Yield Loss Research Articles

Patterns of primates crop foraging and the impacts on incomes of smallholders across the mosaic agricultural landscape of Wolaita zone, southern Ethiopia

Crop foraging by primates is a prevalent form of human-wildlife conflict, especially near protected areas. This behavior poses significant economic challenges for subsistence farmers, jeopardizing both livelihoods and conservation efforts. This study aimed to assess patterns of primate crop-foraging events and estimate maize damage in protected and unprotected fields in southern Ethiopia. Data were collected over 12 months between 2020 and 2021 in the Sodo Zuriya and Damot Gale districts of Southern Ethiopia. A team of six field experts and 25 farmers participated in the study, during which maize damage inflicted by primates was assessed using 25 deployed camera traps. Linear mixed models were used to explore the relationship between maize damage by primates and spatio-temporal variables. Olive baboons and grivet monkeys were found to target maize more frequently during June, July, and August. Olive baboons forage in the morning, while grivet monkeys do so in the afternoon. The average maize yield losses due to primate damage were 43.1% in protected fields and 31.4% in unprotected fields. Of the total damage, 43.1% occurred in protected fields situated 50 meters from the forest edge. Conversely, unprotected fields experienced lower rates of damage: 14.4%, 13.2%, 3.7%, and 0.1% at distances of 50 m, 100 m, 200 m, and 300 m from the forest edge, respectively. Camera traps captured 47 photos of baboons, 21 photos of grivet monkeys, and documented eight primate crop-foraging events. This study revealed that maize fields within 50 meters of the forest edge faced significant damage. Despite the use of wire mesh fencing, it was largely ineffective in deterring olive baboons and grivet monkeys. Additionally, while human guarding is often considered an effective protective strategy, these findings suggest its ineffectiveness due to inconsistent implementation. Overall, this study provides valuable insights for promoting primate conservation and mitigating human-primate conflicts.

Identification of RppSLN from an Elite Landrace: A Major Locus Conferring Resistance to Southern Corn Rust in Maize (Zea mays L.)

Southern corn rust (SCR) is one of the most destructive foliar diseases in maize (Zea mays L.), resulting in significant yield losses. Therefore, the continuous identification of disease-resistant germplasm and the deployment of resistant hybrids is essential for durably controlling SCR. The objective of this research was to identify and characterize resistance loci against SCR in maize to expand disease management strategies. Here, we identified a maize landrace with high resistance to SCR ‘Silunuo’ (SLN) approaching complete immunity. We backcrossed it with a susceptible inbred line, N531, to generate a stable SCR-resistant introgression line N531_R. By crossing it with F35 (a susceptible inbred line), we created a large F2 segregating population and mapped a major SCR-resistant locus on chromosome 10, known as RppSLN. Based on the genome assembly and annotation, we found that RppSLN harbors two NBS-LRR (nucleotide binding site–leucine-rich repeat) genes, namely Zmays10G000430 and Zmays10G000440. These NBS-LRR genes were significantly induced during artificial inoculation with Puccinia polysora, suggesting that they might be candidate genes collectively contributing to the resistance level at this locus. In conclusion, this study identified a major SCR resistance locus directly isolated from a landrace, providing valuable support and information for expanding new disease-resistant germplasms and promoting the utilization of landraces.

Evaluation of Novel Picolinamide Fungicides (QiI) for Controlling Cercospora beticola Sacc. in Sugar Beet

