Mapping Of Resistance Research Articles

QTL Mapping for Adult-Plant Resistance to Leaf Rust in Italian Wheat Cultivar Libellula.

Wheat leaf rust (Lr), which is caused by Puccinia triticina Eriks. (Pt), is one of the most important wheat diseases affecting wheat production globally. Using resistant wheat cultivars is the most economical and environmentally friendly way to control leaf rust. The Italian wheat cultivar Libellula has demonstrated good resistance to Lr in field studies. To identify the genetic basis of Lr resistance in 'Libellula', 248 F6 recombinant inbred lines from the cross 'Libellula'/'Huixianhong' was phenotyped for Lr severity in seven environments: the 2014/2015, 2016/2017, 2017/2018, and 2018/2019 cropping seasons at Baoding, Hebei Province, and the 2016/2017, 2017/2018, and 2018/2019 crop seasons at Zhoukou, Henan Province. Bulked segregant analysis and simple sequence repeat markers were then used to identify the quantitative trait loci (QTLs) for Lr adult-plant resistance in the population. Six QTLs were consequently detected and designated as QLr.hebau-1AL and QLr.hebau-1AS that were presumed to be new and QLr.hebau-1BL, QLr.hebau-3AL, QLr.hebau-4BL, and QLr.hebau-7DS that were identified at similar physical positions as previously reported QTLs. Based on chromosome positions and molecular marker tests, QLr.hebau-1BL and QLr.hebau-7DS share similar flanking markers with Lr46 and Lr34, respectively. Lr46 and Lr34 are race nonspecific adult plant resistance (APR) genes for leaf rust and stripe rust and powdery mildew. QLr.hebau-4BL showed multiple disease resistance to leaf rust, stripe rust, Fusarium head blight, and powdery mildew. The QTL identified in this study, as well as their closely linked markers, may potentially be used in marker-assisted selection in wheat breeding.

Use of whole-genome sequence data for fine mapping and genomic prediction of sea louse resistance in Atlantic salmon.

Sea louse (Lepeophtheirus salmonis) infestation of Atlantic salmon (Salmo salar) is a significant challenge in aquaculture. Over the years, this parasite has developed immunity to medicinal control compounds, and non-medicinal control methods have been proven to be stressful, hence the need to study the genomic architecture of salmon resistance to sea lice. Thus, this research used whole-genome sequence (WGS) data to study the genetic basis of the trait since most research using fewer SNPs did not identify significant quantitative trait loci. Mowi Genetics AS provided the genotype (50k SNPs) and phenotype data for this research after conducting a sea lice challenge test on 3,185 salmon smolts belonging to 191 full-sib families. The 50 k SNP genotype was imputed to WGS using the information from 197 closely related individuals with sequence data. The WGS and 50k SNPs of the challenged population were then used to estimate genetic parameters, perform a genome-wide association study (GWAS), predict genomic breeding values, and estimate its accuracy for host resistance to sea lice. The heritability of host resistance to sea lice was estimated to be 0.21 and 0.22, while the accuracy of genomic prediction was estimated to be 0.65 and 0.64 for array and WGS data, respectively. In addition, the association test using both array and WGS data did not identify any marker associated with sea lice resistance at the genome-wide level. We conclude that sea lice resistance is a polygenic trait that is moderately heritable. The genomic predictions using medium-density SNP genotyping array were equally good or better than those based on WGS data.

Predictive Mapping of Antimicrobial Resistance for Escherichia coli, Salmonella, and Campylobacter in Food-Producing Animals, Europe, 2000-2021.

In Europe, systematic national surveillance of antimicrobial resistance (AMR) in food-producing animals has been conducted for decades; however, geographic distribution within countries remains unknown. To determine distribution within Europe, we combined 33,802 country-level AMR prevalence estimates with 2,849 local AMR prevalence estimates from 209 point prevalence surveys across 31 countries. We produced geospatial models of AMR prevalence in Escherichia coli, nontyphoidal Salmonella, and Campylobacter for cattle, pigs, and poultry. We summarized AMR trends by using the proportion of tested antimicrobial compounds with resistance >50% and generated predictive maps at 10 × 10 km resolution that disaggregated AMR prevalence. For E. coli, predicted prevalence rates were highest in southern Romania and southern/eastern Italy; for Salmonella, southern Hungary and central Poland; and for Campylobacter, throughout Spain. Our findings suggest that AMR distribution is heterogeneous within countries and that surveillance data from below the country level could help with prioritizing resources to reduce AMR.

