Sugarcane smut caused by the fungus Sporisorium scitamineum is one of the major diseases of sugarcane worldwide, causing significant losses in productivity and profitability of this perennial crop....

https://apsjournals.apsnet.org/doi/pdf/10.1094/PHYTO-05-21-0221-RVW

Sugarcane Smut, Caused by Sporisorium scitamineum, a Major Disease of Sugarcane: A Contemporary Review.

The basidiomycetous fungus Sporisorium scitamineum causes a serious sugarcane smut disease in major sugarcane growing areas. Sexual mating is essential for infection to the host; however, its underlying molecular mechanism has not been fully studied. In this study, we identified a conserved farnesyltransferase (FTase) β subunit Ram1 in S. scitamineum. The ram1Δ mutant displayed significantly reduced mating/filamentation, thus of weak pathogenicity to the host cane. The ram1Δ mutant sporidia showed more tolerant toward cell wall stressor Congo red compared to that of the wild-type. Transcriptional profiling showed that Congo red treatment resulted in notable up-regulation of the core genes involving in cell wall integrity pathway in ram1Δ sporidia compared with that of WT, indicating that Ram1 may be involved in cell wall integrity regulation. In yeast the heterodimeric FTase is responsible for post-translational modification of Ras (small G protein) and a-factor (pheromone). We also identified and characterized two conserved Ras proteins, Ras1 and Ras2, respectively, and a MAT-1 pheromone precursor Mfa1. The ras1Δ, ras2Δ and mfa1Δ mutants all displayed reduced mating/filamentation similar as the ram1Δ mutant. However, both ras1Δ and ras2Δ mutants were hypersensitive to Congo red while the mfa1Δ mutant was the same as wild-type. Overall our study displayed that RAM1 plays an essential role in S. scitamineum mating/filamentation, pathogenicity, and cell wall stability.

/pdf/the-farnesyltransferase-b-subunit-ram1-regulates-sporisorium-58tuy7wsqw.pdf

The Farnesyltransferase β-Subunit Ram1 Regulates Sporisorium scitamineum Mating, Pathogenicity and Cell Wall Integrity.

Multicellularity is defined as the developmental process by which unicellular organisms became pluricellular during the evolution of complex organisms on Earth. This process requires the convergence of genetic, ecological, and environmental factors. In fungi, mycelial and pseudomycelium growth, snowflake phenotype (where daughter cells remain attached to their stem cells after mitosis), and fruiting bodies have been described as models of multicellular structures. Ustilaginomycetes are Basidiomycota fungi, many of which are pathogens of economically important plant species. These fungi usually grow unicellularly as yeasts (sporidia), but also as simple multicellular forms, such as pseudomycelium, multicellular clusters, or mycelium during plant infection and under different environmental conditions: Nitrogen starvation, nutrient starvation, acid culture media, or with fatty acids as a carbon source. Even under specific conditions, Ustilago maydis can form basidiocarps or fruiting bodies that are complex multicellular structures. These fungi conserve an important set of genes and molecular mechanisms involved in their multicellular growth. In this review, we will discuss in-depth the signaling pathways, epigenetic regulation, required polyamines, cell wall synthesis/degradation, polarized cell growth, and other cellular-genetic processes involved in the different types of Ustilaginomycetes multicellular growth. Finally, considering their short life cycle, easy handling in the laboratory and great morphological plasticity, Ustilaginomycetes can be considered as model organisms for studying fungal multicellularity.

Molecular Mechanisms Involved in the Multicellular Growth of Ustilaginomycetes.

The MAP kinase high osmolarity glycerol 1 (Hog1) plays a central role in responding to external oxidative stress in budding yeast Saccchromyces cerevisiae. However, the downstream responsive elements regulated by Hog1 remain poorly understood. In this study, we report that a Sporisorium scitamineum ortholog of Hog1, named as SsHog1, induced transcriptional expression of a putative cytochrome P450 oxidoreductase encoding gene SsCPR1, to antagonize oxidative stress. We found that upon exposure to hydrogen peroxide (H2 O2 ), SsHog1 underwent strikingly phosphorylation, which was proved to be critical for transcriptional induction of SsCPR1. Loss of SsCPR1 led to hypersensitive to oxidative stress similar as the sshog1Δ mutant did, but was resistant to osmotic stress, which is different from the sshog1Δ mutant. On the other hand, overexpression of SsCPR1 in the sshog1Δ mutant could partially restore its ability of oxidative stress tolerance, which indicated that the Hog1 MAP kinase regulates the oxidative stress response specifically through cytochrome P450 (SsCpr1) pathway. Overall, our findings highlight a novel MAPK signaling pathway mediated by Hog1 in regulation of the oxidative stress response via the cytochrome P450 system, which plays an important role in host-fungus interaction. This article is protected by copyright. All rights reserved.

MAP kinase Hog1 mediates a cytochrome P450 oxidoreductase to promote the Sporisorium scitamineum cell survival under oxidative stress.

