Agricultural Strategies Research Articles

Global impact of seawater intrusion on coastal agriculture

Abstract Coastal agriculture faces escalating threats from seawater intrusion (SWI), jeopardizing global food security through freshwater scarcity, soil salinization and crop damage. However, research on SWI often fails to consider its impact on coastal agriculture. Linking georeferenced SWI data with cropland presence, this review examines SWI's global distribution and primary drivers. Major attested hotspots include the Mediterranean, South and South-East Asia, and the Bohai Sea region in China. Approximately 87 Mha of cropland globally are vulnerable due to low elevation and coastal proximity, including regions where little to no literature has documented SWI. Main drivers include sea-level rise, drought, groundwater depletion, river modifications, tidal flooding and subsidence. Projections of sea-level rise indicate cropland of North America, the Indian Subcontinent, and South-East Asia as high-risk for SWI. Additionally, regions like South-East Asia and the Indian Subcontinent are expected to experience significant demographic growth in coastal areas. Understanding present and future SWI dynamics is crucial for designing effective mitigation and adaptation strategies in coastal agriculture to support food supply.

Addressing Climate Change Challenges in Thailand’s Agricultural Economy

Climate change is rapidly intensifying, leading to a surge in climate-related disasters worldwide. Thailand's agricultural sector, a cornerstone of its economy and food security, is particularly vulnerable to the adverse effects of these climatic shifts. This study delves into the multifaceted challenges faced by stakeholders in Thailand's agricultural sector, shedding light on the impact of climate change on their livelihoods and the broader food security landscape. Through in-depth interviews and thematic analysis, this research explores the experiences and perspectives of key stakeholders within the agricultural community. Participants consistently highlighted the disruptive influence of erratic rainfall patterns and rising temperatures on crop productivity and economic stability. These climate-induced challenges have exacerbated food shortages, compromised livelihoods, and heightened food insecurity. The study also underscores the critical importance of food security and the imperative to adopt resilient agricultural practices. To mitigate the impacts of climate change, it is essential to integrate climate change education into the Thai education system. This will equip future generations of farmers with the knowledge and skills necessary to adapt to changing climatic conditions and implement sustainable agricultural strategies.

IA-YOLO: A Vatica Segmentation Model Based on an Inverted Attention Block for Drone Cameras

The growing use of drones in precision agriculture highlights the needs for enhanced operational efficiency, especially in the scope of detection tasks, even in segmentation. Although the ability of computer vision based on deep learning has made remarkable progress in the past ten years, the segmentation of images captured by Unmanned Aerial Vehicle (UAV) cameras, an exact detection task, still faces a conflict between high precision and low inference latency. Due to such a dilemma, we propose IA-YOLO (Inverted Attention You Only Look Once), an efficient model based on IA-Block (Inverted Attention Block) with the aim of providing constructive strategies for real-time detection tasks using UAV cameras. The working details of this paper are outlined as follows: (1) We construct a component named IA-Block, which is integrated into the YOLOv8-seg structure as IA-YOLO. It specializes in pixel-level classification of UAV camera images, facilitating the creation of exact maps to guide agricultural strategies. (2) In experiments on the Vatica dataset, compared with any other lightweight segmentation model, IA-YOLO achieves at least a 3.3% increase in mAP (mean Average Precision). Further validation on diverse species datasets confirms its robust generalization. (3) Without overloading the complex attention mechanism and deeper and deeper network, a stem that incorporates efficient feature extraction components, IA-Block, still possess credible modeling capabilities.

