Search

West Bengal is considered a large producer state of rice in India with an output of nearly 55.48% of total crop production of Bengal. In West Bengal, rice has grown in three different cropping seasons such as Aus (autumn rice), Aman (winter rice) and Boro (summer rice), contributing about 20.69% to the total net State Domestic Product (SDP). Rice production in West Bengal hampered by many biotic stresses mostly by stem borers [Scirphophaga incertulas (Walker, 1863), Sesamia inference (Walker, 1856), Chilo polychrysus (Meyrick, 1932), Chilo suppressalis (Meyrick, 1863)] leaf folder [Cnaphalocrocis medinalis (Guenee, 1854)], plant hoppers [Nilaparvata lugens (Stal, 1854), Sogatella furcifera (Horvath, 1899)], leaf hoppers [Nephotettix virescens (Distant, 1908), Nephotettix nigropictus (Stal, 1870)], rice hispa [Dicladispa armigera (Olivier, 1808)], rice bugs [Leptocorisa acuta (Thunberg, 1783), Leptocorisa oratorius (Fabricius, 1794), Brevennia rehi (Lindinger, 1943)], gall midge [Orseolia oryzae (Wood-Mason, 1889)], etc. Demographic parameter has shown that rice pests are greatly affecting rice host either caused directly by creating dead heart (DH), hopperburn, onion leaf, silver shoot during different stages of harvesting or by indirectly transmitting grassy stunt virus (RGSV), rice ragged stunt virus (RRSV), rice tungro viruses (RTV), rice tungro bacilliform virus (RTBV) etc. resulting 9.5% production loss. For minimize the infestation farmers use different rice varieties which provide resistance effect in pest population. For controlling rice pest population farmers mostly use chemical insecticide [e.g. fipronil, acephate, fipronil, monocrotophos] which exhibit good results against rice pests. Beside those other techniques including using biological and biochemical pesticides [neem oil, karanj oil, mahua oil, conidial suspension of M. anisopliae], pheromones [(Z)-11-hexadecinal, (Z)-9-hexadecenal], allomones [5: 1 mixture of 2-(E)-octenyl acetate and octanol 3-octenal], cultutal methods [synchronized planting, using of trap crop etc.] are effective for controlling rice pests. The population ecology based sustainable management of such pest species will support E3 strategy [Ecosystem service-based ecological engineering for ecological pest management (ESS-EE-EPM)] of pest management for successful cultivation of rice in the near future. [ABSTRACT FROM AUTHOR]

Field Experiment to validate the Biointensive IPM (BIPM) package on black rice variety "Kola Chaul" revealed that BIPM package consisting seedlings root dip with Pseudomonas fluorescens @ 2% solution; application of organic manure MUKTA @ 2 t ha-1; application of Beauveria bassiana @ 1013 spores ha-1 against sucking pests, use of bird perch (10 ha-1), 6 releases of Trichogramma japonicum @ 50,000 ha-1 at 10 days interval starting from 30 days after treatment (DAT) for stem borer and leaf folder infestation along with need based application of botanicals NSKE 5% (5 l/ l-1) could suppress the major rice pests and produce higher grain yield as compared to the farmer's practice (FP). Maximum grain yield of 3124.8 kg ha-1 and 3139.10 kg ha-1 was recorded in BIPM field as compared to 2882.6 kg ha-1 and 2897.20 kg ha-1 in farmers practice plot during 2020-21 and 2021-22, respectively. Thus, BIPM practice was observed to be superior to FP with higher benefit: cost ratio. [ABSTRACT FROM AUTHOR]

Imagine a Rice Field, seemingly healthy, yet harboring invisible foes. This paper delves into the world of crop disease detection for the Tan spot, Leaf blight, Sheath decay, Bacterial leaf rot, and False smut Dataset consists of 3546 images. The image segmentation is done by BIRCH clustering followed by GMM clustering; various texture features have been extracted through this. The classification is done using existing models such as VGG16, VGG19, RESNET50, and INCEPTION V3. After comparing various models and validation, the observation was made that VGG19 performs well compared to other models. The overall accuracy obtained for the VGG19 is 95.88.%. The achieved accuracy surpasses that of conventional backpropagation neural network models, indicating significant advancements in crop disease diagnosis. This study introduces a novel approach that opens avenues for future research in the field of deep learning for crop disease diagnosis. [ABSTRACT FROM AUTHOR]