Studies were initiated to find new effective fungicides to use under field conditions to discover novel approaches for optimizing disease management in sugar beet crops. Cercospora leaf spot (CLS), a prevalent foliar disease in sugar beet crops worldwide, is caused by the fungal pathogen Cercospora beticola Sacc. This disease has become the most prevalent pathogen in sugar beet crops across nearly all European growing regions, including Hungary. The epidemic spread of this disease can cause up to 50% yield loss. The use of fungicides has been a cornerstone in managing CLS of sugar beet due to the limited efficacy of non-chemical alternatives. However, the emergence of fungicide-resistant strains of Cercospora beticola Sacc. in recent decades has compromised the effectiveness of certain fungicides, particularly those belonging to the QoI (FRAC Group 11) and DMI (FRAC Group 3) classes. Hungary is among the many countries where resistance to these fungicides has developed due to their frequent application. Picolinamides represent a novel class of fungal respiration inhibitors targeting Complex III within the Quinoine-Inside Inhibitor (QiI) group. Two innovative fungicides from this class, fenpicoxamid and florylpicoxamid (both classified under FRAC Group 21), were evaluated for their efficacy in managing CLS of sugar beet in Hungary during the 2020 and 2021 growing seasons. Both fungicides were applied as formulated products at various application rates and demonstrated superior efficacy in controlling CLS compared to untreated control plots and the reference fungicides difenoconazole and epoxiconazole. The results consistently demonstrated that all tested application rates of fenpicoxamid and florylpicoxamid effectively controlled CLS in sugar beet, exhibiting a clear dose–response relationship. Disease severity, as measured by the area under the disease progress curve (AUDPC), was significantly correlated with yield reduction but showed no significant association with root sugar content. Moreover, data from both study years indicated that picolinamide fungicides applied at a rate of 75 g ai/ha significantly outperformed difenoconazole (100 g ai/ha) in controlling the CLS of sugar beet. Additionally, higher application rates of picolinamides at 100–150 g ai/ha outperformed epoxiconazole at 125 g ai/ha in disease suppression. Fenpicoxamid is currently registered for use in cereals within Europe, and outside of Europe in Banana against Black Sigatoka (eff. Mycosphaerella fijiensis). Florylpicoxamid, while not yet registered in Europe, is undergoing approval processes in various countries worldwide for a range of crops and is continually being evaluated for potential market introduction. Additional details regarding the efficacy of florylpicoxamid against CLS in sugar beet were presented at ‘The 10th International Conference on Agricultural and Biological Sciences (ABS 2024, Győr-Hungary)’ in 2024.

Effect of Two Biofertilisers Based on Endophytic Fungi on Fall Armyworm Infestations in Maize Production in the Kara Region of Togo, West Africa

Aims: The aim of the study was to assess the efficacy of two biofertilisers based on endophytic fungi on infestation rates, foliar damage and maize yield losses caused by the armyworm, Spodoptera frugiperda, a worst maize pest. Study Design: Completely Randomized Design (CRD) with three types of treatments. Place and Duration of Study: Agronomic Experimentation Station of Tchitchao, Kara (Togo), between October 2019 and March 2020. Methodology: A complete randomized block design was used with three types of treatments: (i) maize seeds inoculated with Glomus sp. strain 142, (ii) maize seeds inoculated with Mycotri, (iii) maize seedlings fertilized with NPK and urea and finally (iv) a control consisting of seeds and/or seedlings of maize neither fertilized nor inoculated. Results: The results show that the plots treated with endophytic fungi recorded significantly lower infestation rates compared with the fertiliser treatments and the control. The highest infestation rates were 54% at 38 days after sowing (DAS) and 45% at 31 DAS for treatments with 5.35 x 105 spores/ha Glomus sp. and 0.38 kg/ha Mycotri, respectively, compared with 78% at 31 DAS and 62% at 38 DAS for fertiliser treatments and the control. The highest level of leaf damage, 2.92, was observed at 33 DAS on the plots fertilised with fertiliser, compared with scores of 2.53 and 2.38 for the plots mycorrhised with Glomus sp. and Mycotri, respectively. Yields were significantly higher in the fertilised plots (3.87 t/ha), followed by the mycorrhised plots (2.62-3.01 t/ha) and the control (1.73 t/ha). Conclusion: The endophytic fungi enabled the plants to tolerate fall armyworms attacks better than the controls, offering an alternative to chemical fertilisers and an effective option for managing soil fertility and controlling Spodoptera frugiperda.

Effect of cereal rye cover crop termination timings on weed control and corn yield under a two-pass herbicide program

