Purification and characteristics of pectin lyase from Rhizoctonia solani

Abstract

Pectin lyase was the predominant pectolytic enzyme produced by an anastomosis group 2-2 strain of Rhizoctonia solani both in culture and in infected sugar beet crowns. Sugar beet root cell walls were used as the carbon source in broth still culture. Cell walls from crowns induced more pectin lyase than cell walls from hypocotyl or root. Also, the yield of pectin lyase was higher from infected crown than from infected hypocotyl or root tissue. Rotted crown tissue had a pH of over 7, which was favourable for pectin lyase activity. Rotted root tissue, with a pH below 6, was not as favourable for pectin lyase activity. Healthy tissue had a pH of 6·5 ± 0·3. Pectin lyase was purified by affinity batch chromatography on cross-linked sodium polypectate followed by gel permeation on an agarose-based gel. Pectin lyase interacted with the agarose-based gel and eluted at or near the bed volume which resulted in a final effective purification. The molecular weight of pectin lyase from culture was determined as 35 kDa. The pI was 10.1. The purified enzyme caused wilt when injected into Rhizoctonia-susceptible sugar beet plants, but not when injected into resistant plants.