Susceptible Varieties Research Articles

Evaluation of differential miRNA expression between Fusarium wilt-resistant and -susceptible watermelon varieties

Watermelon (Citrullus lanatus) has been cultivated for nearly one thousand years and remains a commercially important crop. However, continuous planting often leads to the aggravation of many diseases. Watermelon Fusarium wilt (FW) is one of them, which is a fungal soil-borne disease caused by Fusarium oxysporum f. sp. niveum (Fon) that damages plant roots by invading vascular bundles. Therefore, it is imperative to comprehensively characterize the mechanism mediating disease resistance or susceptibility, as well as identify effective resistance genes, in order to breed improved disease-resistant watermelon varieties. miRNAs are endogenous non-coding RNAs that are widely involved in plant growth, development, metabolism, transport, stress response, and pathogen defense. However, there are few reports of disease-associated miRNAs, or their mechanisms of action, in Cucurbitaceae crops. In this study, the roots of both Fon-susceptible and resistant watermelon varieties were infected with GFP-labeled Fon. Three key infection time points were identified. Illumina sequencing was used to obtain Fon-resistance related miRNAs, and degradome sequencing was used to obtain miRNA target genes. A total of 23 differentially expressed miRNAs were identified at the three key infection time points, the degradation group sequencing found their only target gene. The results of this study provide a theoretical basis for studies of miRNA function and regulation during the interaction between Fon and watermelon plants and clues for the screening of watermelon resistance genes. In addition, this information can be used to breed disease-resistant watermelon varieties.

Role of Trichoderma asperelloides and Trichoderma brevicompactum in improving drought tolerance in rice

Drought is considered as one of the major abiotic stresses affecting rice production under rainfed ecologies of Bangladesh hampering the country's self-sufficiency in rice production through reduced crop yield and quality. In the present study, we studied the effect of two species of plant growth promoting Trichoderma v iz; Trichoderma asperelloides and Trichoderma brevicompactum on rice plant development under drought stress and their role in inducing tolerance to drought at physiological and biochemical level. Results reveal that both species are capable of inducing plant tolerance to drought stress when tested on drought tolerant (BRRI dhan56) and drought susceptible (IR64) varieties. As the number of drought stress days increased, there was an increase in root length of both the varieties but increase in root length was more in BRRI dhan56 as compared to IR 64 when seeds of both varieties were primed with Trichoderma. There was significant change in proline, malondialdehyde (MDA), total Phenolic content (TFC), H2O2 content in Trichoderma treated versus non-treated plants for both varieties. These biochemical changes were verified with the expression of aquaporin (AQU), dehydrin (DHN) and DREB genes in both rice varieties treated with both Trichoderma species. Interaction studies of Trichoderma species with two rice genotypes suggested that AQU-2 expressed more in tolerant variety (BRRI dhan56) when primed with Trichoderma asperelloides whereas, both Trichoderma spp. up regulated the expression of DHN-4 and DREB genes in both rice genotypes under drought conditions. The present findings suggest that the both Trichoderma asperelloides and Trichoderma brevicompactum are most effective in improving drought tolerance in rice, and its prospective application will contribute to the advancement of rice genotypes to sustain crop productivity under drought stress.

Evaluation of mTERF gene expressions in response to Phytophthora capsici infection in pepper (Capsicum annuum L.) cultivars