Cover crops, including cereal rye, are generally known to suppress weeds in various cropping systems; however, research on their effective use is lacking. This study investigated the effects of different cereal rye termination timings on weed control and corn performance in a two-pass herbicide program across 5 site-years (2021–2023) in Arkansas, USA. The herbicide program consisted of one application at cereal rye (Secale cereale) termination (cereal rye environment) or at corn (Zea mays) planting (conventional system) and another at the V4 corn stage. Palmer amaranth (Amaranthus palmeri) at V4 corn was better controlled in cereal rye environments regardless of its termination timing (>75%) than in the conventional corn system (<50%), and the control was generally excellent in both systems 4 weeks later, with subtly greater control in the cereal rye environments. In contrast, yellow nutsedge (Cyperus esculentus) control, in general, was slightly less in the cereal rye environments than in the conventional system. Barnyardgrass (Echinochloa crus–galli) and broadleaf signalgrass (Urochloa platyphylla) control was similar to that of Palmer amaranth, especially at the V4 corn stage, with clear benefits in its control with the later termination timings. Corn height was greater (by 8% to 10%) in cereal rye environments terminated at 1 or 2 weeks after corn planting compared to the conventional system or other cereal rye environments. Corn yield was similar between the conventional system and the cereal rye environments terminated before corn planting; however, the yield was 16% to 22% less with those terminated at or after corn planting. These findings indicate the constrained use of cereal rye in corn, with its termination time optimized for 2 weeks before corn planting. Further research could identify factors that mitigate the yield loss from delayed cereal rye termination and improve its use as a cover crop in corn.

Identification and biological characteristics of Fusarium tobaccum sp. nov., a novel species causing tobacco root rot in Jilin Province, China.

Fusarium wilt of tobacco (FWT), caused by Fusarium spp., has emerged as a severe threat to tobacco production in China. In all, 132 isolates of Fusarium were isolated from tobacco and pathogenic to tobacco-causing FWT in Jilin Province, China. In this study, we identified 7 of 132 isolates as a novel species Fusarium tobaccum sp. nov. Zhao Xie & Jie Gao, using multi-gene phylogenetic analyses of translation elongation factor (tef1), β-tubulin (tub2), calmodulin (cmdA), and RNA polymerase II second largest subunit (rpb2) genes, along with subtle morphological differences. Isolates of F. tobaccum sp. nov. were clustered in a distinct branch in the maximum parsimony phylogenetic tree generated from the sequences of tef1-rpb2-tub2-cmdA and can be distinguished from closely related species F. cugenangense, F. callistephi, and F. elaeidis. The morphological characteristics of F. tobaccum sp. nov. are distinct from other Fusarium species. F. tobaccum sp. nov. exhibits abundant aerial mycelia and pigment production on potato dextrose agar (PDA), microconidia with 0-1 septa, and macroconidia with 2-5 septa on carnation leaf-piece agar (CLA), and produces abundant chlamydospores on Spezieller Nährstoffarmer agar (SNA) and CLA. The mycelia of F. tobaccum exhibited optimal growth at a pH of 7.1 and a temperature of 23.6°C. Sucrose and NaNO3 significantly promoted the mycelial growth of F. tobaccum. PD medium was optimal for total sporulation. However, the sporulation ratios of the macrospores of F. tobaccum in PD, SN, and CMC were relatively low (0.48%, 2.51%, and 2.16%, respectively). These findings provided valuable insights into the morphological and biological characteristics of F. tobaccum.IMPORTANCEFusarium wilt of tobacco (FWT) is a prevalent issue in tobacco-growing regions globally, leading to significant losses in yield and quality. This study identified F. tobaccum sp. nov., a novel species of Fusarium causing FWT in China. The identification was based on multi-gene phylogenetic analyses and morphological characteristics. The effects of temperature, pH, carbon source, nitrogen source, medium, and light on the mycelial growth of F. tobaccum sp. nov. were determined. These findings might contribute to future research on the pathogenic mechanisms of this novel species and the development of strategies to control FWT.

An improved DNA extraction method in okra for rapid PCR detection of Okra enation leaf curl virus from diverse Indian regions.