Discovery of a resistance gene cluster associated with smut resistance in peanut

Peanut smut, caused by Thecaphora frezzii Carranza & J.C. Lindq., is an emerging threat for the global peanut industry. The disease’s destructive potential can be exemplified by pod incidence values as high as 70% and yield losses reaching 30%. Because fungicides have shown moderate but highly variable levels of control levels, development and deployment of smut resistant cultivars are the best strategies for disease management. Screening for smut-resistant germplasm requires years of field trials and is currently the only option for breeders because genetic markers for resistance have not yet been developed. The objectives of this study were to perform whole genome sequencing (WGS) on populations developed for smut resistance mapping and subsequently fine map discovered QTL associated with smut resistance. An expedited strategy was employed by phenotyping in the F3 generation. We phenotyped 200 families with 3 plants per family for smut resistance in infested fields during the 2019/2020 season in General Deheza (32°45′23″S 63°47′20″W), Argentina. Each individual was sequenced using iGenomXRipTide library preparation and Illumina NovaSeq sequencing to yield approximately 1 times genome coverage. Analysis of the phenotype and genotype data using Khufu resulted in the identification of a single major smut resistance QTL on chromosome 12 (B02). Chromosome level genome sequences were assembled for the resistant parent (Ascasubi) and susceptible parent (Granoleico) using PacBio HIFI sequencing. A validation population was sequenced using Khufu to validate the QTL region and analysis confirmed the major locus on chromosome 12. The identified variation will be used to develop smut resistant varieties quickly using molecular assisted breeding strategies.

Development of near isogenic lines (NILs) for leaf rust resistance utilizing advanced generation segregating lines of RIL population in wheat (Triticum aestivum L.)

Near-isogenic lines (NILs) are useful genetic resources for basic genetic studies and further understanding of associated molecularmechanisms. The NILs can be developed through standard methods like backcross breeding or advanced generation segregatinglines. The present study aimed the development of NILs for leaf rust resistance from the advanced generation segregating lines withresidual heterozygosity. Advanced generations segregating lines/heterogeneous inbred families (HIFs) segregating for contrastinginfection types (IT ;1 and 3) for leaf rust were identified from the recombinant inbred lines (RILs) between cross of T. timopheevii derivedintrogression line Selection G12, a resistant parent and a susceptible parent Agra local. The molecular analysis using polymorphic SSRmarkers between parents indicated a high level of similarity with 97.07 and 96.49% resemblance among the contrasting NIL pairs fromHIF1 and HIF5, respectively. These NILs may serve as valuable resources for conducting fine mapping and expression analysis of leafrust resistance in wheat and, therefore, will help to identify candidate gene(s) for leaf rust resistance in Selection G12

Multiscale resistivity mapping from an intracontinental hydrothermal mineral system, Adelaide Rift Complex, Australia

