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Sorghum is one of the main staple food crops for millions of subsistence farmers in Africa. Biotic and abiotic challenges are the major production constraints of the crop. Amongst the sorghum biotic constraints, anthracnose is the major devastating disease causing up to 80% of yield reduction. The productivity and profitability of sorghum is limited by several biotic constraints, most notably anthracnose caused by the aggressive fungal pathogen Colletotrichum sublineolum. The most effective and environmentally responsible strategy to control anthracnose is through the incorporation of resistance genes. However, although several sources have been identified, the lack of information with regard to its genetic control of resistance has limited their adequate use in breeding programs. Additionally, the limitations of breeding regarding the leaf and stalk anthracnose resistance and also the need for evaluating materials for resistance and yield in different environments is of major importance. There is limited information about the combining ability, gene action and genetic effects and relationships between anthracnose resistance and grain yield which is required in devising appropriate strategies for developing resistant and high yielding sorghum varieties. This review provides theoretical basis of the progress and challenges for breeding sorghum for anthracnose resistance and improved yield.

Summary The ability of the wheat Lr34 multipathogen resistance gene (Lr34res) to function across a wide taxonomic boundary was investigated in transgenic Sorghum bicolor. Increased resistance to sorghum rust and anthracnose disease symptoms following infection with the biotrophic pathogen Puccinia purpurea and the hemibiotroph Colletotrichum sublineolum, respectively, occurred in transgenic plants expressing the Lr34res ABC transporter. Transgenic sorghum lines that highly expressed the wheat Lr34res gene exhibited immunity to sorghum rust compared to the low‐expressing single copy Lr34res genotype that conferred partial resistance. Pathogen‐induced pigmentation mediated by flavonoid phytoalexins was evident on transgenic sorghum leaves following P. purpurea infection within 24–72 h, which paralleled Lr34res gene expression. Elevated expression of flavone synthase II, flavanone 4‐reductase and dihydroflavonol reductase genes which control the biosynthesis of flavonoid phytoalexins characterized the highly expressing Lr34res transgenic lines 24‐h post‐inoculation with P. purpurea. Metabolite analysis of mesocotyls infected with C. sublineolum showed increased levels of 3‐deoxyanthocyanidin metabolites were associated with Lr34res expression, concomitant with reduced symptoms of anthracnose.

Priming is a natural phenomenon that pre-conditions plants for enhanced defence against a wide range of pathogens. It represents a complementary strategy, or sustainable alternative that can provide protection against disease. However, a comprehensive functional and mechanistic understanding of the various layers of priming events is still limited. A non-targeted metabolomics approach was used to investigate metabolic changes in plant growth-promoting rhizobacteria (PGPR)-primed Sorghum bicolor seedlings infected with the anthracnose-causing fungal pathogen, Colletotrichum sublineolum, with a focus on the post-challenge primed state phase. At the 4-leaf growth stage, the plants were treated with a strain of Paenibacillus alvei at 108 cfu mL−1. Following a 24 h PGPR application, the plants were inoculated with a C. sublineolum spore suspension (106 spores mL−1), and the infection monitored over time: 1, 3, 5, 7 and 9 days post-inoculation. Non-infected plants served as negative controls. Intracellular metabolites from both inoculated and non-inoculated plants were extracted with 80% methanol-water. The extracts were chromatographically and spectrometrically analysed on an ultra-high performance liquid chromatography (UHPLC) system coupled to high-definition mass spectrometry. The acquired multidimensional data were processed to create data matrices for chemometric modelling. The computed models indicated time-related metabolic perturbations that reflect primed responses to the fungal infection. Evaluation of orthogonal projection to latent structure-discriminant analysis (OPLS-DA) loading shared and unique structures (SUS)-plots uncovered the differential stronger defence responses against the fungal infection observed in primed plants. These involved enhanced levels of amino acids (tyrosine, tryptophan), phytohormones (jasmonic acid and salicylic acid conjugates, and zeatin), and defence-related components of the lipidome. Furthermore, other defence responses in both naïve and primed plants were characterised by a complex mobilisation of phenolic compounds and de novo biosynthesis of the flavones, apigenin and luteolin and the 3-deoxyanthocyanidin phytoalexins, apigeninidin and luteolinidin, as well as some related conjugates.

To assess the prevalence and severity of sorghum diseases in western Kenya, a 2-year survey was conducted (July 1995 and 1996), in 91 and 109 farmers' fields, respectively. Fields were generally 25% in 3% of fields surveyed. Grain yield reduction from smut diseases alone was estimated to be 5%. Out of eight probability distribution functions compared, the double Gaussian model best described the frequency of disease severity levels for most diseases. Based on the best-fitting model, the proportion of fields with disease severity level thought to cause yield loss (severity rating >5 on a 1 to 9 scale, where 1 = no disease) was calculated as 26.6% for oval leaf spot, 15.3% for rust, 14.8% for anthracnose, 4.8% for ladder leaf spot, and 1.5% for leaf blight. The production environment influenced the prevalence of disease severity. Severe anthracnose, leaf blight, and ladder leaf spot were confined to fields in the humid LM1 and LM2 agro-ecological zones, rust was ubiquitous, and severe gray leaf spot was more prevalent in the dryer LM4 zone.

