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Pectolytic enzymes were extracted it apple fruits rotted by Botryosphaeria dothidea, and their activities and change of pectic substances were investigated. Exo-polygalacturonase(exo-PG), exo-polymethylgalacturonase(exo-PMG), polygalacturonate-trans-eliminase(PGTE) and pectinmethyl-traps-eliminase(PMTE) were produced by the pathogen. Activities of exo-PG and exo-PMG extracted from rotten apple fruits were high to 21.15 and 24.65 units/㎎ protein in specific activity at seven days after inoculation, respectively. Activities of PGTE and PMTS showed 5.60 and 7.90 units/㎎ protein, respectively, but they were lower than those of the exo-type enzymes. Water-soluble and versene-soluble pectins were 11.50 ㎎/100 ㎎-AIS and 7.31 ㎎/100 ㎎-AIS at 14 days after inoculation, namely, they were increased by 4.23 and 2.16 ㎎/100 ㎎-AIS over those of sound apples, respectively. Total soluble pectic substances of rotten apple were 72.4% of total pectic substances and it was higher by 24.8% than sound apple. Insoluble pactic substance was notably decreased from 15.32 to 7.16 ㎎/100 ㎎-AIS according to progress of decay while total pectic substances were not changed remarkably.
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