Abstract

Macrophomina phaseolina is the causative agent of a wide group of plant diseases exhibiting various symptoms via secreting an array of degrading enzymes including pectinases, and cellulases that mainly affect plant cell walls. This research was conducted during 2018 to 2019 to investigate the fungal biochemical and genetic variations of 25 M. Phaseolina isolates obtained from previously conducted study. Cellulase and pectinase activities were estimated on synthetic media by measuring the clear zone around the inoculation center. Cellulase and pectinase activities of the isolates showed highly variations in the clear zone diameter ranged between (0.5–7) mm and (1–14) mm respectively. Changes in the enzymatic activities were found to correspond to various environmental and biological conditions of the infected plants where the phytopathogen was isolated. Data have been unambiguously shown that unlike pectinase, cellulase activity and pathogenecity of M. Phaseolina as a result increases with gradual increase of humidity and relative temperature between 25–35°C in Jordan. In all tested samples, isolates no. 3, 12, 7, and 17 were recorded to have the highest level of cellulase and pectinase activity. Random amplification of polymorphic DNA (RAPD) of M. phaseolina isolates DNA using OPA09, OPA14 as well as OPA18 operon primers was investigated. Even though bands of certain size were found to be conserved among the 25 isolates, polymorphic bands distinguish every isolate were noticed. Computed dendrogram based on the randomly amplified bands classified the 25 isolates into three major clades. The third major clade, in particular isolate no. 17, was hypothesized to constitute the ancestor of M Phaseolina as it contained only basic bands found on other isolates. Additionally, this isolate was found to be highly distant from other isolates and has the highest pectinase and cellulase activity. In this work RAPD technique was considered as a powerful technique as it was able to discriminate even between very similar fungal isolates.