Smut Disease Research Articles

Establishment of an Agrobacterium tumefaciens-mediated transformation system for Tilletia foetida

Tilletia foetida causes wheat common smut disease with severe loss of yield production and seed quality. In this study, a low-cost, rapid, and efficient Agrobacterium tumefaciens-mediated transformation (ATMT) system for T. foetida mutagenesis was constructed: Transformants were screened with hygromycin B at 100 μg/ml, cefotaxime sodium concentrations with 200 μg/ml, Acetosyringone (AS) concentration at 200 μmol/l, 1 × 106 T. foetida hypha cells/ml, co-cultivation at 22 °C with 24 h and culture was incubated at 16 °C up to day 7. Fourteen transformants were randomly selected and confirmed using the specific primers to amplify the fragment of hygromycin phosphotransferase gene. At the same time, PCR analysis was performed to detect Agrobacterium tumefaciens Vir gene to eliminate false positives. The transformants were cultivated up to 8 generations on hygromycine B-containing complete medium (CM) and confirmed by PCR. The results indicated that 80% of T. foetida transformants were hygromycine B resistant. In conclusion, our analyses identified an efficient T-DNA insertion system for T. foetida and the results will be useful for further understanding the pathogenic mechanism via generation of the insertional mutants.

Examination of the disease onset promotion method for rice false smut disease.

Examination of the disease onset promotion method for rice false smut disease.

Defense response of seedling plumule and mesocotyl of sorghum to infection by Sporisorium sorghi, causing covered kernel smut in relation to disease resistance classes

Susceptibility of sorghum seedlings to infection by Sporisorium sorghi, the fungus causing covered kernel smut (CKS) disease, is limited to the period between the sowing of the seed and emergence of the seedling. Microscopy and PCR diagnosis of 7-day-old infected seedlings detected hyphae of S. sorghi in plumule and mesocotyl tissue but not in coleoptile and radicle tissue. Percent infected seedling plumule and mesocotyl tissue detected by microscopy and PCR corresponded well to field resistance classes for CKS in mature panicles of both sorghums tested with Giza-15 being highly susceptible and hybrid Shandweel-305 being resistant. Bulk extracts of phenolics and antioxidants from seedling plumule and mesocotyl tissues of hybrid Shandweel-305 cv significantly inhibited the in vitro mycelial growth of S. sorghi more than those from Giza-15 cv. Moreover, bulk extracts of plumule and mesocotyl tissue of seedlings grown from seed inoculated with S. sorghi teliospores contained higher phenolic and antioxidant content in the resistant hybrid (Shandweel-305) than the highly susceptible cultivar (Giza-15). Similarly, bulk extracts of plumule and mesocotyl tissue of 7-day-old seedlings grown from seed inoculated with S. sorghi teliospores contained higher phenolic and antioxidant content in the resistant hybrid (Shandweel-305) than the highly susceptible cultivar (Giza-15). Ferulic, isorhamnetin and kaempferol acids were detected only in plumule and mesocotyl tissue of resistant hybrid Shandweel-305, whereas ellagic, fumaric and vanillic acids were detected only in highly susceptible Giza-15 cv. Ferulic acid added to malt dextrose broth medium significantly inhibited in vitro teliospore germination and mycelial growth of S. sorghi, especially when added at the highest concentrations. This research established that the mode of seedling infection of sorghum by S. sorghi is almost exclusively through the plumule and mesocotyl tissue. Within these tissues, the presence of the pathogen can induce host production of phenolics, including the fungitoxic ferulic acid and antioxidants at higher concentrations within the resistant sorghum than in the highly susceptible cultivar.

Ustilaginoidin M1, a new bis-naphtho-γ-pyrone from the fungus Villosiclava virens

Ustilaginoidin M1 (1), a novel bis-naphtho-γ-pyrone, was isolated from the cultures of the fungus Villosiclava virens which was the pathogen of rice false smut disease. Its structure was elucidated by spectroscopic analysis and by comparison of its physical and spectroscopic data with the literature. Compound 1 was tested for its cytotoxicity against five human cancer cell lines.

