Sclerotinia sclerotiorum SsCut1 Modulates Virulence and Cutinase Activity

The plant cuticle is one of the protective layers of the external surface of plant tissues. Plants use the cuticle layer to reduce water loss and resist pathogen infection. Fungi release cell wall-degrading enzymes to destroy the epidermis of plants to achieve the purpose of infection. Sclerotinia sclerotiorum secretes a large amount of cutinase to disrupt the cuticle layer of plants during the infection process. In order to further understand the role of cutinase in the pathogenic process of S. sclerotiorum, the S. sclerotiorum cutinsae 1 (SsCut1) gene was cloned and analyzed. The protein SsCut1 contains the conserved cutinase domain and a fungal cellulose-binding domain. RT-qPCR results showed that the expression of SsCut1 was significantly upregulated during infection. Split-Marker recombination was utilized for the deletion of the SsCut1 gene, ΔSsCut1 mutants showed reduced cutinase activity and virulence, but the deletion of the SsCut1 gene had no effect on the growth rate, colony morphology, oxalic acid production, infection cushion formation and sclerotial development. Complementation with the wild-type SsCut1 allele restored the cutinase activity and virulence to the wild-type level. Interestingly, expression of SsCut1 in plants can trigger defense responses, but it also enhanced plant susceptibility to SsCut1 gene knock-out mutants. Taken together, our finding demonstrated that the SsCut1 gene promotes the virulence of S. sclerotiorum by enhancing its cutinase activity.

Effects and mechanism of Chinese medicine Jiawei Yupingfeng in a mouse model of allergic rhinitis.

OBJECTIVE: Chinese medicine has the potential to modulate allergic rhinitis (AR). There have been studies investigating the treatment efficacy of Yupingfeng San, alone or in combination with other ingredients, in AR, though few have studied the potential mechanisms of these drugs. In the present study, we measured the effects of Jiawei Yupingfeng (JWYPF), a traditional Chinese medicine formula, on mice with ovalbumin-induced AR and explored its underlying mechanism of action. METHODS: Forty BALB/c mice were randomly divided into normal control, allergy control and two treatment groups of ten mice each. In the normal control group, mice were sensitized and challenged with saline. The mice in the allergy control and treatment groups were sensitized and challenged with ovalbumin and aluminum hydroxide gel. The treatments of JWYPF and Nasonex were administered intranasally in the AR mice for one week. Several signs of allergic inflammation, such as nasal eosinophils and inflammatory cytokines, were measured to determine the underlying mechanisms. RESULTS: Mice in the JWYPF and Nasonex groups had significantly lower AR symptom scores than those in the allergy control group (the mean differences between JWYPF and the allergy control, and Nasonex and the allergy control were -2.00 ± 0.35 and -2.40 ± 0.32). After treatment with JWYPF and Nasonex, the levels of ovalbumin-specific IgE and histamine were significantly reduced, as were the levels of interlukin-4 and transforming growth factor-ß, while interferon-γ levels were increased (all P < 0.0001, vs. allergy control). These two treatments also significantly inhibited eosinophil and mast cell infiltration into the nasal cavity but were not statistically different from one-another. CONCLUSION: JWYPF has a potential therapeutic effect on AR via adjusting the rebalance of T helper 1 and T helper 2.

A cerato-platanin protein SsCP1 targets plant PR1 and contributes to virulence of Sclerotinia sclerotiorum.

Cerato-platanin proteins (CPs), which are secreted by filamentous fungi, are phytotoxic to host plants, but their functions have not been well defined to date. Here we characterized a CP (SsCP1) from the necrotrophic phytopathogen Sclerotinia sclerotiorum. Sscp1 transcripts accumulated during plant infection, and deletion of Sscp1 significantly reduced virulence. SsCP1 could induce significant cell death when expressed in Nicotiana benthamiana. Using yeast two-hybrid, GST pull-down, co-immunoprecipitation and bimolecular florescence complementation, we found that SsCP1 interacts with PR1 in the apoplast to facilitate infection by S. sclerotiorum. Overexpressing PR1 enhanced resistance to the wild-type strain, but not to the Sscp1 knockout strain of S. sclerotiorum. Sscp1-expressing transgenic plants showed increased concentrations of salicylic acid (SA) and higher levels of resistance to several plant pathogens (namely Botrytis cinerea, Alternaria brassicicola and Golovinomyces orontii). Our results suggest that SsCP1 is important for virulence of S. sclerotiorum and that it can be recognized by plants to trigger plant defense responses. Our results also suggest that the SA signaling pathway is involved in CP-mediated plant defense .