Aspergillus flavus-secreted proteins during an in vivo fungal-cotton carpel tissue interaction

Cotton bolls (Gossypium hirsutum) were inoculated with Aspergillus flavus to investigate extracellular hydrolases produced during infection. Fungal proteins from the infection site were isolated and analyzed by SDS-PAGE. Protein bands were excised and analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). We identified several proteins including an exoglucanase 1 precursor (AFL2G_03805), a hypothetical protein similar to rhamnogalacturonan lyase A (AFL2G_05136), and a hypothetical protein similar to pectate lyase A (AFL2G_05954). We also matched three peptides to an oryzin precursor protein (AFL2G_01995). Our findings support the conclusion that glucanase, pectinolytic, and proteolytic proteins are important for fungal maceration of cotton carpel tissue during infection.