Rice Blast Research Articles

Salt stress-induced polyamine biosynthesis contributes to blast resistance in rice

Rice blast, caused by the fungal pathogen Magnaporthe oryzae, is a destructive disease that affects rice (Oryzae sativa L.) on a global scale. Polyamines (PAs) play diverse roles in plant growth and development and responses to biotic and abiotic stimuli. Putrescine (PUT), spermidine (SPD), and spermine (SPM) are the primary forms of polyamines (PAs). In this study, we observed that the accumulation of apoplastic PAs significantly increased in rice plants after treatment with salt or M. oryzae. The salt-treated plants exhibited enhanced resistance to rice blast disease. RNA sequencing data indicate that S-adenosylmethionine decarboxylase (SAMDC), a key enzyme involved in the synthesis of polyamines, plays a significant role in enhancing plant resistance. Overexpression of rice SAMDC (OsSAMDC) led to a significant decrease of pathogen infection in the transgenic rice plants. Additionally, OsSAMDC overexpression plants accumulated polyamines in the cytosol and apoplast, particularly SPD and SPM. Conversely, the disease resistance and accumulation of PAs were reduced in OsSAMDC-silenced plants. Exogenous application of PAs inhibited the mycelium growth, spore germination, germ tube elongation, and appressorium formation in M. oryzae. These results demonstrated that OsSAMDC-mediated polyamine biosynthesis, especially SPD and SPM, plays an essential role in rice plants to resist biotic and abiotic stresses.

Combinatorial Targeting of Common Docking and ATP Binding Sites on Mps1 MAPK for Management of Pathogenic Fungi.

Resistance in pathogenic fungi necessitates the development of fungicides with new mechanisms of action. The Mps1 MAPK of Magnaporthe oryzae, the pathogen of rice blast disease, has been shown to be a molecular target for fungicide research. Here, we present compound TAK-733 that interacts with the common docking (CD) site of Mps1 and can be used in combination with ATP-competitive inhibitors. We initially identified compounds PLX-4720 and TAK-733 that interact with Mps1. Subsequent assays show that PLX-4720 is an ATP-competitive inhibitor, whereas TAK-733 binds to the CD site of Mps1─an interaction site for its MAPKK─but not to the ATP-binding pocket as it does in the kinase MEK1. In vivo assays demonstrated that TAK-733 exhibits combinational effects with ATP-competitive inhibitors PLX-4720 and A378-0. Collectively, we present TAK-733 as having a new mechanism of action suitable for combinational application with ATP-competitive inhibitors in the management of pathogenic fungi.

A novel antifungal peptide, SP1.2, from Rhodopseudomonas palustris against the rice blast pathogen.

Rice blast has a significant detrimental impact on rice yields, so developing efficient biological control technologies is an effective means for rice blast prevention and control. The GroEL protein has proven to be effective at preventing and managing the pathogenicity of rice blast. Here, we analyzed the amino acid sequence of the GroEL protein and synthesized the '60 kDa chaperonin signature' (350-373 amino acids) peptide SP1.2, which has potent antifungal activity. Notably, the SP1.2 peptide exhibited potent fungicidal activity against Magnaporthe oryzae, effectively inhibiting appressorium germination. Electron microscopy revealed that SP1.2 disrupted the fungal plasma membrane and bound to multiple bioactive phosphoinositides in vitro, triggering the production of reactive oxygen species. Furthermore, it also caused an increase in the acetylation of M. oryzae and induced autophagy in cells. The spray application of SP1.2 significantly reduced the number of disease spots caused by the fungal pathogen M. oryzae in rice, enhancing the defense response of rice plants. Field trials showed that the control effect was 64.59% after spraying SP1.2. Our study illustrates the antifungal activity of the structurally unique SP1.2 peptide against plant fungal pathogens and paves the way for the future development of this class of peptides as antifungal agents. © 2024 Society of Chemical Industry.

