Functional Secretomics of Phytotoxic Compounds of Monosporascus cannonballus

Monosporascus cannonballus and M. eutypoides are the causative agents of melons’ root rot and vine decline, with little knowledge about their mechanisms of infection. M. cannonballus secretome was isolated and subdivided into two fractions based on molecular weight (smaller and larger than 10 kDa), and further separated via high voltage paper electrophoresis and SDS-PAGE, respectively. Large cell-free filtrates of the fungus were found to contain biologically active proteins that were further characterized via mass spectrometry and revealed to be α-1,2-mannosidase and serine protease. Meanwhile, biochemical analyses of low molecular weight compounds were suggestive to be similar to marasmines. Both fractions were capable of inducing phytotoxicity, once infiltrated into the melon leaves. This is the first report of phytotoxic compounds isolated from M. cannonballus contributing to disease induction in melon plants.