Integrating Management and Marketing Strategies in Organic Farming: A Topic Modeling Analysis of Sustainable Development and Entrepreneurship

Integrating management and marketing with organic farming practices is crucial for the sustainable development of this growing sector. As organic farming products are popular among health-conscious consumers, agricultural entrepreneurs increasingly use innovative business strategies to meet the rising demand. The successful alignment of business and economic principles with organic agriculture enhances value creation and promotes long- term sustainability. Entrepreneurs must focus on strategic networking across production, processing, and marketing to capitalize on these opportunities fully. Despite its growth, the organic agriculture sector still faces challenges that require comprehensive research to develop effective strategies for advancing the industry. This study addresses the intersection of organic agriculture, entrepreneurship, and business strategy by utilizing topic modeling techniques to analyze bibliographic data from 4327 articles published between 1946 and 2023 in the Scopus database. Using Latent Dirichlet Allocation (LDA) topic modeling, five key themes were identified: (1) Soil for organic agriculture, (2) Environment and organic agriculture, (3) Agriculture business, (4) Organic production, and (5) The use of organic substances. With a connection value of 0.419, the topic modeling effectively grouped relevant themes, offering valuable insights into the role of management and marketing in organic farming. These findings provide a solid foundation for future research and innovation, enabling entrepreneurs, researchers, and farmers to align their practices with evolving market trends better, thus fostering the continued growth of organic agriculture.

Soil health improvements under cover crops are associated with enhanced soil content of cytokinins.

Cytokinins (CKs) are phytohormones produced by plants and other soil life. including bacteria, fungi, insects, and earthworms. These organisms can release CKs to the soil, which may have positive implications for soil health and plant growth. However, no studies have examined phytohormones as soil health indicators. In custom-designed rhizo-pots that separated rhizosphere and bulk soils, the cover crops tillage radish and cereal rye were used to manipulate soil health parameters: soil pH, soil organic matter, soil active carbon, soil microbial community diversity, and extracellular enzyme activities involved in C, N and P cycling. Data were compared to impacts of cover crops on CKs that were purified from the complex soil and measured with HPLC-HRMS/MS. From soil we detected free base-CKs (trans-zeatin (tZ), isopentenyladenine (iP)), riboside-CKs (RB-CKs), cis-zeatin riboside (cZR), isopentenyladenosine (iPR) and four methylthiolated CKs: 2-methylthio-zeatin (2MeSZ), 2-methylthio-zeatin ribosides (2MeSZR), 2-methylthio-isopentenyladenine (2MeSiP), and 2-methylthio-isopentenyladenine riboside (2MeSiPR). These CK levels were significantly enhanced in cover cropped soil compared to uncultivated soil, and reflect a positive relationship between soil CK profiles and other soil health parameters - notably, between total CK and active C levels and soil microbial community diversity. This is the first detailed soil CK analysis and assessment of its potential use as a novel, reliable, short-term soil health parameter. The increased CK concentrations in cover cropped soils likely reflects the activity levels of soil life (plants, microbes, animals) and provides a rationale to use CKs as tools to evaluate soil health as influenced by agricultural management strategies.

Insights into lncRNA-mediated regulatory networks in Hevea brasiliensis under anthracnose stress

In recent years, long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) have emerged as critical regulators in plant biology, governing complex gene regulatory networks. In the context of disease resistance in Hevea brasiliensis, the rubber tree, significant progress has been made in understanding its response to anthracnose disease, a serious threat posed by fungal pathogens impacting global rubber tree cultivation and latex quality. While advances have been achieved in unraveling the genetic and molecular foundations underlying anthracnose resistance, gaps persist in comprehending the regulatory roles of lncRNAs and miRNAs under such stress conditions. The specific contributions of these non-coding RNAs in orchestrating molecular responses against anthracnose in H. brasiliensis remain unclear, necessitating further exploration to uncover strategies that increase disease resistance. Here, we integrate lncRNA sequencing, miRNA sequencing, and degradome sequencing to decipher the regulatory landscape of lncRNAs and miRNAs in H. brasiliensis under anthracnose stress. We investigated the genomic and regulatory profiles of differentially expressed lncRNAs (DE-lncRNAs) and constructed a competitive endogenous RNA (ceRNA) regulatory network in response to pathogenic infection. Additionally, we elucidated the functional roles of HblncRNA29219 and its antisense hbr-miR482a, as well as the miR390-TAS3-ARF pathway, in enhancing anthracnose resistance. These findings provide valuable insights into plant-microbe interactions and hold promising implications for advancing agricultural crop protection strategies. This comprehensive analysis sheds light on non-coding RNA-mediated regulatory mechanisms in H. brasiliensis under pathogen stress, establishing a foundation for innovative approaches aimed at enhancing crop resilience and sustainability in agriculture.

