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Corn smut is a fungal infection caused by the fungus “Ustilago maydis”.This fungus can survive in the soil for long period. Corn smut is a plant disease that affects corn yields. This plant disease is severe in hot weather. The common symptoms are the appearance of whitish galls on plants and it’s the main cause for transmission of this disease to other plants. This bibliometric analysis had been conducted to understand the active authors, organizations, journals, and countries involved in the research domain of “corn smut”. All published articles related to “corn smut” from “Scopus”, were analyzed using the VOS viewer to develop analysis tables and visualization maps. This article had set the objective to consolidate the literature regarding the corn smut and also to find out the trends related to the same. Fungal Genetics And Biology is the most active journal with the highest number of publications and Molecular Microbiology is the journal with the highest number of co-authorship links. Plant Cell is the journal with the highest citation. Annual Review Of Phytopathology is the most productive journal in this research domain with the highest average citations. The most active country is the USA and Germany is the most productive country with the highest citations and the highest average citations per publication. Department Of Plant Pathology, University Of Georgia is the most active organization with the highest publications and citations. Environmental and Life Sciences Graduate Program, Trent University is a highly productive organization in this research domain, with the highest co-authorship links and v is the organization with the highest average citation. The most active authors are Gold S.E. and Doehlemann G. with the highest number of publications; citations and co-authorship links respectively. Bottin A. is the most productive author with the highest citation rate. [ABSTRACT FROM AUTHOR]

Abstract Plant-made biopharmaceuticals are biotechnological valuable tools in aquaculture. Herein, the immunogenic potential of an oral corn smut ('huitlacoche')-made antigen (CS) was assessed in Pacific red snapper. The B subunit of the cholera toxin (CTB) was used as an immunostimulant antigen model due to its well-proven mucosal immunostimulatory activity. Test fish received corn smut-based CTB (CS-CTB) or wild-type (CS-WT) as control on day 1 and 7. Changes in humoral and cellular innate immune parameters were evaluated at 7 and 14 dpi (days post-first immunostimulation). Interestingly, total IgM and anti-CTB IgM levels in skin mucus increased in all the assessed time points in the group treated with CS-CTB. Peroxidase activity significantly increased in both serum and skin mucus from immunostimulated fish. The SOD and CAT activities were significantly increased in mucus from stimulated fish with the CS-CTB. The test fish that received CS-CTB showed enhanced phagocytic ability and radical production in head-kidney leukocytes compared with the control group. In addition, oral administration of CS-WT significantly increased the expression levels of pro-inflammatory cytokines. These findings support the use of the corn smut as a biofactory and oral delivery vehicle of novel immunostimulants, such as CTB, for fish aquaculture. Highlights • Total and anti-CTB IgM levels are strongly induced in mucosal skin tissue. • Oral administration of CS-CTB enhances humoral parameters in Pacific red snapper. • Phagocytosis and ROS production are enhanced leukocytes from immunized fish. • Pro-inflammatory cytokine-gene expression was down-regulated by CS-CTB. [ABSTRACT FROM AUTHOR]

Abstract: The biotrophic pathogen Ustilago maydis, the causative agent of corn smut disease, infects one of the most important crops worldwide – Zea mays. To successfully colonize its host, U. maydis secretes proteins, known as effectors, that suppress plant defense responses and facilitate the establishment of biotrophy. In this work, we describe the U. maydis effector protein Cce1. Cce1 is essential for virulence and is upregulated during infection. Through microscopic analysis and in vitro assays, we show that Cce1 is secreted from hyphae during filamentous growth of the fungus. Strikingly, Δcce1 mutants are blocked at early stages of infection and induce callose deposition as a plant defense response. Cce1 is highly conserved among smut fungi and the Ustilago bromivora ortholog complemented the virulence defect of the SG200Δcce1 deletion strain. These data indicate that Cce1 is a core effector with apoplastic localization that is essential for U. maydis to infect its host. [ABSTRACT FROM AUTHOR]