Alterations in Leaf Ultrastructure in Varieties of Sugarcane Infected by Diseases

Given the importance of viral, bacterial and fungal diseases in agriculture and their impact on crop yields, this study evaluated leaf ultrastructural changes in sugarcane varieties infected by these diseases, aiming to find morphological responses that may be associated to the decline of sugarcane yield. Three independent experiments were carried out with sugarcane varieties. In the three experiments, a randomised block design was used with 10 replications. The treatments consisted of the following diseases: mosaic from infection of variety SP86-155 by SCMV (experiment 1); stunting from infection with bacterium Leifsonia xyli subsp. xyli and smut from infection with fungus Sporisorium scitamineum (formally called Ustilago scitaminea) in the variety SP70-3370 (experiment 2); and scald from infection of variety SP78-5495 by bacterium Xanthomonas albilineans (experiment 3). The ultrastructural parameters were evaluated: mesophyll thickness, xylem diameter, phloem beam diameter, epidermal thickness of the adaxial face, epidermal thickness of the abaxial face, cuticle thickness of the adaxial face and cuticle thickness of the abaxial face. Healthy plants were controls for the three experiments. Sugarcane plants with mosaic, stunting, smut and scald diseases show deleterious changes in leaf ultrastructure.

Genome-wide alternative splicing landscapes modulated by biotrophic sugarcane smut pathogen

Alternative splicing (AS) promotes transcriptome and proteome diversity during growth, development, and stress responses in eukaryotes. Genome-wide studies of AS in sugarcane (Saccharum spp.) are lacking, mainly due to the absence of a high-quality sequenced reference genome, sugarcane’s large, complex genome, and the variable chromosome numbers and polyploidy of sugarcane cultivars. Here, we analyzed changes in the sugarcane isoform-level transcriptome and AS landscape during infection with the smut fungus (Sporisorium scitamineum) using a hybrid approach involving Sorghum bicolor reference-based and Trinity de novo mapping tools. In total, this analysis detected 16,039 and 15,379 transcripts (≥2 FPKM) at 5 and 200 days after infection, respectively. A conservative estimate of isoform-level expression suggested that approximately 5,000 (14%) sugarcane genes undergo AS. Differential expression analysis of the alternatively spliced genes in healthy and smut-infected sugarcane revealed 896 AS events modulated at different stages of infection. Gene family and gene ontology functional enrichment analysis of the differentially spliced genes revealed overrepresentation of functional categories related to the cell wall, defense, and redox homeostasis pathways. Our study provides novel insight into the AS landscape of sugarcane during smut disease interactions.

Weather Condition, Seasonal Variation and Ball Development Pattern in Relation to Rice False Smut Disease in Bangladesh

Rice false smut (RFSm) is an international disease. The effect of the disease has become seriously evident in Bangladesh since 2010. The disease is predominant in the country in the ‘T. Aman’ rice growing season. Its occurrence in other rice growing seasons not well studied and recorded. Information on driving weather variable(s) causing the disease epidemic is scanty and not ground-truthed. This study, conducted in the experimental farm of the Bangladesh Rice Research Institute, Gazipur, Bangladesh, attempted to fill those information gaps. The association of disease incidence and weather parameters such as relative humidity, cloud hour and rainfall, was inconsistence except for the daily average temperature. High disease incidence occurred when the average temperature during panicle emergence period ranged between 22-27°C; any temperature below or above the range linearly decreased the disease incidence. RFSm disease was recorded in the study area in all the months, except for in February and March. The distribution in the incidence of disease in the three rice growing seasons followed the order of ‘T. Aman’ > ‘Aus’ > ‘Boro’; it was ~ six times less in ‘Aus’ and ~ eight times less in ‘Boro’ season, compared to ‘T. Aman’ season. New balls formed on infected panicles in batch by batch. High number of such batches formed in ‘T. Aman’ season. The final status of the disease in an infected crop was the accumulation of incidence of the disease in each batch. This study provided key epidemiology on the development of RFSm in nature and it is concluded such information on the disease under local conditions would be the key to designing management options.
 Bangladesh Rice j. 2018, 22(1): 57-64

