Karyopherin SsKapJ is related to mating/filamentation in Sporisorium scitamineum

In order to study the role of karyopherin SsKapJ in the sugarcane smut fungus Sporisorium scitamineum, we generated the deletion mutant using the PEG-mediated protoplast transformation method. The SsKapJ mutant displayed significant reduction in mating/filamentation. Transcriptional profiling revealed that the SsKapJ mutant is involved in regulation of cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) and mitogen-activated protein kinase (MAPK) signaling pathway. Meanwhile, the haploid sporidia of mutant was more sensitive to pyraclostrobin fungicide. However, the mutant showed no difference in sensitivity towards benomyl fungicide or the tested stressful conditions (osmotic pressure, cell wall, redox and ethanol) compared with wild type. In summary, the SsKapJ karyopherin plays an important role in sexual mating/filamentation of S. scitamineum, which could provide a basis for further study on the nuclear transport pathway for regulation of fungal sexual mating/dimorphic switch.