Resistant Cultivars Research Articles

Interactions between Sudangrass Lines Selected for Differing Nitrate Expression and Sorghum Aphid

Sudangrass (Sorghum sudanense Stapf) is widely cultivated as a summer annual forage across the southern Great Plains because of its robust forage yield potential. However, the accumulation of nitrates and the potential harm to livestock have restricted the use of Sudangrass for feeding ruminants. Since 2013, the sorghum aphid (SA), Melanaphis sorghi (Theobald) (Hemiptera: Aphididae), has been damaging sorghum and Sudangrass production. However, the interaction between SA feeding and nitrate accumulation in Sudangrass has not been determined. In this study, we evaluated the effect of SA feeding on different Sudangrass lines, comparing them to a susceptible and a resistant sorghum variety and measuring the physiological responses and nitrate concentration after aphid feeding. Additionally, we evaluated the use of these grass lines on SA demographics. Initial infestations of 100 SA per plant that were allowed to feed and proliferate for 20 days increased nitrate concentrations in Sudangrass by more than 60% compared to controls. Concurrently, the Sudangrass lines selected for high nitrate levels drastically reduced SA demographic parameters, comparable to those of the resistant sorghum control. Although the adoption of resistant cultivars is recommended for aphid management, the Sudangrass lines selected may not be the best option for SA management because their accumulation of nitrates in response to herbivory can cause ruminant poisoning.

Screening of rice cultivars against Scirpophaga incertulas Walker : utilising cluster analysis as a tool to identify resistant cultivars

The field experiment was conducted in the Boro season from December 2022 to April 2023 at the Institutional research farm, Institute of Agriculture, Palli Siksha Bhavana, Visva-Bharati, Sriniketan, Birbhum, West Bengal, for the screening of thirty-three rice cultivars for their resistance to yellow stem borer, Scirpophaga incertulas Walker. The experiment utilized modified percent damage values to grade these cultivars during both vegetative and reproductive stages. Early-duration cultivars displayed varied reactions, with Jaldi 13 (2) exhibiting consistent resistance (2.53% DH, 12.65% D), while others showed moderate resistance or susceptibility with deadheart percentages ranging from 4.73% to 8.51% and corresponding damage percentages between 23.65% and 42.55%. This trend extended to reproductive stages, where all early-duration cultivars demonstrated moderate to high susceptibility, with damage percentages between 30.8% and 54.5%. The mid-early duration cultivars displayed mixed responses, with Sahabhagi (4) demonstrating moderate resistance (4.92% DH) and Sukumar (3) exhibiting moderate susceptibility (8.21% DH) during the vegetative stage. These diverse reactions continued into the reproductive stage, providing a comprehensive understanding of their responses to the pest. Additionally, in medium and late-duration cultivars, a range of reactions persisted, with cultivars like Pratiksha (20) showing moderate resistance (6.63% DH) in the mid-duration category and Ajith (25) displaying moderate resistance (6.33% DH) in the late-duration category. Cluster analysis categorized the cultivars into distinct groups, showcasing a mix of resistant, moderately resistant, and susceptible types across all growth durations. Notably, cultivars like Gotra 1 (10), Parijat (14), Pushpa (17), PNR 546 (19), Pravat (23) and Gotra 2 (31) consistently demonstrated resistance or moderate resistance across different growth stages, suggesting their potential suitability in tailoring resistant breeding programs and pest management strategies against the stem borer in rice cultivation.

A time-course transcriptomic analysis reveals the key responses of a resistant rice cultivar to brown planthopper infestation.

The brown planthopper (BPH) is one of the most problematic pests affecting rice (Oryza sativa L.) yields in Asia. Breeding rice varieties containing resistance genes is the most economical and effective means of controlling BPH. In this study, the key factors in resistance to BPH were investigated between the high-resistance rice variety "R26" and the susceptible variety "TN1" using RNA-sequencing. We identified 9527 differentially expressed genes (DEGs) between the rice varieties under BPH-induced stress. Weighted time-course gene co-expression network analysis (WGCNA) indicated that the increased expression of genes is associated with plant hormones, MAPK signaling pathway and biosynthesis of other secondary metabolites, which were involved in disease resistance. A connection network identified a hub gene, OsREM4.1 (BGIOSGA024059), that may affect rice resistance to the BPH. Knocking out OsREM4.1 in rice can lead to a decrease in callose, making it less resistant to BPH. Overall, the expression of differentially expressed genes varies among rice varieties with different resistance in BPH invasion. Inaddition, R26 enhances resistance to BPH by upregulating genes and secondary metabolites related to stress resistance and plant immunity. In summary, our study provides valuable insights into the genome-wide expression profile of DEGs in rice under BPH invasion through high-throughput sequencing, and further suggests that R26 can be used to develop high resistance rice lines in BPH resistant breeding programs.

