Characterization of Five New Monosporascus Species: Adaptation to Environmental Factors, Pathogenicity to Cucurbits and Sensitivity to Fungicides

Abstract

In this study, five new recently described <i>Monosporascus</i> species, <i>M</i>. <i>brasiliensis</i>, <i>M</i>. <i>caatinguensis</i>, <i>M</i>. <i>mossoroensis</i>, <i>M</i>. <i>nordestinus</i>, and <i>M</i>. <i>semiaridus,</i> which were found on weeds collected from cucurbit cultivation fields in northeastern Brazil, are characterized regarding mycelial growth at different pH levels and salinity (NaCl) concentrations, their pathogenicity to selected cucurbit species, and their sensitivity to fungicides with different modes of action. Our results reveal great variability among the representative isolates of each <i>Monosporascus</i> spp. All of them showed a wide range of tolerance to different pH levels, and NaCl significantly reduced their in vitro mycelial growth, although no concentration was able to inhibit them completely. In pathogenicity tests, all seedlings of cucurbits evaluated, melon, watermelon, cucumber, and pumpkin, were susceptible to the five <i>Monosporascus</i> spp. in greenhouse experiments using artificial inoculation of roots. Moreover, all <i>Monosporascus</i> spp. were highly susceptible to the fungicides fludioxonil and fluazinam. Our findings provide relevant information about the response of these new <i>Monosporascus</i> spp. to environmental factors, plant genotypes and fungicides.