Objective: Cloning of a Homologous Gene of PMK1 Type Mitogen-Activated Protein Kinase (MAPK) from the rice false smut fungus Ustilaginoidea virens.
Methods: According to the conserved amino acid sequence of several filamentous fungus MAPKs, which were homologous to Magnaporthe grisea PMKI, degenerate PCR primers were designed to amplify the MAPK internal DNA fragment from Ustilaginoidea grisea. The complete UVMK1 DNA and cDNA sequences were obtained using Thermal Asymmetric Interlaced-PCR (TAIL-PCR) and RT-PCR methods. Functional Identification was done by using the M. grisea APMKI mutant stain nn78, including appressoria differentiation assay and barley infection test.
Results: The total length of UVMKJ was 1435 bp. It contained 3 introns and encoded 355 amino acids. The induced amino acid sequence showed identical to Magnaporthe grisea PMKI, Fusarium oxysporum FMKJ, Fusarium solani FsMAPK, Colletotrichum lagenarium CMKI, Botrytis cinerea BMKI, Claviceps purpurea CMPKI. After transformation of the APMK1 mutant of M. grisea using a complement vector with the complete cDNA of UVMK1 (under the M. grisea MPG1 promoter), five transformants were obtained. Furthermore, the selected two transformants fully restored their ability to form appressoria and infect a barley leaf.
Conclusion: In this study, we characterized the frst MAPK protein from U. virens, and that UVMK1 is a homologue of M. grisea PMK1.