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Results for “Plant Biology”

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At least 1,243 records · Page 69Linked to original sources

bioRxiv2019

Increased Nitrogen Fixation and Remobilization May Contribute to Higher Seed Protein Content Without a Yield Penalty in a Soybean Introgression Line

The development of soybean varieties with higher seed protein concentration has been hindered by a negative correlation between seed protein concentration and yield. Benning HP, a genotype that breaks this tradeoff, contains a high protein allele introgressed into the cultivar Benning. Because seed protein is thought to be limited by N, field and growth chamber experiments were performed to identify the N flux(es) that enable Benning HPs increased seed protein without a yield penalty. When the N source was completely controlled in growth chambers, Benning HP was able to fix more N than its recurrent parent, but this response depended on the strain of the rhizobia symbiont and was not observed at all developmental stages. In the field, Benning HP remobilized N from its leaves at a higher rate during seed fill, but this response was only observed in one of the years studied. These results demonstrate that Benning HP has higher potential for N fixation and N remobilization from vegetative tissue compared to its lower protein recurrent parent, but those traits are not consistently expressed and may depend on environmental and sink control.

plant biology↗

bioRxiv2019

WRKY1 mediates transcriptional crosstalk between light and nitrogen signaling pathways in Arabidopsis thaliana

Plant responses to multiple stimuli must be integrated to trigger transcriptional cascades that lead to changes in plant metabolism and development. Light (L) and nitrogen (N) are two signaling pathways that are intimately connected to each other and to plant energy status. Here, we describe the functional role of the WRKY1 transcription factor in mediating the regulation between L and N signaling pathways in Arabidopsis thaliana. WRKY1 participates in genome-wide transcriptional reprogramming in leaves in response to individual and combined L and N signals. A regulatory network was identified, consisting of 724 genes regulated by WRKY1 and involved in both N and L signaling pathways. The loss of WRKY1 gene function has marked effects on the L and N response of genes involved in N uptake and assimilation (primary metabolism) as well as stress response pathways (secondary metabolism). Our results support a model in which WRKY1 enables plants to activate genes involved in the recycling of cellular carbon resources when L is limiting but N is abundant, and up-regulate amino acid metabolism genes when both L and N are limiting. In this potential energy conservation mechanism, WRKY1 integrates responses to N and light-energy status to trigger changes in plant metabolism.\n\nSummaryBased on transcriptome analysis, the WRKY1 transcription factor mediates regulation of nitrogen and light signaling pathways in a potential energy conservation mechanism.

plant biology↗

bioRxiv2019

Putative cis-regulatory elements predict iron deficiency responses in Arabidopsis roots

Iron (Fe) is a key cofactor in many cellular redox processes, including respiration and photosynthesis. Plant Fe deficiency (-Fe) activates a complex regulatory network which coordinates root Fe uptake and distribution to sink tissues, while avoiding over-accumulation of Fe and other metals to toxic levels. In Arabidopsis (Arabidopsis thaliana), FIT (FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR), a bHLH transcription factor (TF), is required for up-regulation of root Fe acquisition genes. However, other root and shoot -Fe-induced genes involved in Fe allocation and signaling are FIT-independent. The cis-regulatory code, i.e. the cis-regulatory elements (CREs) and their combinations that regulate plant -Fe-responses, remains largely elusive. Using Arabidopsis genome and transcriptome data, we identified over 100 putative CREs (pCREs) that were predictive of -Fe-induced up-regulation of genes in root tissue. We used large-scale in vitro TF binding data, association with FIT-dependent or FIT-independent co-expression clusters, positional bias, and evolutionary conservation to assess pCRE properties and possible functions. In addition to bHLH and MYB TFs, also B3, NAC, bZIP, and TCP TFs might be important regulators for -Fe responses. Our approach uncovered IDE1 (Iron Deficiency-responsive Element 1), a -Fe response CRE in grass species, to be conserved in regulating genes for biosynthesis of Fe-chelating compounds also in Arabidopsis. Our findings provide a comprehensive source of cis-regulatory information for -Fe-responsive genes, that advances our mechanistic understanding and informs future efforts in engineering plants with more efficient Fe uptake or transport systems.\n\nOne sentence summary>100 putative cis-regulatory elements robustly predict Arabidopsis root Fe deficiency-responses in computational models, and shed light on the mechanisms of transcriptional regulation.

plant biology↗

bioRxiv2019

The receptor-like kinases BAM1 and BAM2 promote the cell-to-cell movement of miRNA in the root stele to regulate xylem patterning