Wheat resistance against infection by Pyricularia oryzae is potentiated by β-aminobutyric acid and not affected by γ-aminobutyric acid

Wheat resistance against infection by Pyricularia oryzae is potentiated by β-aminobutyric acid and not affected by γ-aminobutyric acid

Bio-Solarization as an Integrated Approach in the Management of Rice Blast

Bio-Solarization as an Integrated Approach in the Management of Rice Blast

Bacillus velezensis SS-20 as a potential and efficient multifunctional agent in biocontrol, saline-alkaline tolerance, and plant-growth promotion

The versatile strain Bacillus velezensis SS-20 was studied to determine its agricultural benefits, including its ability to antagonize fungi, promote plant growth, and tolerate saline-alkaline conditions. Firstly, strain SS-20 was found to be an antagonist of plant pathogenic fungi such as Magnaporthe oryzae, Rhizoctonia solani, and Fusarium oxysporum, with control effects up to 82.07 %, 46.57 %, and 23.09 %, respectively. The hyphae of pathogenic fungi treated with SS-20 and its fermentation product were abnormal, swollen, deformed, and distorted. Meanwhile, strain SS-20 dissolved inorganic phosphorus (phosphate solubilization efficiency, 45.95 %), and produced siderophore (siderophore units, 54.18 ± 4.19 %), and poly-γ-glutamic acid (γ-PGA) (13.35 ± 2.61 g/L). Strain SS-20 significantly increased plant height, aboveground fresh weight, and root dehydrogenase activity compared to the control treatment under non-saline conditions (p < 0.05). In addition, strain SS-20 showed significant saline-alkaline tolerance, surviving in 10 % NaCl and pH 9.5, and enhanced plant growth under simulated saline-alkali conditions. Whole-genome sequencing analysis revealed that the chromosome of B. velezensis SS-20 consists of 3,929,792-bp with 46.5 % guanine-cytosine content and 4015 coding sequences. The antiSMASH analysis identified 12 gene clusters within strain SS-20 that encode antimicrobial compounds such as surfactin, fengycin, butirosin A/butirosin B, macrolactin H, bacillibactin, difficidin, and bacilysin, thereby corroborating the strain's biocontrol capabilities. Genes related to plant growth promotion, including siderophores, γ-PGA, indole acetic acid production, phosphate solubilization, glycine-betaine production, and Na+/H+ antiporters, were also annotated. In conclusion, B. velezensis SS-20 represents a promising biotic resource for enhancing plant growth and protecting against environmental stresses.

A Review on: Rice Disease Prediction

Abstract: Rice disease prediction is an emerging technology that leverages machine learning and image processing techniques to forecast disease outbreaks in rice crops. Early and accurate prediction of diseases like rice blast, bacterial leaf blight, and sheath blight is critical for maintaining crop health, optimizing resource use, and enhancing yield quality. This paper explores the use of high-resolution imaging and data-driven models to identify early signs of disease in rice plants. By analyzing data from multiple sources, including aerial imagery and environmental sensors, these predictive systems enable targeted and timely interventions, reducing the spread of infections and minimizing the use of pesticides. The application of predictive technologies not only aids in sustainable farming practices by lowering environmental impact but also aligns with the goals of precision agriculture to support food security and increase productivity. As agricultural practices continue to evolve, predictive models for rice disease management offer a promising solution for addressing the challenges posed by crop diseases in a changing climate

Marker-assisted introgression of a major broad spectrum blast resistance gene Pi54 into a popular rice variety Warangal Samba (WGL-14)

Warangal Samba (WGL-14) is a widely known medium slender-grain rice variety that matures within 135-140 days. This variety has been extensively cultivated in Telangana, India, due to its high yield potential of 7-7.5 t/ha and its favourable cooking qualities. However, it is highly susceptible to rice blast disease caused by the fungus Magnaporthe oryzae. This research sought to improve the blast resistance of WGL-14 by incorporating the Pi54 gene, a widely recognized blast resistance gene, using (MABB) along with selection based on phenotypic traits. NLR-145, a high-yielding rice variety containing the Pi54 gene, was used as the donor parent and crossed with WGL-14 to produce F1 plants. The Pi54MAS marker, which is specific to the Pi54 gene, was employed for foreground selection in F1, BC1F1, BC2F1 and BC3F1 generations, while background selection involved 80 parentals polymorphic SSR markers and phenotypic traits observed in each backcross generation. At BC3F5 generation, 28 lines were selected for their strong resistance to blast, high yields, plant type, grain characteristics and other traits comparable to the recurrent parent. These 28 lines were tested in yield trials during the wet seasons from 2018 to 2020 at the Regional Agricultural Research Station (RARS) in Warangal. At Advanced Varietal Trials (AVT), 3 lines namely WGL-1467, WGL-1472 and WGL-1473 were identified as having strong blast resistance and superior agronomic traits, closely resembling the original WGL-14.