Integrating Greenhouses into Buildings: A Renewed Paradigm for Circular Architecture and Urban Regeneration

In the post-COVID-19 era, there has been an increasing interest in re-evaluating citizens’ living conditions within dense and grey urban areas. The provision of green spaces has always been identified as an important aspect of alleviating contemporary everyday life stress and preventing or limiting mental health-related issues. It is also an important strategy to mitigate urban heat islands and foster adaptation strategies to climate change. Among the numerous experiments of ‘green action’ available to urban planners, urban farming strategies have been widely used in Europe to provide green spaces and ecosystem services, exploring the topics related to self-production of food, biodiversity, and zero-km cultivation. Therefore, finding new spaces for agriculture in urban environments has driven scientists, researchers, and entrepreneurs to develop new soilless technologies (such as hydroponics, aquaponics, and aeroponics) to maximize yields in urban areas, creating new agricultural and architectural models such as the vertical farms (VF) and the building-integrated greenhouses (BIGH). In this regard, the objective of this paper is to recontextualize the integrated greenhouse element for high-tech food production as new iconic architectural models derived from the experience of the Victorian Winter Gardens and the first tropical greenhouses. Revisiting these perspectives, this paper offers opportunities to redefine the greenhouse as a multifunctional asset that aligns with both environmental goals and architectural standards.

Effect of mulching and organic manure on maize yield, water, and nitrogen use efficiency in the Loess Plateau of China.

Current agricultural practices prioritize intensive food production, often at the expense of environmental sustainability. This approach results in greenhouse gas emissions and groundwater pollution due to over-fertilization. In contrast, organic agriculture promotes a more efficient use of non-renewable energy, improves soil quality, and reduces ecological damage. However, the effects of mulching and organic manure on maize yield, water use efficiency (WUE), and nitrogen use efficiency (NUE) in China's Loess Plateau have not been sufficiently researched. In 2017 and 2018, an experiment utilizing a randomized complete block design with two factors (two mulching levels × three organic nitrogen application rates) was conducted. The water content of the upper soil layer was found to be 12.6% to 19.4% higher than that of the subsoil layer. Across all soil depths and years, the soil nitrate-N content in mulched treatments was 10% to 31.8% greater than in non-mulched treatments with varying organic nitrogen rates. Additionally, mulching resulted in an increase in grain yield of 9.4% in 2017 and 8.9% in 2018 compared to non-mulched treatments. A significant interaction was observed between mulching and organic nitrogen application rate concerning WUE, alongside a negative correlation between WUE and NUE. These findings suggest that the application of 270 kg N ha-1 of sheep manure in conjunction with mulching is a highly recommended practice for the Loess Plateau, thereby supporting sustainable agricultural strategies.

Daily Light Integral Maps for Agriculture Lighting Design in Spain

The Daily Light Integral (DLI) is a key metric to optimise plant cultivation, influence photosynthesis, morphology, yield, and nutritional quality. Our study focuses on (i) the creation of the spatiotemporal DLI map for a representative Mediterranean country, Spain, (ii) the presentation of the improved semi-automatic DLI mapping workflow, (iii) the challenge of the comparability of different DLI value scalings in global (continent) and local context (country). DLI maps provide essential insights into the spatial and temporal distribution of natural and artificial light, critical for optimizing agricultural practices and enhancing crop yields. Spain's diverse topography and climate create significant regional and seasonal variations in DLI values. Using data from SunTracker Technologies and global weather stations, we developed detailed DLI maps at 30-meter resolution. These maps reveal high DLI values in coastal and southern regions, especially in summer, and lower values in northern and interior regions during winter. Our findings emphasize the importance of tailored lighting strategies in agriculture, suggesting higher scaling (from 5 to 2 mol·m−2·d−1) resolution for European contexts. This research underpins the development of smart agricultural systems that both quantitatively and qualitatively regulate lighting conditions (supplementary light and shading management) to maximize crop productivity and sustainability. Integrating DLI maps with IoT and AI technologies offers predictive insights for precision agriculture, highlighting the need for advanced training to leverage these tools effectively.

