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The ubiquitin-proteasome system (UPS) plays crucial roles in cellular processes including plant growth, development, and stress responses. In this study, we report that a pair of E3 ubiquitin ligases, AvrPiz-t-interaction protein 6 (APIP6) and IPA1-interaction protein 1 (IPI1), intricately target early flowering3 (ELF3) paralogous proteins to control rice immunity and flowering. APIP6 forms homo-oligomers or hetero-oligomers with IPI1. Both proteins interact with OsELF3-2, promoting its degradation to positively control resistance against the rice blast fungus (Magnaporthe oryzae). Intriguingly, overexpression of IPI1 in Nipponbare caused significantly late-flowering phenotypes similar to the oself3-1 mutant. Except for late flowering, oself3-1 enhances resistance against M. oryzae. IPI1 also interacts with and promotes the degradation of OsELF3-1, a paralog of OsELF3-2. Notably, IPI1 and APIP6 synergistically modulate OsELF3s degradation, finely tuning blast disease resistance by targeting OsELF3-2, while IPI1 controls both disease resistance and flowering by targeting OsELF3-1. This study unravels multiple functions for a pair of E3 ligases in rice. [Display omitted] • APIP6 forms homo-oligomers with itself and hetero-oligomers with IPI1 • Both APIP6 and IPI1 promote OsELF3-2 degradation to enhance rice immunity • IPI1 targets OsELF3-1 to enhance immunity but negatively controls flowering • APIP6/IPI1 hetero-oligomers facilitate the degradation of ELF3 proteins in rice The pair of E3 ubiquitin ligases, APIP6 and IPI1, positively control rice immunity by promoting the degradation of OsELF3-2, while IPI1 delays flowering by destabilizing OsELF3-1. By forming hetero-oligomers, APIP6 and IPI1 synergistically control ELF3-mediated development and immunity in rice. [ABSTRACT FROM AUTHOR]

Immunity and flowering are energy-consuming processes. However, the mechanism underlying the balance between immunity and flowering remains to be elucidated. Here, we report that the E3 ligase ideal plant architecture 1 interactor 1 (IPI1) controls rice immunity and flowering via two different pathways, one dependent on and another independent of its E3 ligase activity. We found that IPI1, a RING-finger E3 ligase, interacts with another E3 ligase, AvrPiz-t-interacting protein 6 (APIP6), and protects APIP6 from degradation by preventing APIP6's self-ubiquitination. Stabilization of APIP6 by IPI1 requires no IPI1 E3 ligase activity and leads to degradation of APIP6 substrates via the ubiquitin-proteasome system (UPS). Meanwhile, IPI1 directly ubiquitinates OsELF3-1 and OsELF3-2, two homologs of EARLY FLOWERING3 (ELF3), targeting them for degradation via the 26S proteasome. IPI1 knockout plants display early flowering but compromised resistance to rice blast. Thus, IPI1 balances rice immunity and flowering via both E3 ligase-dependent and -independent pathways. [Display omitted] • IPI1 functions dependent on or independent of its E3 ligase activity • IPI1 protects APIP6 from degradation, independent of its E3 ligase activity • IPI1 promotes the degradation of OsELF3-1/OsELF3-2 dependent on its E3 ligase activity • IPI1 balances rice immunity and flowering Yi et al. demonstrate that the E3 ligase IPI1 inhibits flowering time by promoting the degradation of OsELF3-1, dependent on its E3 ligase activity, and enhances rice immunity by ubiquitinating OsELF3-2 and stabilizing APIP6, dependent and independent of its E3 ligase activity, respectively. [ABSTRACT FROM AUTHOR]

ABSTRACT Plants need to fine‐tune defense responses to maintain a robust but flexible host barrier to various pathogens. Helix‐loop‐helix/basic helix‐loop‐helix (HLH/bHLH) complexes play important roles in fine‐tuning plant development. However, the function of these genes in plant immunity and how they are regulated remain obscure. Here, we identified an atypical bHLH transcription factor, Oryza sativa (Os)HLH46, that interacts with rice receptor‐like cytoplasmic kinase (RLCK) Os BRASSINOSTEROID‐SIGNALING KINASE1‐2 (OsBSK1‐2), which plays a key role in rice blast resistance. OsBSK1‐2 stabilized OsHLH46 both in vivo and in vitro. In addition, OsHLH46 positively regulates rice blast resistance, which depends on OsBSK1‐2. OsHLH46 has no transcriptional activation activity and interacts with a typical bHLH protein, OsbHLH6, which negatively regulates rice blast resistance. OsbHLH6 binds to the promoter of OsWRKY45 and inhibits its expression, while OsHLH46 suppresses the function of OsbHLH6 by blocking its DNA binding and transcriptional inhibition of OsWRKY45. Consistent with these findings, OsWRKY45 was up‐regulated in OsHLH46‐overexpressing plants. In addition, the oshlh46 mutant overexpressing OsbHLH6 is more susceptible to Magnaporthe oryzae than is the wild type, suggesting that OsHLH46 suppresses OsbHLH6‐mediated rice blast resistance. Our results not only demonstrated that OsBSK1‐2 regulates rice blast resistance via the OsHLH46/OsbHLH6 complex, but also uncovered a new mechanism for plants to fine‐tune plant immunity by regulating the HLH/bHLH complex via RLCKs. [ABSTRACT FROM AUTHOR]

CRISPR/Cas9 technology has been widely adopted for genome editing in a wide range of organisms, including many fungi. Pyricularia oryzae is a filamentous fungal pathogen that causes the devastating rice blast disease. However, an efficient and cost-effective CRISPR/Cas9 system for the rice blast fungus has yet to be established. Here, we report an 84-bp arginyl (Arg)-tRNA promoter-driven CRISPR/Cas9 system, which enables efficient and cost-effective gene editing in P. oryzae. Preliminary screening of three tRNAs from the 179 predicted tRNAs in P. oryzae showed that two Arg-tRNA CRISPR/Cas9 cassettes reproducibly generated MoB56 disruption efficiently. Further, five genes located on distinct chromosomes, including two previously uncharacterized genes, were randomly picked up to test the efficiency of the Mo_tRNAArg24-gRNA-Cas9 cassette. Ppg1 is a gene essential to the pathogenicity and important for mycelial growth and conidiation of P. oryzae, which is located at chromosome 2 and exhibited a relatively low gene replacement rate (< 1/500) by the traditional gene replacement approach. By using the Mo_tRNAArg24-gRNA-Cas9 cassette, Ppg1 gene disruption rate was increased up to 75.9%. In addition, Bip2, an uncharacterized genes located close to the centromere of chromosome 4, was disrupted at 66.7%. For all the five tested genes, our Mo_tRNAArg24-gRNA-Cas9 cassette showed high gene disruption efficiency in P. oryzae, ranging from 66.7% to 100%. Importantly, it rarely induces Cas9 toxicity to P. oryzae. The Mo_tRNAArg24-gRNA-Cas9 cassette described in this study can be adopted as an alternative for functional genomics study in P. oryzae. [ABSTRACT FROM AUTHOR]

Disease outbreaks are shaped by the 'disease triangle,' comprising a virulent pathogen, a susceptible plant, and appropriate environmental conditions. Recent advances have shed light on the intricate environment–plant–pathogen interactions. Rice resistance is manipulated by cytoplasmic and apoplastic effectors secreted by Magnaporthe oryzae. Environmental factors play a significant role in both blast disease epidemics and the regulation of host (or rice) resistance. Strategies such as protein engineering, genome editing, and host-induced gene silencing have been employed effectively to engineer blast-resistant rice plants. Rice blast is a highly destructive crop disease that requires the interplay of three essential factors: the virulent blast fungus, the susceptible rice plant, and favorable environmental conditions. Although previous studies have focused mainly on the pathogen and rice, recent research has shed light on the molecular mechanisms by which the blast fungus and environmental conditions regulate host resistance and contribute to blast disease outbreaks. This review summarizes significant achievements in understanding the sophisticated modulation of blast resistance by Magnaporthe oryzae effectors and the dual regulatory mechanisms by which environmental conditions influence rice resistance and virulence of the blast fungus. Furthermore, it emphasizes potential strategies for developing blast-resistant rice varieties to effectively control blast disease. [ABSTRACT FROM AUTHOR]