The miR172a-SNB module orchestrates induced and adult resistance to multiple diseases via MYB30-mediated lignin accumulation in rice

Plants mount induced resistance and adult plant resistance against different pathogens during the whole growth period. Rice production faces threats from multiple major diseases, including rice blast, sheath blight, and bacterial leaf blight. Here we report that a microRNA module, miR172a-SNB-MYB30, regulates induced resistance and adult plant resistance to these three major diseases via lignification in rice. Mechanistically, pathogens induce expression of miR172a, which down-regulates transcription factor SNB to release its suppression on MYB30, leading to an increase in lignin biosynthesis and disease resistance during the whole growth period. Moreover, expression levels of miR172a and MYB30 are gradually increased and consistently correlated with lignin contents and disease resistance during rice development reaching a peak at full maturity stage, whereas SNB RNA levels are reversely correlated with lignin contents and disease resistance, indicating the involvement of the miR172a-SNB-MYB30 module in plant adult resistance. A high conservation exists in the functional domain of SNB protein and its binding sites in the MYB30 promoter among over 4000 rice accessions; moreover, abnormal expression of miR172a, SNB, or MYB30 compromises yield traits, suggesting an artificial selection of the miR172a-SNB-MYB30 module during rice domestication. Our results reveal a novel role for a conserved miRNA-regulated module that significantly contributes to induced and adult resistance against multiple pathogens via lignin accumulation, advancing our understanding in broad-spectrum resistance and adult resistance.

Genetic Variability Studies in a Biparental RIL Population for Blast Disease in Pearl Millet

Aim: This study aimed to estimate genetic parameters within a pearl millet population comprising 288 recombinant inbred lines (RILs) of the F7 generation along with two parental lines. The investigation focused on exploring the relationships among 13 quantitative traits and Blast disease score across two environments (ENV-I, ENV-II) as well as in pooled environments. Study Design: Alpha Lattice Design. Place and Duration of Study: Patancheru, Telangana and Vizianagaram, Andhra Pradesh during Kharif, 2023. Methodology: The RILs used for this current study developed through the single seed descent method at ICRISAT, Patancheru. The genotypes were assessed at ICRISAT, Patancheru, Hyderabad (ENV-I), and Agricultural Research Station, Vizianagaram, Andhra Pradesh (ENV-II). Combined Analysis of Variance, Heritability, Phenotypic Coefficient of Variation (PCV), Genotypic Coefficient of Variation (GCV), Genetic Advance as percent of Mean (GAM), and Correlation studies were performed in R 4.4.0. Results: The analysis identified significant variation in both the quantitative traits and Blast disease scores among the RILs, highlighting the potential for genetic improvement and selection. High heritability coupled with substantial genetic advance was observed for traits such as Plant Height, Number of Tillers, Panicle Length, Thousand Seed Weight, Seed Yield, Harvest Index, and Blast Score across ENV-I, ENV-II and Pooled environments. PCV and GCV were notably high for the Number of Tillers, Number of Productive Tillers, Thousand Seed Weight, Seed Yield, and Blast Score across ENV-I, ENV-II, and Pooled Environments. Seed Yield showed positive and significant correlations with the Number of Productive Tillers, Harvest Index, Plant Height, and Number of Tillers in all environments. Conversely, Blast Score exhibited negative associations with all studied traits across the environments. Conclusion: High heritability coupled with high GAM, along with medium to high PCV and GCV for traits such as plant height, panicle length, seed yield, harvest index, and thousand seed weight, indicates that these traits are predominantly genetically controlled and can be improved significantly through selection, making them valuable for breeding. Blast disease was negatively correlated with seed yield, thousand seed weight, days to maturity, harvest index, number of leaves, number of productive tillers, plant height, and number of tillers, suggesting that increased susceptibility to blast disease negatively affects key agronomic traits. This implies that genotypes with higher blast disease scores tend to exhibit lower productivity, delayed maturity, and reduced overall plant vigor, making resistance to blast disease a critical factor for achieving optimal crop performance and yield stability.

