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Monocarboxylate transporters (MCTs) play vital roles in carbon source assimilation, drug resistance and virulence. However, the underlying function of MCTs in fungal pathogenesis and development has not been investigated in detail. In this study, we identified and characterized the monocarboxylate transporter gene MCT1 of Colletotrichum gloeosporioides, which is the causal agent of Glomerella leaf spot of apple. Mct1 is localized to the mitochondria and may mediate the uptake of lactate to the cell. However, MCT1 was constitutively expressed but showed an enhanced expression level in response to the presence of the extracellular lactate. Our results indicate that Mct1 plays a role in the metabolism of lactate. More importantly, the Δmct1 mutant showed significantly poor conidiation and a defect in host infection. Taken together, our studies provide evidence for Mct1 as a mitochondrial transmembrane protein mediating conidiation, the metabolism of lactate, and the pathogenicity of C. gloeosporioides. [ABSTRACT FROM AUTHOR]

Glomerella leaf spot of apple, caused by Colletotrichumgloeosporioides, is a devastating disease that leads to severe defoliation and fruit spots. The Colletotrichum species secretes a series of effectors to manipulate the host's immune response, facilitating its colonization in plants. However, the mechanism by which the effector of C. gloeosporioides inhibits the defenses of the host remains unclear. In this study, we reported a novel effector Sntf2 of C. gloeosporioides. The transient expression of SNTF2 inhibits BAX-induced cell death in tobacco plants. Sntf2 suppresses plant defense responses by reducing callose deposition and H2O2 accumulation. SNTF2 is upregulated during infection, and its deletion reduces virulence to the plant. Sntf2 is localized to the chloroplasts and interacts with Mdycf39 (a chloroplast PSII assembly factor) in apple leaves. The Mdycf39 overexpression line increases susceptibility to C. gloeosporioides, whereas the Mdycf39 transgenic silent line does not grow normally with pale white leaves, indicating that Sntf2 disturbs plant defense responses and growth by targeting Mdycf39. [ABSTRACT FROM AUTHOR]

Carbamoyl phosphate synthetase is involved in arginine biosynthesis in many organisms. In this study, we investigate the biological function of Cpa1, a small subunit of carbamoyl phosphate synthetase of Colletotrichum gloeosporioides. The deletion of the CPA1 gene affected vegetative growth, arginine biosynthesis, and fungal pathogenicity. Genetic complementation with native CPA1 fully recovered all these defective phenotypes. We observed that Cpa1-RFP fusion protein is localized at the mitochondria, which is consistent with Cpa2, a large subunit of carbamoyl phosphate synthetase. We identified the proteins that interact with Cpa1 by using the two-hybrid screen approach, and we showed that Dut1 interacts with Cpa1 but without Cpa2 in vivo. Dut1 is dispensable for hyphal growth, appressorial formation, and fungal pathogenicity. Interestingly, the Dut1-Cpa1 complex is localized at the mitochondria. Further studies showed that Dut1 regulates Cpa1-Cpa2 interaction in response to arginine. In summary, our studies provide new insights into how Cpa1 interacts with its partner proteins to mediate arginine synthesis. Image 1 • Cpa1 is important for full virulence. • Cpa1 is indispensable for arginine biosynthesis. • Dut1 interacts with Cpa1 but without Cpa2. • Dut1 regulates Cpa1-Cpa2 interaction in response to arginine. [ABSTRACT FROM AUTHOR]

• CgSet5 is indispensable for full virulence. • CgSet5 is important for conidiation and appressorium formation. • CgSet5 is involved in cell wall integrity. • CgSet5 is involved in peroxisome biogenesis. • CgSet5 methylates the lysine residues 5 and 8 of histone H4. The chromatin modulator Set5 plays important regulatory roles in both cell growth and stress responses of Saccharomyces cerevisiae. However, its function in filamentous fungi remains poorly understood. Here, we report the pathogenicity-related gene CgSET5 discovered in a T-DNA insertional mutant M285 of Colletotrichum gloeosporioides. Bioinformatic analysis revealed that CgSET5 encodes a SET domain-containing protein that is a homolog of the budding yeast S. cerevisiae Set5. CgSET5 is important for hyphae growth and conidiation and is necessary for appressorium formation and pathogenicity. CgSet5 regulates appressorium formation in a mitogen-activated protein kinase-independent manner. Inactivation of CgSET5 resulted in a significant reduction in chitin content within the cell wall, indicating CgSet5 plays a vital role in cell wall integrity. CgSet5 is involved in peroxisome biogenesis. We identified CgSet5 as the histone H4 methyltransferase, which methylates the critical H4 lysine residues 5 and 8 in C. gloeosporioides. We carried out a yeast two-hybrid screen to find CgSet5 interacting partners. We found CgSet5 putatively interacts with an inorganic pyrophosphatase named CgPpa1, which co-localized in the cytoplasm with CgSet5. Finally, CgPpa1 was found to strongly interact with CgSet5 in vivo during appressorium formation by bimolecular fluorescence complementation assays. These data corroborate a complex control function of CgSet5 acting as a core pathogenic regulator, which connects cell wall integrity and peroxisome biogenesis in C. gloeosporioides. [ABSTRACT FROM AUTHOR]