Rice blast is the primary disease affecting rice yield and quality, and its effective detection is essential to ensure rice yield and promote sustainable agricultural production. To address traditional disease detection methods' time-consuming and inefficient nature, we proposed a method called Pyramid-YOLOv8 for rapid and accurate rice leaf blast disease detection in this study. The algorithm is built on the YOLOv8x network framework and features a multi-attention feature fusion network structure. This structure enhances the original feature pyramid structure and works with an additional detection head for improved performance. Additionally, this study designs a lightweight C2F-Pyramid module to enhance the model's computational efficiency. In the comparison experiments, Pyramid-YOLOv8 shows excellent performance with a mean Average Precision (mAP) of 84.3%, which is an improvement of 9.9%, 4.3%, 7.4%, 6.1%, 1.5%, 3.7%, and 8.2% compared to the models Faster-RCNN, RT-DETR, YOLOv3-SPP, YOLOv5x, YOLOv9e, and YOLOv10x, respectively. Additionally, it reaches a detection speed of 62.5 FPS; the model comprises only 42.0 M parameters. Meanwhile, the model size and Floating Point Operations (FLOPs) are reduced by 41.7% and 23.8%, respectively. These results demonstrate the high efficiency of Pyramid-YOLOv8 in detecting rice leaf blast. In summary, the Pyramid-YOLOv8 algorithm developed in this study offers a robust theoretical foundation for rice disease detection and introduces a new perspective on disease management and prevention strategies in agricultural production. [ABSTRACT FROM AUTHOR]

Summary Terpene synthases (TPSs) are key enzymes in terpenoids synthesis of plants and play crucial roles in regulating plant defence against pests and diseases. Here, we report the functional characterization of OsTPS19 and OsTPS20, which were upregulated by the attack of brown planthopper (BPH). BPH female adults performed concentration‐dependent behavioural responses to (S)‐limonene showing preference behaviour at low concentrations and avoidance behaviour at high concentrations. Overexpression lines of OsTPS19 and OsTPS20, which emitted higher amounts of the monoterpene (S)‐limonene, decreased the hatching rate of BPH eggs, reduced the lesion length of sheath blight caused by Rhizoctonia solani and bacterial blight caused by Xanthomonas oryzae. While knockout lines of OsTPS19 and OsTPS20, which emitted lower amounts of (S)‐limonene, were more susceptible to these pathogens. Overexpression of OsTPS19 and OsTPS20 in rice plants had adverse effects on the incidence of BPH, rice blast, and sheath blight in the field and had no significant impacts on rice yield traits. OsTPS19 and OsTPS20 were found to be involved in fine‐tuning the emission of (S)‐limonene in rice plants and play an important role in defence against both BPH and rice pathogens. [ABSTRACT FROM AUTHOR]

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

[Objective] To utilize existing resources to create new excellent restoring and sterile lines, and to breed new hybrid rice varieties with high yield, quality and disease resistance. [Method] The high-yielding, large panicle and strong stem (HR1128/Chenghui 727) F3 selected line was used as the female parent and the early maturing and blast resistant Wushan silk seedling was used as the male parent. A new restoring line Zhunongzhan 110 with strong restoring ability, good combining ability and resistance to rice blast was selected through multiple generations of selection and cross testing with multiple three line sterile lines. In the multi-point comparison experiment, the combination with Zhu 99A showed the characteristics of high yield, high quality, disease resistance and lodging resistance, so it was named Zhuyou 110. In 2020-2021, Zhuyou 110 participated in regional trials of late maturing medium Indica rice in the middle and lower reaches of the Yangtze River and photosensitive late Indica rice in southern China. [Result] In the regional trial of late maturing medium Indica rice in the middle and lower reaches of the Yangtze River, the average yield of Zhuyou 110 in the two-year regional trial was 9.70 t/ hm², enhanced by 6.6% compared with CK. In the 2021 production test, the average yield was 10.13 t/ hm², enhanced by 5.9% compared with CK. It showed high yield, lodging resistance and moderate resistance to rice blast, which reached the second level of the Quality of Edible Rice Varieties (NY/ T 593— 2013) standard in the agricultural industry, approved by the National Crop Variety Approval Committee (Authorization code:Guoshendao 20220021). [Conclusion] Zhuyou 110 had the advantages of high yield, high quality, lodging resistance and moderate resistance to rice blast, which was suitable for planting one mid-season rice in the middle and lower reaches of the Yangtze River and double late-season rice in the southern rice region. [ABSTRACT FROM AUTHOR]

Featured Application: The SMARTerra decision support system provides high-resolution risk maps related to plant diseases and pests, enabling prompt and targeted intervention that minimizes environmental impact while minimizing economic losses. The prediction and monitoring of plant diseases and pests are key activities in agriculture. These activities enable growers to take preventive measures to reduce the spread of diseases and harmful insects. Consequently, they reduce crop loss, make pesticide and resource use more efficient, and preserve plant health, contributing to environmental sustainability. We illustrate the SMARTerra decision support system, which processes daily measured and predicted weather data, spatially interpolating them at high resolution across the entire Sardinia region. From these data, SMARTerra generates risk predictions for plant pests and diseases. Currently, models for predicting the risk of rice blast disease and the hatching of locust eggs are implemented in the infrastructure. The web interface of the SMARTerra platform allows users to visualize detailed risk maps and promptly take preventive measures. A simple notification system is also implemented to directly alert emergency responders. Model outputs by the SMARTerra infrastructure are comparable with results from in-field observations produced by the LAORE Regional Agency. The infrastructure provides a database for storing the time series and risk maps generated, which can be used by agencies and researchers to conduct further analysis. [ABSTRACT FROM AUTHOR]

Background: Fusarium wilt is a devastating soil-borne fungal disease of tomato across the world. Conventional method of disease prevention including usage of common pesticides and methods like soil solarisation are usually ineffective in the treatment of this disease. Therefore, there is an urgent need to identify virulence related genes in the pathogen which can be targeted for fungicide development. Results: Pathogenicity testing and phylogenetic classification of the pathogen used in this study confirmed it as Fusarium oxysporum f. sp. lycopersici (Fol) strain. A recent discovery indicates that EF1α, a protein with conserved structural similarity across several fungal genera, has a role in the pathogenicity of Magnaporthe oryzae, the rice blast fungus. Therefore, in this study we have done structural and functional classification of EF1α to understand its role in pathogenicity of Fol. The protein model of Fol EF1α was created using the template crystal structure of the yeast elongation factor complex EEF1A:EEF1BA which showed maximum similarity with the target protein. Using the STRING online database, the interactive information among the hub genes of EF1α was identified and the protein–protein interaction network was recognized using the Cytoscape software. On combining the results of functional analysis, MCODE, CytoNCA and CytoHubba 4 hub genes including Fol EF1α were selected for further investigation. The three interactors of Fol EF1α showed maximum similarity with homologous proteins found in Neurospora crassa complexed with the known fungicide, cycloheximide. Through the sequence similarity and PDB database analysis, homologs of Fol EF1α were found: EEF1A:EEF1BA in complex with GDPNP in yeast and EF1α in complex with GDP in Sulfolobus solfataricus. The STITCH database analysis suggested that EF1α and its other interacting partners interact with guanosine diphosphate (GDPNP) and guanosine triphosphate (GTP). Conclusions: Our study offers a framework for recognition of several hub genes network in Fusarium wilt that can be used as novel targets for fungicide development. The involvement of EF1α in nucleocytoplasmic transport pathway suggests that it plays role in GTP binding and thus apart from its use as a biomarker, it may be further exploited as an effective target for fungicide development. Since, the three other proteins that were found to be tightly associated Fol EF1α have shown maximum similarity with homologous proteins of Neurospora crassa that form complex with fungicide- Cycloheximide. Therefore, we suggest that cycloheximide can also be used against Fusarium wilt disease in tomato. The active site cavity of Fol EF1α can also be determined for computational screening of fungicides using the homologous proteins observed in yeast and Sulfolobus solfataricus. On this basis, we also suggest that the other closely associated genes that have been identified through STITCH analysis, they can also be targeted for fungicide development. [ABSTRACT FROM AUTHOR]