Metabolomics has emerged as a powerful approach to comprehensively interrogate cellular biochemistry. As such, we applied an untargeted liquid chromatography-mass spectrometry metabolomic strategy to elucidate metabolome changes in the anthracnose-causing hemibiotrophic sorghum pathogen, Colletotrichum sublineolum. An in vitro batch culture study model with different carbon sources, glucose, arabinose and rhamnose, were used to support fungal growth over a period of twelve days. Metabolites representing the intracellular and extracellular (secreted) metabolomes were extracted with methanol and subjected to LC-MS analyses. Chemometric modelling revealed a metabolic variation trajectory, comprising three distinct stages that metabolically describe the adaptation of the fungus to diminishing nutrients. Selected marker gene expression indicated stage one (0–3 d.p.i) as corresponding to the early logarithmic phase. Stage two can be interpreted as an intermediate transitionary stage with stage three corresponding to the stationary phase (9–12 d.p.i). Stage one was characterised by up-regulation of endo-metabolites such as ferricrocin, fatty acids and flavone-conjugates, while stage three was characterised by the secretion of phytotoxins, including colletotrichin and colletotric acid. Ultimately, results from our in vitro model reveal previously unknown insights into the dynamic aspects of metabolome reprogramming in the growth phases of Colletotrichum spp as determined by nutrients obtainable from plant cell walls.

Importance of sorghum as staple food worldwide is unquestionable and silicon (Si) supply has decreased the foliar symptoms of anthracnose, caused by Colletotrichum sublineolum, through potentiation of defense responses and preservation of photosynthetic apparatus. This study investigated the role of Si in cytological changes as well as in the expression of genes involved in auxin metabolism (GH3.1) and in signaling pathways mediated by salicylic acid (SA) (BTHip), jasmonic acid (JA)/ethylene (ET) (LOX), and JA (Jar, AOS 1, and ACCox) by real-time polymerase chain reaction in the leaves of plants non-supplied (-Si) or supplied (+Si) with Si and non-inoculated or inoculated with C. sublineolum. Sheath cells from +Si plants were less colonized by fungal hyphae due to intense phenolics and lignin deposition and high hydrogen peroxide production. Foliar lesions for +Si plants sprayed with an ET signaling inhibitor, ET biosynthesis inhibitor, and JA biosynthesis inhibitor were bigger compared to +Si plants sprayed with water. For +Si plants sprayed with ET and JA signaling inhibitors, foliar lesions were smaller compared to -Si plants sprayed with these same compounds. Suppression of auxin biosynthesis, transporter, and signaling by specific inhibitors resulted in smaller lesions. Expressions of GH3.1, BRHip, LOX, Jar, AOS 1, and ACCox were greater for +Si plants compared to -Si plants during the infection process of C. sublineolum. This study highlighted the potential of Si to boost sorghum resistance to anthracnose through a multistep process involving hormone-signaling pathways, especially regarding auxin metabolism and homeostasis, hydrogen peroxide generation, and plant cell wall strengthening.

Several boron-containing small molecules have been approved by the US FDA to treat human diseases. We explored potential applications of boron-containing compounds in modern agriculture by pursuing multiple research and development programs. Here, we report a novel series of multi-substitution benzoxaboroles (1–36), a compound class that we recently reported as targeting geranylgeranyl transferase I (GGTase I) and thereby inhibiting protein prenylation (Kim et al., 2020). These compounds were designed, synthesized, and tested against the agriculturally important fungal pathogens Mycosphaerella fijiensis and Colletotrichum sublineolum in a structure–activity relationship (SAR) study. Compounds 13, 28, 30, 34 and 36 were identified as active leads with excellent antifungal MIC95 values in the range of 1.56–3.13 ppm against M. fijiensis and 0.78–3.13 ppm against C. sublineolum.

Background: Sorghum (Sorghum bicolor L., Moench) is the 5th most important food crop in the world. But its production in Ethiopia is adversely affected by different biotic and abiotic constraints among which sorghum anthracnose caused by Colletotrichum sublineolum is the major one. Methodology: In this perspective, it is imperative to assess the distribution and severity of sorghum anthracnose along varying agro-ecologies of Southwestern and Western Ethiopia. A total of 117 sorghum farms in 15 districts of 5 administrative zones within two regional states were assessed. Results: The disease was found to be widely distributed in all sorghum growing regions of the surveyed areas with 100% incidence. The severity of sorghum anthracnose varied significantly (p

Sorghum Anthracnose, caused by Colletotrichum sublineolum, is one of the most important disease causing significant economic loss of sorghum production in China. The pathogen C. sublineolum is a highly variable pathogen. So there is an imperative need for screening resistance sources for breeding and resistant varieties deployment. A total of 167 sorghum accessions were evaluated for anthracnose diseases response under field conditions during 2015 and 2016. The results showed that there were 27 accessions rated as highly resistant (HR) accounted for 16.17% and 38 accessions rated as resistant(R) accounted for 22.75% of the total 167 sorghum accessions. Susceptible response was observed for 53 accessions, which accounted for 31.74% of the total. The disease response of 89 accessions from China exhibited a resistant response accounted for 64.03% of the 139 Chinese accessions. The majority of the accessions showed reddening or red spots on inoculated leaves and 64% of the accessions (rate as S and HS) showed acervuli development on inoculated leaves within 15 days of inoculation. Present study indicated that the Chinese accessions could be an important source for anthracnose resistance. These resistant sources used in sorghum breeding should aid in expanding the genetic diversity and in the development of new resistant varieties.