Xylem patterning in the root is established through the creation of opposing gradients of miRNAs and their targets, enabled by the cell-to-cell spread of the former. The miRNAs involved in xylem patterning, miR165/6, move through plasmodesmata, but how their trafficking is regulated remains elusive. Here, we describe that the receptor-like kinases BAM1/2 are required for the intercellular movement of miR165/6 in the stele and hence proper xylem patterning in the root.

plant biology↗

bioRxiv2019

Differential characterization of physiological and biochemical responses during drought stress in finger millet varieties

Drought is the most perilous abiotic stress that affects finger millet growth and productivity worldwide. For the successful production of finger millet, selection of drought tolerant varieties is necessary and critical stages under drought stress, germination and early seedling growth, ought to be fully understood. This study investigated the physiological and biochemical responses of six finger millet varieties (GBK043137, GBK043128, GBK043124, GBK043122, GBK043094 and GBK043050) under mannitol-induced drought stress. Seeds were germinated on sterile soil and irrigated with various concentrations of mannitol (200, 400 and 600 mM) for two weeks. Comparative analysis in terms of relative water content (RWC), chlorophyll, proline, and malondialdehyde (MDA) contents were measured the physiological and biochemical characteristics of drought stress. The results showed that increased level of drought stress seriously decreased germination and early seedling growth of finger millet varieties. However, root growth was increased. In addition, exposition to drought stress triggered a significant decrease in relative water content and chlorophyll content reduction the biochemical parameters assay showed less reduction of relative water content. Furthermore, oxidative damage indicating parameters such as proline concentration and MDA content increased. Varieties GBK043137 and GBK043094 were less affected by drought as shown by significant change in the physiological parameters. Our findings reveal the difference and linkage between the physiological responses of finger millet to drought and are vital for breeding and selection of drought tolerant varieties of finger millet. Further investigations on genomic and molecular to deeply insight the detail mechanisms of drought tolerance in finger millet need to explored.

plant biology↗

bioRxiv2019

Tissue-specific changes in the RNA structurome mediate salinity response in Arabidopsis

RNA structures are influenced by their physico-chemical environment. Few studies have assessed genome-wide impacts of abiotic stresses on in vivo RNA structure, however, and none have investigated tissue-specificity. We applied our Structure-seq method to assess in vivo mRNA secondary structure in Arabidopsis shoots and roots under control and salt stress conditions. Structure-seq utilizes dimethyl sulfate (DMS) for in vivo transcriptome-wide covalent modification of accessible As and Cs, i.e. those lacking base pairing and protection. Tissue type was a strong determinant of DMS reactivity, indicating tissue-specificity of RNA structuromes. Both tissues exhibited a significant inverse correlation between salt stress-induced changes in transcript reactivity and changes in transcript abundance, implicating changes in RNA structure and accessibility in transcriptome regulation. In mRNAs wherein the 5UTR, CDS and 3UTR concertedly increased or decreased in mean reactivity under salinity, this inverse correlation was more pronounced, suggesting that concordant structural changes across the mRNA have the greatest impact on abundance. Transcripts with the greatest and least salt stress-induced changes in DMS reactivity were enriched in genes encoding stress-related functions and included housekeeping functions, respectively. We conclude that secondary structure regulates mRNA abundance, thereby contributing to tissue specificity of the transcriptome and its dynamic adjustment under stress.\n\nOne Sentence Summary: Transcriptome-wide methods reveal dynamic tissue-specific and salt stress-dependent modulation of mRNA accessibility and structure, and correlated mRNA abundance changes.

plant biology↗

bioRxiv2019

Blue carbon sequestration dynamics within a tropical seagrass sediment: Long term incubations for changes over climatic scales

Determination of blue carbon sequestration in seagrass sediments over climatic time scales relies on several assumptions, such as no loss of particulate organic carbon (POC) after one or two years, tight coupling between POC loss and CO2 emissions, no dissolution of carbonates and removal of the stable black carbon (BC) contribution. We tested these assumptions via 500-day anoxic decomposition/mineralisation experiments to capture centennial parameter decay dynamics from two sediment horizons robustly dated as 2 and 18 years old. No loss of BC was detected, and decay of POC was best described for both horizons by near-identical reactivity continuum models. The models predicted average losses of 49% and 51% after 100 years of burial and 20-22 cm horizons, respectively. However, the loss rate of POC was far greater than the release rate of CO2, both before and after accounting for CO2 from anoxic particulate inorganic carbon (PIC) production, possibly as siderite. The deficit could not be attributed to dissolved organic carbon or dark CO2 fixation. Instead, evidence based on {delta}13CO2, acidity and lack of sulphate reduction suggested methanogenesis. The results indicate the importance of centennial losses of POC and PIC precipitation and possibly methanogenesis in estimating carbon sequestration rates.