In order to detect rice false smut quickly and accurately, a lightweight false smut detection model, YOLOv8n-MBS, was proposed in this study. The model introduces the C2f_MSEC module to replace C2f in the backbone network for better extraction of key features of false smut, enhances the feature fusion capability of the neck network for different sizes of false smut by using a weighted bidirectional feature pyramid network, and designs a group-normalized shared convolution lightweight detection head to reduce the number of parameters in the model head to achieve model lightweight. The experimental results show that YOLOv8n-MBS has an average accuracy of 93.9%, a parameter count of 1.4 M, and a model size of 3.3 MB. Compared with the SSD model, the average accuracy of the model in this study increased by 4%, the number of parameters decreased by 89.8%, and the model size decreased by 86.9%; compared with the YOLO series of YOLOv7-tiny, YOLOv5n, YOLOv5s, and YOLOv8n models, the YOLOv8n-MBS model showed outstanding performance in terms of model accuracy and model performance detection; compared to the latest YOLOv9t and YOLOv10n models, the average model accuracy increased by 2.8% and 2.2%, the number of model parameters decreased by 30% and 39.1%, and the model size decreased by 29.8% and 43.1%, respectively. This method enables more accurate and lighter-weight detection of false smut, which provides the basis for intelligent management of rice blast disease in the field and thus promotes food security. [ABSTRACT FROM AUTHOR]

Magnaporthe oryzae causes rice blast disease, which threatens global rice production. The interaction between M. oryzae and rice is regarded as a classic model for studying the relationship between the pathogen and the host. In this study, we found a gene, MoHG1, regulating fungal development and virulence in M. oryzae. The ∆Mohg1 mutants showed more sensitivity to cell wall integrity stressors and their cell wall is more easily degraded by enzymes. Moreover, a decreased content of chitin but higher contents of arabinose, sorbitol, lactose, rhamnose, and xylitol were found in the ∆Mohg1 mutant. Combined with transcriptomic results, many genes in MAPK and sugar metabolism pathways are significantly regulated in the ∆Mohg1 mutant. A hexokinase gene, MGG_00623 was downregulated in ∆Mohg1, according to transcriptome results. We overexpressed MGG_00623 in a ∆Mohg1 mutant. The results showed that fungal growth and chitin contents in MGG_00623-overexpressing strains were restored significantly compared to the ∆Mohg1 mutant. Furthermore, MoHG1 could interact with MGG_00623 directly through the yeast two-hybrid and BiFC. Overall, these results suggest that MoHG1 coordinating with hexokinase regulates fungal development and virulence by affecting chitin contents and cell wall integrity in M. oryzae, which provides a reference for studying the functions of MoHG1-like genes. [ABSTRACT FROM AUTHOR]

This document is an editorial for a special issue of the journal Biomolecules titled "Phytohormones 2022-2023." It emphasizes the significance of plant hormones in regulating plant growth and development, as well as their potential as biotechnological tools. The special issue covers various aspects of plant hormones, including their role in pollen germination, self-incompatibility, nitrogen use efficiency, stress resistance, and the accumulation of biomass and secondary metabolites. The articles in the special issue explore topics such as the presence of ABA in stigma exudates, programmed cell death as a self-incompatibility factor, the interaction between phytohormones and nutrients in woody plants, and the mechanisms underlying delayed recovery of gas exchange after drought relief. Other articles discuss the growth-inhibitory effect of increased planting density and its reduction by ABA-degrading bacteria, the capacity of methyl jasmonate to increase resistance to cadmium stress, the role of lipoxygenase3 in rice plants' defense response to blast disease, and the influence of CKs and ABA on the growth, development, and virulence of the pathogenic fungus Stagonospora nodorum. Additionally, the effects of auxin and jasmonic acid on the formation of adventitious roots and the production of secondary metabolites in Acmella radicans and Salvia bulleyana are explored. The article also discusses the use of auxin indole-3-acetic acid and cytok [Extracted from the article]

In Asian countries, rice is the major agricultural product. Hence, the initial identification of plant disorder via the IoT (Internet of Things) offers to ignore the rice from critical disorders. To increase crop production, the measurements should be considered to completely destroy the rice plant disorders by an effective system. This paper proposed an Intelligent IoT-aided deep learning model for detecting rice blast fungal along with a hybrid heuristic algorithm. The proposed work encompasses with multiple stages that are explained as follows. At first, the required paddy images are gathered from online data resources. Next, the pre-processing of the collected images is made by adaptive mean filtering and contrast enhancement. Further, the adaptive thresholding and morphological operation are adopted for leaf segmentation purposes, where the threshold value is tuned by a Fitness-based Billiards-inspired Rat Swarm Optimizer (FBRSO). Consequently, from the segmented image, the Region of Interest (ROI) is cropped. Finally, the cropped ROI is subjected to the Optimized MobileNetv2 and Multiscale Residual Attention Network (OMMRAN), where it includes MobileNetV2 and Multiscale Residual Attention Network, in which some of the hyperparameters are tuned by FBRSO approach. The performance is validated and compared with other existing approaches for detecting rice diseases effectively. [ABSTRACT FROM AUTHOR]

Rice cultivation in Madurai district, Tamil Nadu, spans distinct cropping seasons: Kar (May -- Jun), Semi-dry (Jul - Aug), Samba/ Late Samba (Aug - Sep), and Navarai (Dec - Jan), each with unique weather conditions and rice varieties. This study explores the correlation between weather parameters temperature, rainfall, humidity, sunshine hours, and wind speed and rice blast disease severity from 2021 to 2023. Using multiple linear regression with ordinary least squares (OLS), the analysis achieves high predictive accuracy (R² = 0.98). Results show that the maximum temperatures correlated negatively with disease severity (r = -0.869 to -0.892), while rainfall (r = 0.768 to 0.804) and wind speed (r = 0.766 to 0.938) correlated positively during the semi-dry season. Relative humidity exhibits varying impacts across seasons. These findings underscore the importance of tailored disease management strategies, such as targeted fungicidal applications during warmer seasons and optimized water management in others. By elucidating these dynamics, the study enhances understanding of weather-disease interactions, providing actionable insights to optimize disease management and enhance crop resilience in Madurai district. [ABSTRACT FROM AUTHOR]

Rice blast is one of the most devastating biotic stresses that limits rice productivity. The North Eastern Hill (NEH) region of India is considered to be one of the primary centres of diversity for both rice and pathotypes of Magnaporthe grisea. Therefore, the present study was carried out to elucidate the genetic basis of leaf and neck blast resistance under Meghalaya conditions. A set of 80 diverse genotypes (natural population) and 2 F2 populations involving resistant parent, a wildtype landrace, LR 5 (Lal Jangali) and susceptible genotypes Sambha Mahsuri SUB 1 (SMS) and LR 26 (Chakhao Poireiton) were used for association analysis of reported major gene-linked markers with leaf and neck blast resistance to identify major effective genes under local conditions. Genotyping using twenty-five gene-specific markers across diverse genotypes and F2 progenies revealed genes Pi5 and Pi54 to be associated with leaf blast resistance in all three populations. Genes Pib and qPbm showed an association with neck blast resistance in both natural and LR 5 × SMS populations. Additionally, a set of 184 genome-wide polymorphic markers (SSRs and SNPs), when applied to F2-resistant and F2-susceptible DNA bulks derived from LR 5 × LR 26, suggested that Pi20(t) on chromosome 12 is one of the major genes imparting disease resistance. Markers snpOS318, RM1337 and RM7102 and RM247 and snpOS316 were associated with leaf blast and neck blast resistance, respectively. The genotypes, markers and genes will help in marker-assisted selection and development of varieties with durable resistance. [ABSTRACT FROM AUTHOR]

This study explores the impact of exogenous salicylic acid (SA) alongside conventional treatment by farmers providing positive (Mancozeb 80 % WP) and negative (water) controls on rice plants (Oryza sativa L.), focusing on antioxidant enzyme activities, phytohormone levels, disease resistance, and yield components under greenhouse and field conditions. In greenhouse assays, SA application significantly enhanced the activities of peroxidase (POX), polyphenol oxidase (PPO), catalase (CAT), and superoxide dismutase (SOD) within 12–24 h post-inoculation (hpi) with Magnaporthe oryzae. Additionally, SA-treated plants showed higher levels of endogenous SA and indole-3-acetic acid (IAA) within 24 hpi compared to the controls. In terms of disease resistance, SA-treated plants exhibited a reduced severity of rice blast under greenhouse conditions, with a significant decrease in disease symptoms compared to negative control treatment. The field study was extended over three consecutive crop seasons during 2021–2023, further examining the efficacy of SA in regular agricultural practice settings. The SA treatment consistently led to a reduction in rice blast disease severity across all three seasons. Yield-related parameters such as plant height, the number of tillers and panicles per hill, grains per panicle, and 1000-grain weight all showed improvements under SA treatment compared to both positive and negative control treatments. Specifically, SA-treated plants yielded higher grain outputs in all three crop seasons, underscoring the potential of SA as a growth enhancer and as a protective agent against rice blast disease under both controlled and field conditions. These findings state the broad-spectrum benefits of SA application in rice cultivation, highlighting its role not only in bolstering plant defense mechanisms and growth under greenhouse conditions but also in enhancing yield and disease resistance in field settings across multiple crop cycles. This research presents valuable insights into the practical applications of SA in improving rice plant resilience and productivity, offering a promising approach for sustainable agriculture practices. [ABSTRACT FROM AUTHOR]