Porphyry mineral systems provide a significant source of critical minerals for modern society, that are predominantly formed in subduction related settings from magmatic hydrothermal fluids derived from an underlying reservoir. However, in post-subduction settings the processes that entrain and focus magmatic hydrothermal fluids throughout the crust, from source to deposit are often poorly constrained. In this paper, we have undertaken a magnetotelluric (MT) survey in an intracontinental tectonic setting across the Adelaide Superbasin, which is a Neoproterozoic passive margin formed during rifting of the supercontinent Rodinia. This region contains the Burra magmatic copper deposit, along with numerous sedimentary-hosted copper deposits. Systematic three-dimensional modelling was undertaken, initially at regional-scale, with 55 km gridded long-period AusLAMP data over a 500 × 500 km area, followed by infilled 10 km gridded broadband MT data, at the district-scale, centred over an area of copper deposits in the Adelaide Rift Complex. The modelling reveals an elongated zone of low electrical resistivity (∼100 Ω.m), in an otherwise resistive crust, at lower crustal depth (20–40 km) that is contiguous with the regional lineament of the Adelaide Rift Complex and copper and gold mineralisation. A narrow zone of low resistivity (∼100 Ω.m) branches through the upper crust (5–20 km) to the surface, that is remarkably aligned with the Burra magmatic mineral system, in an otherwise quite resistive crust (∼1000 Ω.m). Additionally, in the upper crust a zone of low resistivity (1–10 Ω.m at a depth of 5–8 km) extends from the Burra magmatic copper deposit southwards, constrained by anticlinal folding from the ∼500 Ma Delamerian Orogenic deformation of the Adelaide Rift Complex and spatially aligned with the Kapunda sedimentary-hosted copper deposit. We argue that the low electrical resistivity signature encapsulates a whole-of-lithosphere magmatically-hosted copper system, that is further mobilised by low-temperature fluids by mapping the footprint of ore-forming fluids from the source to associated mineralisation. Where later basin wide fluid recycling in a permeability enhanced basin, via neo-tectonism along pre-existing structures/trends, has likely remobilised copper, from a prior magmatic event, with copper being leached in chloride-rich saline fluids at low temperatures.

Genetic crosses within and between species of Cryptosporidium.

Parasites and their hosts are engaged in reciprocal coevolution that balances competing mechanisms of virulence, resistance, and evasion. This often leads to host specificity, but genomic reassortment between different strains can enable parasites to jump host barriers and conquer new niches. In the apicomplexan parasite Cryptosporidium, genetic exchange has been hypothesized to play a prominent role in adaptation to humans. The sexual lifecycle of the parasite provides a potential mechanism for such exchange; however, the boundaries of Cryptosporidium sex are currently undefined. To explore this experimentally, we established a model for genetic crosses. Drug resistance was engineered using a mutated phenylalanyl tRNA synthetase gene and marking strains with this and the previously used Neo transgene enabled selection of recombinant progeny. This is highly efficient, and genomic recombination is evident and can be continuously monitored in real time by drug resistance, flow cytometry, and PCR mapping. Using this approach, multiple loci can now be modified with ease. We demonstrate that essential genes can be ablated by crossing a Cre recombinase driver strain with floxed strains. We further find that genetic crosses are also feasible between species. Crossing Cryptosporidium parvum, a parasite of cattle and humans, and Cryptosporidium tyzzeri a mouse parasite resulted in progeny with a recombinant genome derived from both species that continues to vigorously replicate sexually. These experiments have important fundamental and translational implications for the evolution of Cryptosporidium and open the door to reverse- and forward-genetic analysis of parasite biology and host specificity.

Genetic analysis and molecular mapping of resistance to bacterial leaf pustule disease in soybean

Bacterial leaf pustule (BLP) caused by Xanthomonas axonopodis pv. glycines (Xag) is a serious disease of soybean. A resistant source ‘TS 3’ was identified and the inheritance studies indicated that the duplicate recessive genes govern the resistance. The genetic linkage analysis mapped the resistance locus (rxp-2) on chromosome 2 flanked by the SSR markers Sat_183 and BARCSOYSSR_02_1613 at a distance of 0.9cM and 2.1cM respectively. Similarly, another resistance locus (rxp-6) was mapped between the SSR markers BARCSOYSSR_06_0024 and BARCSOYSSR_06_0013 at a distance of 1.5cM and 2.1cM respectively.

Identification of loci conferring resistance to 4 foliar diseases of maize.