Identification of Cold Tolerance Transcriptional Regulatory Genes in Seedlings of Medicago sativa L. and Medicago falcata L.

Alfalfa species Medicago sativa L. (MS) and Medicago falcata L. (MF), globally prominent perennial leguminous forages, hold substantial economic value. However, our comprehension of the molecular mechanisms governing their resistance to cold stress remains limited. To address this knowledge gap, we scrutinized and compared MS and MF cold-stress responses at the molecular level following 24 h and 120 h low-temperature exposure (4 °C). Our study revealed that MF had superior physiological resilience to cold stress compared with MS, and its morphology was healthier under cold stress, and its malondialdehyde content and superoxide dismutase activity increased, first, and then decreased, while the soluble sugar content continued to accumulate. Transcriptome analysis showed that after 120 h of exposure, there were different gene-expression patterns between MS and MF, including 1274 and 2983 genes that were continuously up-regulated, respectively, and a total of 923 genes were included, including star cold-resistant genes such as ICE1 and SIP1. Gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses revealed numerous inter-species differences in sustained cold-stress responses. Notably, MS-exclusive genes included a single transcription factor (TF) gene and several genes associated with a single DNA repair-related pathway, whereas MF-exclusive genes comprised nine TF genes and genes associated with 14 pathways. Both species exhibited high-level expression of genes encoding TFs belonging to AP2-EREBP, ARR-B, and bHLH TF families, indicating their potential roles in sustaining cold resistance in alfalfa-related species. These findings provide insights into the molecular mechanisms governing cold-stress responses in MS and MF, which could inform breeding programs aimed at enhancing cold-stress resistance in alfalfa cultivars.

A novel highly antifungal compound ZJS-178 targeting myosin I inhibits the endocytosis and mycotoxin biosynthesis of Fusarium graminearum

Chemical fungicides remain a primary tool for managing Fusarium head blight (FHB) due to the lack of resistant wheat cultivars. In this study, we synthesized 101 2-cyanoacrylate compounds and identified ZJS-178 as particularly effective against Fusarium graminearum (the causal agent of FHB), inhibiting both hyphal growth and conidial germination. Notably, ZJS-178 is specific to Fusarium species, with no impact on other fungi. It also shows no cross-resistance with other groups of fungicides, suggesting a unique mode of action. Mechanistic studies revealed that ZJS-178 targets myosin I in F. graminearum, inhibiting ATPase activity and disrupting endocytosis. Furthermore, ZJS-178 impairs toxisome formation, leading to reduced production of the mycotoxin deoxynivalenol (DON). These findings position ZJS-178 as a promising antifungal agent that could pave the way for developing a novel fungicide to manage FHB and other Fusarium-related diseases.

Integrated Management of Sclerotinia Stem Rot of Soybean Including Organically-Allowed Fungicides in the Midwest United States

Sclerotinia stem rot (SSR) is an economically important disease of soybean, especially in the Great Lakes region of the United States. Few studies on SSR have considered organic management practices and how integrated management techniques best apply in these systems. Trials in Wisconsin and Indiana aimed to evaluate management techniques available to organic farmers for their efficacy in SSR control while preserving yield. The practices evaluated included genetically resistant cultivars, tillage techniques, and the application of Organic Materials Review Institute (OMRI) listed foliar fungicides. The resistant cultivar had significantly lower SSR than the susceptible cultivar in three site-years (P < 0.01). The resistant cultivar also had significantly greater yield than the susceptible cultivar in two site-years (P < 0.05). Using a roller-crimped rye cover crop resulted in mixed results on SSR and yield. No effect on SSR or yield by OMRI listed foliar fungicides was observed (P > 0.05). Overall, the results emphasize the importance of planting a resistant soybean cultivar to manage SSR in organic farming systems in the Midwestern United States.