This article explores the relationship between the fungus Ustilaginoidea virens and the WRKY transcription factor OsWRKY31 in rice plants. The researchers discovered that a specific protein, UvSec117, is a key factor in the virulence of U. virens and interacts with OsWRKY31. They also found that OsWRKY31 positively regulates rice's resistance to various diseases. Through further experiments, they identified the target genes of OsWRKY31, which are involved in induced systemic resistance and the salicylic acid/jasmonic acid signaling pathways. This research provides valuable insights into the molecular mechanisms of rice's resistance to grain-infecting pathogens and has implications for breeding disease-resistant rice varieties. [Extracted from the article]

This article, published in Frontiers in Plant Science, discusses the use of advanced AI methods for plant disease and pest recognition. The article highlights the importance of monitoring crop conditions and detecting plant diseases for sustainable agriculture. The research topic explores recent advancements in AI methods for plant disease and pest recognition, with a focus on various crops and fruits. The article also discusses the challenges and limitations in implementing these methods in real-world scenarios. Overall, the research aims to improve the accuracy and efficiency of plant disease and pest recognition in agriculture. [Extracted from the article]

The production and productivity of rice is constrained by various insect pests but very meagre information is available on the seasonal incidence of the Crambidae pests of rice in the subtropical region of Madhya Pradesh. The present study was undertaken on the seasonal incidence of Crambidae pests at the Regional Agricultural Research Station, College of Agriculture, Balaghat, Madhya Pradesh during January -May, 2022. Rice variety JRB-1 was sown in a 300 m² plot, damage of pests were recorded and correlated with the weather data. Stem borer damage manifested in the form of deadhearts and white ears, started from second fortnight of February and gradually increased till late April. Leaf folder incidence was observed from early March to early April. Incidence of these were found to be correlated positively with temperature and wind velocity whereas, negatively with relative humidity and rainfall. The pattern of incidence of these pests of rice in the subtropical region of central India (Balaghat, MP) were more or less similar to those of the tropics. [ABSTRACT FROM AUTHOR]

Background: Alternative polyadenylation (APA) is an important pattern of post-transcriptional regulation of genes widely existing in eukaryotes, involving plant physiological and pathological processes. However, there is a dearth of studies investigating the role of APA profile in rice leaf blight. Results: In this study, we compared the APA profile of leaf blight-susceptible varieties (CT 9737-613P-M) and resistant varieties (NSIC RC154) following bacterial blight infection. Through gene enrichment analysis, we found that the genes of two varieties typically exhibited distal poly(A) (PA) sites that play different roles in two kinds of rice, indicating differential APA regulatory mechanisms. In this process, many disease-resistance genes displayed multiple transcripts via APA. Moreover, we also found five polyadenylation factors of similar expression patterns of rice, highlighting the critical roles of these five factors in rice response to leaf blight about PA locus diversity. Conclusion: Notably, the present study provides the first dynamic changes of APA in rice in early response to biotic stresses and proposes a possible functional conjecture of APA in plant immune response, which lays the theoretical foundation for in-depth determination of the role of APA events in plant stress response and other life processes. [ABSTRACT FROM AUTHOR]