Rice blast disease is one of the major diseases affecting rice plant, significantly impacting both yield and quality. Current detecting methods for rice blast disease mainly rely on manual surveys in the field and laboratory tests, which are inefficient, inaccurate, and limited in scale. Spectral and imaging technologies in the visible and near-infrared (Vis/NIR) region have been widely investigated for crop disease detection. This work explored the potential of integrating canopy reflectance spectra acquired near the ground and aerial multispectral images captured with an unmanned aerial vehicle (UAV) for estimating Soil-Plant Analysis Development (SPAD) values and detecting rice leaf blast disease in the field. Canopy reflectance spectra were preprocessed, followed by effective band selection. Different vegetation indices (VIs) were calculated from multispectral images and selected for model establishment according to their correlation with SPAD values and disease severity. The full-wavelength canopy spectra (450–850 nm) were first used for establishing SPAD inversion and blast disease classification models, demonstrating the effectiveness of Vis/NIR spectroscopy for SPAD inversion and blast disease detection. Then, selected effective bands from the canopy spectra, UAV VIs, and the fusion of the two data sources were used for establishing corresponding models. The results showed that all SPAD inversion models and disease classification models established with the integrated data performed better than corresponding models established with the single of either of the aerial and ground data sources. For SPAD inversion models, the best model based on a single data source achieved a validation determination coefficient ( R c v 2 ) of 0.5719 and a validation root mean square error (RMSECV) of 2.8794, while after ground and aerial data fusion, these two values improved to 0.6476 and 2.6207, respectively. For blast disease classification models, the best model based on a single data source achieved an overall test accuracy of 89.01% and a Kappa coefficient of 0.86, and after data fusion, the two values improved to 96.37% and 0.95, respectively. These results indicated the significant potential of integrating canopy reflectance spectra and UAV multispectral images for detecting rice diseases in large fields. [ABSTRACT FROM AUTHOR]

[Background] Intercropping is considered an effective approach to defending rice disease. [Objectives/Methods] This study aimed to explore the resistance mechanism of rice intraspecific intercropping by investigating soil metabolites and their regulation on the rhizosphere soil microbial community using metabolomic and microbiome analyses. [Results] The results showed that the panicle blast disease occurrence of the resistant variety Shanyou63 (SY63) and the susceptible variety Huangkenuo (HKN) were both decreased in the intercropping compared to monoculture. Notably, HKN in the intercropping system exhibited significantly decreased disease incidence and increased disease resistance-related enzyme protease activity. KEGG annotation from soil metabolomics analysis revealed that phenylalanine metabolic pathway, phenylalanine, tyrosine, and tryptophan biosynthesis pathway, and fructose and mannose metabolic pathway were the key pathways related to rice disease resistance. Soil microbiome analysis indicated that the bacterial genera Nocardioides, Marmoricola, Luedemannella, and Desulfomonile were significantly enriched in HKN after intercropping, while SY63 experienced a substantial accumulation of Ruminiclostridium and Cellulomonas. Omics-based correlation analysis highlighted that the community assembly of Cellulomonas and Desulfomonile significantly affected the content of the metabolites D-sorbitol, D-mannitol, quinic acid, which further proved that quinic acid had a significantly inhibitory effect on the mycelium growth of Magnaporthe oryzae, and these three metabolites had a significant blast control effect. The optimal rice blast-control efficiency on HKN was 51.72%, and Lijiangxintuanheigu (LTH) was 64.57%. [Conclusions] These findings provide a theoretical basis for rice varieties intercropping and sustainable rice production, emphasizing the novelty of the study in elucidating the underlying mechanisms of intercropping-mediated disease resistance. [ABSTRACT FROM AUTHOR]

Saccharomycopsis yeasts are natural organic sulfur auxotrophs due to lack of genes required for the uptake and assimilation of sulfate/sulfite. Starvation for methionine induces a shift to a predatory, mycoparasitic life strategy that is unique amongst ascomycetous yeasts. Similar to fungal plant pathogens that separated from Saccharomycopsis more than 400 million years ago, a specialized infection structure called penetration peg is used for prey cell invasion. Penetration pegs are highly enriched with chitin. Here we demonstrate that an ancient and conserved MAP kinase signaling pathway regulates penetration peg formation and successful predation in the predator yeast S. schoenii. Deletion of the MAP kinase gene SsKIL1, a homolog of the Saccharomyces cerevisiae ScKSS1/ScFUS3 and the rice blast Magnaporthe oryzae MoPMK1 genes, as well as deletion of the transcription factor SsSTE12 generate non-pathogenic mutants that fail to form penetration pegs. Comparative global transcriptome analyses using RNAseq indicate loss of the SsKil1-SsSte12-dependent predation response in the mutant strains, while a methionine starvation response is still executed. Within the promoter sequences of genes upregulated during predation we identified a cis-regulatory element similar to the ScSte12 pheromone response element. Our results indicate that, re-routing MAP-kinase signaling by re-wiring Ste12 transcriptional control towards predation specific genes contributed to the parallel evolution of this predacious behaviour in predator yeasts. Consequently, we found that SsSTE12 is dispensable for mating. Author summary: Saccharomycopsis yeasts represent a unique yeast genus of predator yeasts that attack and kill fungal prey cells. This necrotrophic mycoparasitism is initiated upon starvation, preferably for organic sulphur/methionine as predator yeasts are methionine auxotrophs. We have characterized morphological and cellular features of predation using time lapse fluorescence microscopy. This indicated prey sensing, chitin enrichment of penetration pegs used in the attack of prey cells and coordination of predation with the cell cycle resulting in cessation of daughter cell growth and a block in mitosis during predation. A predator yeast attack from the onset of penetration peg formation to the disappearance of the nuclear GFP-signal in the Saccharomyces cerevisiae prey took ~25 minutes. We identified the MAP kinase KIL1 and its putative target STE12 as key virulence genes that govern penetration peg formation. Comparative transcriptomics of mutant strains with the wild type identified specific hunger and predation responses and associated genes. Predation genes were found to harbor a conserved DNA element in their promoters. These findings can aid in deepening our understanding of necrotrophic predator-prey interactions. [ABSTRACT FROM AUTHOR]

Background: The identification of spotted leaf 50 (spl50), a novel lesion mimic mutant (LMM) in rice, provides critical insights into the mechanisms underlying programmed cell death (PCD) and innate immunity in plants. Results: Based on ethyl methane sulfonate (EMS)-induced mutagenesis, the spl50 mutant mimics hypersensitive responses in the absence of pathogen by displaying spontaneous necrotic lesions after the tillering phase. SPL50, an ARM repeat protein essential for controlling reactive oxygen species (ROS) metabolism and boosting resistance to blast disease, was identified by map-based cloning techniques. This work also demonstrates the detrimental effects of spl50 on photosynthetic efficiency and chloroplast development. The crucial significance of SPL50 in cellular signaling and stress response is shown by its localization to the cytoplasm and constitutive expression in various plant tissues. In light of growing concerns regarding global food security, this study highlights the pivotal role of SPL50 in regulating programmed cell death (PCD) and enhancing the immune response in plants, contributing to strategies for improving crop disease resistance. Conclusions: The novel identification of the SPL50 gene in rice, encoding an ARM repeat protein, reveals its pivotal role in regulating PCD and innate immune responses independently of pathogen attack. [ABSTRACT FROM AUTHOR]

