Regents of the University of Minnesota. Other studies in crop species too reported high prediction accuracies with surprisingly low Nt (Zhao et al. The pathogen is the fungus Exserohilum turcicum (syn. (2012). For instance, Poland et al. Today’s availability of high-density molecular marker data greatly facilitates molecular resistance breeding approaches (Collard and Mackill 2008) and the understanding of the genetic architecture of resistance traits. NCLB severity ratings were adjusted for effects pertaining to the environment and field design. The improvement of the resistance level of the inbred lines within each heterotic group requires allocating the available resources to parallel breeding programs. Severe symptoms can progress rapidly, resulting in blighted leaves. The spots will enlarge and may eventually cover the entire leaf⦠Though, there seems to be some significant tolerance within ⦠This might hamper the application of traditional marker assisted breeding approaches. Again, second-order natural smoothing spline regression was used to visualize this proportion as a function of the distance between the center values of the bins. The pathogen that carries this disease overwinters on the surface of the host plant. Large elliptical lesions of Northern corn leaf blight. Severity of symptoms varies widely, from insignificant to devastating, for some fields in some years. All lines were evaluated for NCLB resistance per se in the trial stations Bingen (Rhineland-Palatinate, Germany) and Pocking (Bavaria, Germany) in 2010. This is an open-access article distributed under the terms of the Creative Commons Attribution Unported License (http://creativecommons.org/licenses/by/3.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Density histograms of pairwise relationship coefficients between dent lines (A), flint lines (B) and between dent and flint lines (C). Northern corn leaf blight (NCLB) symptoms usually appear first on the lower leaves. The objectives of our study were to assess the prospect of genomic prediction of NCLB resistance in maize and the benefit of a training set that combines two heterotic groups. The prior for ui was , where denotes the multivariate-Gaussian density function, the polygenic variance, and A the realized additive relationship matrix. Northern corn leaf blight (NLB) is caused by the fungus Exserohilum turcicum, previously classified as Helminthosporium turcicum. Northern corn leaf blight (NCLB) is a disease of corn caused by the fungus, Exserohilum turcicum. A principal component analysis, based on the full 37,908 SNP marker profiles of the inbred lines, was used to investigate the genetic distinction of the dent and flint heterotic groups. Schematic illustration of the investigated prediction approaches: “within” prediction approach (full line), “across” prediction approach (dotted line) and “combined” prediction approach (dashed line). Forages. Ranging in length from 1 to 7 inches, the lesions develop on the lower corn leaves and spread to other corn foliage, including husks, as the disease progresses. The disease is most prevalent during moderate temperatures (64 to 80 degrees F) with prolonged periods of moisture. The process of generating training and prediction sets was repeated 100 times for all three levels of Nt in the manner described. Northern corn leaf blight (NCLB) is caused by the fungus Exserohilum turcicum and may cause significant yield losses when moderate temperatures and long periods of dew or rain prevail. It also needs to stay at least six hours on the surface of the leaf before it can cause infection. Symptoms The tan lesions of northern corn leaf blight are slender and oblong tapering at the ends ranging in size between 1 to 6 inches. Following Falconer and Mackay (1996) and assuming constant selection intensities, heritabilities and genetic variances across cycles, the aforementioned alternating scheme would lead to a greater selection gain over two cycles than a scheme based on the combined prediction approach, when ( denotes the within group prediction accuracy at 2Nt, the across group prediction accuracy when the training set size in the other group is 2Nt and the prediction accuracy from the combined training sets, when each group has a training set size of Nt). 2011) and livestock (Weber et al. There are two races of the pathogen. 1996), giving breeding for NCLB resistance a high priority for disease control. Spores are produced on this crop residue when environmental conditions become favourable in the spring and early summer. The pathogen that carries this disease overwinters on the surface of ⦠2012; de Roos et al. Northern leaf blight (NLB) can cause severe yield loss in maize; however, scouting large areas to accurately diagnose the disease is time consuming and difficult. Our results encourage the application of genomic prediction in NCLB-resistance breeding programs and the use of combined training sets. 2011; Wisser et al. Southern corn leaf blight is caused by the fungus Bipolaris maydis. The major advantage of genomic prediction is that all polymorphisms affecting a trait are modeled, regardless of effect size, making it a potentially powerful approach for a complex trait like NCLB resistance. (2012) studied the potential of combined training sets for predicting resistance to FHB and related deoxynivalenol toxin (DON) production in barley. (2010b), the expected prediction accuracy can be calculated as(4)where Me = 2NeG/log(4NeG) and G is the genome length in Morgan. There are two types of this plant disease – Northern and Southern corn leaf blight. “Spores are dispersed by wind and splashing water. The Northern Corn Leaf Blight, which is caused by E. turcicum is characterized by long lesions. Spots caused by maize northern leaf blight are larger, and fewer than spots caused ⦠Northern corn leaf blight occurs commonly in most areas of the Midwestern U.S. where corn is grown. Between the dent and flint lines, the mean was −0.49 with standard deviation of 0.18 (Figure 3). For example, even doubling Nt from 100 to 200 for prediction within a group just barely increased the prediction accuracy (4% for FHB and 10% for DON). In the case of Northern corn leaf blight, the one that is responsible for the disease is the Exserohilum turcicum fungus. It has also been known as Helminthosporium turcicum. Leaf spots caused by Calonectria pseudonaviculata - Photo by Sandra Jensen, Cornell University, Bugwood.org. ⦠Northern corn leaf blight is caused by another fungus that ⦠Compared with the increase in prediction