Despite resistance to abiotic stresses, some plant species may still show low resistance to pathogens. This biotic stress resistance can provide advantage and increase productivity in agricultural systems. However, while there is extensive research on the pathways involved in abiotic stress tolerance, the impact on the molecular mechanisms underlying pathogen resistance remains poorly understood. Among the pathogens, Phytophthora capsici, an oomycete, causes severe damage as plant pathogen, leading to blight and fruit rot in pepper and other commercially valuable crops. This study investigates the effects of Phytophthora capsici infection on highly resistant (CM334) and susceptible (Sera Demre) pepper varieties. We examined biochemical changes and gene expression across different vegetative periods (seedling, flowering, and fruiting stages). Specifically, we analyzed biochemical pathways and the mitochondrial transcription termination factor (mTERF) gene regions associated with pathogenicity. In pepper seedlings infected with P. capsici, peroxide levels increased at all developmental stages compared to control groups. Additionally, we observed a rise in H2O2 content, a molecule involved in signal transduction, likely due to the oxidative stress caused by the pathogen. The expression patterns of mTERF genes varied significantly depending on both pathogen application and the developmental stage of the plants. In the seedling stage, inoculation with P. capcici resulted in decreased expression of TERF2, mTERF6, and mTERF8 genes in leaf parts of both resistant and susceptible varieties. However, mTERF28 expression showed a significant increase. Interestingly, mTERF14 and mTERF27 gene expressions increased in the resistant variety but decreased in the susceptible one. These findings, although not providing a complete picture of host resistance mechanisms, highlight the crucial role of specific plant genes in the defense pathways against Phytophthora capsici. This knowledge can contribute to selecting pepper varieties with sustainable resistance to this devastating pathogen.

Optimization of inoculum production of Stemphylium botryosum for large-scale resistance screening of lentils

BackgroundStemphylium blight incited by Stemphylium botryosum poses a significant threat to lentil crops worldwide, inducing severe defoliation and causing substantial yield losses in susceptible varieties under favorable conditions. While some moderate levels of resistance have been identified within lentil germplasm, a low number of resistant cultivars are available to farmers. Adding to the common constraints of resistance breeding, a notable challenge is generating a sufficient number of spores for large-scale screenings, which are essential for pinpointing additional sources of resistance for integration into breeding programs. Therefore, there is a pressing need to improve existing screening methods and tailor them for large-scale material selection. In pursuit of this objective, a protocol for the efficient production of fungal material has been adapted.ResultsOptimization of fungal material production was successfully achieved by comparing the use of fungal mycelia and spores. Spore production was found to be optimal when produced on solid V8-PDA(hi) medium, while liquid Richard’s medium was identified as superior for mycelium yield. Furthermore, a refined screening method was developed by evaluating the resistance of six lentil accessions to stemphylium blight. This assessment included the use of either fungal mycelia (at densities ranging from 1 to 5 g L− 1) or spores (with densities ranging from 5 × 104 to 2 × 105 conidia mL− 1) under three different relative humidity levels (from 50 to 100%). Both humidity levels and inoculum dose significantly influenced the final disease rating (DR) and the relative Area Under the Disease Progress Curve (rAUDPC). Differences among genotypes in final symptom severity (DR) became more pronounced after inoculation with inoculum densities of 5 g L− 1 of mycelium or of 105 and 2 × 105 conidia mL− 1 of spore under 100% relative humidity. Given the challenges associated with the large-scale production of S. botryosum spores, inoculations with 5 g L− 1 of mycelium is highly recommended as a practical alternative for conducting mass-scale screenings.ConclusionsThe findings from this study underscore the critical importance of maintaining high level of humidity during inoculation and disease progression development for accurately assessing resistance to stemphylium blight. The optimization of mycelial production for suspension inoculation emerges as a more reliable and efficient approach for conducting large-scale screening to assess germplasm resistance against stemphylium blight in lentil crops.

Metabolome Revealed the Potential Mechanism of Fusarium Wilt Resistance in Bitter Gourd (Momordica charantia) Based on Liquid Chromatography with Mass Spectrometry.

Fusarium wilt fungus infection of bitter gourd, a major melon vegetable crop, results in massive yield reduction. Through extensive testing, some Fusarium wilt-resistant bitter melon varieties have been produced, but the molecular mechanism of their resistance to the fungus remains unknown. Importantly, after bitter melon plants are infected with Fusarium oxysporum f. sp. momordicae (FOM), apart from altering their gene expression levels, numerous metabolites are produced because of the interaction with the fungus. In the current study, an untargeted metabolomics analysis was performed to investigate the metabolic difference between resistant and susceptible bitter gourd varieties at various timepoints postinoculation with FOM based on liquid chromatography with mass spectrometry. A total of 1,595 positive ion mode and 922 negative ion mode metabolites were identified. Between the resistant and susceptible bitter gourd varieties, 213 unique differentially abundant metabolites (DAMs) were identified, and they were mainly enriched in the alpha-linolenic acid metabolism pathway. By comparing the postinoculation with preinoculation timepoints in the resistant and susceptible bitter gourd varieties, 93 and 159 DAMs were identified, respectively. These DAMs were mainly related to beta-alanine metabolism, among others. Multiple metabolites in the biosynthesis of the phenylpropanoid pathway showed greater variability in the susceptible than the resistant varieties, which may be related to senescence and mortality in the susceptible variety. These results provide new insights into the understanding of metabolite changes after FOM infection and a theoretical foundation for the elucidation of the bitter gourd disease resistance mechanism.