Seed Germination and Grain Quality of Rice as Affected by False Smut Disease

Rice false smut (RFSm) is a disease of interest globally and in Bangladesh. Its occurrence and spread have drawn attention since 2010 in the country. While many reports are available on the yield loss from the disease, little is known of its effect on grain quality. Besides, there has been no information on how RFSm affects the seed quality with respect to germination. This study attempted evaluation of seed germination and grain quality of rice as affected by false smut disease. Three years’ study provided strong indication of inferior milling outturn and head rice yield in RFSm contaminated seeds. Results further revealed reduced amylose content and increased protein content in the contaminated seeds. Tendency in reduced seed germination, and less cooking time was observed in RFSm contaminated seeds. Future research is suggested to fully understand those causations.
 Bangladesh Rice j. 2018, 22(1): 1-7

Productivity, Quality, Growth and Pathological Evaluation of Some Promising Sugarcane Genotypes in Egypt

This study was carried out at El-Mattana Agricultural Research Station, Luxor Governorate, Egypt(lat 25° 17' N,long 32° 33' and alt 76 m ASL)during 2015/16, 2016/17 and 2017/18 harvesting seasons to study the productivity, quality,growth characters and natural infection with several diseases. Ten promising sugarcane genotypes (Saccharum spp.)constituted the studied material and check genotype (commercial genotype), namely GT 54-9 were used as control.Sugarcane genotypes were planted in a randomized complete block design with three replicates.The results of this investigation could be summarized as follow: GT 54-9 had the highest stalk length, stalk weight,sucrose%, purity% and all tested productivity characters. The highest infection with pokkah boeng, smut and mosaicdiseases were observed to such genotype while, this genotype uninfected by streak disease. G 84-47 owned the highestbrix%, sucrose% and cane yield and had lowest DS% for pokkah boeng disease and didn’t infect by smut and two testedvirus diseases. However, the highest brix% were recorded to G 2006-6, which gained the lowest infection by pokkahboeng and smut, the highest infected by streak disease and uninfected by mosaic disease. The lowest mean values of stalklength, sugar yield and stalk weight were scrutinized to G 2010-26, G2011-74 and G 2011-79, respectively. Thesegenotypes didn’t infect by smut and mosaic diseases. In regard to streak disease, the highest and least infections wererecorded to G 2010-26 and G 2011-79, respectively. In addition, the lowest stalk diameter and the highest number oftillers/stool were observed in case of G 2011-13 which had the highest infection by smut and uninfected by the two testedvirus diseases. Also, the lowest tested qualitative traits, sugar recovery % and yield were recorded to G2012-50. Also, G2011-13 and G 2012-50 were the highest infected by smut and uninfected by the two tested virus diseases. G 2010-7 andG 2011-82 showed no distinct behavior for all traits. Both genotypes uninfected by smut and the two tested virus diseases.It could be concluded that, GT 54-9 genotype is suitable for regions which were contaminated only by streak disease forhighest stalk weight, cane and sugar yields and G 84-47 for regions which, was contaminated by smut and the two testedvirus for its highest cane yield. The traits of other genotypes were differed from season to other and had differentresponses to tested diseases.

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

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.