Sorghum anthracnose, caused by Colletotrichum sublineolum, is widely distributed in most grain sorghum-producing areas in Arkansas, and localized epidemics continue to occur across the state. The objectives of this research were to determine the number of pathotypes of C. sublineolum in Arkansas and to determine where these pathotypes are located within the state. Ninety-eight isolates were collected from research stations and production fields located in the Delta region of Arkansas from 2003 through 2005 and were tested for virulence to eight differential grain sorghum breeding lines. Of these, 11 isolates produced conflicting and unreliable results and were excluded from further analysis. Among the remaining 87 isolates, 13 pathotypes were identified. Eleven of these pathotypes were previously unreported, with 53% of the isolates consisting of pathotype 9. Pathotype 9 was distinguished from all other pathotypes by its virulence to all eight differential lines. Pathotype diversity appeared to be more closely associated with the year than with the locations where isolates were collected. Although all host differential lines were susceptible to at least 50% of the isolates evaluated, inbred lines SC326-6, TAM428, and TX2536 were susceptible to more than 90% of the 87 isolates evaluated. These results showed that the C. sublineolum populations in Arkansas are diverse based on the comparisons of pathogenicity to previously published host differentials, and it appears that these field populations varied from year to year.

Development of sorghum anthracnose in time and space on susceptible (‘BTx623’ and ‘Pioneer 8313’) and resistant (‘Cargill 888Y’) sorghum (Sorghum bicolor) cultivars was investigated in field plots inoculated with a mixture of three strains (T430-SW, Ar54-SW, and ArSS-1SW) of Colletotrichum sublineolum in 2001 and 2002. After slow development during early growth stages, sorghum anthracnose developed rapidly after flowering. The logistic model provided a good statistical fit for disease progress curves for sorghum anthracnose in Arkansas. Compared to susceptible cultivars, the resistant cultivar had significantly lower values for the standard area under the disease progress curve, a lower upper asymptote, and delayed epidemic onset. However, there were no significant differences in infection rate and the time of the inflection points, the times at which the disease proportion equaled values of one-half of upper asymptotes, among the three cultivars. The negative exponential model more closely described disease gradients of sorghum anthracnose than the inverse power law model. There were significant differences in intercepts but not in slopes and half-distance between the resistant and susceptible cultivars. The slopes of disease gradients were significantly lower at 78 days after inoculation (DAI) than at 57 DAI on the three cultivars. The results could provide epidemiological components of sorghum anthracnose to help evaluate sorghum cultivars and breeding lines under field conditions.

The metabolome of a biological system provides a functional readout of the cellular state, thus serving as direct signatures of biochemical events that define the dynamic equilibrium of metabolism and the correlated phenotype. Hence, to elucidate biochemical processes involved in sorghum responses to fungal infection, a liquid chromatography-mass spectrometry-based untargeted metabolomic study was designed. Metabolic alterations of three sorghum cultivars responding to Colletotrichum sublineolum, were investigated. At the 4-leaf growth stage, the plants were inoculated with fungal spore suspensions and the infection monitored over time: 0, 3, 5, 7, and 9 days post inoculation. Non-infected plants were used as negative controls. The metabolite composition of aqueous-methanol extracts were analyzed on an ultra-high performance liquid chromatography system coupled to high-definition mass spectrometry. The acquired multidimensional data were processed to create data matrices for multivariate statistical analysis and chemometric modeling. The computed chemometric models indicated time- and cultivar-related metabolic changes that reflect sorghum responses to the fungal infection. Metabolic pathway and correlation-based network analyses revealed that this multi-component defense response is characterized by a functional metabolic web, containing defense-related molecular cues to counterattack the pathogen invasion. Components of this network are metabolites from a range of interconnected metabolic pathways with the phenylpropanoid and flavonoid pathways being the central hub of the web. One of the key features of this altered metabolism was the accumulation of an array of phenolic compounds, particularly de novo biosynthesis of the antifungal 3-deoxyanthocynidin phytoalexins, apigeninidin, luteolinidin, and related conjugates. The metabolic results were complemented by qRT-PCR gene expression analyses that showed upregulation of defense-related marker genes. Unraveling key characteristics of the biochemical mechanism underlying sorghum-C. sublineolum interactions, provided valuable insights with potential applications in breeding crop plants with enhanced disease resistance. Furthermore, the study contributes to ongoing efforts toward a comprehensive understanding of the regulation and reprogramming of plant metabolism under biotic stress.