Discovery of polymethoxylated flavonoids in Artemisia argyi as main active components in inhibiting rice blast fungus

BackgroundRice blast is a devastating disease caused by Magnaporthe grisea, and it is not well controlled globally. As a Traditional Chinese Medicine, Artemisia argyi has been proven to have inhibitory effects on a variety of phytopathogenic fungi. Here, we used bioactivity-guided isolation method and transcriptomics to clarify the antifungal active compounds in A. argyi and their antifungal mechanisms.ResultsIn vitro studies showed that the absolute ethanol extract (AEE) of A. argyi had a strong inhibitory effect on the growth of M. grisea, with a low EC50 value of 1.156 mg/mL, and could cause the destruction of hyphae cell membrane and the leakage of cell contents. To identify the active constituents, we fractionated the AEE using macroporous adsorption resin and silica gel column chromatography. The active fraction (Fr.F-1) was fractionated and had even higher antifungal activity than AEE. The results showed that both AEE and Fr.F-1 could impact primary metabolic pathways and reactive oxygen species homeostasis of M. grisea, decrease the content of reducing sugars and downregulate the expression of genes related to starch and sucrose metabolism. Further fractionation of Fr.F-1 led to the identification of two polymethoxylated flavonoids (eupatilin and 3,5,3ʹ-trihydroxy-7,8,4ʹ-trimethoxyflavone), both of which had antifungal activity and they worked synergistically in Fr.F-1. Finally, we also investigated the effect of AEE, Fr.F-1 and eupatilin on rice blast control. The results showed that AEE, Fr.F-1 and eupatilin application strongly enhanced rice resistance to M. grisea.ConclusionIn brief, these findings indicate that Fr.F-1 subfraction from A. argyi and its main components polymethoxylated flavonoids confer inhibiting activities to M. grisea. This discovery can effectively alleviate the degradation pressure of A. argyi by-products, promote the healthy development of its industry, and provide new a strategy for the development of new botanical fungicides to control rice blast.Graphical

Forecasting rice blast disease severity using weather-dependent regression and time series models

Rice (Oryza sativa) is a staple food crucial for food security and economic stability, especially in developing countries. However, rice cultivation faces significant challenges, with rice blast disease, caused by the fungal pathogen Magnaporthe oryzae, being one of the most severe threats, potentially leading to yield losses of up to 30 %. This study aims to develop and apply regression models, including stepwise regression, multiple linear regression (MLR) and ARIMA (Autoregressive Integrated Moving Average), to predict the severity of rice blast disease based on weather parameters. Weekly data over 7 years (2017-2023) were collected from the Paddy Breeding Station at Tamil Nadu Agricultural University, Coimbatore, encompassing various weather factors such as temperature, relative humidity, rainfall and solar radiation. Data pre-processing included handling missing values, detecting outliers and creating time-lagged variables. The study revealed distinct seasonal patterns in rice blast incidence, with peak occurrences observed from mid-November to late January. Among the regression models, the ARIMA model incorporating weather variables as external regressors demonstrated superior performance with an R-squared value of 0.92, compared to 0.55 for stepwise regression and 0.57 for MLR. Accurate predictions of rice blast outbreaks could enable farmers and agricultural managers to implement timely and targeted disease management strategies, reducing dependence on broad-spectrum fungicides and minimizing crop losses. This study contributes to data-driven agriculture and disease management, potentially leading to more effective, economically viable and environmentally sustainable rice cultivation practices.