The Ectopic Expression of the MpDIR1(t) Gene Enhances the Response of Plants from Arabidopsis thaliana to Biotic Stress by Regulating the Defense Genes and Antioxidant Flavonoids.

The Defective in Induced Resistance 1 (DIR1) gene, a member of the lipid transferase proteins (LTPs), plays a crucial role in plant defense against pathogens. While previous transcriptomic studies have highlighted the significant expression of citrus LTPs during biotic stress, functional annotations of LTPs in the Citrus genera remain limited. In this study, we cloned the Murraya paniculata DIR1 (MpDIR1(t)) gene and overexpressed it in Arabidopsis thaliana to evaluate its stress response mechanisms against biotic stress. The transgenic Arabidopsis lines showed fewer disease symptoms in response to Pseudomonas syringae (Pst DC3000) compared to wild-type Arabidopsis. Defense and pathogenesis-responsive genes such as PR1, PR4, PR5, and WRKY12 were significantly induced, showing a 2- to 12-fold increase in all transgenic lines compared to the wild type. In addition, the Pst DC3000-infected transgenic Arabidopsis lines demonstrated elevated levels of flavonoids and salicylic acid (SA), along with higher expression of SA-related genes, compared to the wild type. Moreover, all transgenic lines possessed lower reactive oxygen species levels and higher activity of antioxidant defense enzymes such as superoxide dismutase, peroxidase, and catalase under Pst DC3000 stress compared to the wild type. The up-regulation of defense genes, activation of the SA pathway, accumulation of flavonoids, and reinforcement of antioxidant defense mechanisms in transgenic Arabidopsis lines in response to Pst DC3000 underscore the critical role of MpDIR1(t) in fortifying plant immunity. Thus, MpDIR1(t) constitutes a promising candidate gene for improving bacterial disease resistance in commercial citrus cultivars.

Resistance of Bt and Non-Bt Soybean Cultivars Adapted to Novel Growing Regions of Brazil to Chrysodeixis includens and Spodoptera frugiperda.

Soybean is a highly valuable commodity crop for Brazil's economy. However, it faces significant threats from the attack of a complex of lepidopteran pests, particularly Chrysodeixis includens (Walker) and Spodoptera frugiperda (J. E. Smith). These pests have been managed primarily using transgenic Bt soybeans, but limited knowledge exists about the resistance levels of Bt and non-Bt cultivars adapted to novel soybean-growing areas in Brazil, such as the Minas Gerais state. This study evaluated the resistance levels of Bt and non-Bt soybean cultivars to C. includens and S. frugiperda, and whether the Bt cultivars can differentially affect these pests across larval stages. No-choice bioassays were conducted using Bt (NS6010 IPRO and P97R50 IPRO) and non-Bt soybeans (UFLA 6301 RR, P96R90 RR, and ANsc 80111 RR) at V4-stage in the laboratory with neonate (24 h) and third-instar larvae. Larvae were fed leaf discs in Petri dishes, recording the mortality, leaf consumption, and weight gain after 7 days. There was high mortality of C. includens neonates on the Bt cultivars, but this trend was not observed for older larvae. For S. frugiperda neonates, there was high mortality on the Bt cultivar NS 6010 IPRO and non-Bt cultivar UFLA 6301 RR, but only the former was effective for older larvae. Although the Bt cultivars did not kill the third instars, antinutritional effects were found, such that leaf tissue consumed was not converted to larval weight gain. These findings are important for defining regional strategies of integrated and resistance management of C. includens and S. frugiperda in expanding regions of soybean cultivation in Brazil.

MAPK and phenylpropanoid metabolism pathways involved in regulating the resistance of upland cotton plants to Verticillium dahliae.