The productivity and profitability of sorghum [ (L.) Moench] is reduced by susceptibility to fungal diseases, such as anthracnose ( P. Henn.). A limited number of resistant accessions are present in the temperate-adapted germplasm; other exotic sources of resistance are not currently available for breeding programs. Among 335 accessions available to breeders from a previously genotyped sorghum association panel (SAP), we found that 75 were resistant to anthracnose. A phylogenetic analysis of these accessions showed high genetic diversity and multiple resistance sources. Genome-wide association scans (GWAS) were conducted using 268,289 single-nucleotide polymorphisms to identify loci associated with anthracnose resistance. Using logistic regressions for binary measures of resistance responses, we identified three loci within a region on chromosome 5 that have been previously associated with three sources of anthracnose resistance. A GWAS limited to Caudatum germplasm identified an association with a region on chromosome 1 and with the same previous region on chromosome 5. Candidate genes within these loci were related to R-gene families, signaling cascades, and transcriptional reprogramming, suggesting that the resistance response is controlled by multiple defense mechanisms. The strategic integration of exotic resistant germplasm into the SAP is needed to identify additional rare resistance alleles via GWAS.

Plant leucine-rich repeat (LRR) domain-containing proteins are known to play important roles in signaling transduction and defense responses. In sorghum, SbLRR2 is pathogen-inducible gene encoding a simple extracellular LRR protein. Here, we demonstrated an earlier and stronger expression of SbLRR2 in a sorghum resistant genotype in comparison to a susceptible genotype following inoculation with the anthracnose pathogen (Colletotrichum sublineolum). In addition, SbLRR2 expression was found to be induced strongly by methyl-jasmonate treatment. Functional analysis was performed in SbLRR2 over-expression (OE) Arabidopsis plants, which showed enhanced resistance against the necrotrophic pathogens Botrytis cinerea and Alternaria brassicicola. In addition, the OE lines were found to have elevated expression of several jasmonate acid (JA)-associated genes and higher endogenous JA contents. Hence, the SbLRR2-mediated defense responses in transgenic Arabidopsis are likely to be dependent on JA-signaling through increased JA production. On the other hand, the OE lines remained susceptible to Pseudomonas syringae pv. tomato like the wild type plants. Consistently, there was no up-regulation of salicylic acid (SA) defense marker gene expression or SA levels in the OE lines. Our results suggested that SbLRR2 is potentially useful for enhancing resistance against necrotrophic pathogens in transgenic dicot crops.

The aim of this study was to evaluate the use of genotype rotation as a sustainable management strategy for the control of foliar anthracnose of sorghum. Three grain sorghum hybrids, one susceptible (BR 304) and two resistant to anthracnose (1G150 and DAS740) were tested in continuous planting and genotype rotation during seven growing seasons. The area under disease progress curve (AUDPC) of sorghum anthracnose severity was significantly lower in the genotype rotation than in the continuous planting. The disease severity in the susceptible genotype BR 304 in rotation with the resistant genotypes 1G150 or DAS740 decreased about 42% and 70% respectively, compared to its continuous planting. A significant reduction of leaf blight disease severity caused by Exserohilum turcicum in DAS740 planted rotated with BR 304 was also observed. The grain yields of the three genotypes were significantly higher in the rotation system compared to continuous planting. The genotype rotation can be considered a practical management strategy for reducing the impact of anthracnose and other diseases in sorghum.

To elucidate genetic mechanisms of host species specificity between graminicolous anthracnose fungi and gramineous plants, infection assays were performed with a Sorghum isolate (Colletotrichum sublineolum), a Digitaria isolate (C. hanaui), a Polypogon isolate (C. cereale), and an Avena isolate (C. cereale). They were specifically virulent on the plants from which they were isolated. When 72 wheat lines were inoculated with an unadapted isolate from Asia Minor bluegrass (Cgp29), however, some exceptional cultivars were recognized. Although most cultivars were resistant to Cgp29, ‘Hope’ was susceptible. In F2 populations derived from crosses between three resistant cultivars—‘Norin 4’ (N4), ‘Chinese Spring’ (CS), and ‘Shin-chunaga’ (Sch)—and the susceptible Hope, resistant and susceptible seedlings segregated in a 3:1 ratio, suggesting that a major gene is involved in the resistance of each cultivar to Cgp29. In F2 populations derived from crosses between the three resistant cultivars, all seedlings were resistant, suggesting that these three cultivars carry the same gene. This resistance gene was designated as “resistance to Colletotrichum cereale 1” (Rcc1). Analysis with the CS–Hope chromosome substitution lines and molecular mapping revealed that Rcc1 was located on the long arm of chromosome 5A. Cytologically, Rcc1 was mainly associated with hypersensitive reaction. These results suggest that major genes similar to those controlling cultivar specificity are involved in the resistance of wheat against the unadapted isolate of C. cereale.

This study was done to investigate biochemical, histological and molecular basis of resistance after a compatible and incompatible interaction between Sorghum varieties andColletotrichum sublineolum. In the susceptible variety, the pathogen invaded all types of tissues but in resistance variety, pathogen invasion was redistricted. Localized cell death was obvious in cortical region of resistant variety that stopped further invasion of pathogen. Epidermis of susceptible variety ruptured shortly after pathogen inoculation and fungal bodies emerged whereas in resistant variety a long delay was noted in occurrence of same event. A steep increase in total phenolics and enzymes related to phenylpropenoid pathway was observed after pathogen challenge in resistant variety as compared to the susceptible one. Histochemical studies revealed heavy deposition of lignin, callose, suberin, phenolics and peroxidases in the resistant variety. These enhanced depositions reduced the pathogen invasion in the host plant. Similarly, RT-PCR analysis revealed higher expression levels of PR protein-genes in the resistant variety. This study presents the nature of a resistant host defense mechanism against a virulent pathogen and made us to integrate defense mechanism for development of resistant varieties in future. Key words: Sorghum bicolor, Colletotrichum sublineolum, cytological, histochemical, phenolics, lignin, peroxidases, RP genes.

