| Magnaporthe oryzae is an important model organism for the study of functionalgenomics of filamentous fungi and molecular plant pathology. Rice blast caused by M.oryzae is widely prevailed and heavy damaged, and difficult to control. Therefore,analyzing the molecular mechanism how M. oryzae deals with host adversity and causesdisease using announced genome sequence and perfectly genetic transformation systemwill provide new idea for exploring efficient strategy to prevent and control rice blast.Pre-mRNA splicing is a common way of gene expression and regulation ineukaryote. This process is catalyzed by spliceosome composed of U1, U2, U4, U5, U6snRNP and other specific proteins. SMN and U1A proteins are both involved in theassembly and reconstruction of snRNPs. In this study, the functions of MoSMN (MOS)and MoU1A in M. oryzae, as ySMN and U1A homologs in Schizosaccharomycespombe, were intensely researched concerning growth and development, adversityresistance and pathogenicity at level of molecular biology. The results as follow:1. MOS gene was cloned, and was identified as single copy. Whereas it wasdetected to contain three transcript isoforms. The three MOS isoforms are all acidproteins containing SMN domain without signal peptide. Spatial structure analysisindicated that N-terminals of the three isoforms possess high homology with2leh1B,the core of SMN-Sip1complex. QRT-PCR analysis revealed that the three transcriptsplay different roles during conidiogenesis and adversity resistance in M. oryzae.2. Genetic studies showed that MOS disruption dramatically reduced pigmentation,conidiation, adversity resistance, differentiation and expanding growth of infectioushyphae, and pathogenicity. However, there are no obviously effects on mycelial growthrate, conidial morphology, and appressorium formation in M. oryzae. 3. RNA-Seq analysis revealed that expression of603genes were down-regulatedin ΔMOS compared with wild strain ZLJ88under oxidative stress. Thesedown-regulated genes are mainly related to the biosynthesis of secondary metabolites,amino acid metabolism, aminoacyl-tRNA synthesis through Gene ontology analysis andPathway enrichment analysis of DEGs. Among the down-regulated18genes withlog2Ratio (ZLJ88/ΔMOS)≥2, at least6are involved in the pathogenicity andsecondary metabolism. In addition, MOS disruption can alter splicing forms of genesinvolved in spliceosome formation and splicing process. Then normal splicing of otherpre-mRNAs in genome are affected.4. Bioinformatics showed that MoU1A contained two identical RNA recognitionmotifs (RRMs). An RRM at N-terminal is comprised of conserved RNP1and RNP2elements. Spatial structure analysis indicated that MoU1A is similar to4pkd.1.B with a30.59%in tertiary structure. Therefore, it is inferred that MoU1A maybe play a role inpre-mRNA splicing.5. MoU1A disruption will cause the death of M. oryzae. Therefore, RNAinterference and gene overexpression technologies were used in this study. The resultsshowed that the MoU1A abnormal expression could change adversity resistance,conidiation amount, the abnormal conidiation-ratio, and the capabilities of branchingafter penetration. Therefore, the pathogenicity was decreased to some extent in M.oryzae. In addition, the mycelial growth rate of RNAi mutant was similar to the widetype, whereas that of overexpression mutant OE-10was significantly less. |
PDF Full Text Request