The Kinds and Activities of Cell Wall-Degrading Enzymes Produced by Valsa ceratosperma
Activities of the cell wall-degrading enzymes ( CWDEs) produced by V. Ceratosperma in vitro and in vivo were detected. The results showed that V. Ceratosperma could produce a series of CWDEs including polygalactu-ronase ( PG) ,polymethylgalacturonase ( PMG) , cellulose ( Cx) , (3-glucosidase and xylanase. The different levels of enzyme activities were obtained with V. Ceratosperma grown on five media differing in carbon sources. These corresponding days when maximum enzyme activity were detected varied also with the type of carbon source used. The CWDEs produced by V. Ceratosperma grown on three different carbon source all could macerate apple callus, however, the CWDEs produed in xylan medium showed the most powerful macerating ability. In addition, time-course experiments showed that the changes of CWDEs activities in detached apple branches inoculated by V. Ceratosperma were different. The activities of PMG and xylanase were first detected at enhanced levels in diseased branches. The PMG activity reached the peak at 13 days post-inocualtion and then it decreased, while activities of the other four enzymes increased as the disease development. In all the CWDEs, the maximum activity of Cx was the lowest, and xylanase maximum activity was the highest which was 1.74 -7.44 times of the other four enzymes.
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