SCREENING OF RICE VARIETIES TOLERANT AND SUSCEPTIBLE TO IRON TOXICITY IN INLAND VALLEY SWAMPS (IVS) IN SIERRA LEONE

Iron toxicity is a nutrient disorder, which is brought about by the uptake of Fe (II) in amounts that disrupt or over-expressseveral metabolic processes, resulting in damage to the rice plant. A pot experiment was conducted in a greenhouse at Sierra Leone Agricultural Business Initiatives (SABI) Center Newton to enable the screening of many different varieties thereby resulting in the identification of both tolerant and susceptible varieties that could be used as breeding materials for rice improvement programs in the tropics. The hot spot iron toxic soils used in the pot were weighed at a uniform rate The parameters or items of measurement to be looked at could be the dry weight of root, dry weight of stem, dry weight of filled grain, dry weight of unfilled grains, plant height (cm) of the genotypes, tiller number of the genotypes, leaf area (cm2)of the genotypes, phenotypic acceptability of the genotypes, Iron-toxicity score of the genotypes Based on their performance in terms of toxicity scores, dry root weight, stem weight, leaf area, unfilled grains, filled grains, tiller count, plant height, and phenotypic acceptability the following varieties have been identified as iron toxicity tolerant with high yield potential Gbassay, Rok-24, Chim, kiamp.

Functional Analysis of the GhIQD1 Gene in Cotton Resistance to Verticillium Wilt.

Cotton is a critical crop with massive economic implications worldwide. Verticillium wilt is a soil-borne ailment caused by Verticillium dahliae, which harms the growth and development of cotton. Therefore, investigating the genes associated with resistance to verticillium wilt is of particular significance. In this study, we identified the GhIQD1 gene through transcriptome analysis and experimentally characterized the role of the GhIQD1 gene in cotton against V. dahliae. The findings indicated that GhIQD1 acts as a calmodulin-binding protein. The expression of GhIQD1 was the highest in stems, and the expression level increased significantly following infection with V. dahliae. The expression in resistant cotton varieties was higher than in susceptible cotton varieties. Through overexpression of the GhIQD1 gene in tobacco, these transgenic plants exhibited improved resistance to V. dahliae. In contrast, by silencing the GhIQD1 gene in cotton through VIGS, the resistance to V. dahliae was reduced. Following inoculation, the leaves yellowed, and the disease index was higher. Transcriptome analysis of transgenic tobacco 72 h after inoculation indicated that overexpression of GhIQD1 increased the enrichment of the calmodulin pathway and stimulated the production of plant hormones alongside secondary metabolites. Consequently, we investigated the relationship between the GhIQD1 gene and plant disease-resistant hormones SA, JA, and ABA. In summary, this study uncovered the mechanism by which GhIQD1 conferred resistance to V. dahliae in cotton through positive regulation of JA and ABA, providing crucial information for further research on the adaptation of plants to pathogen invasion.

Impact of Smut (Sporisorium scitamineum) on Sugarcane’s Above-Ground Growth and the Determinants of the Disease Intensity in the Ethiopian Sugarcane Plantations