The extraction of DNA from okra (Abelmoschus esculentus) is challenging due to its high mucilage and polysaccharide content, which can hinder both the yield and quality of DNA.In this study, an improved DNA isolation method is described incorporating a key modification being the use of solution I (1 M NaCl and 2% Sarcosyl) as a pre-treatment before applying the CTAB buffer, resulting in high-purity genomic DNA in just 1h and 45min., making it suitable for handling large sample sizes due to its rapid processing capabilities. This enhanced DNA extraction method was crucial for the accurate and rapid molecular detection of Okra enation leaf curl virus (OELCuV), a monopartitebegomovirus that has spread across various regions of India. Transmitted by the whitefly (Bemisia tabaci), OELCuV causes leaf curling, enations, and stunted growth in okra, leading to significant yield losses. The surveys conducted during the 2020-21 and 2021-22 sowing seasons revealed disease incidence ranging from 14.03 to 67.57%. The extracted DNA via the improved DNA extraction method enhanced the speed of PCR based molecular identification of OELCuV, using virus-specific coat protein primers. The amplified CP genes were cloned and sequenced to study the CP gene based diversity among OELCuV isolates from different states of India. The CP gene nucleotide identity among the studied OELCuV isolates ranged from 95.57 to 99.27%, while comparison with previously reported Indian OELCuV CP sequences, the nucleotide identity ranged from 89.35 to 98.83%.The successful application of this optimized DNA extraction method sped up the detection process but also holds promise for broader use in the molecular study of okra and other mucilaginous crops, particularly in the rapid and reliable identification ofbegomoviruses. The optimized DNA extraction method significantly accelerated the detection of OELCuV, demonstrating its efficiency and reliability. This method shows strong potential for broader applications in the molecular study of okra and other mucilaginous crops, making it a valuable tool for future research and disease management.

Disease-driven yield losses in wheat (Triticum aestivum) crop under different agroclimatic locations of Punjab

The experiments were conducted during winter (rabi) seasons of 2021–22 and 2022–23 at Punjab Agricultural University, Ludhiana, Punjab to examine the yield losses due to diseases in wheat (Triticum aestivum L.) crop under different agroclimatic locations of Punjab. The experiment was conducted in split-plot design (SPD) having three dates of sowing (14th–15th October, 8th–9th November and 3rd–4th December) in main plots and wheat varieties, viz. PBW 725, HD 2967 and HD 3086 with two microclimate modification levels M1 (recommended irrigation) and M2 (additional water sprays) in sub plots, replicated four times. The yellow rust severity was maximum at Ludhiana (56.14%, 57.17%) and Gurdaspur (56.75%, 58.42%) in HD 2967 under early sown conditions in M2 treatment during 2021–22 and 2022–33, respectively. The Karnal bunt incidence was comparatively higher at Ludhiana (18.5% and 13.4%) and Gurdaspur (21.4% and 16.7%) in variety PBW 725 under normal sowing condition in M2 than other treatments during both the years of study, respectively. Grain yield during 2021–22 and 2022–23 was more in early sowing at Ludhiana (43.3 q/ha, 48.1 q/ha) and Gurdaspur (44.5 q/ha, 50.8 q/ha) than other dates of sowing. In variety × microclimate modification levels treatments, grain yield was maximum at Ludhiana (43.1 q/ha, 47.2 q/ha) and Gurdaspur (44.0 q/ha, 50.2 q/ha) in variety PBW 725 under M1 than other treatments during both the years of study. Early date of sowing recorded more yield losses followed by late and normal sowing and losses were more at Gurdaspur as compared to Ludhiana. Average yield losses during 2022–23 were higher i.e. 5.6% and 7.1% as compared to 1.6% and 2.3% during 2021–22 at Ludhiana and Gurdaspur, respectively.

Survey and molecular characterization of begomovirus, and assessment of yield losses caused by leaf curl disease of sunflower (Helianthus annuus)

A comprehensive survey was conducted during winter (rabi) and rainy (kharif) seasons of 2019–20 to 2021–22 in the Kurnool, Nandyal, and Prakasam districts of Andhra Pradesh, focusing on the incidence of leaf curl disease in hybrid sunflower (Helianthus annuus L.) crop. The results revealed a high incidence of the disease, ranging from 40–94.5% across most of the surveyed hybrid varieties. Leaf curl-infected samples collected from the surveyed fields were analyzed by PCR using specific primers for the DNA-A component of the virus to confirm the presence of the pathogen. The PCR-amplified fragments were cloned and sequenced. Sequence analysis revealed that the sunflower isolate (Snf-AP) shared 99.2% nucleotide identity with the tomato leaf curl Karnataka virus (ToLCKV), which infects sunflower crops in Karnataka. This indicates a strong geographical and genetic connection between the viral strains affecting sunflowers in Andhra Pradesh and Karnataka. This genetic similarity is significant, as it suggests that the same or closely related viral strains are responsible for sunflower leaf curl disease across broader regions. The disease was found to affect sunflowers at all growth stages, with the highest incidence (42.3%) observed at the star bud stage. Infection at the star bud stage leads to substantial seed yield losses, with reductions of up to 82.8%. This level of damage underscores the economic impact of early infections, as yield losses of this magnitude can severely affect the profitability of sunflower farming. Additionally, a positive correlation was found between the whitefly population, weather parameters, and disease development.