plant biology↗

bioRxiv2019

Resistance to Candidatus Liberibacter solanacearum in tomato landraces from Mexico

Candidatus Liberibacter solanacearum (CLso) is an economically important plant-pathogen of tomato (Solanum lycopersicum) crops in the United States, Mexico, Central America, and New Zealand. Currently, there are no reports of resistance to CLso in tomato cultivars. Identification and development of CLso-resistant cultivars may offer the most efficient way to manage this tomato disease. Resistance of 46 tomato landraces collected in different regions of Mexico, representing a wide range of genetic variability from this country was evaluated. Two assays were done in consecutively years to assess the resistance to CLso under greenhouse conditions. Plants from both tests were inoculated with CLso through 20 Bactericera cockerelli insects per plant. In the first trial, landraces FC22 and FC44 showed a significantly higher proportion of resistant plants, less symptoms severity, and longer incubation time, followed by landraces FC40 and FC33 compared with the rest of the 42 landraces and 2 susceptible cultivars 60 days post inoculation (dpi). In the second assay, only landraces FC22 and FC44 had again significantly higher proportion of resistant plants, less symptoms severity, relative lower CLso titers, and longer incubation time in comparison with landraces FC40 and FC33 and the two susceptible cultivars 60 dpi, corroborating their resistance to CLso. Presence of CLso DNA in all resistant plants from both assays discards scape plants and indicates that the methodology used was adequate to discriminate between resistant and susceptible plants. These results confirm that landraces FC22 and FC44 are promising resistant sources for the development of CLso-resistant cultivars of tomato.\n\nAuthor summaryThe bacterium \"Candidatus Liberibacter solanacearum\" (CLso) is an important plant-pathogen of tomato crops in the United States, Mexico, Central America, and New Zealand. Tomato growers are lacking of cultivars with resistance to this pathogen and the development of resistant cultivars of this crop would make a sustainable business for these growers and healthy tomato consumption for humans. Tomato landraces from countries that are center of domestication of cultivated crops like Mexico, are potentially sources of resistance to plant-pathogens. Therefore, two tests were done looking for resistance sources to this pathogen and we found two tomato landraces (FC22 and FC44) showing high level of resistance to CLso because they had significantly higher resistant plants, less symptoms severity, lower CLso DNA concentration, and delay of the first symptoms in the inoculated plants in comparison with the two commercial cultivars and 44 tomato landraces collected from Mexico 60 days post infection. These landraces are promising resistant sources for the development of CLso-resistant cultivars of tomato.

plant biology↗

bioRxiv2019

Nitrogen Availability Modulates the Host Control of the Barley Rhizosphere Microbiota.

The microbiota populating the rhizosphere, the interface between roots and soil, can modulate plant growth, development and health. These microbial communities are not stochastically assembled from the surrounding soil but their composition and putative function are controlled, at least partially, by the host plant. Here we use the staple cereal barley as a model to gain novel insights into the impact of differential applications of nitrogen, a rate-limiting step for global crop production, on the host genetic control of the rhizosphere microbiota. Using a high-throughput amplicon sequencing survey, we determined that nitrogen availability for plant uptake is a factor promoting the selective enrichment of individual taxa in the rhizosphere of wild and domesticated barley genotypes. Shotgun sequencing and metagenome-assembled genomes revealed that this taxonomic diversification is mirrored by a functional specialisation, manifested by the differential enrichment of multiple GO-terms, of the microbiota of plants exposed to nitrogen conditions limiting barley growth. Finally, a plant soil feedback experiment revealed that the host control on the barley microbiota underpins the assembly of a phylogenetically diverse group of bacteria putatively required to sustain plant performance under nitrogen-limiting supplies. Taken together, our observations indicate that under nitrogen conditions limiting plant growth, plant-microbe and microbe-microbe interactions fine-tune the host genetic selection of the barley microbiota at both taxonomic and functional levels. The disruption of these recruitment cues negatively impacts plant growth. ImportanceThe microbiota inhabiting the rhizosphere, the thin layer of soil surrounding plant roots, can promote the growth, development, and health of their host plants. Previous research indicated that differences in the genetic composition of the host plant coincide with differences in the composition of the rhizosphere microbiota. This is particularly evident when looking at the microbiota associated to input-demanding modern cultivated varieties and their wild relatives, which have evolved under marginal conditions. However, the functional significance of these differences remains to be fully elucidated. We investigated the rhizosphere microbiota of wild and cultivated genotypes of the global crop barley and determined that nutrient conditions limiting plant growth amplify the host control on microbes at the root-soil interface. This is reflected in a plant- and genotype-dependent functional specialisation of the rhizosphere microbiota which appears required for optimal plant growth. These findings provide novel insights into the significance of the rhizosphere microbiota for plant growth and sustainable agriculture