Foliar diseases of maize are among the most important diseases of maize worldwide. This study focused on 4 major foliar diseases of maize: Goss's wilt, gray leaf spot, northern corn leaf blight, and southern corn leaf blight. QTL mapping for resistance to Goss's wilt was conducted in 4 disease resistance introgression line populations with Oh7B as the common recurrent parent and Ki3, NC262, NC304, and NC344 as recurrent donor parents. Mapping results for Goss's wilt resistance were combined with previous studies for gray leaf spot, northern corn leaf blight, and southern corn leaf blight resistance in the same 4 populations. We conducted (1) individual linkage mapping analysis to identify QTL specific to each disease and population; (2) Mahalanobis distance analysis to identify putative multiple disease resistance regions for each population; and 3) joint linkage mapping to identify QTL across the 4 populations for each disease. We identified 3 lines that were resistant to all 4 diseases. We mapped 13 Goss's wilt QTLs in the individual populations and an additional 6 using joint linkage mapping. All Goss's wilt QTL had small effects, confirming that resistance to Goss's wilt is highly quantitative. We report several potentially important chromosomal bins associated with multiple disease resistance including 1.02, 1.03, 3.04, 4.06, 4.08, and 9.03. Together, these findings indicate that disease QTL distribution is not random and that there are locations in the genome that confer resistance to multiple diseases. Furthermore, resistance to bacterial and fungal diseases is not entirely distinct, and we identified lines resistant to both fungi and bacteria, as well as loci that confer resistance to both bacterial and fungal diseases.

Spatial mapping of posture-dependent resistance to passive displacement of the hypertonic arm post-stroke

BackgroundMuscles in the post-stroke arm commonly demonstrate abnormal reflexes that result in increased position- and velocity-dependent resistance to movement. We sought to develop a reliable way to quantify mechanical consequences of abnormal neuromuscular mechanisms throughout the reachable workspace in the hemiparetic arm post-stroke.MethodsSurvivors of hemiparetic stroke (HS) and neurologically intact (NI) control subjects were instructed to relax as a robotic device repositioned the hand of their hemiparetic arm between several testing locations that sampled the arm's passive range of motion. During transitions, the robot induced motions at either the shoulder or elbow joint at three speeds: very slow (6°/s), medium (30°/s), and fast (90°/s). The robot held the hand at the testing location for at least 20 s after each transition. We recorded and analyzed hand force and electromyographic activations from selected muscles spanning the shoulder and elbow joints during and after transitions.ResultsHand forces and electromyographic activations were invariantly small at all speeds and all sample times in NI control subjects but varied systematically by transport speed during and shortly after movement in the HS subjects. Velocity-dependent resistance to stretch diminished within 2 s after movement ceased in the hemiparetic arms. Hand forces and EMGs changed very little from 2 s after the movement ended onward, exhibiting dependence on limb posture but no systematic dependence on movement speed or direction. Although each HS subject displayed a unique field of hand forces and EMG responses across the workspace after movement ceased, the magnitude of steady-state hand forces was generally greater near the outer boundaries of the workspace than in the center of the workspace for the HS group but not the NI group.ConclusionsIn the HS group, electromyographic activations exhibited abnormalities consistent with stroke-related decreases in the stretch reflex thresholds. These observations were consistent across repeated testing days. We expect that the approach described here will enable future studies to elucidate stroke's impact on the interaction between the neural mechanisms mediating control of upper extremity posture and movement during goal-directed actions such as reaching and pointing with the arm and hand.

“Land[s] beyond the White World”: (Re)imagining the International through Fiction

From the turn of the nineteenth century Black Internationalists collectively mapped and subverted the (white) International as a colonial legal imaginary, its sociopolitical, historical and geographical myths and those of “modern” International Law. While the most visible artefacts of this world(un)making project are conventional—namely, the Pan-African Conference and Congresses of 1900, 1919, 1921, 1923, 1927 and 1945—Black Internationalists also turned to fiction to both imagine and craft the worlds they could not live without and dismantle the worlds they could not live within (to paraphrase Ruha Benjamin). This article traces these poetic and political worldmaking and unmaking practices through the novels of Pauline Hopkins, WEB DuBois and Peter Abrahams, and maps their intersections with International Law. Doing so surfaces their “alternative clocks and maps of global racial resistance” (per Charles Mills), and suggests pathways to lands (still) “beyond the White World” and its calcified colonial legal imaginaries. It also reveals the worlds that International Law makes, and those it (still) makes impossible.