Verticillium dahliae causes a serious decline in cotton yield and quality, posing a serious threat to the cotton industry. However, the mechanism of resistance to V. dahliae in cotton is still unclear, which limits the breeding of resistant cultivars. To analyze the defense mechanisms of cotton in response to V. dahliae infection, we compared the defense responses of two upland cotton cultivars from Xinjiang (JK1775, resistant; Z8,susceptible) using transcriptome sequencing at different infection stages. The results revealed a significant differential expression of genes in the two cotton cultivars post V. dahliae infection, with the number of DEGs in JK1775 being higher than that in Z8 at different infection stages of V. dahliae. Interestingly, the DEGs of both JK1775 and Z8 were enriched in the MAPK signaling pathway in the early and late stages of infection. Importantly, the upregulated DEGs in both cultivars were significantly enriched in all stages of the phenylpropanoid metabolic pathway. Some of these DEGs were involved in the regulation of lignin and coumarin biosynthesis, which may be one of the key factors contributing to the resistance of upland cotton cultivars to V. dahliae in Xinjiang. Lignin staining experiments further showed that the lignin content increased in both resistant and susceptible varieties after inoculation with V. dahliae. This study not only provides insights into the molecular mechanisms of resistance to Verticillium wilt in Xinjiang upland cotton but also offers important candidate gene resources for molecular breeding of resistance to Verticillium wilt in cotton.

Identification of Magnaporthe oryzae candidate secretory effector proteins through standardizing the filtering process of the canonical parameters

AbstractThe virulence of Magnaporthe oryzae largely hinges on its secretory effectors. Therefore, identification and thorough understanding of the effector functionality is crucial for unravelling the pathogenicity of the pathogen. In the present study, we employed a modified computational pipeline with deep machine learning techniques with an integration of Magnaporthe effector reference datasets (MOED) that predicted 434 M. oryzae candidate secretory effector proteins (MoCSEPs) from the genomic data. The reliability of the modified CSEP prediction workflow through utilization of precise parametric filtering is considered valid as it predicted 100 functional effectors (97.08%) out of 103 previously identified effector proteins within the Magnaporthe genus. Insights into secretion patterns and subcellular localization elucidated the role of these proteins in host cell recognition. Furthermore, structural classification of MoCSEPs, based on conserved motifs, combined with an exploration of their biological functions, revealed their significance in host adaptability and localization. Experimental validation done through examining expression of the MoCSEPs revealed varied secretion patterns in the resistant (40 expressed) and susceptible (92 expressed) rice cultivars at different time intervals after pathogen inoculation owing to different degrees of resistance by the host cultivars. The present work thus provides the strategic model of canonical parametric evaluation within the MOED and deepens the understanding on the role of secretory proteins of M. oryzae in establishing successful parasitic infection in rice. The predicted MoCSEPs could be used as biomarkers for disease diagnosis and tracking evolutionary shifts in M. oryzae.

Artificial Seed Bioassay for Assessing Genotypic Resistance of Pigeon Pea to Callosobruchus chinensis

Pulse beetle, Callosobruchus chinensis is a significant pest of stored legumes, particularly pigeon pea (Cajanus cajan), causing substantial damage and economic losses. This study investigates the resistance of various pigeonpea genotypes to C. chinensis using artificial seeds in a controlled single-choice bioassay. Artificial seeds in bioassays help provide consistent conditions for studying pigeon pea resistance to pests like C. chinensis. Unlike natural seeds, which can vary in traits like size, texture, and composition, artificial seeds ensure that any observed resistance is due to the plant's genetics, not differences in the seeds themselves. Despite using seeds with different proportions of resistant and susceptible genotypes, no significant differences were observed in the beetle oviposition behavior. The findings suggest that factors other than nutritional content may influence bruchid resistance, emphasize the need for further research into specific phytochemicals responsible for resistance. This work has important implications for the development of more resistant pigeon pea cultivars.

Insights into the molecular basis of beet curly top resistance in sugar beet through a transcriptomic approach at the early stage of symptom development

Curly top disease caused by Beet curly top virus (BCTV) is a limiting factor for sugar beet production. The most economical and sustainable control of BCTV in sugar beet would be via the growth of resistant cultivars, although most commercial cultivars possess only low-to-moderate quantitative resistance. A double haploid line (KDH13) showed a high level of resistance to BCTV infection. However, the mechanism of resistance and response of this line to BCTV infection is unknown. Here, we tested the response of this line to both local and systemic BCTV infections. The virus replicated at a high level in locally infected tissue but lower than in susceptible KDH19 plants. Resistant KDH13 plants systemically infected with BCTV showed only mild enation without leaf curling after 30 days. In contrast, severe leaf curling appeared after 12 days in susceptible plants with higher virus accumulation. Transcriptome analysis of the BCTV-infected KDH13 plants at the early stage of symptom development showed only 132 genes that were exclusively deregulated compared to the regulation of a large number of genes (1018 genes) in KDH19 plants. Pathway enrichment analysis showed that differentially expressed genes were predominantly involved in hormone metabolism, DNA methylation, immune response, cell cycle, biotic stress and oxidative stress. The auxin level in both resistant and susceptible plants increased in response to BCTV infection. Remarkably, exogenous application of auxin caused leaf curling phenotype in the absence of the virus. This study demonstrates the response of resistant and susceptible plants to BCTV infection at both local and systemic infections and highlights the defence-related genes and metabolic pathways including auxin for their contribution towards BCTV symptom development and resistance in sugar beet.