Rice blast is a common disease caused by Magnaporthe oryzae which affects rice production worldwide, including Brazil. To reduce the use of harmful pesticides, sustainable control options are necessary for managing rice blast. One possible option is to use plant extracts because they produce secondary metabolites capable of inhibiting the pathogen and controlling the disease. This study aimed to evaluate the potential of ethanolic extracts of leaves and flowers from Banisteriopsis laevifollia, a native Brazilian plant, to antagonise M. oryzae. In vitro antifungal activity assays were carried out, in which mycelium growth reduction, conidia germination, and appressorium formation of M. oryzae were evaluated. In addition, in vivo assay for suppression of leaf blast severity by extracts was done. We also explored the identification of secondary metabolites from ethanolic extracts of leaves and flowers by HPLC-HRMS. Results showed that both leaf and flower extracts inhibited mycelial growth in 21.72% and 30.49%, respectively, due to the inhibition of ergosterol production. Additionally, both extracts inhibited melanin production in the mycelium of M. oryzae by inhibiting tyrosine production. Both leaf and flower extracts significantly inhibited conidia germination and appressorium formation. Furthermore, rice leaves treated with the extracts suppressed by 18.17% and 18.97% leaf blast severity, with the 1.00 mg/mL concentration of flower extract and 0.75 mg/mL concentration of leaf extract, respectively, showing the most significant reduction of leaf blast. The extracts contain phenolic compounds, including 2,3,7,8-tetrahydroxy-chromeno-(5,4,3)- chromene-5,10-dione, 3-(4-hydroxyphenyl)-2-propenoic acid, 2-(3,4-dihydroxyphenyl)-3,4-dihydro-1(2H)-benzopyran-3,5,7-triol, 3,4',5,7-tetrahydroxyflavone, 3',4',5,7-tetrahydroxyflavone, 4',5,7-trihydroxyflavanone, 3,3',4',5,7-pentahydroxyflavone, 3,3',4',5,7-pentahydroxyflavone -3-O-glucoside, and 3,3',4',5,7-pentahydroxyflavone-3-O-rutinoside, which are likely responsible for the antifungal activity of the extracts. Overall, this study demonstrates the potential of plant extracts as a sustainable alternative for the management of rice blast. [ABSTRACT FROM AUTHOR]

The rice blast fungus Magnaporthe oryzae poses a significant challenge to maintaining rice production. Developing rice varieties with resistance to this disease is crucial for its effective control, To understand the genetic variability of blast isolates collected between 2015 and 2017, the 27 monogenic rice lines that carry specific resistance genes were used to evaluate blast disease reactions. Based on criteria such as viability, virulence, and reactions to resistance genes, 20 blast isolates were selected as representative strains. To identify novel resistance genes, a quantitative trait locus analysis was carried out utilizing a mixture of the 20 representative rice blast isolates and a rice population derived from crossing the blast-resistant cultivar 'Cheongcheong' with the blast-susceptible cultivar 'Nagdong'. This analysis revealed a significant locus, RM1227-RM1261 on chromosome 12, that is associated with rice blast resistance. Within this locus, 12 disease resistance-associated protein genes were identified. Among them, OsDRq12, a member of the nucleotide-binding, leucine-rich repeat disease resistance family, was chosen as the target gene for additional computational investigation. The findings of this study have significant implications for enhancing rice production and ensuring food security by controlling rice blast and developing resistant rice cultivars. [ABSTRACT FROM AUTHOR]

A study published in the journal iMeta examines the role of beneficial microbes in protecting rice plants from fungal pathogens. The researchers found that certain microbes in the rice plants' microbiome can directly suppress fungal infections. They created a simplified community of three beneficial bacteria, which was shown to enhance rice resistance against fungal pathogens in both lab and field conditions. The study suggests that these beneficial microbes could be used as biocontrol agents to improve rice productivity and manage plant diseases in a cost-effective way. [Extracted from the article]

This study demonstrates that root-associated Kosakonia oryziphila NP19, isolated from rice roots, is a promising plant growth-promoting bioagent and biopesticide for combating rice blast caused by Pyricularia oryzae. In vitro experiments were conducted on fresh leaves of Khao Dawk Mali 105 (KDML105) jasmine rice seedlings. The results showed that NP19 effectively inhibited the germination of P. oryzae fungal conidia. Fungal infection was suppressed across three different treatment conditions: rice colonized with NP19 and inoculated by fungal conidia, a mix of NP19 and fungal conidia concurrently inoculated on the leaves, and fungal conidia inoculation first followed by NP19 inoculation after 30 h. Additionally, NP19 reduced fungal mycelial growth by 9.9–53.4%. In pot experiments, NP19 enhanced the activities of peroxidase (POD) and superoxide dismutase (SOD) by 6.1–63.0% and 3.0–67.7%, respectively, indicating a boost in the plant's defense mechanisms. Compared to the uncolonized control, the NP19-colonized rice had 0.3–24.7% more pigment contents, 4.1% more filled grains per panicle, 26.3% greater filled grain yield, 34.4% higher harvest index, and 10.1% more content of the aroma compound 2-acetyl-1-pyrroline (2AP); for rice colonized with NP19 and infected with P. oryzae, these increases were 0.2–49.2%, 4.6%, 9.1%, 54.4%, and 7.5%, respectively. In field experiments, blast-infected rice that was colonized and/or inoculated with NP19 treatments had 15.1–27.2% more filled grains per panicle, 103.6–119.8% greater filled grain yield, and 18.0–35.8% higher 2AP content. A higher SOD activity (6.9–29.5%) was also observed in the above-mentioned rice than in the blast-infected rice that was not colonized and inoculated with NP19. Following blast infection, NP19 applied to leaves decreased blast lesion progression. Therefore, K. oryziphila NP19 was demonstrated to be a potential candidate for use as a plant growth-promoting bioagent and biopesticide for suppressing rice blast. [ABSTRACT FROM AUTHOR]

In the ongoing arms race between rice and Magnaporthe oryzae, the pathogen employs effectors to evade the immune response, while the host develops resistance genes to recognise these effectors and confer resistance. In this study, we identified a novel Pik allele, Pik‐W25, from wild rice WR25 through bulked‐segregant analysis, creating the Pik‐W25 NIL (Near‐isogenic Lines) named G9. Pik‐W25 conferred resistance to isolates expressing AvrPik‐C/D/E alleles. CRISPR‐Cas9 editing was used to generate transgenic lines with a loss of function in Pik‐W25‐1 and Pik‐W25‐2, resulting in loss of resistance in G9 to isolates expressing the three alleles, confirming that Pik‐W25‐induced immunity required both Pik‐W25‐1 and Pik‐W25‐2. Yeast two‐hybrid (Y2H) and split luciferase complementation assays showed interactions between Pik‐W25‐1 and the three alleles, while Pik‐W25‐2 could not interact with AvrPik‐C, ‐D, and ‐E alleles with Y2H assay, indicating Pik‐W25‐1 acts as an adaptor and Pik‐W25‐2 transduces the signal to trigger resistance. The Pik‐W25 NIL exhibited enhanced field resistance to leaf and panicle blast without significant changes in morphology or development compared to the parent variety CO39, suggesting its potential for resistance breeding. These findings advance our knowledge of rice blast resistance mechanisms and offer valuable resources for effective and sustainable control strategies. [ABSTRACT FROM AUTHOR]

Species-unique genes that encode specific proteins and have no homologs in other species play certain roles in the evolution of species and adaptations to external environments. Nevertheless, the biological roles of unique genes in plant pathogenic fungi remain largely unknown. Here, four Magnaporthe-unique genes (MUG1–MUG4), which were highly expressed during the early infection stages, were functionally characterized in the rice blast fungus Magnaporthe oryzae. Subcellular localization assays revealed that Mug1, Mug2, and Mug4 were localized to the cytoplasm and that Mug3 was localized into the nuclei. Furthermore, through gene knockout and phenotypic analysis, only MUG1 was found to be indispensable for fungal virulence and conidiation. Detailed microscopic analysis revealed that the deletion mutants of MUG1 clearly exhibited reduced appressorial turgor pressure and invasive hyphal development. Taken together, our findings indicate that the Magnaporthe-unique gene MUG1 plays a vital role in infection-related morphogenesis and virulence in rice blast fungi and suggest the specific and important roles of species-unique genes. [ABSTRACT FROM AUTHOR]