Novel Synthesis, and Application of Carboxymethylated Cassia fistula‐Based Hydrogel for Extended‐Release of Dinotefuran

AbstractThe agricultural industry prioritizes minimizing crop yield losses caused by pests, making it essential to develop effective, safe and sustainable pesticide formulations. Hydrogels are promising carriers for pesticide delivery, due to their high surface area, large pore volume, and pore size. In this study, we synthesized Cassia fistula (CA‐g‐AA) and its derivative carboxymethylated Cassia fistula‐grafted polysodium acrylate hydrogel (CMCA‐g‐AA) using free radical polymerization, with N, N'‐methylene bisacrylamide (MBA) as a crosslinker, for the ex‐situ encapsulation of dinotefuran. Characterization was performed using FTIR, 13C CPMAS‐NMR, SEM, TGA, rheology, and XRD. The maximum swelling capacity of hydrogels was investigated in distilled water. CA‐g‐AA and CMCA‐g‐AA hydrogels exhibited a dinotefuran loading percentage of 37 and 39% and released dinotefuran for 26 and 29 h, respectively. The dinotefuran release kinetics was analyzed by using the Korsmeyer‐Peppas and Higuchi models. Under drought like conditions, CMCA‐g‐AA‐treated soil sustained plant growth for 7 days, compared to CA‐g‐AA (5 days) and untreated soil (3 days). The novel hydrogel CMCA‐g‐AA enhanced soil water absorption and retention along with highlighting its potential for extended pesticide release. Thus, the developed CMCA‐g‐AA hydrogel is an efficient strategy for sustainable agriculture.

GIS-based assessment of soil erosion impact and mitigation strategies for sustainable agriculture in Ghana's most vulnerable region

GIS-based assessment of soil erosion impact and mitigation strategies for sustainable agriculture in Ghana's most vulnerable region

Trends of temperature and precipitation extreme indices in north Maharashtra

Climate change has intensified extreme weather events, posing major challenges to agriculture-dependent regions like Northern Maharashtra. This study analyzed temperature and precipitation extremes across five districts—Nashik, Dhule, Nandurbar, Jalgaon and Ahmednagar using data from 1982 to 2022 with the help of RClimDex model. Key temperature indices, including tropical nights (TR25), warm days (TX90p), and frost days (FD13) showed an increase in warm events and a decline in cool nights and frost days. Reduced diurnal temperature range (DTR) indicated less nighttime cooling, consistent with global warming. For precipitation, extreme rainfall events are rising as indicated by the maximum 1-day precipitation (Rx1day), while consecutive dry days (CDD) are shortening. These shifts heighten risks such as crop heat stress, altered growing seasons, soil erosion, and water management challenges. The study underscores the urgent need for adaptive agricultural strategies, improved irrigation, and early warning systems to mitigate the impacts of climate change and enhance resilience in Northern Maharashtra.

CMIP6 multi-model ensemble projection of reference evapotranspiration using machine learning algorithms