Submitted by Alison Souza (alisonsouza@ufgd.edu.br) on 2019-04-15T11:47:16Z No. of bitstreams: 1 CassioLuizCaetano.pdf: 856476 bytes, checksum: 81f88ca6277bf861847d1bb9cc4399b0 (MD5) Made available in DSpace on 2019-04-15T11:47:17Z (GMT). No. of bitstreams: 1 CassioLuizCaetano.pdf: 856476 bytes, checksum: 81f88ca6277bf861847d1bb9cc4399b0 (MD5) Previous issue date: 2016-09-06 Conselho Nacional de Pesquisas (CNPq) Cultivares de sorgo são estudadas como potenciais fontes de biocombustíveis, devido à sua alta produção de biomassa e de açúcar. Contudo, alguns fatores podem interferir na produtividade de biomassa e açúcares do sorgo, podendo citar as doenças. Assim, o presente trabalho teve por objetivo a avaliação de doenças foliares em duas cultivares de sorgo sacarino tratadas ou não com fungicida e sua correlação com a produção de biomassa e sólidos solúveis totais. O experimento foi conduzido a campo, na Fazenda Experimental de Ciências Agrárias (FAECA) da Universidade Federal da Grande Dourados (UFGD). Foram avaliadas duas cultivares de sorgo sacarino (BRS 506 e BRS 511), em duas épocas de semeadura: 25 de novembro de 2014, para o ensaio de safra, e 02 de março 2015, para ensaio de safrinha. O delineamento experimental foi inteiramente casualizado, com quatro repetições, em esquema fatorial 2x4 (cultivares x tratamentos). Os tratamentos constituíram da aplicação de epoxiconazol + piraclostrobina nos seguintes esquemas: 0 - sem tratamento; 1 - uma aplicação (45 dias após a emergência - DAE); 2 - duas aplicações (45 e 66 DAE) e 3 - três aplicações (45, 66 e 87 DAE). Um segundo ensaio de safrinha foi montado em delineamento experimental inteiramente casualizado, com quatro repetições em esquema fatorial 2x2 (cultivar x tratamento) onde os tratamentos constituíram da aplicação de protioconazol + trifloxistrobina nos seguintes esquemas: a primeira aplicação aos 45 DAE seguidas de mais 4 aplicações a cada 14 dias; e sem aplicação do fungicida. Foram avaliadas a severidade das doenças foliares ocorrentes, diâmetro do colmo, altura de planta, volume de caldo, biomassa verde e teor de sólidos solúveis totais. Os dados foram submetidos à análise de variância e quando significativos foram realizados os testes de médias. Foi realizada análise de correlação entre os dados de severidade de doença e as características agronômicas estudadas. Existem diferenças entre as cultivares quanto à suscetibilidade a mancha alvo. A aplicação de epoxiconazol + piraclostrobina tem efeito positivo no controle de doenças foliares, acumulo de biomassa e diminui a perca de sólidos solúveis totais. O fungicida protioconazol + trifloxistrobina diminuiu a severidade da antracnose, cercosporiose e ferrugem, não apresentou resultados no controle da helmintosporiose e mancha alvo e não resultou em incremento de biomassa e açúcares. Doenças foliares se correlacionam de forma negativa com a produção de biomassa e sólidos solúveis totais, em sorgo sacarino. Sorghum cultivars have been studied as potential biofuels sources due to their large potential to produce sugar and biomass. However, some features may influence the viability of biomass or sugar production from sorghum, for example plant diseases. The aim of this study was evaluate leaf diseases of two different sweet sorghum cultivars treated or not with fungicides, and the correlation between the fungicides applications and the sorghum biomass and the total soluble solids. The trial was conducted under field conditions at the Agriculture Science Experimental Farm (FAECA) at the Federal University of Grande Dourados (UFGD). Two sorghum cultivars (BRS 506 and BRS 511) were evaluated in two sowing seasons: November 25, 2014, and March 2, 2015. The experimental design was completely randomized, with four replications, in a 2x4 factorial design (cultivars x treatments). The treatments consisted in applications of Epoxiconazole + Pyraclostrobin with theses days: 0 – control (nor application), 1- one fungicide application at 45 days after the sorghum emergence, 2 – two fungicide applications at 45 and 66 days after the sorghum emergence, 3- three fungicide applications at 45, 66 and 87 days after the sorghum emergence. A second field trial was set up in March using a completely randomized design, in a factorial design (2x2) with four replications. The treatments consisted of Prothioconazole + Trifloxystrobin applications at the following application arrangement: first application at 45 days after sorghum emergence followed by four applications applied every 14 days, and another treatment with no fungicide application. The parameters evaluated were disease severity, stem diameter, plant height, broth volume, green biomass content and total soluble solids content were evaluated in the experiment. The data were submitted to analysis of the variance, and once significant were performed in the means tests. The correlation analysis between disease severity data and agronomic characteristics was performed. There are differences among cultivars regarding susceptibility to the target spot. The application of epoxiconazole + pyraclostrobin has a positive effect on the foliar diseases control, biomass accumulation and decrease the loss of total soluble solids. The fungicide prothioconazole + trifloxystrobin decreased the severity of anthracnose, cercosporiosis and rust; however, did not showed results in the control of helmintosporiosis and target spot and did not resulted in an increase of the biomass and sugars. Foliar diseases are negatively correlated with the production of biomass and total soluble solids in sweet sorghum.

