Transcriptome analysis reveals the pathogenic mechanisms of Geotrichum citri-aurantii invading citrus during early stages

Citrus, as an important horticultural product, is consistently decayed by Geotrichum citri-aurantii (G. citri-aurantii), causing serious economic losses. The infection pattern and pathogenic mechanism of G. citri-aurantii on citrus need to be explored to effectively prevent and controll sour rot. Hence, the early infestation and potential pathogenicity of G. citri-aurantii on citrus was systematically investigated. During G. citri-aurantii invading citrus, cell wall degradation enzymes were secreted and the activities of primary cell wall degradation enzymes reached the peak at 48 h. Scanning electron microscope (SEM) observed that the formation, increase and robust growth of mycelia occurred at 12, 24, 48 h post-inoculation, respectively, which became critical infestation time points. RNA-seq analysis revealed that the potential pathogenic mechanism of G. citri-aurantii infection on citrus was mainly related to secretion of cell wall degradation enzymes, participation in arginine metabolism and antioxidative stress reaction. This research provides some new insights for the potential pathogenic mechanism of G. citri-aurantii invading citrus.