Functional Characterization Of The SCH9 Serine/Threonine Protein Kinase In Fusarium Graminearum

Fusarium graminearum Schw. is an important plant pathogen. Studies on this pathogen, have always been a research hotspot at home and abroad. F.graminearum can infect a variety of crops, causing huge economic losses. Trichothecenes, produced by F.graminearum, not only poison human and livestock, but also seriously reduce the commercial value of wheat. Since the publication of the whole genome sequence of PH-1, the functional genomics have been developed rapidly. Some new techniques have been used to study gene functions of F. graminearum, and especially, the knockout method based on vivo homologous recombination has many advantages.The genome size of PH-1 strain is 36.1 Mb in four chromosomes. Kinases are a famlily of proteins that can transfer the phosphate group from donors (such as ATP) to a specific target enzyme, and such process is termed as phosphorylation. Phosphorylation and dephosphorylation mediated by protein kinase and protein phosphatase are common regulation ways of signal transduction in vivo, which were involved in almost all of the physiological and pathological processes. At present, about 120 protein kinase genes have been predicted in F. graminearum. As a protein kinase, SCH9 gene plays an essential role. Sch9 is a substrate of yeast TORC1. There are 6 amino acids of AGC-type protein kinase Sch9 C terminal can be directly phosphorylated by TORC1. While rapamycin treatment, nitrogen starvation, short-term osmotic stress, oxidative stress or heat stress , Sch9 occurs dephosphorylation. Through phosphorylation and dephosphorylation, Sch9 to regulate ribosome production, translation initiation, cells enter the G0 and so on.We used the split PCR and PEG-mediated protoplast transformation to obtain hygromycin-resistant transformants and then screened these transformants by PCR with four pairs of primers and southern blot to get fgsch9 deletion mutants. We conducted a series of assays for fgsch9 deletion mutant, including colonial morphology, growth rate, conidiation, germination, sexual production, plant infection and stress assays. The fgsch9 deletion mutant is defective in growth rate, conidiation, germination, aerial hyphae, response to stresses, toxin production, virulence in wheat and maize, however, it is normal in conidia morphology and sexual production. Such data suggest that SCH9 plays an essential role in growth, metabolism, pathogenicity and response to stresses.