a maximum in 15 days. The increases of the activities correlated with the isozyme patterns beta 1,3-glucanases and chitinases, was revealed of using an activity gel electrophoresis and Western blot analysis. One acidic isozyme of both glucanases and chitinases was shown to be a defense related enzyme in leaf tissue. Gene expression of the hydrolytic enzymes in response to pathogen infection in other tissues of rice i.e., shoot and root is still under investigated.
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