As a main causal agent of wheat crown rot, Fusarium pseudograminearum secrets numerous proteins into the host during the infection process to regulate host immune responses and contribute to the virulence of F. pseudograminearum.  In this study, the secreted protein Fp00392 from F. pseudograminearum was found to trigger cell death in Nicotiana benthamiana.  Purified Fp00392 protein could activate the ROS burst, callose deposition, and the upregulation of defense-related genes in N. benthamiana.  Moreover, the VIGS assay in N. benthamiana showed that Fp00392-triggered cell death is independent of BAK1 and SOBIR1.  Furthermore, the transcript level of Fp00392 was significantly induced during F. pseudograminearum infection.  Knockout of Fp00392 significantly attenuated the pathogenicity of F. pseudograminearum on wheat coleoptiles.  Deletion of Fp00392 affected the sensitivity of F. pseudograminearum to H₂O₂ and Congo Red.  Overall, these results indicate that Fp00392 can not only induce plant immune response as a PAMP, but it can also promote F. pseudograminearum infection as a virulence factor.

Magnaporthe oryzae is the causal agent of rice blast.  Glycosylation plays key roles in vegetative growth, development, and infection of M. oryzae.  However, several glycosylation-related genes have not been characterized.  In this study, we identified a Glyco_transf_22 domain-containing protein, MoAlg9, and found that MoAlg9 is localized to the endoplasmic reticulum (ER).  Deletion of MoALG9 significantly affected conidial production, normal appressorium formation, responses to stressors, and pathogenicity of M. oryzae.  We also found that the ΔMoalg9 mutant was defective in glycogen utilization, appressorial penetration, and invasive growth in host cells.  Moreover, we further demonstrated that MoALG9 regulates the transcription of several target genes involved in conidiation, appressorium formation, and cell wall integrity.  In addition, we found that the Glyco_transf_22 domain is essential for normal MoAlg9 function and localization.  We also provide evidence that MoAlg9 is involved in N-glycosylation pathway in M. oryzae.  Taken together, these results show that MoAlg9 is important for conidiation, appressorium formation, maintenance of cell wall integrity, and the pathogenesis of M. oryzae.

Rice blast, caused by Magnaporthe oryzae, is a fungal disease that causes devastating damage to rice production worldwide.  During infection, pathogens secrete effector proteins that modulate plant immunity.  Disulfide bond formation catalyzed by protein disulfide isomerases (PDI) is essential for protein folding and maturation.  However, the biological function of Pdi1 in M. oryzae has not yet been characterized.  In this study, we identified the endoplasmic reticulum (ER)-located protein, MoPdi1, in M. oryzae.  MoPdi1 regulates conidiation, cell wall stress, and pathogenicity of M. oryzae.  Furthermore, the CGHC active sites in the a and a’ redox domain of MoPdi1 were essential for the biological function of MoPDI1.  Further tests demonstrated that MoPdi1 was involved in the regulation of ER stress and positively regulated ER phagy.  We also found that MoPdi1 interacted with MoHut1.  Deletion of MoPDI1 led to the bereft of MoHut1 dimerization, which depends on the formation of disulfide bonds.  In addition, MoPdi1 affected the normal secretion of the cytoplasmic effector AVR-Pia.  We provided evidence that MoHut1 is important for the vegetative growth, conidiation, and pathogenicity in M. oryzae.  Therefore, our findings could provide a suitable target point for designing antifungal agrochemicals against rice blast fungus.