The development of sustainable smut management techniques requires an understanding of the impacts of smut on sugarcane growth and the relationships between smut intensity and meteorological variables, varieties, and crop types. Thus, assessments were made with the objectives to 1) determine the effect of smut on the above-ground growth of sugarcane, and 2) quantify the association of smut with weather variables, varieties and crop types. The effect of smut on above-ground growth was assessed in six fields planted with NCo 334 (wider coverage) having 6 months of age in Fincha and Metehara fields in 2021. Data on above-ground growth were taken from 20 randomly selected smut-affected and healthy stools from each field. Besides, 6 years’ data (2015 to 2021) on the numbers of smut-affected stools and smut whips of 79 fields were collected. Furthermore, 10 years’ (2011 to 2021) weather data were acquired from the sugar plantations. The results demonstrated reduction in the above-ground growth of sugarcane in the range of 18.39% and 73.42% due to smut. In addition, weather variables explained about 68.48% and 66.58% of the variability in the number of smut-affected stools and whips respectively. Smut intensity increased with crop types for susceptible varieties. The tight association between the smut epidemic and crop types, varieties, and weather, implied that these parameters must be carefully considered in management decisions. Continuous monitoring of smut disease, meteorological variables, varieties, and crop types in all the sugarcane plantations could be done as a part of integrated smut management in the future.

Studies on the transmission of Squash Leaf Curl China Virus causing yellow mosaic and leaf curl disease in pumpkin

Viruses pose a significant threat to pumpkin cultivation, leading to substantial yield losses and reduced fruit quality. Understanding the transmission dynamics and disease progression of Squash Leaf Curl China Virus (SLCCV), a major virus affecting pumpkin, will contribute to developing effective management strategies for this crop. Our study aimed to develop an efficient mechanical inoculation method for SLCCV in pumpkin and investigate whitefly transmission. Mechanical inoculation was assessed using different buffers (I, II, and III) for preparing the viral inoculum. Buffer III, consisting of phosphate buffer, β-mercaptoethanol, and Na2SO3, showed the highest severity of symptoms and incidence of infection in the susceptible pumpkin variety Pusa Vishwas. The summer season was the most favourable for virus transmission, and plant parts such as expanded leaves, middle leaves, and stems exhibited higher infectivity than other parts. A minimum of two whiteflies per plant successfully transmitted the virus to pumpkin plants, resulting in yellow mosaic symptoms and stunted growth. The transmission efficiency increased with an increase in number of whiteflies per plant. A minimum acquisition access feeding period (AAP) of 10 min. and an inoculation access feeding period (IAP) of 24 h were optimal for whitefly-mediated transmission of SLCCV. These findings highlight the importance of vector control strategies, such as insecticides and physical barriers to prevent whitefly-mediated transmission of SLCCV in pumpkin. This is the first report of sap transmission of SLCCV in pumpkin, emphasizing the importance of developing and implementing comprehensive control strategies that address all possible routes of infection.

Genetic diversity and heritability of tomato parental lines assembled for Ralstonia solanacearum resistance

Bacterial wilt is a disease caused by Ralstonia solanacearum, which affects over 450 plant species and causes significant reduction in crop yields including of tomato (Solanum lycopersicum) worldwide. Developing and identifying tomato genotypes with Ralstonia solanacearum tolerance and high yield potential, presents an opportunity for improvement of crop productivity. The objective of this study was to explore the heritability of tomato resistance against bacterial wilt and the genetic variation within the population for breeding purposes. A breeding population was created by crossing two bacterial wilt-resistant (MT56 and BL333) and three commercially desirable susceptible (Assila, Rambo and Heinz) tomato varieties, using North Carolina Design II, in a screen house at the Makerere University Agricultural Research Institute, Kabanyolo (MUARIK). Results showed that the Area Under Disease Progress Curve was significant (P<0.001), indicating that cumulative disease progress was less in resistant genotypes of segregating generations. Disease severity increased with days after inoculation (DAI), with Heinz showing the highest level of susceptibility. The General Combining Ability for male parent (GCAm) was significant (P< 0.01), and Specific Combining Ability (SCAf×m) and GCAf were significant (P<0.01) for the F2 generation. Broad-sense heritability was higher than the narrow-sense heritability in both F1 and F2 generations, suggesting that non-additive gene action predominately controlled tomato resistance to bacterial wilt infestation. The genetic diversity ranged from 0.5 to 0.6759, with a mean value of 0.5787. Polymorphism Information Content (PIC) varied from 0.375 to 0.6357, with a mean of 0.4888, indicating a high degree of variation. SLM 12-2 was the most polymorphic marker, with a PIC of 0.6357. The Unweighted Pair-Group Method with Arithmetic Average (UPGMA) classified all tomato genotypes into six clusters, namely Clusters 1 and 2 (Susceptible parents), Cluster 3 (Resistant parents), Clusters 4 and 5 (New source of resistance), and Cluster 6 (F1P1×P5).