Changes in reference crop evapotranspiration (ETo) due to climate change (CC) can severely impact food and water security, emphasizing the need for integrating ETo projections into agricultural water management strategies. In this study, ETo changes were projected for two future time slices with respect to the baseline using several machine learning techniques, incorporating minimum and maximum temperature, diurnal temperature range, and extraterrestrial radiation across Iran. Additionally, an ensemble of 10 CMIP6 Global Climate Models, downscaled by the NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP-CMIP6), was employed. The X-means clustering algorithm was also exploited to classify ETo based on various characteristics, including minimum, maximum, average, skewness, and standard deviation, as well as ETo ranges of 0–5, 5–10, and greater than 10 mm d⁻¹. This clustering approach divided the study area into five distinct clusters. Apart from cluster I, where the Support Vector Machine outperformed, the Random Forest technique provided more accurate ETo predictions. The findings project an average ETo increase of 4.8 % and 5.3 % during 2030–2049, and 8.0 % and 13.3 % for 2080–2099 under SSP245 and SSP585, respectively. Geographically, the highest ETo increases are anticipated primarily in the northern and western parts of the country, predominantly within clusters I and II. Notably, the ETo rise will exceed 40 % relative to the baseline during the late century under the SSP585. Furthermore, the most significant ETo increment is expected during winter. Future projections also indicate that cluster V, which already experiences significant daily ETo peaks, will face even more ETo extremes. Given the critical importance of these regions for sustaining food and water security and preserving natural resources, the substantial rise in ETo under future CC poses a significant threat to natural sustainability in Iran. This highlights the critical necessity for adaptive strategies in agricultural water management to mitigate the adverse CC effects. In this context, the current findings can assist decision-makers in identifying hotspots and quantifying CC impacts, thereby enabling the design of crucial adaptations.

Assessments of Challenges and Opportunities for Practicing Irrigated Rice Production in Ethiopia

Rice production in Ethiopia, though not traditionally a staple, has become a key focus in the country’s efforts to enhance food security and reduce dependency on imports. Despite favorable agroecological conditions for rice farming, productivity remains low due to several challenges, including inadequate access to improved seeds, irrigation systems, and modern mechanization. This study evaluates the challenges and opportunities for practicing irrigated rice production in Ethiopia, analyzing both challenges and opportunities through a mixed-methods approach. Primary data was collected via field surveys, key informant interviews, and focus group discussions with farmers, agricultural experts, and policymakers across diverse regions. Key challenges include poor water management, limited adoption of modern technologies, high input costs, weak market access, climate variability, and infrastructure limitations. However, Ethiopia's diverse agroecological zones and government support provide opportunities for sustainable rice cultivation, particularly through improved irrigation, adoption of modern technologies, and enhanced market linkages. The study concludes that a comprehensive, multi-faceted approach involving government, NGOs, and farmers is essential to unlocking the potential of irrigated rice production in Ethiopia. Recommendations include improving water management, promoting public-private partnerships, expanding access to credit, and implementing climate-smart agricultural strategies to boost rice production and enhance food security.

Co-production of sustainability indicators in a vulnerable South American agricultural frontier

Deforestation linked to agricultural activities is a major sustainability concern. Planning towards sustainable agricultural landscapes in the (sub-)tropics requires indicators that capture the many aspects of social-ecological cost and benefit of agriculture. Agricultural production strategies are developed using the best available data and knowledge such as high-yield locations, distance to storage facilities, or certification bonuses. However, there is often a divide between sustainable production data generated by the scientific community and current data that are of interest to actors, such as those in the agribusiness sector. Here, we describe how the harmonization of crop production, conservation, and social data used by scientists and agribusiness is possible using a participatory exercise based on knowledge co-production (i.e., generation of knowledge in a collaborative way) of socio-economic and environmental indicators (such as agricultural production, logistics, or the location of indigenous communities). This was made available through an online decision support platform that facilitated the generation of sustainable entrepreneurial strategies. We tested this exercise for the social-environmentally vulnerable Argentine Chaco dry forest, subject to some of the highest rates of deforestation globally, mainly due to soybean production. The cooperation between participants of this exercise built a knowledge exchange network that was key for informing decision-makers and highlighted information gaps including agricultural productivity, accessibility of regions, and the vulnerability of rural communities. Our exercise may be applicable to other agricultural commodity frontiers and showcases the value of including actors’ priorities in the design of indicators to ensure their policy impact and to achieve food systems’ sustainability.