Type 2 alternative NADH dehydrogenases (NDH‐2) participate indirectly in the generation of the electrochemical proton gradient by transferring electrons from NADH and NADPH into the ubiquinone pool. Due to their structural simplicity, alternative NADH dehydrogenases have been proposed as useful tools for gene therapy of cells with defects in the respiratory complex I. In this work, we report the presence of three open reading frames, which correspond to NDH‐2 genes in the genome of Ustilago maydis. These three genes were constitutively transcribed in cells cultured in YPD and minimal medium with glucose, ethanol, or lactate as carbon sources. Proteomic analysis showed that only two of the three NDH‐2 were associated with isolated mitochondria in all culture media. Oxygen consumption by permeabilized cells using NADH or NADPH was different for each condition, opening the possibility of posttranslational regulation. We confirmed the presence of both external and internal NADH dehydrogenases, as well as an external NADPH dehydrogenase insensitive to calcium. Higher oxygen consumption rates were observed during the exponential growth phase, suggesting that the activity of NADH and NADPH dehydrogenases is coupled to the dynamics of cell growth. [ABSTRACT FROM AUTHOR]

Ustilago maydis is a well-established model system for biotrophic fungal plant pathogens. The fungus has a dimorphic life cycle with a yeast-like saprophytic phase switching to filamentous, pathogenic growth upon hyphal fusion. Due to its highly differentiated development and the amenability for reverse-genetics U. maydis provides a model system for both fungal cell biology as well as the study of biotrophic plant interaction. The present article highlights key findings in different aspects of cell biology on the corn smut disease and provides an outlook on the most intriguing open questions. [ABSTRACT FROM AUTHOR]

Vacuole proteases have important functions in different physiological processes in fungi. Taking this aspect into consideration, and as a continuation of our studies on the analysis of the proteolytic system of Ustilago maydis, a phytopathogenic member of the Basidiomycota, we have analysed the role of the pep4 gene encoding the vacuolar acid proteinase PrA in the pathogenesis and morphogenesis of the fungus. After confirmation of the location of the protease in the vacuole using fluorescent probes, we obtained deletion mutants of the gene in sexually compatible strains of U. maydis ( FB1 and FB2), and analysed their phenotypes. It was observed that the yeast to mycelium dimorphic transition induced by a pH change in the medium, or the use of a fatty acid as sole carbon source, was severely reduced in Δ pep4 mutants. In addition, the virulence of the mutants in maize seedlings was reduced, as revealed by the lower proportion of plants infected and the reduction in size of the tumours induced by the pathogen, when compared with wild-type strains. All of these phenotypic alterations were reversed by complementation of the mutant strains with the wild-type gene. These results provide evidence of the importance of the pep4 gene for the morphogenesis and virulence of U. maydis. [ABSTRACT FROM AUTHOR]

Abstract: Several strains of Ustilago maydis, a causal agent of corn smut disease, exhibit a ‘killer’ phenotype that is due to persistent infection by double-stranded RNA Totiviruses. These viruses produce potent killer proteins that are secreted by the host. This is a rare example of virus/host symbiosis in that these viruses are dependent upon host survival and, to that end, produce antifungal proteins that kill competing, uninfected strains of U. maydis. Two of the best-studied examples of this killer phenomenon are U. maydis strains P4 and P6 that secrete killer proteins KP4 and KP6, respectively. The mature form of KP4 is comprised of 105 residues while KP6 consists of two subunits, a and b chains, 76 and 82 residues in length, respectively. KP6 is not homologous to any known protein, and only recently has KP4 been shown to have possible homologs in pathogenic fungi. While very little is known as to the mode of action of KP6, we have shown that KP4 blocks L-type Ca2+ channels in fungi and animal cells in a reversible and cytostatic manner. In contrast, preliminary results suggest that KP6 acts via a completely different mechanism and is a potent cytolytic antifungal protein. When KP4 is expressed in maize, the resulting transgenic lines are nearly immune to U. maydis infection. Therefore, a greater understanding of the modes of action of these potent antifungal proteins could lead to development of broad-spectrum antifungal agents. [Copyright &y& Elsevier]