Septin GTPases are morphogenetic proteins that are widely conserved in eukaryotic organisms fulfilling diverse roles in cell division, differentiation and development. In the filamentous fungal pathogen Magnaporthe oryzae, the causal agent of the devastating blast diseases of rice and wheat, septins have been shown to be essential for plant infection. The blast fungus elaborates a specialised infection structure called an appressorium with which it mechanically ruptures the plant cuticle. Septin aggregation and generation of a hetero-oligomeric ring structure at the base of the infection cell is indispensable for plant infection. Furthermore, once the fungus enters host tissue it develops another infection structure, the transpressorium, enabling it to move between living host plant cells, which also requires septins for its function. Specific inhibition of septin aggregation—either genetically or with chemical inhibitors—prevents plant infection. Significantly, by screening for inhibitors of septin aggregation, broad spectrum anti-fungal compounds have been identified that prevent rice blast and a number of other cereal diseases in field trials. We review the recent advances in our understanding of septin biology and their potential as targets for crop disease control. [ABSTRACT FROM AUTHOR]

The flowering period of rice significantly impacts variety adaptability and yield formation. Properly shortening the reproductive period of rice varieties can expand their ecological range without significant yield reduction. Targeted genome editing, like CRISPR/Cas9, is an ideal tool to fine-tune rice growth stages and boost yield synergistically. In this study, we developed a CRISPR/Cas9-mediated multiplex genome-editing vector containing five genes related to three traits, Hd2, Ghd7, and DTH8 (flowering-stage genes), along with the recessive rice blast resistance gene Pi21 and the aromatic gene BADH2. This vector was introduced into the high-quality japonica rice variety in Zhejiang province, Jiahe212 (JH212), resulting in 34 T0 plants with various effective mutations. Among the 17 mutant T1 lines, several displayed diverse flowering dates, but most exhibited undesirable agronomic traits. Notably, three homozygous mutant lines (JH-C15, JH-C18, and JH-C31) showed slightly earlier flowering dates without significant differences in yield-related traits compared to JH212. Through special Hyg and Cas marker selection of T2 plants, we identified seven, six, and two fragrant glutinous plants devoid of transgenic components. These single plants will serve as sib lines of JH212 and potential resources for breeding applications, including maintenance lines for indica–japonica interspecific three-line hybrid rice. In summary, our research lays the foundation for the creation of short-growth-period CMS (cytoplasmic male sterility, CMS) lines, and also provides materials and a theoretical basis for indica–japonica interspecific hybrid rice breeding with wider adaptability. [ABSTRACT FROM AUTHOR]

Rice blast caused by the pathogenic fungus Magnaporthe oryzae poses a significant threat to rice cultivation. The identification of robust resistance germplasm is crucial for breeding resistant varieties. In this study, we employed functional molecular markers for 10 rice blast resistance genes, namely Pi1, Pi2, Pi5, Pi9, Pia, Pid2, Pid3, Pigm, Pikh, and Pita, to assess blast resistance across 91 indica rice backbone varieties in South China. The results showed a spectrum of resistance levels ranging from highly resistant (HR) to highly susceptible (HS), with corresponding frequencies of 0, 19, 40, 27, 5, and 0, respectively. Yearly correlations in blast resistance genes among the 91 key indica rice progenitors revealed Pid2 (60.44%), Pia (50.55%), Pita (45.05%), Pi2 (32.97%), Pikh (4.4%), Pigm (2.2%), Pi9 (2.2%), and Pi1 (1.1%). Significant variations were observed in the distribution frequencies of these 10 resistance genes among these progenitors across different provinces. Furthermore, as the number of aggregated resistance genes increased, parental resistance levels correspondingly improved, though the efficacy of different gene combinations varied significantly. This study provides the initial steps toward strategically distributing varieties of resistant indica rice genotypes across South China. [ABSTRACT FROM AUTHOR]

Crop disease pandemics are often driven by asexually reproducing clonal lineages of plant pathogens that reproduce asexually. How these clonal pathogens continuously adapt to their hosts despite harboring limited genetic variation, and in absence of sexual recombination remains elusive. Here, we reveal multiple instances of horizontal chromosome transfer within pandemic clonal lineages of the blast fungus Magnaporthe (Syn. Pyricularia) oryzae. We identified a horizontally transferred 1.2Mb accessory mini-chromosome which is remarkably conserved between M. oryzae isolates from both the rice blast fungus lineage and the lineage infecting Indian goosegrass (Eleusine indica), a wild grass that often grows in the proximity of cultivated cereal crops. Furthermore, we show that this mini-chromosome was horizontally acquired by clonal rice blast isolates through at least nine distinct transfer events over the past three centuries. These findings establish horizontal mini-chromosome transfer as a mechanism facilitating genetic exchange among different host-associated blast fungus lineages. We propose that blast fungus populations infecting wild grasses act as genetic reservoirs that drive genome evolution of pandemic clonal lineages that afflict cereal crops. [ABSTRACT FROM AUTHOR]

King grass (Pennisetum sinese), also known as sugar cane grass, is being affected by emerging leaf blast pathogen which is responsible for causing foliar disease in Baoshan City, Yunnan Province, China. The pathogen was isolated from the typical infected plants showing symptoms like eye-shaped and whitish color in the center with brown-black necrotic borders surrounded by a yellow halo sample on potato dextrose agar (PDA) media. The leaves of various plants including maize (Zea mays), hybrid rice (Oryza sativa), and wheat (Triticum aestivum), were inoculated with the pathogen in an in vitro assay to evaluate the infection potential of the pathogen and transmission risk. Our study verified that Psp1 is pathogenic to the king grass leaves and it is considered as the main causal agent of leaf blast in the study area. Further, morphological characterization and molecular analysis based on ITS region and LSU gene confirmed the pathogen as Pyricularia pennisetigena. During pathogenicity assay, both Psp1 and LP11 isolates of a rice blast pathogen induced symptoms of varying severity in a total of different nine plants. Among these, the pathogen Psp1 exhibited significant symptoms, including conidial emergence on king grass leaves (Pennisetum alopecuroides and Pe. flaccidum) indicating high pathogenicity to these plants. This suggests that Psp1 pose a considerable a high pathogenic risk to Pennisetum spp. This work lays a groundwork for future implementation of integrated management strategies for leaf blast in local king grass, offering a theoretical basis and research foundation for such endeavor. [ABSTRACT FROM AUTHOR]

In this paper, we investigated the monitoring and characterization of the pest Magnaporthe oryzae, known as rice blast, in the Bomba rice variety at the Albufera Natural Park, located in Valencia, Spain during the 2022 and 2023 seasons. Using reflectance data from different Sentinel-2 satellite bands, various vegetative indices were calculated for each year. Significant differences in reflectance in the visible (B4), infrared (B8), red-edge (B6 and B7), and SWIR (B11) bands were detected between healthy and unhealthy fields. Additionally, variations were observed in the vegetation indices, with RVI and IRECI standing out for their higher accuracy in identifying blast-affected plots compared to NDVI and NDRE. Early differences in band values, vegetative indices, and spectral signatures were observed between the unhealthy and healthy plots, allowing for the anticipation of control treatments, whose effectiveness relies on timely intervention. [ABSTRACT FROM AUTHOR]

Summary: The retromer complex is a conserved sorting machinery that maintains cellular protein homeostasis by transporting vesicles containing cargo proteins to defined destinations. It is known to sort proteins at the vacuole membranes for retrograde trafficking, preventing their degradation in the vacuole. However, the detailed mechanism of retromer recruitment to the vacuole membrane has not yet been elucidated.Here, we show that the vacuolar SNARE complex MoPep12‐MoVti1‐MoVam7‐MoYkt6 regulates retromer‐mediated vesicle trafficking by recruiting the retromer to the vacuole membrane, which promotes host invasion in Magnaporthe oryzae.Such recruitment is also essential for the retrieval of the autophagy regulator MoAtg8 and enables appressorium‐mediated host penetration. Furthermore, the vacuolar SNARE subunits are involved in suppressing the host defense response by regulating the deployment of retromer‐MoSnc1‐mediated effector secretion.Altogether, our results provide insights into the mechanism of vacuolar SNAREs‐dependent retromer recruitment which is necessary for pathogenicity‐related membrane trafficking events in the rice blast fungus. [ABSTRACT FROM AUTHOR]