Genome-wide analysis of NPR1-like genes in citrus species and expression analysis in response to citrus canker (Xanthomonas axonopodis pv. citri).

Citrus fruits, revered for their nutritional value, face significant threats from diseases like citrus canker, particularly impacting global citrus cultivation, notably in Pakistan. This study delves into the critical role of NPR1-like genes, the true receptors for salicylic acid (SA), in the defense mechanisms of citrus against Xanthomonas axonopodis pv. citri (Xcc). By conducting a comprehensive genome-wide analysis and phylogenetic study, the evolutionary dynamics of Citrus limon genes across diverse citrus cultivars are elucidated. Structural predictions unveil conserved domains, such as the BTB domain and ankyrin repeat domains, crucial for the defense mechanism. Motif analysis reveals essential conserved patterns, while cis-regulatory elements indicate their involvement in transcription, growth, response to phytohormones, and stress. The predominantly cytoplasmic and nuclear localization of NPR1-like genes underscores their pivotal role in conferring resistance to various citrus species. Analysis of the Ks/Ka ratio indicates a purifying selection of NPR1-like genes, emphasizing their importance in different species. Synteny and chromosomal mapping provide insights into duplication events and orthologous links among citrus species. Notably, Xac infection stimulates the expression of NPR1-like genes, revealing their responsiveness to pathogenic challenges. Interestingly, qRT-PCR profiling post-Xac infection reveals cultivar-specific alterations in expression within susceptible and resistant citrus varieties. Beyond genetic factors, physiological parameters like peroxidase, total soluble protein, and secondary metabolites respond to SA-dependent PR genes, influencing plant characteristics. Examining the impact of defense genes (NPR1) and plant characteristics on disease resistance in citrus, this study marks the inaugural investigation into the correlation between NPR1-associated genes and various plant traits in both susceptible and resistant citrus varieties to citrus bacterial canker.

Duplicated Copy Number Variant of the Maize 9-Lipoxygenase ZmLOX5 Improves 9,10-KODA-Mediated Resistance to Fall Armyworms.

Extensive genome structure variations, such as copy number variations (CNVs) and presence/absence variations, are the basis for the remarkable genetic diversity of maize; however, the effect of CNVs on maize herbivory defense remains largely underexplored. Here, we report that the naturally occurring duplication of the maize 9-lipoxygenase gene ZmLOX5 leads to increased resistance of maize to herbivory by fall armyworms (FAWs). Previously, we showed that ZmLOX5-derived oxylipins are required for defense against chewing insect herbivores and identified several inbred lines, including Yu796, that contained duplicated CNVs of ZmLOX5, referred to as Yu796-2×LOX5. To test whether introgression of the Yu796-2×LOX5 locus into a herbivore-susceptible B73 background that contains a single ZmLOX5 gene is a feasible approach to increase resistance, we generated a series of near-isogenic lines that contained either two, one, or zero copies of the Yu796-2×LOX5 locus in the B73 background via six backcrosses (BC6). Droplet digital PCR (ddPCR) confirmed the successful introgression of the Yu796-2×LOX5 locus in B73. The resulting B73-2×LOX5 inbred line displayed increased resistance against FAW, associated with increased expression of ZmLOX5, increased wound-induced production of its primary oxylipin product, the α-ketol, 9-hydroxy-10-oxo-12(Z),15(Z)-octadecadienoic acid (9,10-KODA), and the downstream defense hormones regulated by this molecule, 12-oxo-phytodienoic acid (12-OPDA) and abscisic acid (ABA). Surprisingly, wound-induced JA-Ile production was not increased in B73-2×LOX5, resulting from the increased JA catabolism. Furthermore, B73-2×LOX5 displayed reduced water loss in response to drought stress, likely due to increased ABA and 12-OPDA content. Taken together, this study revealed that the duplicated CNV of ZmLOX5 quantitively contributes to maize antiherbivore defense and presents proof-of-concept evidence that the introgression of naturally occurring duplicated CNVs of a defensive gene into productive but susceptible crop varieties is a feasible breeding approach for enhancing plant resistance to herbivory and tolerance to abiotic stress.

