| Rice blast disease, caused by Magnaporthe oryzae, is one of the most destructive causal agents during rice cultivation and severely threaten the yield of rice crops. Recently, with the whole-genome sequencing of M. oryzae and the development of molecular biology, gene function studies to understand the fungi development and its pathogenicity related molecular mechanisms would be crucial for preventing the occurrence of the disease.Most likely all organisms have to cope with oxidative stress conditions during their life-span. In Schizosaccharomyces pombe, Pap1dominates the response to low ROS levels while Yap1, the Papl homologue in Saccharomyces cerevisiae, also induces the expression of oxidative stress response (OSR) genes. Yapl is restricted to the cytoplasm due to the nuclear export by Crml in the presense of Ran/Gspl. Upon exposured to H2O2, Yap1is oxidated to its intra-molecular disulfide bond, the activated form of the regulator, which may mask the NES in a way that prevents recognition by Crml and allow Yapl to accumulate in the nucleus. Guo et al. characterized a bZIP transcription factor (TF) MoAp1, a homolog of Pap1that regulates the oxidative stress response in M. oryzae. In this study, we focused on the localization of MoApl response to the oxidative stress in M. oryzae. While exposured to2mM H2O2, MoApl localized to the nucleus of conidia, as well as the invasive hyphae after inoculated barley24h. But when the predicted nuclear location signal (NLS) near the N-terminal of MoApl was deleted, the MoAplANLS could no longer localize to the nucleus when treated with2mM H2O2. In addition, we characterized MoCrm1and MoGsp1in M. oryzae, which were the homologs of Crm1and Gsp1in S. cerevisiae respectively. Both MoCRM1and MoGSPl were essential in M. oryzae and their silencing mutants had effects on the export of MoAp1from the nucleus but none on the pathogenicity. The results above indicated that MoApl plays a role in response to oxidative stress in M. oryzae based on the nuclear localization, of which the mechanism is just like Yap1in S. cerevisiae, and the predicted NLS near the N-terminal may be a crucial domain for nuclear import. In addition, the export of MoAp1to cytoplasm requires both MoCrm1and MoGspl.Tupl-Cyc8is one of the most important transcriptional corepressors in many species and participates in several important processes via associating with a variety of DNA-binding repressor proteins that direct its recruitment to particular subsets of genes. Tupl plays a crucial role in fungal dimorphism and virulence of animal and plant fungal pathogens. Alberto Eli’as-Villalobos et al. observed that infections with△tupl cells led to a reduction in tumor formation, plant death, and a failure of spore formation, indicating that Tupl is required for full pathogenic development in Ustilago maydis. We characterized MoTupl in M. oryzae, a homolog of Tupl in S. pombe. The deletion of MoTUP1from M. oryzae resulted in reduced mycelia growth and defects in conidiogenesis. Pathogenicity assay indicated that MoTUPl deletion mutants lost the ability to invade in both rice and barley. Rice epidermis penetration observation showed that the hyphal tips of the mutants could form appressorium-like structures but they were unable to invade into the rice epidermis cells. In conclusion, the above results indicated that MoTupl is an important regulation factor during the growth and development, and it is responsible for the pathogenicity on rice and barley in M. oryzae. |
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