Plant pathogens cause devastating diseases, leading to serious losses to agriculture. Mechanistic understanding of pathogenesis of plant pathogens lays the foundation for the development of fungicides for disease control. Mitophagy, a specific form of autophagy, is important for fungal virulence. The role of cardiolipin, mitochondrial signature phospholipid, in mitophagy and pathogenesis is largely unknown in plant pathogenic fungi. The functions of enzymes involved in cardiolipin biosynthesis and relevant inhibitors were assessed using a set of assays, including genetic deletion, plant infection, lipidomics, chemical‐protein interaction, chemical inhibition, and field trials. Our results showed that the cardiolipin biosynthesis‐related gene MoGEP4 of the rice blast fungus Magnaporthe oryzae regulates growth, conidiation, cardiolipin biosynthesis, and virulence. Mechanistically, MoGep4 regulated mitophagy and Mps1‐MAPK phosphorylation, which are required for virulence. Chemical alexidine dihydrochloride (AXD) inhibited the enzyme activity of MoGep4, cardiolipin biosynthesis and mitophagy. Importantly, AXD efficiently inhibited the growth of 10 plant pathogens and controlled rice blast and Fusarium head blight in the field. Our study demonstrated that MoGep4 regulates mitophagy, Mps1 phosphorylation and pathogenesis in M. oryzae. In addition, we found that the MoGep4 inhibitor, AXD, displays broad‐spectrum antifungal activity and is a promising candidate for fungicide development. Summary Statement: This study demonstrated that MoGep4 regulates mitophagy, Mps1 activation and pathogenesis in Magnaporthe oryzae. Additionally, we found that the MoGep4 inhibitor, alexidine dihydrochloride, displays broad‐spectrum antifungal activity and is effective in disease control in the field. [ABSTRACT FROM AUTHOR]

ABSTRACT Magnaporthe oryzae (M. oryzae) is a devastating hemibiotrophic pathogen. Its biotrophic invasive hyphae (IH) are enclosed in the extrainvasive hyphal membrane produced by plant cells, thus generating a front line of the battlefield between the pathogen and the host plants. In plants, defense‐related complexes such as proteins, callose‐rich materials and vesicles, are directionally secreted to this interface to confer defense responses, but the underlying molecular mechanism is poorly understood. In this study, we found that a Myosin gene, Myosin A1 (OsMYA1), contributed to rice defense. The OsMYA1 knockout mutant exhibited decreased resistance to M. oryzae infection. OsMYA1 localizes to the actin cytoskeleton and surrounds the IH of M. oryzae. OsMYA1 interacts with an exocyst subunit, OsExo70H1, and regulates its accumulation at the plasma membrane (PM) and pathogen–plant interface. Furthermore, OsExo70H1 interacted with the rice syntaxin of the plants121 protein (OsSyp121), and the distribution of OsSyp121 to the PM or the pathogen–plant interface was disrupted in both the OsMYA1 and OsExo70H1 mutants. Overall, these results not only reveal a new function of OsMYA1 in rice blast resistance, but also uncover a molecular mechanism by which plants regulate defense against M. oryzae by OsMYA1‐initiated vesicle secretory pathway, which originates from the actin cytoskeleton to the PM. [ABSTRACT FROM AUTHOR]

Rice blast disease is the most devastating disease constraining crop productivity. Vertical resistance to blast disease is widely studied despite its instability. Clusters of genes or QTLs conferring blast resistance that offer durable horizontal resistance are important in resistance breeding. In this study, we aimed to refine the reported QTLs and identify stable meta-QTLs (MQTLs) associated with rice blast resistance. A total of 435 QTLs were used to project 71 MQTLs across all the rice chromosomes. As many as 199 putative rice blast resistance genes were identified within 53 MQTL regions. The genes included 48 characterized resistance gene analogs and related proteins, such as NBS–LRR type, LRR receptor-like kinase, NB-ARC domain, pathogenesis-related TF/ERF domain, elicitor-induced defense and proteins involved in defense signaling. MQTL regions with clusters of RGA were also identified. Fifteen highly significant MQTLs included 29 candidate genes and genes characterized for blast resistance, such as Piz, Nbs-Pi9, pi55-1, pi55-2, Pi3/Pi5-1, Pi3/Pi5-2, Pikh, Pi54, Pik/Pikm/Pikp, Pb1 and Pb2. Furthermore, the candidate genes (42) were associated with differential expression (in silico) in compatible and incompatible reactions upon disease infection. Moreover, nearly half of the genes within the MQTL regions were orthologous to those in O. sativa indica, Z. mays and A. thaliana, which confirmed their significance. The peak markers within three significant MQTLs differentiated blast-resistant and susceptible lines and serve as potential surrogates for the selection of blast-resistant lines. These MQTLs are potential candidates for durable and broad-spectrum rice blast resistance and could be utilized in blast resistance breeding. [ABSTRACT FROM AUTHOR]

Dihydroorotase (DHOase) is the third enzyme in the six enzymatic reaction steps of the endogenous pyrimidine nucleotide de novo biosynthesis pathway, which is a metabolic pathway conserved in both bacteria and eukaryotes. However, research on the biological function of DHOase in plant pathogenic fungi is very limited. In this study, we identified and named MoPyr4, a homologous protein of Saccharomyces cerevisiae DHOase Ura4, in the rice blast fungus Magnaporthe oryzae and investigated its ability to regulate fungal growth, pathogenicity, and autophagy. Deletion of MoPYR4 led to defects in growth, conidiation, appressorium formation, the transfer and degradation of glycogen and lipid droplets, appressorium turgor accumulation, and invasive hypha expansion in M. oryzae, which eventually resulted in weakened fungal pathogenicity. Long-term replenishment of exogenous uridine-5'-phosphate (UMP) can effectively restore the phenotype and virulence of the ΔMopyr4 mutant. Further study revealed that MoPyr4 also participated in the regulation of the Pmk1-MAPK signaling pathway, co-localized with peroxisomes for the oxidative stress response, and was involved in the regulation of the Osm1-MAPK signaling pathway in response to hyperosmotic stress. In addition, MoPyr4 interacted with MoAtg5, the core protein involved in autophagy, and positively regulated autophagic degradation. Taken together, our results suggested that MoPyr4 for UMP biosynthesis was crucial for the development and pathogenicity of M. oryzae. We also revealed that MoPyr4 played an essential role in the external stress response and pathogenic mechanism through participation in the Pmk1-MAPK signaling pathway, peroxisome-related oxidative stress response mechanism, the Osm1-MAPK signaling pathway and the autophagy pathway. [ABSTRACT FROM AUTHOR]

The rice blast fungus Magnaporthe oryzae stands as a formidable adversary to one of the world's most important crops, rice, which feeds over half of the global population. Its ability to rapidly evolve and adapt underscores the urgent need for a comprehensive understanding of its infection strategies. In a large-scale study published in Cell, Cruz-Mireles et al. (Cell 187:2557-73, 2024) utilized phosphoproteomics to globally map the phosphorylation landscape during the infection-related development by M. oryzae, identifying 2062 activated phosphoproteins carrying 8005 phosphosites. A subset of these phosphosites were conserved in the proteins of diverse fungal pathogens and appeared to be associated with biotrophic and hemibiotrophic infection. Thirty-two of these phosphoproteins are regulated by pathogenicity mitogen-activated kinase 1 (Pmk1), a central component of the MAPK signaling pathway, including VTi 1–2 suppressor, whose regulation by Pmk1 is essential for rice blast disease. Together, this global phosphorylation atlas offers a rich tapestry of potential therapeutic targets for developing green agrochemicals to control fungal diseases of plants. [ABSTRACT FROM AUTHOR]

Kasugamycin (KSM), an aminoglycoside antibiotic, has been widely used as a natural fungicide to control plant diseases, particularly for managing rice blast. However, its uptake mechanism and transport in rice remain to be explored. In this article, rice seedlings were treated by the foliar spraying method, and the content of KSM in rice leaves, stems and roots under different treatments was detected by high‐performance liquid chromatography tandem mass spectrometry (HPLC‐MS/MS), respectively. Results showed that leaf‐applied KSM could be transported to the phloem and migrate to roots and stems after uptake by leaves. Concentration, temperature and pH had significant effects on the uptake of KSM. Compared with the control, the competitive inhibitors d‐glucose and phlorizin both inhibited the uptake of KSM, demonstrating that sugar transporter proteins were involved in the uptake process. The energy inhibitors dinitrophenol (DNP) and carbonyl cyanide chlorophenylhydrazone (CCCP) also significantly inhibited the uptake of KSM, indicating that the uptake of KSM required energy consumption. Thus, the uptake of KSM by rice was an active process involving sugar transporter proteins, and it could migrate downward through the phloem. This study contributes to the promotion of the scientific application of antibiotics and the biological control of crop diseases. It will also provide a theoretical basis for the development of root‐targeted pesticides and transport pesticides with phloem mobility. [ABSTRACT FROM AUTHOR]