Insights on mining the pangenome of Sphingobacterium thalpophilum NMS02 S296 from the resistant banana cultivar Pisang lilin confirms the antifungal action against Fusarium oxysporum f. sp. cubense.

Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc), poses a significant global threat to banana cultivation. Conventional methods of disease management are increasingly challenged, thus making it necessary to explore alternative strategies. Bacterial endophytes, particularly from resistant genotypes, are gaining attention as potential biocontrol agents. Sphingobacterium thalpophilum, isolated from the resistant banana cultivar Pisang lilin (JALHSB010000001-JALHSB010000029), presents an intriguing prospect for combating Fusarium wilt. However, its underlying biocontrol mechanisms remain poorly understood. This study aimed to elucidate the antifungal efficacy of S. thalpophilum NMS02 S296 against Foc and explore its biocontrol mechanisms at the genomic level. Whole genome sequencing of S. thalpophilum NMS02 S296 was conducted using next-generation sequencing technologies and bioinformatics analyses were performed to identify genes associated with antifungal properties. In vitro assays were used to assess the inhibitory effects of the bacterial isolate on the mycelial growth of Foc. To explore the biomolecules responsible for the observed antagonistic activity, metabolites diffused into the agar at the zone of inhibition between Foc S16 and S. thalpophilum NMS02 S296 were extracted and identified. Whole genome sequencing revealed an array of genes encoding antifungal enzymes and secondary metabolites in S. thalpophilum NMS02 S296. In vitro experiments demonstrated significant inhibition of Foc mycelial growth by the bacterial endophyte. Comparative genomic analysis highlighted unique genomic features in S. thalpophilum linked to its biocontrol potential, setting it apart from other bacterial species. The study underscores the remarkable antifungal efficacy of S. thalpophilum NMS02 S296 against Fusarium wilt. The genetic basis for its biocontrol potential was elucidated through whole genome sequencing, shedding light on the mechanisms behind its antifungal activity. This study advanced our understanding of bacterial endophytes as biocontrol agents and offers a promising avenue for plant growth promotion towards sustainable strategies to mitigate Fusarium wilt in banana cultivation.

A fungal endophyte induces local cell wall-mediated resistance in wheat roots against take-all disease.

Take-all disease, caused by the Ascomycete fungus Gaeumannomyces tritici, is one of the most important root diseases of wheat worldwide. The fungus invades the roots and destroys the vascular tissue, hindering the uptake of water and nutrients. Closely related non-pathogenic species in the Magnaporthaceae family, such as Gaeumannomyces hyphopodioides, occur naturally in arable and grassland soils and have previously been reported to reduce take-all disease in field studies. However, the mechanism of take-all protection has remained unknown. Here, we demonstrate that take-all control is achieved via local but not systemic host changes in response to prior G. hyphopodioides root colonisation. A time-course wheat RNA sequencing analysis revealed extensive transcriptional reprogramming in G. hyphopodioides-colonised tissues, characterised by a striking downregulation of key cell wall-related genes, including genes encoding cellulose synthases (CESA), and xyloglucan endotransglucosylase/hydrolases (XTH). In addition, we characterise the root infection biologies of G. tritici and G. hyphopodioides in wheat. We investigate the ultrastructure of previously described "subepidermal vesicles" (SEVs), dark swollen fungal cells produced in wheat roots by non-pathogenic G. hyphopodioides, but not by pathogenic G. tritici. We show that G. hyphopodioides SEVs share key characteristics of fungal resting structures, containing a greater number of putative lipid bodies and a significantly thickened cell wall compared to infection hyphae. We hypothesise that SEVs are fungal resting structures formed due to halted hyphal growth in the root cortex, perhaps as a stress response to locally induced wheat defence responses. In the absence of take-all resistant wheat cultivars or non-virulent G. tritici strains, studying closely related non-pathogenic G. hyphopodioides provides a much needed avenue to elucidate take-all resistance mechanisms in wheat.