Ectopic expression of a truncated NLR gene from wild Arachis enhances resistance to Fusarium oxysporum

Fusarium oxysporum causes devastating vascular wilt diseases in numerous crop species, resulting in substantial yield losses. The Arabidopsis thaliana-F. oxysporum f.sp. conglutinans (FOC) model system enables the identification of meaningful genotype–phenotype correlations and was applied in this study to evaluate the effects of overexpressing an NLR gene (AsTIR19) from Arachis stenosperma against pathogen infection. AsTIR19 overexpression (OE) lines exhibited enhanced resistance to FOC without any discernible phenotype penalties. To elucidate the underlying resistance mechanisms mediated by AsTIR19 overexpression, we conducted whole transcriptome sequencing of an AsTIR19-OE line and non-transgenic wild-type (WT) plants inoculated and non-inoculated with FOC using Illumina HiSeq4000. Comparative analysis revealed 778 differentially expressed genes (DEGs) attributed to transgene overexpression, while fungal inoculation induced 434 DEGs in the OE line, with many falling into defense-related Gene Ontology (GO) categories. GO and KEGG enrichment analysis showed that DEGs were enriched in the phenylpropanoid and flavonoid pathways in the OE plants. This comprehensive transcriptomic analysis underscores how AsTIR19 overexpression reprograms transcriptional networks, modulating the expression of stress-responsive genes across diverse metabolic pathways. These findings provide valuable insights into the molecular mechanisms underlying the role of this NLR gene under stress conditions, highlighting its potential to enhance resistance to Fusarium oxysporum.

Plant Viral Synergism: Co-Expression of P1 and NIa-Pro Cistrons of Wheat Streak Mosaic Virus and Triticum Mosaic Virus Is Required for Synergistic Interactions in Wheat.

Synergistic interactions among unrelated viruses in mixed infections can cause significant yield losses, and viral determinants of these interactions are poorly understood. Wheat (Triticum aestivum L.) co-infection with wheat curl mite-transmitted wheat streak mosaic virus (WSMV) and Triticum mosaic virus (TriMV) results in disease synergism with a drastically increased symptom phenotype of stunted growth, leaf bleaching, and enhanced titers of both viruses. In this study, we examined the viral determinants responsible for WSMV-TriMV disease synergism through transient expression of select cistrons of WSMV in wheat through TriMV and vice-versa. We found that expression of WSMV P1, NIa, or NIaPro cistrons in wheat through TriMV or vice-versa elicited moderate to severe symptoms with a moderate or no increase in virus titer. However, co-expression of P1 and NIaPro cistrons of WSMV in wheat through TriMV or vice-versa exhibited a WSMV-TriMV disease synergism-like phenotype. Additionally, we found that the P3 cistron of both viruses is dispensable for synergism, whereas HCPro and NIaVPg cistrons of WSMV and TriMV are not the primary determinants but might have a minor role in efficient synergism. In co-infected wheat, accumulation of vsiRNAs was increased, similar to viral genomic RNA copies, despite the presence of dual viral RNA silencing suppressors (VRSS), which function through sequestration of vsiRNAs. Our findings revealed that WSMV-TriMV disease synergism is not caused by the suppression of host post-transcriptional gene silencing by dual VRSS in co-infected wheat and the P1 and NIaPro cistrons of both viruses collectively drive synergistic interactions between WSMV and TriMV in wheat.

A small antimicrobial peptide derived from a Burkholderia bacterium exhibits a broad-spectrum and high inhibiting activities against crop diseases.