WITHDRAWN: Expression of the Arabidopsis SWEET genes during rice false smut infection in the transgenic Arabidopsis thaliana containing increased levels of ATP and sucrose

Ustilaginoidea virens is a causal agent of rice false smut disease which hampers the global rice production. This pathogen is able to continually reach into the central vascular tissues and is able to hijack nutrients from the host plants. It is known that during the later stage of U. virens colonization, the floral region particularly the basal area which is having conducive micro-environment in terms of nutrients and moisture content witnessed the presence of a dense mass of mycelia. Nevertheless, the mechanism which underlies U. virens infection in relation to sugar transport is not well established using a molecular approach. Here, we analyzed contents of sugar that are present in leaves pre and post U. virens infection using a transgenic Arabidopsis thaliana leaves containing increased levels of ATP and sucrose. Glucose and sucrose contents in the leaves of the transgenic Arabidopsis lines were significantly increased compared to WT after U. virens infection, suggesting that U. virens growth and translocation of sugar are directly linked. From the four A. thaliana SWEET genes tested, two AtSWEETs which belong to Clade III were up-regulated significantly upon U. virens infection particularly in the OE7 transgenic line. Our studies suggest that active sugar translocation between the sugar producing tissues probably was triggered by U. virens infection, and the identified SWEET family genes are directly involved in facilitating this process.

A fungal substrate mimicking molecule suppresses plant immunity via an inter-kingdom conserved motif

Ustilago maydis is a biotrophic fungus causing corn smut disease in maize. The secreted effector protein Pit2 is an inhibitor of papain-like cysteine proteases (PLCPs) essential for virulence. Pit2 inhibitory function relies on a conserved 14 amino acids motif (PID14). Here we show that synthetic PID14 peptides act more efficiently as PLCP inhibitors than the full-length Pit2 effector. Mass spectrometry shows processing of Pit2 by maize PLCPs, which releases an inhibitory core motif from the PID14 sequence. Mutational analysis demonstrates that two conserved residues are essential for Pit2 function. We propose that the Pit2 effector functions as a substrate mimicking molecule: Pit2 is a suitable substrate for apoplastic PLCPs and its processing releases the embedded inhibitor peptide, which in turn blocks PLCPs to modulate host immunity. Remarkably, the PID14 core motif is present in several plant associated fungi and bacteria, indicating the existence of a conserved microbial inhibitor of proteases (cMIP).

ENDOPHYTIC BACTERIA ASSOCIATED WITH SUGARCANE AND ITS POTENTIAL TO SUPPRESS SPORISORIUM SCITAMINEUM, THE CAUSAL FUNGAL PATHOGEN OF SMUT DISEASE

Bacterial endophytic ubiquitously colonize the internal tissues of the plant. The purpose of this study was to isolate and identify the endophytic bacteria from sugarcane stalks which have antagonistic activity against Sporisorium scitamineum, the causal pathogen of sugarcane smut disease, and to study their activity to produce some secondary metabolites i.e. enzymes and growth-promoters. Sugarcane samples were collected from five governorates in Upper-Egypt namely, Giza, Beni-Suef, Sohag, Qena, and Luxor. A total of 240 isolates of endophytic bacteria were isolated from 160 samples of healthy sugarcane stalks (variety GT-54-9). Isolated endophytes were screened for its antagonistic activity against S. scitamineum, in vitro, using dual culture method. Only, 62 isolates showed different degrees of antagonistic activity. Ten isolates of endophytic bacteria were selected to study their potential to produce enzymes (chitinase, β 1,3 glucanase, phenylalanine ammonia lyase) and growth-promoters (siderophores, indole acetic acid (IAA), salicylic acid (SA)). These isolates were pre-identified using the morphological and physiological properties according to Bergy's manual as Pseudomonas sp., Serratia sp., Enterobacteria sp., Herbaspirillium sp., Gluconacetobacter sp. Anabaenopsis sp. and Azospirillumsp. All endophetic bacteria produced β 1,3gluconase and indole acetic acid (IAA), while Pseudomonas sp. produced salicylic acid and phenylalanine ammonia lyase, Ana baenopsis sp. produced phenylalanine ammonia lyase, Gluconacetobacter sp. produced chitinase and Herbaspirillium sp. produced siderophore. Meanwhile, isolates of Anabaenopsis sp. and Pseudomonas sp. were the most effective to produce β 1,3glucanase and indole acetic acid compared with other entophytic bacteria.