Geophysical Approach for Groundwater Resource Assessment: A Case Study of Oda Community Akure, Southwestern Nigeria

The geophysical investigation for groundwater was carried out at Oda town, Akure south local government area of Ondo State. Fourteen (14) points were sounded using a Schlumberger array with AB/2 of 80 m and the resulting geoelectric parameters were used in the estimation of the aquifer layer parameters of the subsurface. The first layer resistivity value ranges from 29 to 164 Ωm and thickness ranges from 0.6 to 2.5 m. The second layer has a resistivity value ranging from 21-1361 Ωm with a thickness ranging from 1.5 m to 14.6 m. The third layer resistivity value is from 68 to 297 Ωm with thickness ranging from 4 m to 12.4 m. The fourth layer which is the deepest layer has a resistivity value ranging from 180 to 4364 Ωm with depth ranging from 4 m to 19.5 m. The parameters interpreted from the geoelectric data were used to generate the aquifer thickness and resistivity maps, with bedrock relief which were combined to produce the groundwater potential map of the area. These maps were used to characterise the study area into low to high groundwater potential zones. The southwestern and eastern parts were identified as productive groundwater potential zones. The result was validated by taking water column depth from eight existing hand-dug wells. A significant correlation was obtained between the groundwater potential model and the well water column. The surveyed area is generally suitable for hand-dug well aside from the north-eastern part where groundwater potential is low and water volume is observed.

QTL mapping for seedling and adult plant resistance to stripe and leaf rust in two winter wheat populations

The two recombinant inbred line (RIL) populations developed by crossing Almaly × Avocet S (206 RILs) and Almaly × Anza (162 RILs) were used to detect the novel genomic regions associated with adult plant resistance (APR) and seedling or all-stage resistance (ASR) to yellow rust (YR) and leaf rust (LR). The quantitative trait loci (QTLs) were detected through multi-year phenotypic evaluations (2018–2020) and using high-throughput DArTseq genotyping technology. RILs exhibited significant genetic variation with p < 0.001, and the coefficient of variation ranged from 9.79% to 47.99% for both LR and YR in all Environments and stages of evaluations. The heritability is quite high and ranged between 0.47 and 0.98. We identified nine stable QTLs for YR APR on chromosomes 1B, 2A, 2B, 3D, and 4D and four stable QTLs for LR APR on chromosomes 2B, 3B, 4A, and 5A. Furthermore, in silico analysis revealed that the key putative candidate genes such as cytochrome P450, protein kinase-like domain superfamily, zinc-binding ribosomal protein, SANT/Myb domain, WRKY transcription factor, nucleotide sugar transporter, and NAC domain superfamily were in the QTL regions and probably involved in the regulation of host response toward pathogen infection. The stable QTLs identified in this study are useful for developing rust-resistant varieties through marker-assisted selection (MAS).

Electrical resistivity mapping of potassium-doped few-layer CVD graphene by EBAC measurements

The electron beam absorbed current (EBAC) method identifies the open and/or short points in various semiconductor devices, which can be applied to characterize the current path and local resistance in graphene. In this study, potassium (K)-doped few-layer graphene with inhomogeneous K atoms seemed to be one of the appropriate materials to characterize the current path by EBAC. Nonuniform contrast in the EBAC image due to inhomogeneous local resistances is observed, which is explained by the variation of the Fermi level in the graphene channel from the G-band peak shifts from Raman spectroscopy. The changes in the contrast of the EBAC images are obtained by applying a gate voltage. These changes are attributed to the modulation of the local carrier densities by applying the gate voltage. For comparison, uniform contrast in EBAC images and uniform G-band peak positions of undoped few-layer graphene field effect transistors are confirmed. The obtained results suggest that homogeneous Fermi level leads to a uniform current path. EBAC enables us to evaluate the uniformity of local resistance and current through a pass in the graphene channel, which can be applied to other two-dimensional materials, such as transition metal dichalcogenides, graphene oxide, and hexagonal boron nitride.