Crop diseases cause significant quality and yield losses to global crop products each year and are heavily controlled by chemicals along with very limited antibiotics composed of small molecules. However, these methods often result in environmental pollution and pest resistance, necessitating the development of new bio-controlling products to mitigate these hazards. To identify effective antimicrobial peptides (AMPs) considered as potential sources of future antibiotics, AMPs were screened from five bacterial strains showing antagonism against a representative phytopathogenic fungus (Rhizoctonia Solani) through the Bacillus subtilis expression system, which has been developed for identifying bacterial AMPs by displaying autolysis morphologies. A total of 5000 colonies were screened, and five displaying autolysis morphologies showed antagonism against R. solani. A novel AMP with the strongest antagonism efficiency was determined and tentatively named HR2-7, which is composed of 24 amino acids with an alpha-helical structure. HR2-7 has strong and broad-spectrum antimicrobial activity, tested against 10 g-positive and -negative bacteria and four phytopathogenic fungi by contact culture in plates with minimal lethal concentrations of 4.0 μM. When applied as purified peptide or in fermented B. subtilis culture solution, HR2-7 showed strong controlling efficiency on plants against diverse fungal and bacterial pathogens. Based on current understanding, HR2-7 is recognized as the first AMP derived from an agricultural antagonistic bacterium. It exhibits wide-ranging and notable antimicrobial efficacy, offering a supplementary approach for managing plant diseases, in addition to conventional chemical pesticides and antibiotics.

Creeping Stem 1 regulates directional auxin transport for lodging resistance in soybean.

Soybean, a staple crop on a global scale, frequently encounters challenges due to lodging under high planting densities, which results in significant yield losses. Despite extensive research, the fundamental genetic mechanisms governing lodging resistance in soybeans remain elusive. In this study, we identify and characterize the Creeping Stem 1 (CS1) gene, which plays a crucial role in conferring lodging resistance in soybeans. The CS1 gene encodes a HEAT-repeat protein that modulates hypocotyl gravitropism by regulating amyloplast sedimentation. Functional analysis reveals that the loss of CS1 activity disrupts polar auxin transport, vascular bundle development and the biosynthesis of cellulose and lignin, ultimately leading to premature lodging and aberrant root development. Conversely, increasing CS1 expression significantly enhances lodging resistance and improves yield under conditions of high planting density. Our findings shed light on the genetic mechanisms that underlie lodging resistance in soybeans and highlight the potential of CS1 as a valuable target for genetic engineering to improve crop lodging resistance and yield.

The molecular dialogue between Zymoseptoria tritici and wheat.

Zymoseptoria tritici is a highly damaging pathogen that causes high wheat yield losses in temperate climates. Z. tritici emerged during the domestication of wheat in the Fertile Crescent and has been extensively used as a model system for population genetic and genomic studies. New genetic tools and resources have provided a better understanding of the molecular components involved in the wheat-Z. tritici interaction, highlighted by the cloning of three wheat resistance genes and four Z. tritici avirulence genes. Despite the considerable progress made in the last few years, the mechanisms that mediate Z. tritici colonization remain largely unknown. In this review, we summarize the latest advances in understanding the molecular components mediating wheat-Z. tritici interactions and we discuss future research lines to close current knowledge gaps.

QTL mapping and genome-wide association analysis reveal genetic loci and candidate gene for resistance to gray leaf spot in tropical and subtropical maize germplasm.

Using QTL mapping and GWAS, two candidate genes (Zm00001d051039 and Zm00001d051147) were consistently identified across the three different environments and BLUP values. GWAS analysis identified the candidate gene, Zm00001d044845. These genes were subsequently validated to exhibit a significant association with maize gray leaf spot (GLS) resistance. Gray leaf spot (GLS) is a major foliar disease of maize (Zea mays L.) that causes significant yield losses worldwide. Understanding the genetic mechanisms underlying gray leaf spot resistance is crucial for breeding high-yielding and disease-resistant varieties. In this study, eight tropical and subtropical germplasms were crossed with the temperate germplasm Ye107 to develop a nested association mapping (NAM) population comprising 1,653 F2:8 RILs, consisting of eight recombinant inbred line (RIL) subpopulations, using the single-seed descent method. The NAM population was evaluated for GLS resistance in three different environments, and genotyping by sequencing of the NAM population generated 593,719 high-quality single-nucleotide polymorphisms (SNPs). Linkage analysis and genome-wide association studies (GWASs) were conducted to identify candidate genes regulating GLS resistance in maize. Both analyses identified 25 QTLs and 149 SNPs that were significantly associated with GLS resistance. Candidate genes were screened 20Kb upstream and downstream of the significant SNPs, and three novel candidate genes (Zm00001d051039, Zm00001d051147, and Zm00001d044845) were identified. Zm00001d051039 and Zm00001d051147 were located on chromosome 4 and co-localized in both linkage (qGLS4-1 and qGLS4-2) and GWAS analyses. SNP-138,153,206 was located 0.499kb downstream of the candidate gene Zm00001d051039, which encodes the protein IN2-1 homolog B, a homolog of glutathione S-transferase (GST). GSTs and protein IN2-1 homolog B scavenge reactive oxygen species under various stress conditions, and GSTs are believed to protect plants from a wide range of biotic and abiotic stresses by detoxifying reactive electrophilic compounds. Zm00001d051147 encodes a probable beta-1,4-xylosyltransferase involved in the biosynthesis of xylan in the cell wall, enhancing resistance. SNP-145,813,215 was located 2.69kb downstream of the candidate gene. SNP-5,043,412 was consistently identified in three different environments and BLUP values and was located 8.788kb downstream of the candidate gene Zm00001d044845 on chromosome 9. Zm00001d044845 encodes the U-box domain-containing protein 4 (PUB4), which is involved in regulating plant immunity. qRT-PCR analysis showed that the relative expression levels of the three candidate genes were significantly upregulated in the leaves of the TML139 (resistant) parent, indicating that these three candidate genes could be associated with resistance to GLS. The findings of this study are significant for marker-assisted breeding aimed at enhancing resistance to GLS in maize and lay the foundation for further elucidation of the genetic mechanisms underlying resistance to gray leaf spot in maize and breeding of new disease-resistant varieties.

