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Genetic, morphological and pathogenic characterization of Chilean isolates of Chondrostereum purpureum

Javier Chilian: INIA Quilamapu

<div><em>Chondrostereum purpureum</em> is a Basidiomycete that cause silver leaf disease. It severely affects yield and quality in several fruit species, such as apple (up to 60%) and blueberry (40%). The objective was to characterize <em>C. purpureum</em> isolates from different hosts and geographic localities, based on their genetic, morphologic and pathogenic features. A survey was conducted through the Chilean fruit production area, from 2014 to 2017. Thirty nine isolates were obtained from symptomatic woods of 10 different hosts. Isolates were grown in PDA media. Then, their morphology were described and growth measured. DNA was extracted from colonies growing edge and PCR conducted. A sequence-characterized amplified regions (SCAR) was used to group <em>C. purpureum</em> isolates. Apple cuttings cv. Gala Brookfield were inoculate using mycelial plugs and the internal necrosis was measured after 21d incubation. Cultural characteristics were similar between isolates from different hosts and geographic origins, however, there were variations on mycelial growth rate (8 to 35 mm in diameter). All isolates were pathogenic showing different virulences, such as Cato isolate (60% internal necrosis) compared to the Osorno´s one (30%). Banding patterns allowed the identification of seven groups. Cluster analysis of this molecular patterns did not match groups based on virulence, morphology, geographic location or host, indicating that <em>C. purpureum</em> is highly diverse in Chile.</div>