Classification of rice disease is one significant research topics in rice phenotyping. Recognition of rice diseases such as Bacterialblight, Blast, Brownspot, Leaf smut, and Tungro are a critical research field in rice phenotyping. However, accurately identifying these diseases is a challenging issue due to their high phenotypic similarity. To address this challenge, we propose a rice disease phenotype identification framework which utilizing the transfer learning and SENet with attention mechanism on the cloud platform. The pre-trained parameters are transferred to the SENet network for parameters optimization. To capture distinctive features of rice diseases, the attention mechanism is applied for feature extracting. Experiment test and comparative analysis are conducted on the real rice disease datasets. The experimental results show that the accuracy of our method reaches 0.9573. Furthermore, we implemented a rice disease phenotype recognition platform based microservices architecture and deployed it on the cloud, which can provide rice disease phenotype recognition task as a service for easy usage. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) are conserved noncoding small RNAs that play essential regulatory roles in gene function by regulating target genes. Pardosa pseudoannulata is an important natural predatory enemy of insect pests and plays a significant role in controlling pests in rice fields, with temperature having a significant impact on their growth and development. To understand the response of miRNAs to temperature stress in P. pseudoannulata, we performed miRNA identification analyses of adult spiders exposed to 10°C and 40°C for 12 h, as low‐temperature and high‐temperature treatment groups, respectively. We obtained 54.74 M clean reads from 69.84 M raw reads after filtering out low‐quality reads, and 78 miRNAs including 13 novel miRNAs were identified from three small RNA libraries (10°C, 25°C and 40°C). At the low temperature and the high temperature, eight (one upregulated and seven downregulated) and ten (nine upregulated and one downregulated) differentially expressed miRNAs were identified, respectively. These differentially expressed miRNAs negatively regulated 43 and 12 target mRNA (the unigenes in our previous transcriptome sequence data) in response to low‐ and high‐temperature stress, respectively. These target genes are mainly involved in translation, ribosome structure and biotransformation, as well as the generation and conversion of energy. This study represents the first report of miRNA identification related to the Araneae spider species in response to temperature stress. These results will greatly facilitate our understanding of the physiological and biochemical mechanisms of spiders in response to temperature stress, which might be beneficial for the conservation and utilization of this species as an important natural insect enemy of pests in rice ecosystems. [ABSTRACT FROM AUTHOR]

Key message: OsMKK1, a MAPK gene, positively regulates rice Xa21-mediated resistance response and also plays roles in normal growth and development process of rice. The mitogen-activated protein kinase (MAPK) cascade was highly conserved among eukaryotes, which played crucial roles in plant responses to pathogen infection. Bacterial blight is the most devastating bacterial disease. Xa21 confers broad-spectrum resistance to Xanthomonas oryzae pv. Oryzae (Xoo). This study identified that the transcription level of OsMKK1 was up-regulated in resistant response against Xoo, thus overexpression (OsMKK1-OX) and RNA interference (OsMKK1-RNAi) transgenic rice lines under the background of Xa21 was constructed. Compared with recipient control plants 4021, the OsMKK1-OX lines significantly enhanced disease resistance to Xoo, on the contrary, the resistance of OsMKK1-RNAi lines was weakened, demonstrated that OsMKK1 played a positive role in Xa21-mediated disease resistance pathway. A number of pathogenesis-related proteins, including PR1A, PR2 and PR10A showed enhanced expression in OsMKK1-OX lines, supported that these PR genes may be regulated by OsMKK1 to participate in the defense responses. In addition, the agronomic traits of OsMKK1 transgenic plants were affected. Overall, these results revealed the role of OsMKK1 in Xa21-mediated resistance against Xoo and in the normal growth and development process in rice. [ABSTRACT FROM AUTHOR]

Summary: Rice blast, the most destructive disease of cultivated rice world‐wide, is caused by the filamentous fungus Magnaporthe oryzae. To cause disease in plants, M. oryzae secretes a diverse range of effector proteins to suppress plant defense responses, modulate cellular processes, and support pathogen growth. Some effectors can be secreted by appressoria even before host penetration, while others accumulate in the apoplast, or enter living plant cells where they target specific plant subcellular compartments. During plant infection, the blast fungus induces the formation of a specialized plant structure known as the biotrophic interfacial complex (BIC), which appears to be crucial for effector delivery into plant cells. Here, we review recent advances in the cell biology of M. oryzae–host interactions and show how new breakthroughs in disease control have stemmed from an increased understanding of effector proteins of M. oryzae are deployed and delivered into plant cells to enable pathogen invasion and host susceptibility. [ABSTRACT FROM AUTHOR]