Determining the optimal ratio of resistant to susceptible bentgrass cultivars to reduce dollar spot severity

AbstractDollar spot, caused by Clarireedia spp., is the most prevalent disease on creeping bentgrass golf fairways. Interseeding newer dollar spot‐resistant cultivars into susceptible bentgrass stands could reduce dollar spot severity and the need for resultant fungicide use. This study was conducted to determine the optimal ratio of resistant to susceptible cultivars in a blend that will result in dollar spot reduction. Greenhouse experiments were conducted on cultivar blend ratios (0%, 10%, 25%, 50%, 75%, 90%, 100%) of dollar spot‐resistant (Pure Select, 007XL, Coho) and susceptible (Penncross) bentgrass challenged with inoculation of two Clarireedia spp. isolates. Disease severity was determined using visual estimates and digital image analysis. Dollar spot severity was significantly influenced by the Clarireedia isolate, with a fungicide‐resistant isolate being more aggressive and producing more disease than a sensitive one. Dollar spot severity was highest on Penncross alone, with no statistical differences observed among the resistant cultivar monostands. Mean disease severity of the blended cultivar ratios was divided into three statistically different groups—low resistance (10% and 25%), medium resistance (50% and 75%), and high resistance (90% and 100%). Compared to Penncross, blending a 10% resistant cultivar reduced AUDPC (area under the disease progress curve) values by 2% and 3% in Experiments 1 and 2, respectively, while blending a 90% resistant cultivar yielded 20% and 32% reductions. These results indicate dollar spot severity decreases as the ratio of the resistant cultivar in a stand increases, and blending resistant cultivars into susceptible has the potential for reducing disease.

Occurrence of Yam Mosaic Virus and Yam Mild Mosaic Virus on Dioscorea spp. Germplasm Collection in Cuba-Epidemiology of Associated Diseases.

Potyvirus diseases are one of the main challenges facing the production of yam (Dioscorea spp.). The objective of this study was to identify the potyviruses present in the Dioscorea spp. germplasm collection at Instituto de Investigaciones de Viandas Tropicales (INIVIT) to establish methodologies for the characterization of the associated diseases. For this purpose, immunochemical and molecular methods were used to identify the potyviruses present. The symptomatology of Dioscorea spp. at INIVIT's germplasm collection was described. In addition, the severity and incidence in the germplasm collection and production areas were evaluated. As a result, the first report of yam mosaic virus (Potyvirus yamtesselati) and yam mild mosaic virus (Potyvirus yamplacidum) in Cuba is presented. The existence of resistant, tolerant, and susceptible cultivars to potyvirus-associated diseases in the germplasm collection was detected, and the incidence of these diseases was higher than 64% in the production areas evaluated. This study represents a step forward in the establishment of certification programs for propagating material of Dioscorea spp. in Cuba.

Understanding the origins, impacts, and remedies for mungbean yellow mosaic virus

Mungbean (Vigna radiata) is a crucial crop worldwide, especially in Asian countries, where it significantly contributes to agricultural yields. However, the Mungbean Yellow Mosaic Virus (MYMV), a begomovirus, causes substantial yield reductions. Despite ongoing efforts to identify resistant cultivars, most available varieties remain susceptible, potentially resulting in yield losses of up to 100%. In Pakistan, challenges such as inadequate irrigation, disease outbreaks, and poor-quality seed stocks exacerbate the impact of MYMV on mungbean production. Whiteflies (Bemisia tabaci) are the primary vectors for MYMV. Molecular characterization reveals that virus particles aggregate in the host nuclei, disrupting cell structure and leading to yield losses, with early infection stages resulting in more severe reductions. Efforts to manage MYMV include evaluating mungbean germplasm for resistance and emphasizing the importance of genetic resistance in disease control. Despite difficulties in developing resistant cultivars, ongoing research aims to reduce the impact of MYMV on mungbean production. This review explores the effect of MYMV on mungbean production, particularly in Pakistan, and examines the associated economic consequences. It also investigates the genetic susceptibility of mungbean cultivars, the influence of environmental conditions, and the dynamics of whitefly populations, which collectively contribute to MYMV incidence. The review highlights the correlation between whitefly populations and disease incidence and discusses strategies for managing MYMV and its vector. This paper provides a comprehensive overview of current approaches to develop sustainable and effective methods for mitigating MYMV-induced yield losses in mungbean cultivation.