Amplified fragment length polymorphism (AFLP) based genetic diversity was analyzed for 232 Colletotrichum sublineolum isolates collected between 2002 and 2004 from three geographically distinct regions of Texas, and from Arkansas, Georgia, and Puerto Rico. Results revealed significant levels of polymorphism (59%) among the isolates. Even so, genetic similarity between isolates was high, ranging from 0.78 to 1.00. Clustering of similar isolates did not correlate with either geographic origin or year of collection. Pathotypes of 20 of the isolates were determined using 14 sorghum lines previously used in Brazil and the United States and 4 from Sudan. Seventeen new pathotypes were established from the 18 isolates that gave uniform and consistent reactions on all host differentials over 2 years of greenhouse testing. Differentials BTx378 and QL3 were resistant to all isolates while BTx623 and TAM428 were universally susceptible both years. Each of these lines had shown differential responses in prior studies indicating that the pathogen population has sufficient diversity to adapt rapidly to changes in resistant host lines deployed. When the 2-step pathotype classification scheme was used, the 18 isolates examined in this study were placed in four pathotype groups (A, C, D and G), which would further then be separated into ten distinct pathotypes. Common sets of differentials and a standardized nomenclature will allow for comparison to be made among pathotypes of C. sublineolum detected from different regions and also could help direct planting of appropriate sorghum lines and aid in the development of more durable forms of resistance.

Seventy-two sorghum accessions were randomly selected from the Ethiopia, Mali, Sudan, and Uganda germplasm collections maintained by the US National Plant Germplasm System to evaluate variation in anthracnose resistance. The accessions were planted in a randomized complete block design in College Station, Texas during the 2007 and 2008 growing seasons. Twenty-six accessions exhibited a resistant response across growing seasons with 8 accessions showing a susceptible response. Twenty-nine accessions showed variation in disease response within and between experiments. Seven accessions were rated as resistant in 2007 but showed a susceptible reaction in 2008. The frequency of resistant germplasm varied based on country of origin with 80% of the accessions from Mali, 48% of the accessions from Uganda, 24% of the accessions from Sudan, and 7% of the accessions from Ethiopia exhibiting a resistance response. When the same accessions were evaluated in Isabela, Puerto Rico, 100% of the accessions from Mali, 43% of the accessions from Uganda, and 28% of the accessions from Sudan exhibited a resistant response. All the accessions from Ethiopia were susceptible to anthracnose when evaluated in Isabela, Puerto Rico. In both locations, 22 accessions exhibited a resistant response. Four accessions rated as resistant in Texas were found to be susceptible in Puerto Rico; whereas, five accessions rated as resistant in Puerto Rico showed a susceptible response in Texas. These results indicated that the Mali, Sudan, and Uganda sorghum collections may be an important source of anthracnose resistance. However, the identification of anthracnose resistant germplasm from many diverse regions could result in the identification of new sources of genetic variation for resistance. Also, greater genetic variation for resistance could be present in regions with a high frequency of resistant germplasm.

Erpelding J.E. (2011): Anthracnose field evaluation of sorghum germplasm from Botswana. Plant Protect. Sci., 47: 149-156. Sorghum anthracnose is a disease of worldwide importance and host-plant resistance is the most practical method of disease management. In this study, 154 sorghum accessions from the Botswana collection maintained by the United States National Plant Germplasm System were inoculated with Colletotrichum sublineolum and evaluated for disease resistance at the Tropical Agriculture Research Station in Isabela, Puerto Rico during 2007 and 2008. A resistant response was observed for 69 accessions in 2007 and for 48 accessions in 2008 with no acervuli development observed on inoculated leaves. The low frequency of resistant germplasm is expected from a region of low annual rainfall. However, disease severity was low for the susceptible accessions with a mean severity of 11% for the 85 susceptible accessions observed in 2007 and 17% for the 106 susceptible acces - sions identified in 2008. The highest frequency of resistant accessions was observed for the Ngamiland district with 58% of the accessions rated as resistant, whereas the frequency of resistant accessions ranged from 22% to 36% for the other districts. The lowest mean disease severity was also observed for the susceptible accessions from the Ngamiland district with the highest mean disease severity observed for susceptible accessions from the Kgatleng district. The resistant accessions identified in this study would be useful for the development of disease resistant varieties and the results indicated an ecogeographic association with disease resistance.