A C2H2-type zinc finger protein TaZFP8-5B negatively regulates disease resistance

BackgroundZinc finger proteins (ZFPs) are important regulators in abiotic and biotic stress tolerance in plants. However, the role of the ZFPs in wheat responding to pathogen infection is poorly understood.ResultsIn this study, we found TaZFP8-5B was down-regulated by Puccinia striiformis f. sp. tritici (Pst) infection. TaZFP8-5B possesses a single C2H2-type zinc finger domain with a plant-specific QALGGH motif, and an EAR motif (LxLxL) at the C-terminus. The EAR motif represses the trans-activation ability of TaZFP8-5B. Knocking down the expression of TaZFP8 by virus-induced gene silencing increased wheat resistance to Pst, whereas TaZFP8-5B-overexpressing reduced wheat resistance to stripe rust and rice resistance to Magnaporthe oryzae, suggesting that TaZFP8-5B plays a negative role in the modulation of plant immunity. Using bimolecular fluorescence complementation, split-luciferase, and yeast two-hybrid assays, we showed that TaZFP8-5B interacted with a wheat calmodulin-like protein TaCML21. Knock-down of TaCML21 reduced wheat resistance to Pst.ConclusionsThis study characterized the function of TaZFP8-5B and its interacting protein TaCML21. Our findings provide a new perspective on a regulatory module made up of TaCML21-TaZFP8-5B in plant immunity.

Multilayer optimized deep learning model to analyze spectral indices for predicting the condition of rice blast disease

Rice blast disease is one of the most destructive infectious diseases that affects world food security. Proper monitoring and an accurate decision-making process can assist in disease management strategy. Ground surveys and sampling are the less accurate, expensive, and time-consuming processes that are ineffective to check epidemic. Satellite data-driven approach might be an ideal cost and time-efficient technique that can provide an accurate result due to its revisit across farmland. Temperature variation is a salient feature of this disease trajectory. Hence, land surface temperature can be a cardinal property for disease risk estimation. Spectral indices-based analysis can be more efficient for tracking the disease density. In this study, the MODIS satellite-based Land Surface Temperature (LST) parameter is used to indicate the disease in the field. The indicated risk estimation is also examined using ground truth observation to provide less erroneous labeling. Various spectral combination based remote sensing indices were accumulated to audit the disease states. Remote sensing indices such as Normalized Difference Vegetation Index (NDVI), Soil Adjusted Vegetation Index (SAVI), Enhanced Vegetation Index (EVI), Normalized Difference Moisture Index (NDMI), and Moisture Stress were obtained from the Sentinel-2 archive. These images, depicting the various indices, are processed through a novel optimized deep learning model to predict the disease condition of farmland. The model is developed using various residual networks with L2 regularization and batch normalization to enhance the performance of the model. A combination of convolution layers is used to extract crucial spectral information from the remote sensing images and processed through fully connected layers to prognosticate the state of the disease. The model can predict with 89.67% accuracy using the EVI parameters for different geographical positions compared with other remote sensing parameters and has less chance of erroneous possibilities. The proposed system will lead to improved agricultural monitoring management for the incidence of leaf blast disease in real-time.

Rapid and visual detection of Pyricularia oryzae using coupled recombinase polymerase amplification-lateral flow dipstick assay.

Rice blast, caused by Pyricularia oryzae, is one of the most destructive fungal diseases in rice, severely impacting rice production worldwide every year. Rapid, accurate and visual detection of P. oryzae is essential for more effective prevention and control. In this study, we developed a recombinase polymerase amplification-lateral flow dipstick (RPA-LFD) assay to detect P. oryzae. Species-specific RPA primer pairs and probe were designed based on target gene MGG_15975. The optimized reaction temperature and time were set at 37 °C and 25 min, respectively. Specificity analysis showed that the assay could specifically detect P. oryzae isolates from rice, whereas other fungal species or Pyricularia species from grasses were not detected. Additionally, this assay demonstrated highly sensitivity, capable of detecting as low as 10-2 ng/µL of P. oryzae genomic DNA, which was found to be 100 times more sensitive than conventional PCR. Furthermore, using this assay, P. oryzae was effectively detected in diseased leaves in rice fields, and could also be identified at an early stage of infection before obvious lesions appeared in artificially inoculated rice seedlings. Therefore, the RPA-LFD assay developed in our study for the detection of P. oryzae is rapid, highly sensitive and efficient, which has the potential application for early diagnosis of P. oryzae infection in rice fields.

