Transcriptome analysis of sugarcane reveals differential switching of major defense signaling pathways in response to Sporisorium scitamineum isolates with varying virulent attributes.

Sugarcane smut caused by the basidiomycetous fungus Sporisorium scitamineum is one of the most devastating diseases that affect sugarcane production, globally. At present, the most practical and effective management strategy for the disease is the cultivation of resistant cultivars. In this connection, a detailed understanding of the host's defense mechanism in response to smut isolates with varying degrees of virulence at the molecular level would facilitate the development of reliable and durable smut-resistant sugarcane varieties. Hence, in this study, a comparative whole transcriptome analysis was performed employing Illumina RNA-seq in the smut susceptible cultivar Co 97009 inoculated with two distinct S. scitamineum isolates, Ss97009 (high-virulent) and SsV89101 (low-virulent) during the early phases of infection (2 dpi and 5 dpi) and at the phase of sporogenesis (whip emergence) (60 dpi). Though the differential gene expression profiling identified significant transcriptional changes during the early phase of infection in response to both the isolates, the number of differentially expressed genes (DEGs) were more abundant at 60 dpi during interaction with the high virulent isolate Ss97009, as compared to the low virulent isolate SsV89101. Functional analysis of these DEGs revealed that a majority of them were associated with hormone signaling and the synthesis of defense-related metabolites, suggesting a complex network of defense mechanisms is being operated in response to specific isolates of the smut pathogen. For instance, up-regulation of hormone-related genes, transcription factors, and flavonoid biosynthesis pathway genes was observed in response to both the isolates in the early phase of interaction. In comparison to early phases of infection, only a few pathogenesis-related proteins were up-regulated at 60 dpi in response to Ss97009, which might have rendered the host susceptible to infection. Strikingly, few other carbohydrate metabolism-associated genes like invertases were up-regulated in Ss97009 inoculated plants during the whip emergence stage, representing a shift from sucrose storage to smut symptoms. Altogether, this study established the major switching of defense signaling pathways in response to S. scitamineum isolates with different virulence attributes and provided novel insights into the molecular mechanisms of sugarcane-smut interaction.

Protoplast-mediated transformation in Sporisorium scitamineum facilitates visualization of in planta developmental stages in sugarcane.

BACKGROUND: Sporisorium scitamineum is the causative agent of smut disease in sugarcane. The tricky life cycle of S. scitamineum consists of three distinct growth stages: diploid teliospores, haploid sporidia and dikaryotic mycelia. Compatible haploid sporidia representing opposite mating types (MAT-1 and MAT-2) of the fungus fuse to form infective dikaryotic mycelia in the host tissues, leading to the development of a characteristic whip shaped sorus. In this study, the transition of distinct stages of in vitro life cycle and in planta developmental stages of S. scitamineum are presented by generating stable GFP transformants of S. scitamineum. METHODS AND RESULTS: Haploid sporidia were isolated from the teliospores of Ss97009, and the opposite mating types (MAT-1 and MAT-2) were identified by random mating assay and mating type-specific PCR. Both haploid sporidia were individually transformed with pNIIST plasmid, harboring an enhanced green fluorescent protein (eGFP) gene and hygromycin gene by a modified protoplast-based PEG-mediated transformation method. Thereafter, the distinct in vitro developmental stages including fusion of haploid sporidia and formation of dikaryotic mycelia expressing GFP were demonstrated. To visualize in planta colonization, transformed haploids (MAT-1gfp and MAT-2gfp) were fused and inoculated onto the smut susceptible sugarcane cultivar, Co 97009 and examined microscopically at different stages of colonization. GFP fluorescence-based analysis presented an extensive fungal colonization of the bud surface as well as inter- and intracellular colonization of the transformed S. scitamineum in sugarcane tissues during initial stages of disease development. Noticeably, the GFP-tagged S. scitamineum led to the emergence of smut whips, which established their pathogenicity, and demonstrated initial colonization, active sporogenesis and teliospore maturation stages. CONCLUSION: Overall, for the first time, an efficient protoplast-based transformation method was employed to depict clear-cut developmental stages in vitro and in planta using GFP-tagged strains for better understanding of S. scitamineum life cycle development.

An Open-Label Prospective Study to Compare the Efficacy and Safety of Topical Fluticasone Versus Tacrolimus in the Proactive Treatment of Atopic Dermatitis.

BACKGROUND: Atopic dermatitis (AD), a chronic, recurrent inflammatory skin condition primarily affects children. Topical treatment, systemic treatment, and phototherapy are mainstays of treatment. Topical corticosteroids (TCS) are first-line therapy for AD but are associated with various adverse effects. Topical calcineurin inhibitors (TCI) can be used as an alternative to TCS. OBJECTIVE: The aim of the study is to compare the efficacy of topical preparations of fluticasone and tacrolimus in reducing the severity of disease and, to assess the quality of life (QoL), and to estimate if any association exists between severity of disease and QoL. METHODS: Thirty-seven children with AD randomly received one of the 2 topical treatments, with daily application for the first 4 weeks in the acute phase and twice weekly for next 4 weeks in the maintenance phase. The severity of disease was assessed using SCORing Atopic Dermatitis (SCORAD), and QoL was assessed using the Children's Dermatology Life Quality Index (CDLQI). RESULTS: At the end of the acute phase, there was a reduction in SCORAD score of 69.29% in the fluticasone group and 64.2% in the tacrolimus group (P < 0.001). In the maintenance phase, the score had risen in the fluticasone group by a mean difference of 0.81, while in the tacrolimus group it decreased by 0.99. Both fluticasone and tacrolimus groups improved in children's QoL (P < 0.001). Positive correlation (r = 0.4668) exists between SCORAD and QoL. The most common adverse skin reaction noted was skin burning with tacrolimus. CONCLUSIONS: Fluticasone and tacrolimus are equally efficacious in the treatment of AD and have similar benefits with children's QoL. Tacrolimus is better than fluticasone at reducing the extent of lesions.