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 Monosporascus species, M. brasiliensis, M. caatinguensis, M. mossoroensis, M. nordestinus, and M. semiaridus, 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 Monosporascus 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 Monosporascus spp. in greenhouse experiments using artificial inoculation of roots. Moreover, all Monosporascus spp. were highly susceptible to the fungicides fludioxonil and fluazinam. Our findings provide relevant information about the response of these new Monosporascus spp. to environmental factors, plant genotypes and fungicides.

Effect of environmental factors, fungicide sensitivity, and pathogenicity of Fusarium spp. associated with fruit rot of melon

“…In a previous study carried out by Pacheco Marino et al (2016), the same in vitro growth reduction trend was verified in different NaCl concentrations for two Fusarium isolates within the FIESC and FSSC complex. Salt stress is one of the main environmental restrictions in semi‐arid regions where cucurbits are grown, such as northeastern Brazil (Cavalcante et al, 2020). The increase in salinity can have a direct response on the vegetative structure (mycelium) of the fungus, causing osmotic stress or acting as a toxic component, interfering with the stability of the membranes and/or enzymatic activity of the fungus (Adler, 1996; Pacheco Marino et al, 2016).…”

Post-genomic analysis of Monosporascus cannonballus and Macrophomina phaseolina - potential target selection

“…This thermophilic fungus, with an optimal growth temperature ranging from 25 to 35ºC, is well-adapted to semi-arid and arid conditions, thus thriving in the northeast region of Brazil (Sales Júnior et al, 2018). Despite the ongoing challenges in controlling this pathogen, there are currently no registered products for its management, with limited reports of fludioxonil and fluazinam inhibiting M. cannonballus mycelial growth (Sales Júnior et al, 2018;Cavalcante et al, 2020;Tavares et al, 2023). Integrated management combining various control techniques appears to be the best approach for disease control (Sales Júnior et al, 2018).…”