Evaluation and in-situ monitoring of interfacial property and thermal shock resistance of epoxy adhesive with different MWCNT contents for CFRP/GFRP hybrid composite

While glass fiber-reinforced composite (GFRC) and carbon fiber-reinforced composite (CFRC) (G/C) hybrid composites enable lightweight construction and improve mechanical properties, the difference in thermal strain between materials causes delamination at the interface. To address this issue, multi-walled carbon nanotubes (MWCNT) were applied to optimize thermal strain and provide a buffering effect. The mechanical properties were evaluated using the V-notched shear test, and the epoxy adhesive with 0.3 wt% MWCNT exhibited the best performance. The thermal strain of the materials was measured, and the epoxy adhesive showed similar thermal strain to the substrates as the MWCNT content increased. To evaluate adhesion properties and durability under different thermal shock conditions, single lap shear and cyclic short beam shear tests were performed. The load behavior of the specimens was monitored using electrical resistance (ER) mapping. It was determined that the epoxy adhesive with 0.3 wt% MWCNT exhibited superior adhesive properties and durability compared to other conditions under both thermal and cyclic loading.

Association Mapping of Resistance to Tan Spot in the Global Durum Panel.

Tan spot, caused by the necrotrophic fungal pathogen Pyrenophora tritici-repentis (Ptr), is an important disease of durum and common wheat worldwide. Compared with common wheat, less is known about the genetics and molecular basis of tan spot resistance in durum wheat. We evaluated 510 durum lines from the Global Durum Wheat Panel (GDP) for sensitivity to the necrotrophic effectors (NEs) Ptr ToxA and Ptr ToxB and for reaction to Ptr isolates representing races 1 to 5. Overall, susceptible durum lines were most prevalent in South Asia, the Middle East, and North Africa. Genome-wide association analysis showed that the resistance locus Tsr7 was significantly associated with tan spot caused by races 2 and 3, but not races 1, 4, or 5. The NE sensitivity genes Tsc1 and Tsc2 were associated with susceptibility to Ptr ToxC- and Ptr ToxB-producing isolates, respectively, but Tsn1 was not associated with tan spot caused by Ptr ToxA-producing isolates, which further validates that the Tsn1-Ptr ToxA interaction does not play a significant role in tan spot development in durum. A unique locus on chromosome arm 2AS was associated with tan spot caused by race 4, a race once considered avirulent. A novel trait characterized by expanding chlorosis leading to increased disease severity caused by the Ptr ToxB-producing race 5 isolate DW5 was identified, and this trait was governed by a locus on chromosome 5B. We recommend that durum breeders select resistance alleles at the Tsr7, Tsc1, Tsc2, and the chromosome 2AS loci to obtain broad resistance to tan spot.

Fine mapping of high-temperature adult-plant resistance to stripe rust in wheat cultivar Louise

Fine mapping of high-temperature adult-plant resistance to stripe rust in wheat cultivar Louise

Genome-Wide Association Mapping of Bacterial Leaf Streak Resistance in Two Elite Barley Breeding Panels.

Bacterial leaf streak (BLS), caused chiefly by the pathogen Xanthomonas translucens pv. translucens, is becoming an increasingly important foliar disease of barley in the Upper Midwest. The deployment of resistant cultivars is the most economical and practical method of control. To identify sources of BLS resistance, we evaluated two panels of breeding lines from the University of Minnesota (UMN) and Anheuser-Busch InBev (ABI) barley improvement programs for reaction to strain CIX95 in the field at St.Paul and Crookston, MN, in 2020 and 2021. The percentage of resistant lines in the UMN and ABI panels with mid-season maturity was 1.8% (6 of 333 lines) and 5.2% (13 of 251 lines), respectively. Both panels were genotyped with the barley 50K iSelect SNP array, and then a genome-wide association study was performed. A single, highly significant association was identified for BLS resistance on chromosome 6H in the UMN panel. This association was also identified in the ABI panel. Seven other significant associations were detected in the ABI panel: two each on chromosomes 1H, 2H, and 3H and one on chromosome 5H. Of the eight associations identified in the panels, five were novel. The discovery of resistance in elite breeding lines will hasten the time needed to develop and release a BLS-resistant cultivar.