Synthesis of Novel Chromene Derivatives Bearing Hydrazide/Thiazol/Oxazol/Oxime Moieties as Potential Antifungal Agents.

Four series of novel hydrazide/thiazol/oxazol/oxime ester hybrids of chromene derivatives were designed and synthesized to explore natural-product-based fungicide candidates. Preliminary antifungal activity assay results demonstrated that hydrazide-chromene and thiazol-chromene derivatives exhibited excellent and broad-spectrum inhibitory activity against ten phytopathogenic fungi. Among them, six compounds 4b, 4c, 4d, 4e, 4h, and 4l displayed the most remarkable antifungal effects. Notably, compounds 4e and 4l showed comparable protective and curative effects with chlorothalonil against potatoes and cherry tomatoes infected by Fusarium solani and Botrytis cinerea, respectively. Meanwhile, compound 4e also exerted potential protective and curative effects against rice and pepper leaves infected by Pyricularia oryzae and Phytophthora capsici, respectively. Additionally, a preliminary antifungal mechanism study revealed that compound 4e could significantly inhibit the germination of spores and promote increased mycelium permeability and content leakage by disrupting the fungal membrane structure. The in vitro cytotoxicity results indicated that almost all of the hydrazide-chromene derivatives possessed relatively low cytotoxicity. These findings provide the foundation for the application of chromene-based derivatives as novel fungicide candidates.

Genomic surveillance for tackling emerging plant diseases, with special reference to wheat blast

Abstract Plant diseases are responsible for 20–40% of global crop yield losses, posing a significant threat to food security in the face of an ever-growing population. Genomic surveillance emerges as a powerful tool for diagnosing, early warning, and mitigating emerging plant diseases. This approach provides molecular insights into plant-pathogen interactions, essential for developing durable management strategies. Various omics techniques, including metagenomics, are employed in genomic surveillance to systematically monitor and analyze pathogen genomes. These analyses enable early detection of emerging threats, characterization of pathogen populations, tracking of pathogen movement, and accurate prediction of disease outbreaks. Genomic data serve as the foundation for point-of-care disease management using genome-specific primers and CRISPR technology. Despite its significant advantages, genomic surveillance faces challenges such as data analysis complexity, protocol standardization, ethical considerations, and technology accessibility. Key strategies to address these challenges include open data sharing, open science, and international collaboration. Recent advancements in sequencing technologies, bioinformatics tools, and collaborative networks offer promising solutions to these challenges, enhancing the potential of genomic surveillance in plant pathology. This comprehensive review updates the current progress and future prospects of genomic surveillance in disease detection and sustainable plant health management. It critically discusses the challenges of large-scale application and explores mitigation strategies through open data sharing, open science, and international collaboration.

The blast pathogen effector AVR-Pik binds and stabilizes rice heavy metal-associated (HMA) proteins to co-opt their function in immunity.

Intracellular nucleotide-binding domain and leucine-rich repeat-containing (NLR) receptors play crucial roles in immunity across multiple domains of life. In plants, a subset of NLRs contain noncanonical integrated domains that are thought to have evolved from host targets of pathogen effectors to serve as pathogen baits. However, the functions of host proteins with similarity to NLR integrated domains and the extent to which they are targeted by pathogen effectors remain largely unknown. Here, we show that the blast fungus effector AVR-Pik binds a subset of related rice proteins containing a heavy metal-associated (HMA) domain, one of the domains that has repeatedly integrated into plant NLR immune receptors. We find that AVR-Pik binding stabilizes the rice small HMA (sHMA) proteins OsHIPP19 and OsHIPP20. Knockout of OsHIPP20 causes enhanced disease resistance towards the blast pathogen, indicating that OsHIPP20 is a susceptibility gene (S-gene). We propose that AVR-Pik has evolved to bind HMA domain proteins and co-opt their function to suppress immunity. Yet this binding carries a trade-off, it triggers immunity in plants carrying NLR receptors with integrated HMA domains.