Polyamines levels increase in smut teliospores after contact with sugarcane glycoproteins as a plant defensive mechanism.

Previous studies have already highlighted the correlation between Sporisorium scitamineum pathogenicity and sugarcane polyamine accumulation. It was shown that high infectivity correlates with an increase in the amount of spermidine, spermine and cadaverine conjugated to phenols in the sensitive cultivars whereas resistant plants mainly produce free putrescine. However, these previous studies did not clarify the role of these polyamides in the disorders caused to the plant. Therefore, the purpose of this research is to clarify the effect of polyamines on the development of smut disease. In this paper, commercial polyamines were firstly assayed on smut teliospores germination. Secondly, effects were correlated to changes in endogenous polyamines after contact with defense sugarcane glycoproteins. Low concentrations of spermidine significantly activated teliospore germination, while putrescine had no activating effect on germination. Interestingly, it was observed that the diamine caused nuclear decondensation and breakage of the teliospore cell wall whereas the treatment of teliospores with spermidine did not induce nuclear decondensation or cell wall breakdown. Moreover, the number of polymerized microtubules increased in the presence of 7.5mM spermidine but it decreased with putrescine which indicates that polyamines effects on Sporisorium scitamineum teliospore germination could be mediated through microtubules interaction. An increased production of polyamines in smut teliospores has been related to sugarcane resistance to the disease. Teliospores incubation with high molecular mass glycoproteins (HMMG) from the uninoculated resistant variety of sugarcane, Mayari 55-14, caused an increase of the insoluble fraction of putrescine, spermidine and spermine inside the teliospore cells. Moreover, the level of the soluble fraction of spermidine (S fraction) increased inside teliospores and the excess was released to the medium. The HMMG glycoproteins purified from Mayarí 55-14 plants previously inoculated with the pathogen significantly increased the levels of both retained and secreted soluble putrescine and spermidine. Polyamines levels did not increase in teliospores after incubation with HMMG produced by non resistant variety Barbados 42231 which could be related to the incapacity of these plants to defend themselves against smut disease. Thus, a hypothesis about the role of polyamines in sugarcane-smut interaction is explained.

A core effector UV_1261 promotes Ustilaginoidea virens infection via spatiotemporally suppressing plant defense

False smut is a destructive grain disease of rice worldwide, characterized by false smut balls formed in rice flowers. Here we identified a small secreted protein UV_1261 contributing to virulence of Ustilaginoidea virens, the causal agent of this disease. The sequence of UV_1261 was highly conserved among isolates of U. virens and absent in other fungi. UV_1261 encodes a protein targeted to plant chloroplasts. Its expression exhibited a bimodal pattern during pathogenesis. Ectopic expression of UV_1261 in Nicotiana benthamiana and Arabidopsis led to suppression of flg22-induced ROS burst, callose deposition, and expression of defense-related genes, as well as enhanced susceptibility to powdery mildew in Arabidopsis. Down-regulation of UV_1261 via exogenous siRNA treatment resulted in reduced number of false smut balls. Consistently, stably knocking-down UV_1261 caused less number of false smut balls associated with higher expression of defense-related genes in rice flower. Taken together, our data demonstrate that UV_1261 is a core effector of U. virens essential for virulence and suppressing defense in rice flower, and thus may serve as a potential molecular target for controlling rice false smut disease.

