Functional Analysis Of CmMPK1 In Conidiation And Mycoparasitism Of Coniothyrium Minitans

Coniothyrium minitans is an important fungus for biological control of Sclerotinia sclerotiorum. Presently, some genes have been reported to function in conidial production and parasitism. The mechanisms of parasitism and conidiation are complicated. Conidiation is crucial for commercial use of all biological agents, therefore it is necessary to study the conidiation regulating network of C. minitans. In this research we cloned a MAPK gene Cm MPK1 by molecular biological techniques in C. minitans, and investigated the functions of Cm MPK1 in conidiation and parasitism. The results are listed as follows:The gene includes five extrons and encodes a kinase protein with 384 amino acids. It contains a S-TKc conserved domain and belongs to PKc-superfamily. In filamentous fungi, Cm MPK1 clustered with MPKB in Aspergillus nidulans and Taphrina deformans, MAP1 in Blumeria graminis, and FUS3 in Saccharomyces cerevisiae. Cm MPK1 belongs to the branch of FUS3 / KSS1 in MAPK cascade pathway. The expression level of Cm MPK1 at the conidial production stage is higher than that at the hyphal growth stage.Cm MPK1 in the FUS3/KSS1-MAPK pathway is required for condition, formation of pigment and sclerotial mycoparasitism. The Cm MPK1 knockout mutants and Cm MPK1 complementary mutants were obtained. The Cm MPK1 knockout mutants lost the ability to produce conidia and form pigment. The sclerotial parasitization ability was significantly decreased, while biomass production was significantly increased in the Cm MPK1 knockout mutants. All the defective phenotypes were restored in the Cm MPK1 complementary mutants. In addition, compared to strain ZS-1, the tolerance to the high concentration of calcium condition was enhanced and the production of ROS was increased in Cm MPK1 knockout mutants. The knockout mutant was more sensitive to carbendazim. These phenomena might be related to calcium signal transduction pathways, ROS regulation and cytoskeleton stability.The expression of gene Cm NOX1, Cm HOG1, Cm SLT2 and Cm AMN1 were down regulated in Cm MPK1 knockout mutant. There were no direct interaction between Cm MPK1 and Cm NOX1, Cm HOG1, Cm SLT2 and Cm AMN1 identified by yeast two hybridization techniques. The results suggested that FUS3/KSS1-MAPK pathyway, CWI-MAPK pathyway and HOG-MAPK may regulate the production of conidiia and sclerotial parasitization complicatedly.