Phospholipids are important components of biological membranes, participating in various biological processes, including plant development and responses to biotic and abiotic stresses. A previous study showed that mutation of the rice OsCDS5 (CDP‐DAG Synthase) gene alters lipid metabolism, causing enhanced abiotic stress responses, yellowing of leaves at the seedling stage and delayed plant development. Here, we observed that the Oscds5 mutant shows enhanced resistance to rice blast, bacterial blight and bacterial leaf streak. Mutation of OsCDS5 promotes production of reactive oxygen species and increases the expression level of multiple defence‐related genes. Transcriptomic analyses indicate that genes involved in responses to stress, biotic/abiotic stimuli and metabolic processes are highly upregulated and enriched in mutant Oscds5. Metabolomic analyses showed that differential metabolites were enriched in the lipid metabolic and tryptophan metabolic pathways. The decreased level of phosphatidylinositol and increased level of serotonin probably contribute to enhanced disease resistance of the Oscds5 mutant. Taken together, mutation of OsCDS5 enhances abiotic and biotic stress responses, and OsCDS5 may be a promising target for genetic engineering to enhance the resilience of rice to abiotic and biotic stresses simultaneously. [ABSTRACT FROM AUTHOR]

Ustilaginoidea virens is the causal agent of rice false smut, which has recently become one of the most important rice diseases worldwide. Ustilaginoidins, a major type of mycotoxins produced in false smut balls, greatly deteriorates grain quality. Histone acetylation and deacetylation are involved in regulating secondary metabolism in fungi. However, little is yet known on the functions of histone deacetylases (HDACs) in virulence and mycotoxin biosynthesis in U. virens. Here, we characterized the functions of the HDAC UvHOS3 in U. virens. The ΔUvhos3 deletion mutant exhibited the phenotypes of retarded growth, increased mycelial branches and reduced conidiation and virulence. The ΔUvhos3 mutants were more sensitive to sorbitol, sodium dodecyl sulphate and oxidative stress/H2O2. ΔUvhos3 generated significantly more ustilaginoidins. RNA‐Seq and metabolomics analyses also revealed that UvHOS3 is a key negative player in regulating secondary metabolism, especially mycotoxin biosynthesis. Notably, UvHOS3 mediates deacetylation of H3 and H4 at H3K9, H3K18, H3K27 and H4K8 residues. Chromatin immunoprecipitation assays indicated that UvHOS3 regulates mycotoxin biosynthesis, particularly for ustilaginoidin and sorbicillinoid production, by modulating the acetylation level of H3K18. Collectively, this study deepens the understanding of molecular mechanisms of the HDAC UvHOS3 in regulating virulence and mycotoxin biosynthesis in phytopathogenic fungi. [ABSTRACT FROM AUTHOR]

Agricultural pests can be effectively controlled using microbes, providing an eco-friendly alternative to available synthetic pesticides. Suitable entomopathogenic bacterial strains were collected from agricultural fields and evaluated for their insecticidal potential against Cnaphalocrocis medinalis. In the four tested entomopathogenic bacteria (W1, Yc1, S1, EB01), the larval mortality ranged from 38 to 74%. Among these isolates, Bacillus subtilis (EB01) induced the highest mortality (74%). In greenhouse conditions, the tests confirm that the results were dosage-dependent: B. subtilis infection considerably delayed the overall development period, reduced pupal conversion, and decreased adult emergence with induced morphological deformities. Larvae fed B. subtilis-treated leaves initiate bacterial infection and broadly damage the midgut tissue, including the epithelial and peritrophic layers. The bacterial growth in the C. medinalis hemolymph considerably increases the activity of enzymes like α and β esterase (85.14 and 44% at 96 h) compared to the control. The isolate B. subtilis-treated diet significantly reduced the larval digestive α and β galactosidase enzyme activity (88.17 and 91.88% at 96 h). Furthermore, germination bioassay with strain EB01 in rice varieties (TN1 and ASD16) significantly increased both varieties' germination and biomass index. This study shows that the B. subtilis EB01 strain potentially inhibited the biological activity of C. medinalis and improved the rice seeds' germination index. It can be a potential biocontrol agent in sustainable pest-management strategies. [ABSTRACT FROM AUTHOR]