Evaluation of F1 hybrids against root knot nematode (<i>Meloidogyne incognita</i>) resistance in Brinjal (<i>Solanum melongena</i> L.)

Brinjal is one of the most important commercial solanaceous vegetable crops. Root knot nematodes cause severe yield losses in brinjal both in open and poly house conditions. Host plant resistance is considered to be a viable solution and cost-effective method to manage the root knot nematodes. Ten genotypes along with their nineteen F1 hybrids were screened for resistance to root knot nematode and biochemical basis of resistance was assessed. Two F1 hybrids viz., IIHR-824 x VI046101, IIHR-824 x IIHR-766, parents viz., IIHR-824 and VI046103 were found to be resistance to M. incognita with gall index/ egg mass index of 1. Three F1 hybrids, IIHR-824 x IIHR-356, IIHR-824 x IIHR-835, VI046103 x IIHR-834 showed moderately resistant reaction. The root biochemical compounds analysis indicated that, total phenolic content (67.05 mg/g) and flavonoids (121.32 mg/g) were found higher in the inoculated roots of resistant line i.e. IIHR-824 indicating their role in conferring resistance. The identified F1 hybrids having resistance can be explored for commercial cultivation.

Molecular methods for the detection and identification of parasitoids within larval wheat midges.

Three species of cecidomyiid midges (Diptera: Cecidomyiidae) cause significant yield losses on wheat in Europe: Sitodiplosis mosellana (Géhin), Contarinia tritici (Kirby) and Haplodiplosis marginata (von Roser). Eggs and young larvae may be parasitised by a complex of hymenopteran parasitoids belonging to the Pteromalidae and Platygastridae families which contributes to natural pest control. We have developed molecular tools for detecting and identifying seven parasitoid species previously encountered in Belgium inside individual wheat midge larvae. Barcode DNA sequences from COI, 18S and 28S genes were obtained from the midges and parasitoid species. Each of the three genes allowed all the species to be distinguished although 18S was the only one displaying a barcoding gap, both between parasitoids and midges, and at the species level. Based on the 18S gene, we developed a TaqMan assay to assess parasitism in midge larvae, regardless of the midge and parasitoid species. Next, two group-specific PCR primer pairs were generated, allowing the separate amplification of midge DNA or parasitoid DNA in parasitised individuals and subsequent identification by Sanger sequencing. Finally, species-specific primers were designed to identify six parasitoid species by simple PCR amplification. These tools were successfully applied to assess the parasitism rate of S. mosellana larvae in seven Belgian fields.