FsCGBP, a Cutinase G-Box Binding Protein, Regulates the Growth, Development, and Virulence of Fusarium sacchari, the Pathogen of Sugarcane Pokkah Boeng Disease.

Fusarium sacchari is a causal agent of sugarcane Pokkah boeng, an important fungal disease that causes a considerable reduction in yield and sugar content in susceptible varieties of sugarcane worldwide. Despite its importance, the fungal factors that regulate the virulence of this pathogen remain largely unknown. In our previous study, mapping of an insertional mutant defect in virulence resulted in the identification of a cutinase G-box binding protein gene, designated FsCGBP, that encodes a C2H2-type transcription factor (TF). FsCGBP was shown to localize in the nuclei, and the transcript level of FsCGBP was significantly upregulated during the infection process or in response to abiotic stresses. Deletion or silencing of FsCGBP resulted in a reduction in mycelial growth, conidial production, and virulence and a delay in conidial germination in the F. sacchari. Cutinase genes FsCUT2, FsCUT3, and FsCUT4 and the mitogen-activated protein kinase (MAPK) genes FsHOG1, FsMGV1, and FsGPMK1, which were significantly downregulated in ΔFsCGBP. Except for FsHOG1, all of these genes were found to be transcriptionally activated by FsCGBP using the yeast one-hybrid system in vitro. The deletion of individual cutinase genes did not result in any of the phenotypes exhibited in the ΔFsCGBP mutant, except for cutinase activity. However, disruption of the MAPK pathway upon deletion of FsMGV1 or FsGPMK1 resulted in phenotypes similar to those of the ΔFsCGBP mutant. The above results suggest that FsCGBP functions by regulating the MAPK pathway and cutinase genes, providing new insights into the mechanism of virulence regulation in F. sacchari.

Evaluation of the Groundnut Improvement Network for Africa Core Collection for Resistance to Groundnut Rosette and Late Leaf Spot Diseases

Groundnut Rosette Disease (GRD) and Late Leaf Spot (LLS) are two of the most important diseases across Africa. GRD results in up to 100% and LLS up to 50% yield losses in susceptible varieties. Co-occurrence of the two diseases, which often happens, is thus detrimental for the farmer. The use of resistant varieties remains the best approach to manage these diseases. Breeding for both diseases has resulted in resistance varieties but with limited knowledge on the diversity of varieties developed. The aim of this work was to utilize the Groundnut Improvement Network for Africa (GINA) core collection which is of known diversity to identify lines with sources of resistance to both GRD and LLS. The collection was evaluated across three seasons at Nakabango and Serere, two known GRD and LLS hotspots in Uganda. Analysis of Variance (ANOVA) revealed significant differences among genotypes for both LLS and GRD at different stages of the plant growth. Several lines were identified with moderate to good resistance to GRD, LLS or both GRD and LLS. Fifteen of the lines demonstrated good resistance to both diseases across the three seasons in Nakabango. These lines can be utilized as parents for improving populations for resistance across breeding programs in Africa.

Genome-wide identification of the TIFY gene family in tobacco and expression analysis in response to Ralstonia solanacearum infection

The TIFY gene family plays an essential role in plant development and abiotic and biotic stress responses. In this study, genome-wide identification of TIFY members in tobacco and their expression pattern analysis in response to Ralstonia solanacearum infection were performed. A total of 33 TIFY genes were identified, including the TIFY, PPD, ZIM&ZML and JAZ subfamilies. Promoter analysis results indicated that a quantity of light-response, drought-response, SA-response and JA-response cis-elements exist in promoter regions. The TIFY gene family exhibited expansion and possessed gene redundancy resulting from tobacco ploidy change. In addition, most NtTIFYs equivalently expressed in roots, stems and leaves, while NtTIFY1, NtTIFY4, NtTIFY18 and NtTIFY30 preferentially expressed in roots. The JAZ III clade showed significant expression changes after inoculation with R. solanacearum, and the expression of NtTIFY7 in resistant varieties, compared with susceptible varieties, was more stably induced. Furthermore, NtTIFY7-silenced plants, compared with the control plants, were more susceptible to bacterial wilt. These results lay a foundation for exploring the evolutionary history of TIFY gene family and revealing gene function of NtTIFYs in tobacco bacterial wilt resistance.