plant biology↗

bioRxiv2019

A new approach to crop model calibration: phenotyping plus post-processing.

Crop models contain a number of genotype-dependent parameters, which need to be estimated for each genotype. This is a major difficulty in crop modeling. We propose a hybrid method for adapting a crop model to new genotypes. The genotype-dependent parameters of the model could be obtained by phenotyping (or gene-based modeling). Then field data for example from variety trials could be used to provide a simple empirical correction to the model, of the form a+b times an environmental variable. This approach combines the advantages of phenotyping, namely that the genotype-specific parameters have a clear meaning and are comparable between genotypes, and the advantages of fitting the model to field data, namely that the corrected model is adapted to a specific target population. It has the advantage of being very simple to apply, and furthermore gives useful information as to which environmental variables are not fully accounted for in the initial model. In this study, this empirical correction is applied to the SUNFLO crop model for sunflower, using field data from a multi-environment trial network. The empirical correction reduced mean squared error (MSE) on the average by 54% for prediction of yield and by 26% for prediction of oil content, compared to the initial model. Most of the improvement came from eliminating bias, with some further improvement from the environmental term in the regression.

plant biology↗

bioRxiv2019

A novel mutant allele uncouples brassinosteroid-dependent and independent functions of BRI1

Plants depend on an array of cell surface receptors to integrate extracellular signals with developmental programs. One of the best-studied receptors is BRASSINOSTEROID INSENSITIVE 1 (BRI1), which upon binding of its hormone ligands forms a complex with shape-complimentary co-receptors and initiates a signal transduction cascade leading to a wide range of responses. BR biosynthetic and receptor mutants have similar growth defects on the macroscopic level, which had initially led to the assumption of a largely linear signalling pathway. However, recent evidence suggests that BR signalling is interconnected with a number of other pathways through a variety of different mechanisms. We recently described that feedback information from the cell wall is integrated at the level of the receptor complex through interaction with RLP44. Moreover, BRI1 is required for a second function of RLP44, the control of procambial cell fate. Here, we report on a BRI1 mutant, bri1cnu4, which differentially affects canonical BR signalling and RLP44 function in the vasculature. While BR signalling is only mildly impaired, bri1cnu4 mutants show ectopic xylem in the position of procambium. Mechanistically, this is explained by an increased association of RLP44 and the mutated BRI1 protein, which prevents the former from acting in vascular cell fate maintenance. Consistent with this, the mild BR response phenotype of bri1cnu4 is a recessive trait, whereas the RLP44-mediated xylem phenotype is semi-dominant. Our results highlight the complexity of plant plasma membrane receptor function and provide a tool to dissect BR signalling-related roles of BRI1 from its non-canonical functions.\n\nOne sentence summaryA novel mutant allows to dissect brassinosteroid signalling related and non-canonical functions of the receptor-like kinase BRI1.

plant biology↗

bioRxiv2019

Nectar- and stigma-specific expression of a chitinase could partially protect against fire blight in certain apples

To attract pollinators many angiosperms secrete stigma exudate and nectar in their flowers. As these nutritious fluids are ideal infection points for pathogens, both secretions contain various antimicrobial compounds. Erwinia amylovora, the causing bacterium of the devastating fire blight apple disease, is the model pathogen that multiplies in flower secretions and infects through the nectaries. Although Erwinia resistant apples are not available, certain cultivars are tolerant. It was reported that in stigma infection assay, the Freedom cultivar was Erwinia tolerant while the Jonagold was susceptible. We hypothesized that differences in the nectar protein compositions lead to different susceptibility. Indeed we found that an acidic chitinase III protein (Machi3-1) selectively accumulates in the nectar and stigma of the Freedom cultivar. We demonstrate that MYB binding site containing repeats of the Freedom Machi3-1 promoter are responsible for the strong nectar- and stigma-specific expression. As we found that in vitro the Machi3-1 protein impairs growth and biofilm formation of Erwinia at physiological concentration, we propose that the Machi3-1 contribute to the tolerance by inhibiting Erwinia multiplication in the stigma exudate and in the nectar. We show that the Machi3-1 allele was introgressed from Malus floribunda 821 into different apple cultivars including the Freedom.\n\nHighlightCertain apple cultivars accumulate to high levels in their nectar and stigma an acidic chitinase III protein that can protect against pathogens including fire blight disease causing Erwinia amylovora

