Effects of culture ages on the production and activities of polygalacturonase and cellulase (CX) enzymes produced by Pythium aphanidermatum (Edson Fitzpat.) Isolated from soft stem rot disease of cowpea.

Abstract

Effect of culture ages was investigated on the production and activities of polygalacturonase (PG) and Cx cellulase enzymes. Pythium aphanidermatum was isolated from cowpea seedlings infected by soft stem rot disease and prepared into pure culture through successive culturing. Two discs (2 mm each) of two-day-old culture of P. aphanidermatum were put into 21 Erlenmeyer flasks containing 50 ml of Reese and Levinson’s solution, consisting of Sodium Polypectate (NaPP) as carbon source, and incubated for 7 days at 38oC. At one-day interval, content of 3 flasks was independently centrifuged at 10,000g for 30 min. The PG enzyme activity was determined viscometrically and expressed as the Relative Viscometric Unit (RVU). Data collected were analysed using analysis of variance (Anova) and the means separated by the Duncan Multiple Range Test. Activity of Cx cellulase enzyme was also evaluated by the same method used for PG enzyme but using, carboxylmethyl cellulose (CMC) as the carbon source. The results showed that there was significant difference in the production and activities of PG and Cx enzymes in the various days of the incubation. The PG and Cx enzymes were produced progressively from the 1st day of incubation and reached their peak on the 5th day for PG (RVU 105) and 4th day for Cx (RVU 49), after which, production and activities of the enzymes started declining. Results suggested that soft stem rot disease in cowpea is a monocyclic disease, whereby any attacked plant that is able to withstand the disease is capable of surviving after the peak of the infection.

Key words: Pythium aphanidermatum, polygalacturonase, Cx cellulose,enzymes, viscometric, rot, disease.