Reduction of pesticide dosage and off‐target drift with enhanced control efficacy in unmanned aerial vehicle‐based application using lecithin adjuvants

AbstractBACKGROUNDUnmanned aerial vehicles (UAVs) are increasingly used in precision agriculture, particularly for pesticide application in rice cultivation. One challenge is off‐target pesticide drift, which raises environmental concerns and reduces pesticide efficiency. Lecithin adjuvants have been suggested to enhance droplet stability, reduce drift, and improve control efficacy. This study aims to evaluate the efficiency of lecithin adjuvants in reducing pesticide drift and improving deposition during UAV‐based pesticide application under various paddy field conditions.RESULTSThe addition of 1% lecithin adjuvants in 75% dosage of tricyclazole and ferimzone dual active ingredient formulations reduced off‐target drift by 2.62 to 3.16 times compared to the 100% and 75% dosage of standard formulations, with deposition efficiency along the spray path increasing by up to 155%. Wind direction and speed were found to be the primary environmental factor affecting deposition efficiency and drift rate. The control efficacy against leaf blast disease was significantly improved, with a maximum efficacy of 73.7% observed in the adjuvant‐treated group. Initial pesticide residues on rice plants were the highest in treatments with adjuvants, but their harvest products, brown rice and dried straw, were still within safe limits for human consumption.CONCLUSIONLecithin adjuvants significantly reduce off‐target drift and enhance pesticide deposition during UAV‐based application. This method allowed for lower pesticide dosages without compromising control efficacy, contributing to more sustainable agricultural practices. These findings highlight the potential of adjuvants to improve UAV pesticide application and reduce the environmental impact of pesticide use. © 2024 Society of Chemical Industry.

Identification and characterization of cysteine-rich polycomb-like protein (CPP) gene family in rice (Oryza sativa L.) in response to phytohormones and Xanthomonas oryzae pv. oryzae stress

Cysteine-rich polycomb-like proteins (CPPs) are found in both monocotyledonous and dicotyledonous plants. These CPPs are part of nine various families of proteolytic enzymes, and they play a crucial role in various physiological, especially defence mechanisms. Nevertheless, there is a lack of findings regarding the function of CPPs in disease resistance in rice (Oryza sativa). We recently discovered eleven CPPs in the rice genome. They can be divided into three clades: I, II, and III along with CPPs from other plants like Arabidopsis thaliana (eight members), Cucumis sativus (five members), and Glycine max (thirteen members) based on their phylogenetic relationships. It is interesting to observe how segmental duplication (SD) has assisted the emergence of the OsCPP genes in rice, whereas no evidence of tandem duplication (TD) has been detected. Synteny analyses revealed three pairs of orthologous CPP genes amongst O. sativa and A. thaliana, as well as three pairs between O. sativa and C. sativus. These OsCPPs possess ten conserved amino acid motifs and several exons and introns, as determined by their gene structures. Additionally, they possess distinctive domains such as TCR and TCR superfamily domains. Cis-regulatory elements identified in the OsCPP promoter sequences were shown to be sensitive to auxin, abscisic acid, gibberellins, salicylic acid, methyl jasmonate, and light. Furthermore, stress-responsive elements and tissue-specific expression elements were identified. A large number of OsCPP genes are expressed in different kinds of tissues and organs. Several of these genes are induced by abscisic acid and jasmonic acid. Moreover, specific OsCPP genes are stimulated by Xanthomonas oryzae pv. oryzae (Xoo), the pathogen responsible for bacterial leaf blight in rice. In particular, the pathogen causes a notable overexpression of OsCPP9, suggesting its potential involvement in the plant's defense system. These results highlight the possible contributions of OsCPP genes to rice resistance against Xoo disease.