Field experiments were conducted in the 2007 and 2008 cropping seasons in Wolayta, southern Ethiopia, to assess the reaction of 56 Ethiopian sorghum accessions and two susceptible checks (AL70 and BTx623) to anthracnose from naturally occurring inoculum. Final anthracnose severity (FAS), relative area under the disease progress curve (rAUDPC, where a commonly used susceptible cultivar, AL70, was set to 1), and anthracnose progress rate were used as evaluation parameters. All the evaluation parameters revealed significant variation among the tested accessions. In 2007, anthracnose severity varied between 6.6 and 77.7%, and in 2008 it ranged from 9.7% to 76%. The Ethiopian sorghum accessions had rAUDPC ranging from 0.13 to 0.88 in 2007 and from 0.18 to 1.35 in 2008. Anthracnose progress rate varied between 0.02 and 0.06 and from 0.01 to 0.05 units per day in 2007 and 2008, respectively. Results from the three parameters were highly correlated (0.18–0.87), suggesting FAS would be a suitable selection parameter for germplasm screening. Fifteen accessions in 2007 and 18 in 2008 were rated as resistant, with six accessions rated as resistant in both years, suggesting germplasm from Ethiopia would be useful for breeding resistance to anthracnose.

Sorghum accessions from Uganda were evaluated for grain mold and anthracnose resistance during the 2005 and 2006 growing seasons at the Texas A&M University Research Farm, near College Station, TX. Accession PI534117 and SC719-11E exhibited the lowest grain mold severities of 2.4, whereas, accessions PI534117, PI534144, PI576337, PI297199, PI533833, and PI297210, with SC748-5 were highly resistant to anthracnose in both years. Accessions PI534117, PI297134, PI297156 exhibited low grain mold severities in 2006. Significant negative correlation was recorded between grain mold and percent germination and high temperature in both years. In 2006, daily precipitation recorded significant positive correlation with grain mold. The seed mycoflora was analyzed across sorghum lines and treatments. In 2005, Curvularia lunata and Fusarium thapsinum were the most frequently recovered fungal species with 31 and 21% incidence, respectively, followed by Alternaria spp. (19%) and F. semitectum (13%). In 2006, predominant colonizers were F. thapsinum (58%), followed by Alternaria and F. semitectum with 15 and 10, percent respectively, while C. lunata had a 6% incidence. In this study, PI534117 holds promise for multiple disease resistance, as it had the lowest disease severity of grain mold and was highly resistant to anthracnose in both years. It also has a high germination rate, a high seed weight, and its short stature is more advantageous for the new A-line conversion program.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:41:01Z No. of bitstreams: 1 S1516-89132011000100001.pdf: 68182 bytes, checksum: b04905feb290e47baada13781c02bc87 (MD5) Made available in DSpace on 2013-08-22T18:41:01Z (GMT). No. of bitstreams: 1 S1516-89132011000100001.pdf: 68182 bytes, checksum: b04905feb290e47baada13781c02bc87 (MD5) Previous issue date: 2011-02-01 Made available in DSpace on 2013-09-30T19:27:16Z (GMT). No. of bitstreams: 2 S1516-89132011000100001.pdf: 68182 bytes, checksum: b04905feb290e47baada13781c02bc87 (MD5) S1516-89132011000100001.pdf.txt: 16629 bytes, checksum: 34f3b4df496ad2f781ddf56ae134c845 (MD5) Previous issue date: 2011-02-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:07:34Z No. of bitstreams: 2 S1516-89132011000100001.pdf: 68182 bytes, checksum: b04905feb290e47baada13781c02bc87 (MD5) S1516-89132011000100001.pdf.txt: 16629 bytes, checksum: 34f3b4df496ad2f781ddf56ae134c845 (MD5) Made available in DSpace on 2014-05-20T15:07:34Z (GMT). No. of bitstreams: 2 S1516-89132011000100001.pdf: 68182 bytes, checksum: b04905feb290e47baada13781c02bc87 (MD5) S1516-89132011000100001.pdf.txt: 16629 bytes, checksum: 34f3b4df496ad2f781ddf56ae134c845 (MD5) Previous issue date: 2011-02-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Yeasts isolated from sugar cane and maize rhizosphere, leaves and stalks were screened against the phytopathogenic molds Colletotrichum sublineolum and Colletotrichum graminicola, both causal agents of the anthracnose disease in sorghum and maize, respectively. Strains identified as Torulaspora globosa and Candida intermedia were able to inhibit the mold growth, with the first species also exhibiting killer activity. No previous report on the application and potentiality of these yeasts as biocontrol agents were found neither the killer phenotype in Torulaspora globosa. Universidade Federal de São Carlos (UFSCar) Centro de Ciências Agrárias Universidade Estadual Paulista Centro de Estudos Ambientais Universidade Estadual Paulista Centro de Estudos Ambientais

The United States National Plant Germplasm System maintains 151 sorghum accessions from Burundi of which 148 accessions were evaluated for resistance to Colletotrichum sublineolum at the Tropical Agriculture Research Station in Isabela, Puerto Rico in replicated evaluations during the 2007 and 2008 growing seasons. For the 2007 experiment, 120 accessions showed a resistant response with 89 of these accessions rated as resistant in 2008. The resistant accessions showed reddening of inoculated leaves with no acervuli development, whereas accessions rated as susceptible showed acervuli development on inoculated leaves. Mean infection severity based on the percentage of infected leaf area for the susceptible accessions was 2% in 2007 and 2.5% for the 2008 experiment. Only four accessions showed an infection severity more than 10% and eight accessions showed a susceptible response across replications and growing seasons. Results of this study indicate that sorghum germplasm from Burundi is an important source of anthracnose resistance for sorghum improvement and that germplasm from regions of high annual rainfall is frequently associated with anthracnose resistance.