Assessing potato cultivars for resistance against late blight under high altitudinal conditions of North Western Himalayas

Different stages in plant development significantly influence the incidence of potato late blight disease in India. In the present study, the disease progression was monitored weekly in five selected potato cultivars viz. Kufri Jyoti, Kufri Giriraj, Gulmarg Special, Shalimar Potato-I, and Gurez local, during the 2018 and 2019 cropping seasons. The severity of potato late blight, caused by Phytophthora infestans, increased with fluctuations in weather variables. Calculations for the area under the disease progress curve (AUDPC) and the rate of disease spread (r-value) at different growth stages of potatoes were used to track disease progression. Notably, the Kufri Jyoti cultivar demonstrated resistance compared to the other cultivars, with lower severity values and susceptibility scale values (48.40%; 5.6 and 4.9) in 2018 and 2019, respectively. The average rate of disease progress was also lower in Kufri Jyoti (0.064 and 0.060) compared to the local cultivar (0.076 and 0.074) in 2018 and 2019, respectively. These observations indicate that weather parameters have a strong positive impact on the incidence of potato late blight.

Screening of Gerbera Cultivars against Root-Knot Nematode Meloidogyne incognita

Aims: To find out the source of resistance against root-knot nematode, Meloidogyne incognita in different gerbera cultivars and their evaluation. Study Design: Completely Randomized Design. Place and Duration of Study: Biswanath College of Agriculture, Biswanath Chariali, Assam during rabi season 2023. Methodology: Suckers of six gerbera cultivars were planted in pots and were inoculated with freshly hatched second stage juveniles of M. incognita (1 J2/cm3 soil) fifteen days after planting. Results: Upon observation 2 months after inoculation results showed that three cultivars viz. Pink Melody, Red Seven and Arka Krishika were recorded as susceptible with gall index 3.6, 3.6 and 3.4 respectively. Other three cultivars viz. Orange Sun Brust, Pride of Sikkim and Saffron were recorded as moderately resistant with gall index 3.0. Upon evaluation the cultivar Orange Sun Brut recorded maximum plant growth parameters followed by the cultivar Saffron and minimum plant growth parameters were recorded in the cultivar Pink Melody. Conclusion: From this experiment it is concluded that no one cultivar found to be resistant against root-knot nematode. Three cultivars were found to be moderately resistant and others were susceptible. Moderately resistant cultivars can be planted in nematode infested areas as alternative to susceptible cultivars.

Evaluation of Ergot Resistance in Hard Red Spring Wheat in North Dakota.

Higher levels of ergot (Claviceps purpurea [Fr.] Tul.) were reported in North Dakota hard red spring wheat (HRSW) in 2018, leading to questions pertaining to management and cultivar resistance. To better understand pathogen and HRSW cultivar responses, greenhouse experiments were conducted from 2020 to 2021 to evaluate the aggressiveness of nine C. purpurea isolates and ergot resistance in 21 HRSW cultivars. Results from the aggressiveness assay indicated significant cultivar-by-isolate interactions for the total weight of sclerotia produced and ergot incidence. Mean data across all cultivars by isolate combinations suggested isolates CC-3 and IA-Tim were the most aggressive, and these were subsequently used in ergot resistance experiments. Results from ergot resistance screening indicated that none of the HRSW cultivars were immune to C. purpurea because all cultivars produced sclerotia. However, differences in ergot incidence, kernel incidence, aborted kernel incidence, total sclerotia weight, sclerotia length, and sclerotia width occurred among cultivars. Both 'ND-Frohberg' and 'TCG-Spitfire' had the lowest ergot incidence values and were among the lowest in total sclerotia weight. 'Waldron' and 'LCS-Trigger' had the highest ergot incidence and the highest total sclerotia weight. Given that most concerns with ergot occur postharvest, we suggest two categories to describe ergot resistance: host resistance (fate of inoculation for a stigma) and logistical resistance (size characteristics of a sclerotium that influence its ability to remain with a seed lot after harvest and cleaning). This research provides a strong foundation for our understanding of HRSW resistance to ergot that will influence variety decisions in ergot-prone areas in North Dakota.