Distribution of species of Fusarium and Alternaria genera on cereals in Ukraine

In recent years phytosanitary situation in agrophytocenooses has worsened, and damage caused by diseases increased. In the conditions of field experiments in the vegetative seasons of 2015–2018 the dissemination of Fusarium and Alternaria spp., and composition of Fusarium species in Ukraine were studied. The selection of plant samples was carried out twice – at the beginning of vegetation and before entering into wintering. In autumn the samples of winter wheat with the symptoms of root rot from more than 150 fields from different oblasts of Ukraine were selected. Later these samples were analyzed using PCR method in real time to determine the species composition of Fusarium genus. In the analysis of grain material from different regions of Ukraine we determined high level of Fusarium infection. Fusariosis of grain were observed in several areas in more than 50% of samples from all regions of county. In all oblasts of Ukraine, the high level of Alternarìa infection were identified also. It is found out that the main sources of the root rot are F. tricinctum, F. graminearum, F. poae and F. avenaceum. The role of F. avenaceum, as the pathogen of root rot was at the level of F. graminearum and F. sporotrichioides in most regions of Ukraine. The studies reveiled that the dominant species in the grain material were F. tricinctum and F. graminearum, presence of which exceeded 20–25%. Quite often F. poae and F. sporotrichioides was observed, presence of which in grain equaled 15–20%. In the Central, Eastern and Southern regions, the dominant species was F. avenaceum with a level of identification 15–23%. F. culmorum, F. langsethiae were within 5–7%. The species composition of fusariosis in the grain and the species composition of pathogens that cause fusariosis root rot in general are similar. Fusariosis becomes one of the most common and harmful diseases of grain crops, and cause no less harm than smut diseases. The fact that their danger continues to grow is explained by adverse weather conditions (alternation of wet and arid periods) and reduction of general level of cultivation: distribution of corn fields, decrease of expenses on tillage, and low-quality pesticides, often generics. It should be noted that the best precursors for cereal crops, for example, soy bean, is also vulnerable to fusariosis. Therefore, performing protective measures at preparing of grain for sowing and in the period of vegetation of the crop will contribute to total reduction of the levels of infection of agrophytocenoses with Fusarium species and potential damage to the cultivated plants. The study revealed that species of fungi belonging to the Alternaria and Fusarium genera infect wheat grain in the yields of each year. The results of data analysis of the genera showed antagonistic interaction between them. Perhaps, particularly at such negative interaction in the vegetative season of 2018, during, practically continuous warm rains in the "grain belt" of Ukraine during the generative period of development of wheat, the grain was infected with Alternaria spp. at moderate presence of Fusarium species. These patterns in the interaction of Alternaria and Fusarium spp. are expedient to be taken into account during development of systems of control of fusariosis using fungicides. Absence of contamination of grains with mycotoxins of Fusarium species does not reduce the levels of danger for crops posed by probable increase in the levels of presence of Alternaria mycotoxins – alternariol, alternariol monomethyl ether, tenuazonic acid, etc. Certainly, the results of the vegetation season of 2018 year and the large-scale alternariosis infication require clarifications to the current normative documentation. The conducted researches are important for improvement of protection systems for crops in intensive technologies of cultivation.

Specificity and seasonal prevalence of anther smut disease Microbotryum on sympatric Himalayan Silene species.

Host sympatry provides opportunities for cross-species disease transmission and compounded disease effects on host population and community structure. Using the Silene-Microbotryum interaction (the castrating anther smut disease), eleven Himalayan Silene species were assessed in regions of high host diversity to ascertain levels of pathogen specificity. We also investigated disease prevalence, seasonal dynamics of infection and flowering patterns in five co-blooming Silene species. We identified several new Microbotryum lineages with varying degrees of specialization that is likely influenced by degrees of host divergence and ecological similarities (i.e. shared pollinator guilds). Affected species had 15%-40% of plants infected by anther smut. Flowering was seasonally overlapping among host species (except for the species pair S.asclepiadea and S.atrocastanea), but diseased flowering onset was earlier than healthy plants, leading to dramatic seasonal shifts in observed disease prevalence. Overlapping distributions and flowering provides opportunities for floral pathogen movement between host species, but host specialization may be constrained by the plant phylogenetic relatedness, adaptation to micro-habitats and difference in pollinator/vector guilds.

Introgression of peanut smut resistance from landraces to elite peanut cultivars (Arachis hypogaea L.).