accuracy when increasing Nt by adding individuals from the same group (e.g., moving from Nt = 25 to Nt = 50 within groups), the increase in prediction accuracy was only marginal, when the same increase in Nt was achieved by adding individuals from the other group. Similar results on the required marker density for prediction purposes in elite germplasm of maize were reported by Riedelsheimer et al. 2008). In general, the LD within the group of dent lines was slightly greater compared with the group of flint lines, whereas the LD across the set of dent and flint lines was lowest (Figure 2A). Northern leaf blight (NLB), also called northern corn leaf blight or turcicum blight, is a fungal foliar disease of maize caused by Setosphaeria turcica (anamorph: Exserohilum turcicum). Both gray leaf spot and northern corn leaf blight are also active in the lower canopy of corn across the state. Additionally, timely planting can be useful for avoiding conditions that favor the disease. One likely explanation for this are the commonly low effective population sizes Ne and consequently low effective number of independent chromosome segments Me, found in plant breeding populations (Riedelsheimer et al. In maize breeding, the two parental lines of a hybrid are taken from genetically distinct heterotic groups (dent and flint in Central Europe) for maximum exploitation of heterosis (Messmer et al. Northern corn leaf blight (NCLB), caused by the fungus Exserohilum turcicum, is an increasingly important disease in the U.S. Corn Belt. Northern Corn Leaf Blight (NCLB) is continuing to develop in several eastern Nebraska counties. 2012; Albrecht et al. Northern corn leaf spot caused by the fungus Cochliobolus carbonum has become more prevalent with the greater use of no-till systems. This research was funded by the German Federal Ministry of Education and Research (BMBF) within the AgroClustEr Synbreed—Synergistic plant and animal breeding (FKZ: 0315528d). “BEAGLE” software (Browning and Browning 2009), version 3.3.1, was used to impute all remaining missing marker genotypes, resulting in 37,908 SNP markers available for further analysis. Therefore, using training sets combining both heterotic groups might be a possibility of increasing training set sizes and thereby prediction accuracies. Northern Corn Leaf Blight in Northern New York By Amanda Bond, K. O’Neil, M. Hunter and G. Bergstrom Symptoms of northern corn leaf blight (NCLB) are seen across New York State and Northern New York, as well as the US Corn Belt, each season. Genomic prediction could greatly aid resistance breeding efforts. The Northern Corn Leaf Blight, which is caused by E. turcicum is characterized by long lesions. The training sets for the “combined” prediction approach were created by merging the training sets from both heterotic groups (Figure 1). Accordingly, indirect selection is superior to direct selection when LY is shorter than a certain fraction of LX, which depends on H2 of the target trait and the accuracy of genomic predictions. At the turn of the 20th century, northern corn leaf blight (NCLB) was a common problem for corn growers in New England. This makes it more challenging to establish a sufficiently sized training set within each heterotic group. 2012). (B) Proportion of markers with equal linkage phase across heterotic groups as a function of Δ in Mbp between markers on the same chromosome. Because the inbred lines were in very advanced selfing generations (> S6), heterozygous marker genotypes also were treated as genotyping errors and considered as missing. NCLB can slice ⦠However, its application to small breeds seems to be more challenging, mainly because difficulties of assembling large-enough training sets. Northern corn leaf blight is an infection caused by a fungus that is fairly common in the Midwest, wherever corn is grown. Large elliptical-shaped lesions on corn leaves herald this fungal disease. A genomic BLUP model was used to predict genotypic values. 2011; Lorenz et al. Northern Corn Leaf Blight Angela Madeiras, UMass Extension Plant Diagnostic Laboratory At the turn of the 20th century, northern corn leaf blight (NCLB) was a common problem for corn growers in New ⦠KwaZulu-Natal and Mpumalanga, it is common and causes serious yield Subscribe via email. Northern corn leaf blight (NCLB) is most devastating maize foliar disease in Himalayan region of the world, caused by fungus Exerohillum turcicum. Helminthosporium turcicum). The Bayesian version of genomic best linear unbiased prediction (Kärkkäinen and Sillanpää 2012) was used to predicted genotypic values as(1)where μi denotes the linear predictor, yi is the scaled and centered phenotypic entry mean of inbred line i and ui its total genetic value. Genetic diversity among Flint and Dent lines revealed by RFLPs, Prediction of total genetic value using genome-wide dense marker maps, Disease development and yield losses associated with northern corn leaf blight on corn, Genome-wide nested association mapping of quantitative resistance to northern leaf blight in maize, Measuring the relationship between northern corn leaf blight and yield losses, Maize introduction into Europe: the history reviewed in the light of molecular data, Genomic and metabolic prediction of complex heterotic traits in hybrid maize, Evaluation of genomic prediction methods for fusarium head blight resistance in wheat, Genomic prediction of hybrid performance in maize with models incorporating dominance and population specific marker effects, Genome-wide association mapping of flowering time and northern corn leaf blight (, Efficient methods to compute genomic predictions, Accuracy of genomic breeding values in multi-breed beef cattle populations derived from deregressed breeding values and phenotypes, The genetic architecture of disease resistance in maize: a synthesis of published studies, Accuracy of genomic selection in European maize elite breeding populations, A Bayesian Decision Theory Approach for Genomic Selection, Optimising Genomic Selection in Wheat: Effect of Marker Density, Population Size and Population Structure on Prediction Accuracy, BGGE: A New Package for Genomic-Enabled Prediction Incorporating Genotype × Environment Interaction Models, http://www.g3journal.org/lookup/suppl/doi:10.1534/g3.112.004630/-/DC1, http://creativecommons.org/licenses/by/3.0/, Genomic Prediction of Northern Corn Leaf Blight Resistance in Maize with Combined or Separated Training Sets for Heterotic Groups. 2012). 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