Mechanism of Bacillus cooperating with silicon to re-balance chlorophyll metabolism and restore carbon metabolism of Glycyrrhiza uralensis Fisch. Seedlings exposed to salt-drought stress

Salt-drought is a major environmental event affecting crop productivity and quality by causing chlorophyll (Chl) and carbon balance disorder. There has been growing interest in the application of endophyte and silicon (Si), as inoculants for saline and drought land restoration. This study investigates the impact of Bacillus (Bs), Si, and Bs + Si on the disorder of Chl metabolism and carbon balance of G. uralensis seedlings under salt-drought stress (SD). Results showed that both Bs and Si treatments enhanced Chl and carbon metabolism, with the combined Bs and Si treatment showing a synergistic effect. Specifically, Bs + Si enhanced the mutual conversion of Chl a and Chl b, restored the equilibrium in Chl a and Chl b content, and increased RuBisco activity by 31.07%, thereby promoting carbon fixation. Subsequently, Bs + Si re-balanced the carbohydrate content, by increasing the sucrose synthase (SS), and β-amylase (BMY) activities by 49.57%, and 83.59% respectively, and decreasing sucrose phosphate synthase (SPS), and granule-bound starch synthase (GBSS) activities by 38.93%, 40.93% respectively etc involved in the metabolism of sucrose and starch. Furthermore, Bs + Si facilitated the restoration of the typical progression of the tricarboxylic acid (TCA) cycle and glycolysis pathway (EMP). These findings highlight the synergistic role of Bs and Si in enhancing the salt and drought resilience of G. uralensis seedlings, offering promising strategies for sustainable agriculture, improving crop resilience to climate change, and achieving the “dual carbon” goals of carbon peaking and carbon neutrality.

Computational approach to identify novel genomic features conferring high fitness in Bacillus atrophaeus CNY01 and Bacillus velezensis AK-0 associated with plant growth promotion (PGP) in apple

A comparative genomic analysis approach provides valuable information about genetic variations and evolutionary relationships among microorganisms, aiding not only in the identification of functional genes responsible for traits such as pathogenicity, antibiotic resistance, and metabolic capabilities but also in enhancing our understanding of microbial genomic diversity and their ecological roles, such as supporting plant growth promotion, thereby enabling the development of sustainable strategies for agriculture. We used two strains from different Bacillus species, Bacillus velezensis AK-0 and Bacillus atrophaeus CNY01, which have previously been reported to have PGP activity in apple, and performed comparative genomic analysis to understand their evolutionary process and obtain a mechanistic understanding of their plant growth-promoting activity. We identified genomic features such as mobile genetic elements (MGEs) that encode key proteins involved in the survival, adaptation and growth of these bacterial strains. The presence of genomic islands and intact prophage DNA in Bacillus atrophaeus CNY01 and Bacillus velezensis AK-0 suggests that horizontal gene transfer has contributed to their diversification and acquisition of adaptive traits, enhancing their evolutionary advantage. We also identified novel DNA motifs that are associated with key physiological processes and metabolic pathways.

Progress and Innovations in Hydrogels for Sustainable Agriculture

The growing global demands for food security, efficient water use, and environmentally resilient agricultural strategies call for a sustainable agricultural revolution. Water scarcity, the excessive use of pesticides, and soil degradation are viewed as threats to food security. Hydrogels, three-dimensional hydrophilic polymer networks, appear to be revolutionary solutions for the future. Hydrogels have emerged as a promising solution for enhancing crop resilience, enhancing crop yields, and agribusiness productivity. The development and prospects of hydrogels bring about a revolution in sustainable agriculture by focusing on their unique properties, including excellent water absorption capacity, biodegradability, and controlled nutrient/agrochemical delivery. Hydrogels have the potential to transform traditional farming practices into novel crop varieties with improved traits like disease resistance, insect resistance, and drought resistance. Hydrogels enhance soil moisture retention, thereby facilitating seed germination and establishment. Thus, it has been demonstrated that hydrogel application has a significant impact on soil quality and resilience under challenging conditions. With this in mind, this review emphasizes that hydrogels are the way forward for sustainable agriculture, taking into consideration the economic benefits like reduced irrigation and increased crop yields while highlighting the need for regulatory considerations in terms of their safety, biodegradability, environmental impact, and long-term soil effects.