plant biology↗

bioRxiv2019

Rhythms of Transcription in Field-Grown Sugarcane Are Highly Organ Specific

We investigated whether different specialized organs in field-grown sugarcane follow the same temporal rhythms in transcription. We assayed the transcriptomes of three organs during the day: leaf, a source organ; internodes 1 and 2, sink organs focused on cell division and elongation; and internode 5, a sink organ focused on sucrose storage. The leaf had twice as many rhythmic transcripts (>68%) as internodes, and the rhythmic transcriptomes of the two internodes were more similar to each other than to those of the leaves. More transcripts were rhythmic under field conditions than under circadian conditions and most of their peaks were during the day. Among the transcripts that were considered expressed in all three organs, only 7.4% showed the same rhythmic time course pattern. The central oscillators of these three organs -- the networks that generate circadian rhythms -- had similar dynamics with different amplitudes. The differences between the rhythmic transcriptomes in circadian conditions and field conditions highlight the importance of field experiments to understand the plant circadian clock in natura. The highly specialized nature of the rhythmic transcriptomes in sugarcane organs probably arises from amplitude differences in tissue-specific circadian clocks and different sensitivities to environmental cues. One sentence summaryThe rhythmic transcriptome of field-grown sugarcane is highly organ-specific.

plant biology↗

bioRxiv2019

Molecular changes in Mesembryanthemum crystallinum guard cells underlying the C3 to CAM transition

Crassulacean acid metabolism (CAM) is a specialized type of photosynthesis: stomata close during the day, enhancing water conservation, and open at night, allowing CO2 uptake. Mesembryanthemum crystallinum (common ice plant) is a facultative CAM species that can shift from C3 photosynthesis to CAM under salt or drought stresses. However, the molecular mechanisms underlying the stress induced transition from C3 to CAM remain unknown. Here we determined the transition time from C3 to CAM in M. crystallinum under salt stress. In parallel, single-cell-type transcriptomic profiling by 3-mRNA sequencing was conducted in guard cells to determine the molecular changes in this key cell type during the transition. In total, 495 transcripts showed differential expression between control and salt-treated samples during the transition, including 285 known guard cell genes, seven CAM-related genes, 18 transcription factors, and 185 other genes previously not found to be expressed in guard cells. PEPC1 and PPCK1, which encode key enzymes of CAM photosynthesis, were up-regulated in guard cells after seven days of salt treatment, indicating that guard cells themselves can transition from C3 to CAM. This study provides important information towards introducing CAM stomatal behavior into C3 crops to enhance water use efficiency.\n\nSummary statementWe determined the timing of salt induced transition of common ice plant from C3 to CAM and identified transcriptomic changes during the transition. The data support the notion that guard cells themselves can transition from C3 to CAM.

plant biology↗

bioRxiv2019

The disease progression and molecular defense response in Chenopodium quinoa infected with Peronospora variabilis, the causal agent of quinoa downy mildew

The downy mildew disease, caused by the biotrophic oomycete Peronospora variabilis, is the largest environmental threat to quinoa (Chenopodium quinoa Willd.) cultivation in the Andean highlands. However, so far no molecular information on the quinoa-Peronospora interaction has been reported. Here, we have developed tools to study the downy mildew disease in quinoa at gene expression level. Living P. variabilis could be isolated and maintained in the presence of a fungicide, allowing the characterization of downy mildew disease progression in two differently susceptible quinoa cultivars under controlled conditions. Quinoa gene expression changes induced by P. variabilis were analysed by qRT-PCR for quinoa homologues of Arabidopsis thaliana pathogen-associated genes. Overall, we observed a slower disease progression and higher tolerance in the quinoa cultivar Kurmi than in the cultivar Maniquena Real. We also observed that quinoa orthologs of A. thaliana genes involved in the salicylic acid defense response pathway (AtCAT2 and AtEP3) did not have changes in its gene expression. In contrast, quinoa orthologs of A. thaliana gene markers of the induction of the jasmonic acid response pathway (AtWRKY33 and AtHSP90) were significantly induced in plants infected with P. variabilis. These genes could be used as defense response markers to select quinoa cultivars that are more tolerant to P. variabilis infection.

