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Morphological and molecular identification of seedborne fungi in squash (Cucurbita maxima)

Gianfranco Romanazzi: Marche Polytechnic University

<div>Squash (<em>cucurbita maxima</em>) is one of the important vegetable in tropical and temperate regions. This crop can be affected by several diseases transmitted by seeds, which become a responsible for the dispersion of many pathogens. Low percentages of seed infection can still result in severe economic losses. Early detection of seedborne fungi is the first step to control diseases. Squash fruits were collected from two regions in Tunisia and were evaluated according to three levels of lesion extension: asymptomatic fruit, infected fruit showing lesions on the squash skin without colonization of the fruit cavity, and infected fruit showing lesions that had colonized the fruit cavity. Using blotter method, morphological identification of seedborne fungi was showed that <em>Didymella bryoniae</em>, <em>Alternaria alternata</em>, <em>Fusarium moniliforme</em>, <em>Fusarium solani</em>, <em>Myrothecium verrucaria</em>, <em>Myrothecium roridum</em> and <em>Pleospora herbarum</em> were the most frequent fungi. Morphological identification was confirmed by molecular diagnosis using the available genus-specific and species-specific primers. Furthermore, specific primers were designed from DNA sequence in the internal transcribed spacer (ITS) region of nuclear rDNA, to identify <em>Myrothecium</em> spp., <em>M. verrucaria</em>, <em>M. roridum</em> and <em>Pleospora</em> spp. Those results can be useful to prevent squash seedborne pathogen dispersal and related losses of production later occurring in the field.</div>