Identification of the allelic state of the Rca2 gene for resistance to anthracnose and determination of genetic relatedness in garden strawberry genotypes

The studies were conducted between 2022-2023. The purpose of the work was to analyze the relationship of hybrids and varieties of strawberries resistant and susceptible to anthracnose and to determine the putative allelic status of the anthracnose resistance gene Rca2. Selection of ISSR primers for identifying polymorphism and constructing dendrites of genetic similarity of 19 garden strawberry genotypes from the collection of the Federal State Budgetary Scientific Institution Federal Scientifi c Center for Horticulture. Th e eff ectiveness of ISSR primers was assessed by the ISSR-PCR method, followed by gel electrophoresis of ISSR-PCR products in an agarose gel. To assess the allelic state of the Rca2 gene, the SCAR marker STS-Rca2_240 was used. The genetic distance of the analyzed strawberry samples was determined using the Jaccard coeffi cient. Cluster analysis was carried out using the STATISTICA program (StatSoft ). The putative allelic status of the anthracnose resistance gene Rca2 in the studied varieties and hybrids was established. Diagnostic fragment of the STS-Rca2_240 marker, 240 bp in size. was found in the Alpha variety. Based on an array of genetic similarity coefficients, dendrograms were constructed, during the analysis of which the relationship of the studied variety samples was established. Promising forms were identifi ed that had a high degree of genetic similarity to varieties resistant to anthracnose, and forms that were closely related to susceptible varieties.

Resistance of winter wheat varieties to root rots causative agents against artificial infection

Goal. The study of the varieties of domestic and foreign selection of winter wheat for resistance to the main pathogens of root rot (Fusarium graminearum and Bipolaris sorokiniana) and the determination of their harmfulness.
 Methods. Laboratory method — for the isolation of pathogens in pure culture, for artificial infection with pathogens of root rot, for the determination of growth parameters of winter wheat; dispersive, statistical and regressive methods for the reliability of the obtained results.
 Results. The agressiveness and the virulence of the main causative agents of winter wheat root rot under artificial seed infection have been established. The assessment of the resistance of winter wheat varieties to Fusarium and Helminthosporium root rot was carried out, the development of the disease in relatively resistant varieties ranged from 0.1 to 0.9 points, the spread was 10.0—45.5%; the development of weak–resistant varieties was 1.0—1.2 points, prevalence of 40.9—50.0%; the developmen tof susceptible varieties was 1.7—2.23 points, spreading — 71.8—94.0%. The harmfulness of Fesarium graminearum and Bipolaris sorokiniana on seedling and root length was studied. In susceptible to Fusarium rot varieties of Novosmuglianka, Poliska 90, Lisova Pisnia, the seedling length was reduced by 5.7—6.9 cm, the root length was reduced by 2.51—3.21 cm compared to relatively resistant Samurai varieties.
 Conclusions. The most common types of root rot in Zhytomyr region are Fusarium and Helminthosporous root rot. No root rot resistant varieties of winter wheat were found among the research varieties, but relatively resistant and weak-resistant varieties were selected. For sowing on agricultural enterprises, relatively resistant to Fusarium graminearum and Bipolaris sorokiniana varieties of Samurai, Kraievyd, Podolianka, Scagen can be recommended. Weak-resistant to Fusariosis can be recommended Bohemia, Podarunok Podillia varieties and weak-resistant to helminth sporiasis can be recommended Poliska 90. In protection of winter wheat crops from harmful organisms, the correct selection of varieties plays a special role, therefore, when developing the integrated protection technology, special attention should be paid to the varieties that show resistance to certain diseases and types of pathogens.