plant biology↗

bioRxiv2019

Xyloglucan homeostasis and microtubule dynamics synergistically maintain meristem geometry and robustness of phyllotaxis in Arabidopsis

The shoot apical meristem (SAM) gives rise to all aerial organs of the plant. The cell walls are supposed to play a central role in this process, translating molecular regulation into dynamic changes of growth rates and directions, although their precise role in morphogenesis during organ formation remains not well understood. Here we investigate the role of xyloglucans (XyGs), which form a major, yet functionally poorly characterized, wall component in the SAM. Using immunolabeling, biochemical analysis, genetic approaches, micro-indentation, laser ablations and live imaging, we show that XyGs are important for meristem shape and phyllotaxis, although no difference in cell wall stiffness could be observed when XyGs are perturbed. Mutations in enzymes required for XyG synthesis also affect other cell wall components such as cellulose content and the pectin methylation status. Interestingly, we show that the control of cortical microtubules dynamics by the severing enzyme KATANIN becomes vital when XyGs are perturbed or absent. This suggests an active role of the cytoskeleton in compensating for altered wall composition.

plant biology↗

bioRxiv2019

Diverse phenotypic responses and phosphate content in foxtail millet genotypes under greenhouse and field conditions

Phosphorous (P) is an important macronutrient for the growth of all agricultural crops. This study reports phenotype analysis for P responses in field (two different seasons, monsoon and summer) and greenhouse, using 54 genotypes of foxtail millet (Setaria italica) under P-fertilized (P+) and unfertilized (P-) conditions. Variation was seen for plant height, leaf number and length, tillering ability and seed yield traits. Genotypes ISe 1234 and ISe 1541 were P+ responders, and the genotypes ISe 1181, ISe 1655, ISe 783 and ISe 1892 tend more towards low P tolerance for total seed yield. Genotypes that performed well under P-conditions were almost as productive as genotypes that performed well under P+ conditions suggesting some genotypes are well adapted to nutrient-poor soils. In the greenhouse, significant variation was seen for root hair density and root hair number and for fresh and dry weights of shoot and root under P-stress. However, there was not much difference in the shoot and root total P and inorganic phosphate (Pi) levels of five selected high and low responding genotypes. In the root and leaf tissues, total P and Pi contents of five high responding genotypes were higher than the five low responding genotypes.\n\nHighlightEnormous phenotypic and phosphate content variation of foxtail millet under low-phosphate supply in greenhouse and natural field conditions identifies genotypic plasticity for future breeding for improved P use efficiency.

plant biology↗

bioRxiv2019

Modeling of yield Losses and risk analysis of fungicide profitability for managing Fusarium Head Blight in Brazilian spring wheat

Fusarium head blight (FHB), caused by the Fusarium graminearum species complex, is a serious disease of wheat in Brazil. A review of literature on fungicide efficacy for field trials evaluated in Brazil was conducted to obtain FHB-yield data and explore their relationship. Thirty-seven studies (9 years and 11 locations) met the criteria for inclusion (FHB index [≥] 5% and max-min range [≥] 4 percent points [p.p.]). Studies were group into two production situations: low (Yl [≤] 3,631 kg ha-1) or high (Yh > 3,631 kg ha-1) yield, based on the median of maximum yields across trials. Population-average intercepts, but not the slopes, from fitting a random-coefficients model, differed significantly between Yl (2,883.6 kg ha-1) and Yh (4,419.5 kg ha-1). The calculated damage coefficient was 1.05 %-1 and 1.60 %-1 for Yh and Yl, respectively. A crop model simulated attainable wheat yields for 10 planting dates within each year during a 28-year period, including prior (1980-1989) and after (1990-2007) FHB resurgence. Simulated losses using disease predictions to penalize yield were in general agreement in magnitude with literature reports, for both periods. Economic analysis for scenarios of variable fungicide costs and wheat prices, and one versus two sprays of tebuconazole, showed that the probability of not-offsetting the costs was higher (> 0.75) prior to FHB resurgence than after the 1990. Our approach may be useful for designing of longlasting, yet profitable, contingency tactics to management FHB in wheat. Currently one spray of triazole fungicide during flowering is more likely a profitable decision than applying two sprays, for which there is greater uncertainty.

plant biology↗