Production of cell wall-degrading enzymes by Botryosphaeria spp. and their genetic relationship based upon ITS and RAPD sequences

Eight isolates of Botryosphaeria spp. (anamorphs and teleomorphs) collected from different host plants and fruit at different geographical locations in Brazil, were evaluated for their growth and the production of cell wall-degrading enzymes (laccases, pectinases and b-1,3-glucanases), when grown on basal medium in the absence and presence of the laccase inducer, veratryl alcohol (VA). They were compared with an Australian isolate identified as Botryosphaeria rhodina for reference purposes. The genetic relationship among the nine isolates (fruit, leaf, tree and vegetable) was determined based upon the Internal Transcribed Spacer (ITS) sequence of rDNA, and Random Amplification of Polymorphic DNA (RAPD) data. ITS sequence analysis showed eight closely-related isolates classified as B. rhodina and its anamorph, Lasiodiplodia theobromae, and one isolate that was out of the main cluster and identified as B. ribis. RAPD analysis resolved the isolates into 2 main clusters, one constituted by four isolates with high polymorphism (Group-I), and a second (3 isolates) without polymorphism (Group-II). Strains belonging to Group-I produced higher levels of basal and VA-induced laccase, as well as b-1,3-glucanase; whereas the Group-II strains produced lower levels of these enzymes. There appears to be no correlation between pectinase production and genetic diversity among the nine isolates examined. However, the strain characterized as B. ribis positioned out of the main cluster, was found to be the highest producer of pectinases when grown in the presence of VA. In this case, it appears, in contrast to the other Botryosphaerial spp. studied where the cell wall-degrading enzymes were repressed by VA, that VA de-repressed the synthesis of pectinase. Supported by FUNDAÇÃO ARAUCÁRIA, CAPES, PROPPG-UEL.