Smut disease caused by the fungal pathogen Thecaphora frezii Carranza & Lindquist is threatening the peanut production in Argentina. Fungicides commonly used in the peanut crop have shown little or no effect controlling the disease, making it a priority to obtain peanut varieties resistant to smut. In this study, recombinant inbred lines (RILs) were developed from three crosses between three susceptible peanut elite cultivars (Arachis hypogaea L. subsp. hypogaea) and two resistant landraces (Arachis hypogaea L. subsp. fastigiata Waldron). Parents and RILs were evaluated under high inoculum pressure (12000 teliospores g-1 of soil) over three years. Disease resistance parameters showed a broad range of variation with incidence mean values ranging from 1.0 to 35.0% and disease severity index ranging from 0.01 to 0.30. Average heritability (h2) estimates of 0.61 to 0.73 indicated that resistance in the RILs was heritable, with several lines (4 to 7 from each cross) showing a high degree of resistance and stability over three years. Evidence of genetic transfer between genetically distinguishable germplasm (introgression in a broad sense) was further supported by simple-sequence repeats (SSRs) and Insertion/Deletion (InDel) marker genotyping. This is the first report of smut genetic resistance identified in peanut landraces and its introgression into elite peanut cultivars.

Proteomic Analysis of the Resistance Mechanisms in Sugarcane during Sporisorium scitamineum Infection.

Smut disease is caused by Sporisorium scitamineum, an important sugarcane fungal pathogen causing an extensive loss in yield and sugar quality. The available literature suggests that there are two types of smut resistance mechanisms: external resistance by physical or chemical barriers and intrinsic internal resistance mechanisms operating at host–pathogen interaction at cellular and molecular levels. The nature of smut resistance mechanisms, however, remains largely unknown. The present study investigated the changes in proteome occurring in two sugarcane varieties with contrasting susceptibility to smut—F134 and NCo310—at whip development stage after S. scitamineum infection. Total proteins from pathogen inoculated and uninoculated (control) leaves were separated by two-dimensional gel electrophoresis (2D-PAGE). Protein identification was performed using BLASTp and tBLASTn against NCBI nonredundant protein databases and EST databases, respectively. A total of thirty proteins spots representing differentially expressed proteins (DEPs), 16 from F134 and 14 from NCo310, were identified and analyzed by MALDI-TOF/TOF MS. In F134, 4 DEPs were upregulated and nine were downregulated, while, nine were upregulated and three were downregulated in NCo310. The DEPs were associated with DNA binding, metabolic processes, defense, stress response, photorespiration, protein refolding, chloroplast, nucleus and plasma membrane. Finally, the expression of CAT, SOD, and PAL with recognized roles in S. scitamineum infection in both sugarcane verities were analyzed by real-time quantitative PCR (RT-qPCR) technique. Identification of genes critical for smut resistance in sugarcane will increase our knowledge of S. scitamineum-sugarcane interaction and help to develop molecular and conventional breeding strategies for variety improvement.

New Insights of Ustilago maydis as Yeast Model for Genetic and Biotechnological Research: A Review.

The basidiomycete Ustilago maydis is a biotrophic organism responsible for corn smut disease. In recent years, it has become one of the most promising models for biochemical and biotechnological research due to advantages, such as rapid growth, and easy genetic manipulation. In some aspects, this yeast is more similar to complex eukaryotes, such as humans, compared to standard laboratory yeast models. U. maydis can be employed as a tool to explore physiological processes with more versatility than other fungi. Previously, U. maydis was only considered as a phytopathogenic fungus, but different studies have shown its potential as a research model. Therefore, numerous promising studies have focused on deepening our understanding of the natural interactions, enzyme production, and biotechnological capacity. In this review, we explore general characteristics of U. maydis, both as pathogenic and "innocuous" basidiomycete. Additionally, a comparison with other yeast models focusing on genetic, biochemical, and biotechnological research are analyzed, to emphasize the versatility, dynamism, and novelty that U. maydis has as a research model. In this review, we highlight the applications of the yeast form of the fungus; however, since the filamentous form is also of relevance, it is addressed in the present work, as well.