Innate Immunity in Rice: A Defense Against Bacterial Leaf Blight

Rice (Oryza sativa L.) is one of the major staple food crops of the world and sustainable rice production is important for ensuring global food security. Throughout the growing season, a variety of pathogens including fungi, bacteria, viruses, and nematodes, infect different parts of the crop resulting in yield loss. Bacterial leaf blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the major limiting factors in rice production. Being a vascular pathogen, X. oryzae pv. oryzae interferes with a range of physiological and biochemical exchange process in rice. The earlier the pathogen infection, more will be the loss and grain quality is also severely affected due to infection. The spread of the pathogen is too rapid in the favourable climatic conditions. The disease results in 20 to 30 per cent annual loss in rice production and under severe conditions, the yield loss goes up to 80 per cent. Plant pathogens employ different ways to attack host plants and impair plant growth and reproduction. Unlike vertebrates, plants lack mobile immune cells and an adaptive immune system. Plants mainly rely on two interconnected tiers of the innate immune system to perceive and respond to pathogen infection. This innate immune system or basal resistance mediated by a repertoire of Resistance or R genes in plants acts as the first line of pre-formed and inducible defenses that protect the host plants from large number of pathogens. Over the years, extensive investigation on the molecular interactions between rice and Xanthomonas oryzae pv. oryzae has made impressive progress in understanding the molecular basis of rice innate immunity against bacterial leaf blight. Improving plant immunity has been considered as one of the best choices available for achieving economical and sustainable management of bacterial leaf blight in a durable manner. In this review, we summarize the molecular basis of two tiered innate immune system including PAMP triggered immunity (PTI) and Effector triggered immunity (ETI) as well as R genes involved in rice - Xanthomonas oryzae pv. oryzae interaction.

Pilot Evaluation of Field Pea Accessions Under Water Deficit Conditions

Field pea, a key pulse crop for sustainable agriculture, faces significant production challenges due to drought, exacerbated by extreme climatic changes. This study evaluated 17 field pea plant introductions (PIs) and two commercial varieties under greenhouse conditions to assess their performance, determine the relationships between agronomic traits and grain yield (GY), and identify genotypes with stable yields under drought stress. Two water treatments were applied: 100% field capacity for well-watered (WW) and 60% field capacity for water deficit (WD) conditions, with drought stress imposed 21 days after planting. Significant genotypic variation was observed under both conditions. Water deficit significantly reduced GY, the number of pods per plant (NPP), plant height (PH), aboveground dry vegetative biomass (ADVB), and days to maturity (DTM) while increasing stomatal density on both adaxial (SD.ADX) and abaxial leaf surfaces (SD.ABX). Traits associated with GY in WW, such as NPP, PH, ADVB, and SD.ADX, showed stronger correlations under WD, with DTM being significantly associated with GY only in WD. Top-performing genotypes in both conditions exhibited higher pod numbers, increased aboveground dry vegetative biomass, late maturity, and lower adaxial stomatal density. Notably, PI 272215 was identified as a top performer under both conditions, with an 88% yield stability index. PI 180702 demonstrated comparable performance to PI 272215 but with no yield loss under the same conditions. These findings can be used for future field pea breeding programs aimed at developing drought-tolerant field pea varieties.

Evaluation of the Sensitivity of Thirteen (13) Promising Cassava Varieties to Diseases (Viruses-Bacteria) and Pests (Mealybugs-Mites) in Central Côte d’Ivoire

Cassava (<i>Manihot esculenta</i>), a plant with starch-rich roots, plays a crucial role in global food security. For producers, it has become both a subsistence and cash crop. In Côte d’Ivoire, it ranks second among crops after yam. However, cassava is severely affected by bacteria, fungi, viruses, mites, and mealybugs, causing yield losses ranging from 20% to 90%. This study was conducted at the Food Crop Research Station (FCRS) of the National Center for Agronomic Research (NCAR) in Bouake in central Côte d’Ivoire. The plant material consisted of thirteen varieties of cassava of the <i>Manihot esculenta</i> species, from the national cassava collection. It aimed to assess the performance of thirteen promising cassava varieties, originating from the national cassava collection, against these diseases and pests under natural infestation conditions. The results revealed that the Yacé variety showed the highest sensitivity to viruses, with an incidence (I) of 96.25% and a severity index (IGS) of 2.8. In contrast, the Yavo variety was the least sensitive, with an incidence of 11.50% and a severity index of 1.3. All varieties studied demonstrated high sensitivity to bacterial blight and mite attacks, with high incidence rates observed in Bocou1 (71.25%) and Bocou3 (68.75%). However, mealybug infestation was relatively low, ranging from 8.75% (Yavo) to 33.75% (Bocou2). Except for mosaic disease, the severity indices for diseases and pests were similar across all varieties.