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POSTERS: Population biology and genetics

Chondrostereum purpureum diversity in symptomatic and reversed plants
Daina Grinbergs - Universidad de Concepción. Andres France- INIA Quilamapu, Javier Chilian- INIA Quilamapu, Ernesto Moya-Elizondo- Universidad de Concepcion

Chondrostereum purpureum is a fungus that causes the silverleaf disease, producing wood necrosis and foliar silvering through an endoPG enzyme. The reversion of foliar symptoms has been observed and postulated that is driven by a non-genetic mechanism. Eventually, C. purpureum populations inhabiting these plants have lost their ability to produce disease. Thus, the objective was to characterize C. purpureum isolates from symptomatic and reversed plants based on morphologic, genetic and pathogenic traits. The pathogen was isolated from symptomatic and reversed plants. Isolates morphology was described and radial growth at 5, 10, 15, 20, 25, 30 and 35°C was measured. DNA was extracted, amplified and the banding patterns analyzed. Mycelial discs were inoculated on apple cuttings and after 20 days internal necrosis was measured. Moreover, expression levels of the gene that codifies for endoPG production was studied using qPCR. From all the C. purpureum isolates, 80% were obtained from diseased plants and 20% from reversed ones. Morphology was similar among them, however, there was a wide variation on mycelial growth and pathogenicity, from avirulent to the complete necrosis of the cuttings, as well as in the endoPG gene expression. Different genetic groups were found in diseased plants, but reversed ones weren’t diverse. These results contributes to the reversion understanding, indicating that the C. purpureum features may participate on silverleaf symptom expression.