Sporisorium scitamineum is the fungal pathogen causing severe sugarcane smut disease that leads to massive economic losses globally. S. scitamineum invades host cane by dikaryotic hyphae, formed after sexual mating of two haploid sporidia of opposite mating type. Therefore, mating/filamentation is critical for S. scitamineum pathogenicity, while its molecular mechanisms remain largely unknown. The AGC (cyclic AMP [cAMP]-dependent protein kinase 1 [protein kinase A {PKA}], cGMP-dependent protein kinase [PKG], and protein kinase C [PKC]) kinase family is a group of serine/threonine (Ser/Thr) protein kinases conserved among eukaryotic genomes, serving a variety of physiological functions, including cell growth, metabolism, differentiation, and cell death. In this study, we identified an AGC kinase, named SsAgc1 (for S. scitamineum Agc1), and characterized its function by reverse genetics. Our results showed that SsAgc1 is critical for S. scitamineum mating/filamentation and pathogenicity, and oxidative stress tolerance under some circumstances. Transcriptional profiling revealed that the SsAgc1 signaling pathway may control expression of the genes governing fungal mating/filamentation and tryptophan metabolism, especially for tryptophol production. We showed that tryptophan and tryptophol could at least partially restore ssagc1Δ mating/filamentation. Overall, our work revealed a signaling pathway mediated by AGC protein kinases to regulate fungal mating/filamentation, possibly through sensing and responding to tryptophol as signal molecules. IMPORTANCE The AGC signaling pathway represents a conserved distinct signaling pathway in regulation of fungal differentiation and virulence, while it has not been identified or characterized in the sugarcane smut fungus Sporisorium scitamineum. In this study, we identified a PAS domain-containing AGC kinase, SsAgc1, in S. scitamineum. Functional analysis revealed that SsAgc1 plays a regulatory role on the fungal dimorphic switch.

https://journals.asm.org/doi/pdf/10.1128/mSphere.00259-19

The AGC Kinase SsAgc1 Regulates Sporisorium scitamineum Mating/Filamentation and Pathogenicity.

The fungal pathogen Sporisorium scitamineum causes sugarcane smut disease. The formation and growth of dikaryotic hypha after sexual mating is critical for S. scitamineum pathogenicity, however regulation of S. scitimineum mating has not been studied in detail. We identified and characterized the core components of the conserved cAMP/PKA pathway in S. scitamineum by reverse genetics. Our results showed that cAMP/PKA signalling pathway is essential for proper mating and filamentation, and thus critical for S. scitamineum virulence. We further demonstrated that an elevated intracellular ROS (reactive oxygen species) level promotes S. scitamineum mating-filamentation, via transcriptional regulation of ROS catabolic enzymes, and is under regulation of the cAMP/PKA signalling pathway. Furthermore, we found that fungal cAMP/PKA signalling pathway is also involved in regulation of host ROS response. Overall, our work displayed a positive role of elevated intracellular ROS in fungal differentiation and virulence.

cAMP/PKA signalling pathway regulates redox homeostasis essential for Sporisorium scitamineum mating/filamentation and virulence.

Smart classrooms are a relatively confined public space for college students. SARS-COV-2 and other respiratory viruses have been shown to pose a more significant threat to human health in relatively confined spaces. Using numerical simulation method to simulate the transmission and concentration distribution of virus-carrying droplets in smart classrooms in three different seasons (summer, winter, transitional seasons: spring and autumn). The Realizable k-ε model is used to simulate the airflow pattern in the smart classroom, and the Lagrangian method is used to simulate the transmission of droplets. The transmission process of droplets produced from the teacher standing on the platform and the student sitting on the seat is studied. The influence of three kinds of outdoor temperature on droplet transmission and the body deposition fraction of people in the smart classroom is analyzed. The results show that droplet transmission speed is maximum at the temperature of 5 degrees when the outdoor temperature is 5 °C, 20 °C, and 35 °C respectively. At 10 s, the transmission distance of droplets increases by 9.55% compared with that at 20 °C and 10.31% compared with that at 35 °C. In addition, the body deposition fraction is also affected by the location of the vent, with downwind contact being 6 times more likely than upwind contact. The research results can provide suggestions and measures for epidemic prevention and control in smart classrooms. 

https://doi.org/10.1016/j.heha.2022.100015

Analysis of the spread of cough droplets and body deposition fraction in the smart classroom in different seasons

The invention discloses a new use of a xanthomonas axonopodis pv citri (Xac) generated small molecule compound as a copper preparation synergist Specifically, a small molecule compound of certain concentration is added into a copper preparation bactericide (like oxine-copper, cuaminosulfate, copper hydroxide, etc) and can significantly increase the bactericidal effect of the copper preparationThe small molecule compound is extracted from a xanthomonas axonopodis pv citri Xac fermentation broth (or can be obtained by artificial chemical synthesis) The synergist provided by the inventioncan significantly improve the bactericidal effect of the copper preparation, greatly reduce the dosage of chemical pesticides, and finally promote the harmonious development of the planting industry and the environment while weakening the drug resistance of pathogens

Application of xanthomonas axonopodis pv. citri (Xac) generated small molecule as copper preparation bactericide synergist in disease control

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cAMP/PKA signalling pathway regulates redox homeostasis essential for Sporisorium scitamineum mating/filamentation and virulence.

Analysis of the spread of cough droplets and body deposition fraction in the smart classroom in different seasons

Application of xanthomonas axonopodis pv. citri (Xac) generated small molecule as copper preparation bactericide synergist in disease control