As a signaling molecule, nitric oxide (NO) regulates the development and stress response in different organisms. The major biological activity of NO is protein S‐nitrosylation, whose function in fungi remains largely unclear. Here, it is found in the rice blast fungus Magnaporthe oryzae, de‐nitrosylation process is essential for functional appressorium formation during infection. Nitrosative stress caused by excessive accumulation of NO is harmful for fungal infection. While the S‐nitrosoglutathione reductase GSNOR‐mediated de‐nitrosylation removes excess NO toxicity during appressorium formation to promote infection. Through an indoTMT switch labeling proteomics technique, 741 S‐nitrosylation sites in 483 proteins are identified. Key appressorial proteins, such as Mgb1, MagB, Sps1, Cdc42, and septins, are activated by GSNOR through de‐nitrosylation. Removing S‐nitrosylation sites of above proteins is essential for proper protein structure and appressorial function. Therefore, GSNOR‐mediated de‐nitrosylation is an essential regulator for appressorium formation. It is also shown that breaking NO homeostasis by NO donors, NO scavengers, as well as chemical inhibitor of GSNOR, shall be effective methods for fungal disease control. [ABSTRACT FROM AUTHOR]

Endoplasmic reticulum (ER) is an enclosed three-dimensional eukaryotic membrane network composed of flattened sacs. Fusion of homologous membranes to the ER membrane is essential for the maintenance of this network structure. In yeast, ER membrane fusion is mediated by Sey1p, whose paralogues function distinctly in different species. In this study, we investigated the biological functions of MoSEY1 in the devastating rice blast fungus Magnaporthe oryzae by functional genomic approach. Compared to wild type, deletion of MoSEY1 considerably decreased the growth and conidia production of M. oryzae. Additionally, the absence of MoSEY1 delayed appressorium formation and invasive hyphae growth. The appressorium function was also impaired in ΔMosey1 mutant. Subcellular localization analysis revealed that MoSey1 is localized at the ER. The ΔMosey1 mutant showed augmented sensitivity to ER stress. Additionally, we found that MoSey1 regulated the unfolded protein response, autophagy, and protein secretion in M. oryzae. In conclusion, our study unveiled the involvement of MoSey1 in the development, pathogenesis, and ER functions in M. oryzae. [ABSTRACT FROM AUTHOR]

Bioengineering of plant immune receptors has emerged as a key strategy for generating novel disease resistance traits to counteract the expanding threat of plant pathogens to global food security. However, current approaches are limited by rapid evolution of plant pathogens in the field and may lack durability when deployed. Here, we show that the rice nucleotide-binding, leucine-rich repeat (NLR) immune receptor Pik-1 can be engineered to respond to a conserved family of effectors from the multihost blast fungus pathogen Magnaporthe oryzae. We switched the effector binding and response profile of the Pik NLR from its cognate rice blast effector AVR-Pik to the host-determining factor pathogenicity toward weeping lovegrass 2 (Pwl2) by installing a putative host target, OsHIPP43, in place of the native integrated heavy metal-associated domain (generating Pikm-1OsHIPP43). This chimeric receptor also responded to other PWL alleles from diverse blast isolates. The crystal structure of the Pwl2/OsHIPP43 complex revealed a multifaceted, robust interface that cannot be easily disrupted by mutagenesis, and may therefore provide durable, broad resistance to blast isolates carrying PWL effectors in the field. Our findings highlight how the host targets of pathogen effectors can be used to bioengineer recognition specificities that have more robust properties compared to naturally evolved disease resistance genes. [ABSTRACT FROM AUTHOR]

ABSTRACT NAC transcription factors (TFs) are pivotal in plant immunity against diverse pathogens. Here, we report the functional and regulatory network of MNAC3, a novel NAC TF, in rice immunity. MNAC3, a transcriptional activator, negatively modulates rice immunity against blast and bacterial leaf blight diseases and pathogen‐associated molecular pattern (PAMP)‐triggered immune responses. MNAC3 binds to a CACG cis‐element and activates the transcription of immune‐negative target genes OsINO80, OsJAZ10, and OsJAZ11. The negative function of MNAC3 in rice immunity depends on its transcription of downstream genes such as OsINO80 and OsJAZ10. MNAC3 interacts with immunity‐related OsPP2C41 (a protein phosphatase), ONAC066 (a NAC TF), and OsDjA6 (a DnaJ chaperone). ONAC066 and OsPP2C41 attenuate MNAC3 transcriptional activity, while OsDjA6 promotes it. Phosphorylation of MNAC3 at S163 is critical for its negative functions in rice immunity. OsPP2C41, which plays positive roles in rice blast resistance and chitin‐triggered immune responses, dephosphorylates MNAC3, suppressing its transcriptional activity on the target genes OsINO80, OsJAZ10, and OsJAZ11 and promoting the translocation of MNAC3 from nucleus to cytoplasm. These results establish a MNAC3‐centered regulatory network in which OsPP2C41 dephosphorylates MNAC3, attenuating its transcriptional activity on downstream immune‐negative target genes in rice. Together, these findings deepen our understanding of molecular mechanisms in rice immunity and offer a novel strategy for genetic improvement of rice disease resistance. [ABSTRACT FROM AUTHOR]

Summary: Plants typically activate distinct defense pathways against various pathogens. Heightened resistance to one pathogen often coincides with increased susceptibility to another pathogen. However, the underlying molecular basis of this antagonistic response remains unclear.Here, we demonstrate that mutants defective in the transcription factor ETHYLENE‐INSENSITIVE 3‐LIKE 2 (OsEIL2) exhibited enhanced resistance to the biotrophic bacterial pathogen Xanthomonas oryzae pv oryzae and to the hemibiotrophic fungal pathogen Magnaporthe oryzae, but enhanced susceptibility to the necrotrophic fungal pathogen Rhizoctonia solani.Furthermore, necrotroph‐induced OsEIL2 binds to the promoter of OsWRKY67 with high affinity, leading to the upregulation of salicylic acid (SA)/jasmonic acid (JA) pathway genes and increased SA/JA levels, ultimately resulting in enhanced resistance.However, biotroph‐ and hemibiotroph‐induced OsEIL2 targets OsERF083, resulting in the inhibition of SA/JA pathway genes and decreased SA/JA levels, ultimately leading to reduced resistance. Our findings unveil a previously uncharacterized defense mechanism wherein two distinct transcriptional regulatory modules differentially mediate immunity against pathogens with different lifestyles through the transcriptional reprogramming of phytohormone pathway genes. [ABSTRACT FROM AUTHOR]

Very‐long‐chain fatty acids (VLCFAs) regulate biophysical properties of cell membranes to determine growth and development of eukaryotes, such as the pathogenesis of the rice blast fungus Magnaporthe oryzae. The fatty acid elongase Elo1 regulates pathogenesis of M. oryzae by modulating VLCFA biosynthesis. However, it remains unknown whether and how Elo1 associates with other factors to regulate VLCFA biosynthesis in fungal pathogens. Here, we identified Ifa38, Phs1 and Tsc13 as interacting proteins of Elo1 by proximity labelling in M. oryzae. Elo1 associated with Ifa38, Phs1 and Tsc13 on the endoplasmic reticulum (ER) membrane to control VLCFA biosynthesis. Targeted gene deletion mutants Δifa38, Δphs1 and Δtsc13 were all similarly impaired as Δelo1 in vegetative growth, conidial morphology, stress responses in ER, cell wall and membrane. These deletion mutants also displayed severe damage in cell membrane integrity and failed to organize the septin ring that is essential for penetration peg formation and pathogenicity. Our study demonstrates that M. oryzae employs a fatty acid elongase complex to regulate VLCFAs for maintaining or remodelling cell membrane structure, which is important for septin‐mediated host penetration. [ABSTRACT FROM AUTHOR]