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Abstract: Ustilago maydis, the causal agent of corn smut, has emerged as a basidiomycete model system for signal transduction, dimorphism, and disease development. The well-characterized cAMP/PKA signaling pathway mediates filamentation in response to environmental cues, and in the absence of the cAMP signal, haploid cells grow filamentously. Prior to this report, the G-protein alpha and beta subunits, Gpa3 and Bpp1, respectively, were demonstrated to function upstream of adenylate cyclase, Uac1. In other fungal systems, adenylate cyclase is also positively regulated by the adenylate cyclase-associated protein (CAP). A CAP ortholog, Cap1, was identified by sequence homology in the U. maydis genome. Yeast 2-hybrid analysis indicated that Cap1 bound itself and the C-terminus of Uac1. Deletion of cap1 resulted in abnormal colony formation with filamentous cells that reverted to budding in the presence of exogenous cAMP. The Δcap1 strains had a reduced ability to form mating filaments compared to wild type strains. Pathogenicity was significantly reduced in Δcap1 strains in wild type and solopathogenic genetic backgrounds. These results suggest that Cap1 is an additional component of the cAMP/PKA signaling pathway that coordinates production of cAMP upstream of Uac1. [ABSTRACT FROM AUTHOR]

The basidiomycete Ustilago maydis is the causal agent of corn smut disease and induces tumor formation during biotrophic growth in its host maize (Zea mays). We have conducted a combined metabolome and transcriptome survey of infected leaves between 1 d post infection (dpi) and 8 dpi, representing infected leaf primordia and fully developed tumors, respectively. At 4 and 8 dpi, we observed a substantial increase in contents of the nitrogen-rich amino acids glutamine and asparagine, while the activities of enzymes involved in primary nitrogen assimilation and the content of ammonia and nitrate were reduced by 50% in tumors compared with mock controls. Employing stable isotope labeling, we could demonstrate that U. maydis-induced tumors show a reduced assimilation of soil-derived 15NO3 and represent strong sinks for nitrogen. Specific labeling of the free amino acid pool of systemic source leaves with [15N]urea revealed an increased import of organic nitrogen from systemic leaves to tumor tissue, indicating that organic nitrogen provision supports the formation of U. maydis-induced tumors. In turn, amino acid export from systemic source leaves was doubled in infected plants. The analysis of the phloem amino acid pool revealed that glutamine and asparagine are not transported to the tumor tissue, although these two amino acids were found to accumulate within the tumor. Photosynthesis was increased and senescence was delayed in systemic source leaves upon tumor development on infected plants, indicating that the elevated sink demand for nitrogen could determine photosynthetic rates in source leaves. [ABSTRACT FROM AUTHOR]

Abstract: The basidiomycete Ustilago maydis, the causative agent of corn smut disease, has emerged as a model organism for dimorphism and fungal phytopathogenicity. In this work, we line out the key conserved enzymes for β-carotene biosynthesis encoded by the U. maydis genome and show that this biotrophic fungus accumulates β-carotene. The amount of this pigment depended on culture pH and aeration but was not affected by light and was not increased by oxidative stress. Moreover, we identified the U. maydis gene, cco1, encoding a putative β-carotene cleavage oxygenase. Heterologous overexpression and in vitro analyses of purified enzyme demonstrated that Cco1 catalyzes the symmetrical cleavage of β-carotene to yield two molecules of retinal. Analyses of β-carotene and retinal contents in U. maydis cco1 deletion and over-expression strains confirmed the enzymatic function of Cco1, and revealed that Cco1 determines the β-carotene content. Our data indicate that carotenoid biosynthesis in U. maydis is carried out to provide retinal rather than to deliver protective pigments. The U. maydis genome also encodes three potential opsins, a family of photoactive proteins that use retinal as chromophore. Two opsin genes showed different light-regulated expression patterns, suggesting specialized roles in photobiology, while no mRNA was detected for the third opsin gene in the same experiments. However, deletion of the cco1 gene, which should abolish function of all the retinal-dependent opsins, did not affect growth, morphology or pathogenicity, suggesting that retinal and opsin proteins play no relevant role in U. maydis under the tested conditions. [Copyright &y& Elsevier]