Investigation of resistance using STMS markers against Ascochyta blight in the chickpea varieties

Chickpea (Cicer arietinum L.), a prominent legume plant, is an important agricultural plant that is widely grown both in Türkiye and around the world. Ascochyta blight, caused by the fungal phytopathogen Ascochyta rabiei, is one of the major causative agents responsible for yield reductions across the spectrum of chickpea diseases. The impact of diseases varies depending on crops, countries, seasons and cropping systems, and yield loss data collected under well-defined conditions is limited. It is noteworthy that this pathogen shows significant genetic diversity in Türkiye's agricultural environment. In light of this, this study aimed to conduct a research to determine the resistant/tolerant and susceptible genotypes of 34 certificated chickpea varieties grown in different regions of Türkiye by using Sequence Tagged Microsatellite Site (STMS) markers that are related to the genes that provide resistance against Ascochyta blight. The results obtained in this study showed that the primers Ta2, Ta146 and Ts54 used as STMS markers have distinctive features in providing highly effective results in the detection of resistant/tolerant and susceptible varieties of Ascochyta blight.

Genome-Wide Association Study for Identification of Marker-Trait Associations Conferring Resistance to Scald from Globally Collected Barley Germplasm.

Scald is one of the major economically important foliar diseases in barley, causing up to 40% yield loss in susceptible varieties. The identification of quantitative trait loci and elite alleles that confer resistance to scald is imperative in reducing the threats to barley production. In this study, genome-wide association studies were conducted using a panel of 697 barley genotypes to identify quantitative trait loci for scald resistance. Field experiments were conducted over three consecutive years. Among different models used for genome-wide association studies analysis, FarmCPU was shown to be the best-suited model. Nineteen significant marker-trait associations related to scald resistance were identified across six different chromosomes. Eleven of these marker-trait associations correspond to previously reported scald resistance genes Rrs1, Rrs4, and Rrs2, respectively. Eight novel marker-trait associations were identified in this study, with the candidate genes encoding a diverse class of proteins, including region leucine-rich repeats, AP2/ERF transcription factor, homeodomain-leucine zipper, and protein kinase family proteins. The combination of identified superior alleles significantly reduces disease severity scores. The results will be valuable for marker-assisted breeding for developing scald-resistant varieties.

Phenotypical and molecular characterization of new pepper genotypes resistant to Chili pepper mild mottle virus firstly detected in Europe and other tobamoviruses

The tobamoviruses pose a recent threat to local varieties of Gernika pepper (cv. “Derio”) and Ibarra chili (cv. “Ibarroria”), causing a substantial decrease in both yield and fruit quality. Tobamoviruses such as Tomato mosaic virus (ToMV), Tobacco mild green mosaic virus (TMGMV) or Pepper mild mottle virus (PMMoV) are the viruses that cause the greatest impact in pepper crops of northern Spain. The emergence of a novel Tobamovirus, Chili pepper mild mottle virus (CPMMoV; GenBank MN164455.1), firstly identified in Europe, exacerbates these hazards. This situation has jeopardized the ongoing cultivation in some of the virus affected plots. A molecular marker-assisted backcrossing (MABC) breeding program was thus initiated to introduce the L3 and L4 resistance genes into these susceptible local varieties. MABC consisted of one crossing followed by four backcrosses and two self-fertilizations. After each crossbreeding event, the selection criteria of plants were based on plants resistance and fruits resemblance with the original sensitive varieties. This study allowed the homozygous introgression of resistance genes in the new obtained genotypes, reducing the reliance on hybrid seed production and associated costs. The resulting genotypes demonstrated robust resistance when inoculated with PMMoV 1.2, PMMoV 1.2.3, and CPMMoV. In addition, greenhouse yield trials were performed during two consecutive years to identify and select the most productive genotypes harboring the L3 or L4 gene, with the aim of registering some of them as commercial varieties. The productivity of the new selected genotypes did not display significant differences when compared to the original sensitive varieties. The introduction of genetic resistance in these local pepper varieties not only mitigates the immediate hazard posed by Tobamovirus but also fosters the preservation of local agricultural genetic resources, ensuring their continued cultivation and economic sustainability.