Insect-derived bacteria as biocontrol tool and a potent suppressor of plant pathogenic fungi in tomato cultivation

Sustainable agriculture is increasingly emphasized, focusing on microorganisms' role in maintaining soil fertility and inhibiting plant pathogens. Seeking novel sources of plant-beneficial bacteria, our study explores insects due to their established associations with plants and bacteria. The insect gut, hosting various bacteria, may hold microbes protecting against fungal infections, particularly plant pathogens. Traditional sources of plant growth-promoting bacteria are the rhizosphere and host plant tissues; however, insects serve as diverse bacterial reservoirs in the environment. This study aimed to identify insect-gut-derived bacteria with antifungal properties and cellulase enzyme production, predicting high plant tissue colonization abilities. Cellulase, crucial for breaking down cellulose, is essential for both industry and the environment. We sought to assess the potential of these bacteria as biocontrol agents against plant pathogenic fungi, with a focus on tomato plants. Bacterial isolates from insect bodies, including Lactococcus lactis, Pantoea ananatis, and Serratia liquefaciens, exhibited robust antifungal properties and cellulase activity. In vitro tests and glasshouse tests, confirmed their ability to inhibit the growth of plant-pathogenic fungi, indicating potential for biological control. Moreover, selected strains demonstrated high cellulase enzyme activity, vital for nutrient competition and rapid colonization of plant surfaces. The study introduces insect-gut-derived bacteria as promising biocontrol agents against plant pathogenic fungi. The identified strains, capable of inhibiting fungal growth and producing cellulase, offer sustainable alternatives to synthetic fungicides for protecting tomato plants. The findings advance agricultural practices by harnessing insect-associated bacteria, contributing to eco-friendly and efficient pest management strategies in modern agriculture.

Evolution of copper resistance in Xanthomonas euvesicatoria pv. perforans population.

The widespread use of antimicrobials that target bacterial pathogens has driven evolution of resistance, compromising the efficacy of these bactericides. Understanding the emergence and spread of resistance genes via mobile genetic elements is crucial for combating antimicrobial resistance. Copper resistance (CuR) in Xanthomonas euvesicatoria pv. perforans has severely affected the efficacy of copper-based bactericides for controlling bacterial leaf spot disease of tomato and pepper. Here, we investigated the evolutionary pathways of CuR acquisition and dissemination in X. euvesicatoria pv. perforans using an extensive collection of strains. We determined that chromosomally encoded CuR predominates over plasmid-borne CuR in multiple distinct phylogenetic groups of X. euvesicatoria pv. perforans. Our analysis revealed a single site of chromosomal integration by a CuR genomic island, although the genomic island showed sequence variation among phylogenetic groups. While chromosomal CuR was more prevalent, strains with plasmid-borne resistance conferred greater copper tolerance. Additionally, we identified strains carrying two copies of CuR genes, on plasmid and chromosome, that exhibited increased copper tolerance. Strains of X. euvesicatoria pv. perforans from the USA shared identical CuR gene sequences whether on plasmids or chromosome while different alleles were found in strains from other countries. In contrast to X. euvesicatoria pv. perforans, plasmid-borne CuR predominated in closely related pathovar, X. euvesicatoria pv. euvesicatoria. Overall, these findings contribute to a better understanding of the evolution and persistence of CuR in X. euvesicatoria pv. perforans and its closest relatives.IMPORTANCEThe emergence of antimicrobial resistance is a significant threat to agricultural production as it reduces the efficacy of various antimicrobials including copper-based bactericides that are widely used to control plant diseases. The challenge of increasing antimicrobial resistance entering a production system necessitates a deeper understanding of the dynamics and mechanisms by which pathogens acquire resistance. As a result of this research, we have identified different mechanisms of copper resistance acquisition as well as levels of copper resistance in a devastating plant pathogen, X. euvesicatoria pv. perforans. The evolution and dissemination of copper resistance in strains through plasmid or chromosomally integrated genomic island or both presents barriers to current management approaches, where growers rely heavily on copper-based bactericides to manage disease outbreaks. This knowledge is crucial when considering the continued use of existing antimicrobials or adopting alternative antimicrobials in efforts to implement enhanced antimicrobial stewardship strategies in agriculture.