The Colletotrichum siamense Hydrophobin CsHydr1 Interacts with the Lipid Droplet-Coating Protein CsCap20 and Regulates Lipid Metabolism and Virulence

Abstract

Previous studies of the lipid droplet-coating protein Cap20 in Colletotrichum show that it plays a key role in appressorium development and virulence. In this study, the hydrophobin CsHydr1, which contains a signal peptide of 19 amino acids and a hydrophobic domain (HYDRO), was shown to interact with CsCap20 in Colletotrichum siamense. The CsHydr1 deletion mutant showed slightly enhanced mycelial growth, small conidia, slow spore germination and appressoria formation, cell wall integrity and virulence. Like CsCAP20, CsHydr1 is also localized on the lipid droplet surface of C. siamense. However, when CsCap20 was absent, some CsHydr1 was observed in other parts. Quantitative lipid determination showed that the absence of either CsHydr1 or CsCap20 reduced the content of lipids in mycelia and conidia, while the effect of CsCap20 was more obvious; these results suggest that an interaction protein CsHydr1 of CsCap20 is localized on the lipid droplet surface and involved in lipid metabolism, which affects appressorium formation and virulence in C. siamense.

The fatty acid 2-hydroxylase CsSCS7 is a key hyphal growth factor and potential control target in Colletotrichum siamense

“…Homologous recombination for CsSCS7 gene deletion was performed as described previously ( 21 , 55 ). According to the sequence of CsSCS7 obtained above, we designed CsSCS7-UF/CsSCS7-UR and CsSCS7-DF/CsSCS7-DR to amplify fragments upstream and downstream of the ORF region and named them U (upstream) and D (downstream), and the linkers were added individually.…”

“…For pathogenicity assessment assays, 10 µL of spore suspensions (1 × 10 5 /mL) of the tested strains was dropped on the tender leaves with or without wounding as described by Wang et al ( 21 ). Three technical replicates of each treatment were included in the experiment, and 30 leaves were inoculated for each treatment.…”

“…are members of an important genus of plant pathogenic filamentous fungi ( 1 ). C. siamense is reportedly one of the major pathogenic species of many tropical or subtropical crops, including rubber trees ( 21 ). Our research group previously screened and identified the fatty acid hydroxylase CsSCS7, which exhibit 51% identity to S. cerevisiae SCS7, as the interacting protein of the core member CsPbs2 of the HOG MAPK in C. siamense ( 22 ).…”

The Plasma Membrane H+ ATPase CsPMA2 Regulates Lipid Droplet Formation, Appressorial Development and Virulence in Colletotrichum siamense

“…To determine the localization of lipids, mycelia and conidia of strains were stained with Nile Red solution (Solarbio, Beijing, China) as described by Wang et al [35]. The fluorescence channel of RFP was used for observation.…”

“…These proteins often play roles in appressorial development and affect virulence in pathogenic fungi. For example, MPL1 in Metarhizium anisopliae and Cap20 in Colletotrichum gloeosporioides encode lipid droplet coat proteins and play an important role in lipid metabolism, appressorial turgor pressure and virulence [24,34,35]. Nem1 in Magnaporthe oryzae is also a lipid droplet-associated protein that plays a key role in LD biogenesis and regulates appressorial function during infection [31].…”