The effects of nitrapyrin (NI), urea (U) and Zn rates on rhizosphere pH, smut incidence (S.I.), dry matter (D.M.). grain yield (G.Y.) and ear leaf N and Zn contents were studied in cemented plots, containing calcareous and non-calcareous soils. Treatments were comprised of 3 U applications (46, 92 and 138 kg N acre-1), combined with 2 NI rates (0 and 0.22kg acre-1) and 2 levels of Zn (0 and 8 kg acre-1). Corn seeds, cv 'Amoun' were planted in 1993 and 1994 and the seedlings were artificially infected with U. maydis-spores at the 6 and 10 leaf growth stages. Results have shown that corn plants grown in calcareous soil imposed greater advantage in D.M. and G.Y., accompanied by a relatively low smut infection than those grown in non-calcareous soil. Unlike the diversion effects of NI on soil pH and plant Zn content, its application was beneficial for improving yield and plant Zn content. Urea applications decreased the soil pH by 0.6 unit at the highest N rate and exerted stimulatory effects on ear leaf N and Zn contents. By increasing U rate to 138kg N acre-1, smut severity was increased by 6%. In contrast, by Zn fertilization, smut severity was decreased by 10.3%, accompanied by marked increases in G.Y. and leaf Zn content. Mixed results were detected on S.I. data, when NI was combined with U rates. In the presence of Zn, smut severity was dropped to 20.1 % at 138kg N acre-1. The results also showed that in the absence of Zn supply, S.I. was dominated in NI-treated plants and the reverse was true when Zn was included. Satisfactory results were achieved when 92 kg N acre-1 were combined with 0.22 and 8 kg acre-1 of NI and Zn, respectively. [ABSTRACT FROM AUTHOR]

Maize head smut is a worldwide disease, widely occurred in most maize fields. The disease had occurred in large area in the late 1970s, and became a limiting factor restricting the improvement of maize yield and total yield in China. After efforts of several generations of agricultural scientific workers, the symptoms, pathogen, infection pathway, infection conditions, infection regularity and resistance genetic law of maize head smut have been studied. This paper introduces the incidence symptoms, pathogen sources, infection pathway, infection conditions, and physiological races of maize head smut, and put forwards the corresponding prevention measures, such as crop rotation, selection of resistant varieties, seed dressing, soil treatment with fungicides, promoting seedling emergence and strengthening field management. [ABSTRACT FROM AUTHOR]

Histopathology of fungus Ustilago maydis causal agent of common corn smut was investigated in exposure to both light and electron microscopy in cultivars SC301, SC647 and DC704 that were known before as sensitive, semiresistant and resistant cultivars, respectively. For providing fungal inoculum, mixture of teliospors were collected from Khozestan province, then cultured in CMA and PDA + 10% dextorose media and incubated 5 days at 25°C. Fungal inoculums were inoculated under 2 different methods, injection and spray; then samples were collected and fixed 2, 4, 11 and 25 days after inoculation. 18 days after inoculation, disease symptoms were first observed in injection and then spray method. Fungal penetration in host by scanning electron microscopy showed that penetration is possible both in direct and indirect ways and fungus makes a swollen and brilliant appressorium. Light microscopy of fungal extension showed that infection cells were larger than intact ones and extension of fungal hyphes were first intercellular and then intraceilular. Some intracellular branches were lobed and others terminated in pointed finger like or other kinds of swelling. At the site of teliospore formation, cavity of mycelium was formed that contained both mature and immature teliospores. These young teliospores were surrounded with gelatinus sheath. Corn infection happened easily under control conditions and made an appropriate system for investigation of some aspects of pathogen interaction. [ABSTRACT FROM AUTHOR]

The article presents abstracts on topics related to plant physiology which include the significance of dynamic acclimation photosynthesis on plant development, the impact of corn smut disease to photosynthesis and nitrogen metabolism, and the study on the plasticity of root gravitropism.

The article presents a study on gene clusters in fungus that cause the corn smut disease. Ustilago maydis, an agent that causes agricultural blight, contains gene clusters sharing characteristics similar to bacterial pathogenicity. The biotrophic agent must keep its host alive to survive and reproduce. The article suggests that strategies that focus on blocking P-type ATPases and other elements required for secretion and delivery of proteins in the host may help control the virulence factors.