DETERMINATION OF OPTIMAL OBSERVATION NETWORK PARAMETERS FOR MAPPING PALEOCHANNEL BY THE ELECTRICAL RESISTIVITY TOMOGRAPHY METHOD BASED ON NUMERICAL AND PHYSICAL MODELING

Link for citation: Osipova P.S., Olenchenko V.V., Chekryzhov A.V. Determination of optimal observation network parameters for mapping paleochannel by the electrical resistivity tomography method based on numerical and physical modeling. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 10, рр. 232-242. In Rus. The relevance of the study is explained by the need to determine the methodological features of applying the electrical resistivity tomography method to map paleochannels when prospecting for placer gold. The main aim: to determine the necessary and enough parameters of the observation network for paleochannel mapping based on numerical and physical modeling. Object: electrical fields on the physical and numerical model of the paleochannel. Methods: electrical resistivity tomography, physical experiment, numerical simulation. Results. Electrical soundings by electrical tomography were carried out on a physical model of a river valley. In addition, a numerical experiment was performed on a three-dimensional model of a river valley fragment with a paleochannel. The unit of the survey scale is the distance between two electrodes, which in the experiment is 1 cm and is equivalent to 5 m in real field studies. The distance between the profiles varied from 2 to 12 cm with a step of 2 cm, which corresponds to different survey scales. In accordance with geological concepts, the authors formed a model of a river valley with a segmentally gently stage of channel formation. Three-dimensional inversion was carried out for the data set obtained at the maximum density of the observation network, and then for the data sparse to the desired scale. On the resistivity map, the paleochannel is recognized by a ribbon-shaped high-resistivity anomaly. The analysis of the maps showed that to determine the shape of the paleochannel in plan, it is necessary to use the observation network scale of 1:3000, at which the distance between the profiles is 30 m. The physical experiment results were confirmed by mathematical modeling. The scale should be reduced to 1:5000 with detailing in individual areas to improve the economic efficiency of geophysical research.

Mapping of prehaustorial resistance against wheat leaf rust in einkorn (Triticum monococcum), a progenitor of wheat

Wheat leaf rust (Puccinia triticina) is one of the most significant fungal diseases of wheat, causing substantial yield losses worldwide. Infestation is currently being reduced by fungicide treatments and mostly vertical resistance. However, these measures often break down when the fungal virulence pattern changes, resulting in a breakdown of vertical resistances. In contrast, the prehaustorial resistance (phr) that occurs in the einkorn–wheat leaf rust interaction is race-independent, characterized by an early defense response of plants during the prehaustorial phase of infestation. Einkorn (Triticum monococcum) is closely related to Triticum urartu as a progenitor of wheat and generally shows a high level of resistance against leaf rust of wheat. Hence, einkorn can serve as a valuable source to improve the level of resistance to the pathogen in future wheat lines. In particular, einkorn accession PI272560 is known to exhibit a hypersensitive prehaustorial effector triggered immune reaction, preventing the infection of P. triticina. Remarkably, this effector-triggered immune reaction turned out to be atypical as it is non-race-specific (horizontal). To genetically dissect the prehaustorial resistance (phr) in PI272560, a biparental F2 population of 182 plants was established after crossing PI272560 with the susceptible T. boeoticum accession 36554. Three genetic maps comprising 2,465 DArT-seq markers were constructed, and a major QTL was detected on chromosome 5A. To locate underlying candidate genes, marker sequences flanking the respective QTL were aligned to the T. urartu reference genome and transcriptome data available from the parental accessions were used. Within the QTL interval of approximately 16.13 million base pairs, the expression of genes under inoculated and non-inoculated conditions was analyzed via a massive analysis of cDNA (MACE). Remarkably, a single gene located 3.4 Mbp from the peak marker within the major QTL was upregulated (20- to 95-fold) after the inoculation in the resistant accession in comparison to the susceptible T. boeoticum accession. This gene belongs to a berberine bridge enzyme-like protein that is suspected to interact on the plant surface with glycoside hydrolases (GH) secreted by the fungus and to induce a hypersensitive defense reaction in the plant after fungal infections.