The high degree of variability of the fungus Colletotrichum sublineolum, causal agent of sorghum anthracnose, has hindered the development of resistant hybrids. The objective of this research was to compare the aggressiveness of different fungal isolates and evaluate the genetic resistance (vertical and horizontal resistance) of various sorghum lines and hybrids. Twelve isolates, collected from different regions, were inoculated on 87 lines and 63 hybrids in the field and disease severity was evaluated. The diallel crossing method provided information about the vertical and horizontal resistance of the host, as well as the aggressiveness/ virulence of the pathogen. This genetical method was very promising for the identification of horizontal resistance in the sorghum- Colletotrichum sublineolum pathosystem, and for the prediction of anthracnose resistance in hybrids in the absence of vertical resistance. Dilatory resistance was detected in 14.94% of the inbred lines, and in 19.04% of the hybrids. Significant differences in aggressiveness and virulence of the isolates were also observed.

Sorghum anthracnose, caused by Colletotrichum sublineolum, is found in most grain-sorghum-producing areas, including Arkansas. Yield losses can be severe in susceptible sorghum hybrids, suggesting that host resistance will continue to be critical for maintaining high yields. However, genetic control is often unsuccessful because of haplotype and pathotype variability within the C. sublineolum population. The objective of this research was to assess the levels of resistance of selected grain sorghum hybrids to isolates of the recently described pathotypes of C. sublineolum found in Arkansas. Field experiments were conducted in 2005 and 2006 to evaluate the reaction of 10 sorghum hybrids to eight C. sublineolum pathotypes by collecting anthracnose severity ratings at 7, 14, 21, and 28 days after inoculation. Based on these disease severity ratings, the area under the disease progress curve was calculated for each pathotype by hybrid interaction. These data showed that different levels of resistance are available in the current grain sorghum hybrids to different pathotypes. Cargill 888Y was resistant to all pathotypes in both years. However, Asgrow A571, DEKALB DKS53-11, FFR 318, and Pioneer 84G62 were moderately susceptible to susceptible to all pathotypes tested in both years. Pathotype 9 caused the most disease on 7 of the 10 hybrids evaluated in 2005 but, in 2006, pathotypes 12 and 13 surpassed pathotype 9 for disease severity on 9 of the 10 hybrids. More work is needed to assess host resistance and the effect of sorghum anthracnose on yield parameters of grain sorghum hybrids planted in Arkansas.

Lentinula edodes (cogumelo "shiitake") é um fungo basidiomiceto que apresenta propriedades nutricionais, medicinais e antibióticas. Compostos de interesse para o homem têm sido isolados do basidiocarpo e dos filtrados de cultura obtidos a partir do crescimento micelial. O presente trabalho teve como objetivos avaliar o efeito de diferentes preparações de L. edodes sobre patógenos da cultura do sorgo, Exserohilum turcicum e Colletotrichum sublineolum, bem como a proteção das plantas de sorgo contra estes patógenos. Em testes com placas de Petri e lâminas de vidro para microscopia, extratos aquosos obtidos do basidiocarpo inteiro e de suas partes individualizadas, píleo e estipe, reduziram a taxa de crescimento micelial e inibiram a germinação de esporos dos fungos, enquanto a atividade antifúngica do filtrado de crescimento micelial foi menos pronunciada. Em mesocótilos de sorgo, as diferentes preparações do "shiitake" não provocaram o acúmulo de fitoalexinas. O extrato aquoso do basidiocarpo e o composto lentinana reduziram parcialmente a severidade das doenças provocadas por E. turcicum na cv. Brandes e por C. sublineolum na cv. Tx-398-B, quando pulverizados 48 horas antes da inoculação das plantas, sob condições de casa de vegetação. Portanto, L. edodes apresenta potencial como agente de controle biológico ou como um modelo para a síntese de substâncias fungicidas.Lentinula edodes ("shiitake" mushroom) is a fungus that presents nutritional, medicinal and antibiotic properties. Valuable compounds have been isolated from the fruiting bodies and from mycelium growth filtrates. The present work had as objectives the evaluation of the effect of L. edodes preparations on two sorghum pathogens, Exserohilum turcicum and Colletotrichum sublineolum, as well as the protection of sorghum plants against those fungi. When in vitro studies were carried out, aqueous extracts from the whole fruiting bodies and also from fruiting body parts, cap and stem, reduced the mycelium growth and the spore germination of the plant pathogens, while the antifungal activity of L. edodes´s mycelium growth filtrate was less pronounced. The shiitake preparations did not induce phytoalexin accumulation in sorghum mesocotyls. Aqueous extracts from fruiting bodies and lentinan partially reduced disease severity caused by E. turcicum in the cv. Brandes and by C. sublineolum in the cv. Tx-398-B, when applied 48 hours before plant inoculation. Therefore, L. edodes exhibits potential as a biological control agent or as a model for the synthesis of fungicidal compounds.