The article discusses a study that investigated the effectiveness of different biocontrol agents and botanical extracts against Xanthomonas oryzae pv. oryzae, the bacteria responsible for bacterial blight in rice. The study found that Bacillus subtilis and Pseudomonas fluorescens were effective in inhibiting the growth of the bacteria, while garlic extract showed the highest inhibitory effect. Other botanical extracts, such as tulsi and neem, also demonstrated effectiveness. These findings are consistent with previous research and provide valuable insights for managing bacterial blight in rice, particularly for farmers in Gujarat. [Extracted from the article]

Rice production in the Anhui province is threatened by fungal diseases. We obtained twenty-five fungal isolates from rice and wild rice leaves showing leaf spot disease collected along the Yangtze River. A phylogenetic analysis based on internal transcribed spacer (ITS), translation elongation factor 1 alpha (TEF1-α), and beta tubulin (TUB2) sequences revealed one isolate (SS-2-JB-1B) grouped with Nigrospora sphaerica, one (QY) with Nigrospora chinensis, twenty-two with Nigrospora oryzae, and one isolate (QY-2) grouped in its own clade, which are related to but clearly different from N. oryzae. Nineteen tested isolates, including sixteen strains from the N. oryzae clade and the three isolates of the other three clades, caused disease on detached rice leaves. The three isolates that did not belong to N. oryzae were also able to cause disease in rice seedlings, suggesting that they were rice pathogens. Isolate QY-2 differed from the other isolates in terms of colony morphology, cell size, and susceptibility to fungicides, indicating that this isolate represents a new species that we named Nigrospora anhuiensis. Our analysis showed that N. sphaerica, N. chinensis, and the new species, N. anhuiensis, can cause rice leaf spot disease in the field. This research provides new knowledge for understanding rice leaf spot disease. [ABSTRACT FROM AUTHOR]

Nigrospora oryzae is one of several fungal pathogens known to cause brown streaks, leaf spots, and latent infections in rice. In this study, the entire 42.09-Mb genome of N. oryzae was sequenced at a depth of 169× using the Oxford Nanopore Technologies platform. The draft genome sequence was comprised of 26 scaffolds, possessed an average GC content of 58.83%, and contained a total of 10,688 protein-coding genes. Analysis of the complete genome sequence revealed that CAZyme-encoding genes account for 6.11% of all identified genes and that numerous transcription factors (TFs) associated with diverse biological processes belong predominantly to Zn-clus (22.20%) and C2H2 (10.59%) fungal TF classes. In addition, genes encoding 126 transport proteins and 3307 pathogen–host interaction proteins were identified. Comparative analysis of the previously reported N. oryzae reference strain GZL1 genome and the genome of a representative strain ZQ1 obtained here revealed 9722 colinear genes. Collectively, these findings provide valuable insights into N. oryzae genetic mechanisms and phenotypic characteristics. [ABSTRACT FROM AUTHOR]

Mesoporous silica nanoparticles (MSNs) can be used as carrier materials for the controlled release of pesticides while reducing their negative environmental impact. In this study, we screened an active ingredient, p-cymene (PC), with an excellent inhibitory effect on rice bacterial blight. Subsequently, the PC was successfully loaded onto MSNs via physisorption (PC@MSNs). PC@MSNs, characterized by a regular spherical shape, smooth surface, and an MSN average size of 262.9 nm, achieved an 8.6% drug loading capacity. The release kinetics of the PC from the PC@MSNs demonstrated a sustained release (288 h) pattern influenced by drug diffusion. The efficacy of the PC@MSNs against Xanthomonas oryzae pv. Oryzae paralleled those of PC. Acute toxicity assays revealed that the PC@MSNs were less toxic to aquatic life (LC50 = 257.867 mg/L) and that the formulation showed no adverse effects on rice seedling growth. In summary, these results suggest that PC@MSNs can broaden PC's scope of application in managing rice diseases. [ABSTRACT FROM AUTHOR]

Simple Summary: Microbes play important roles in the biochemistry, physiology and survival of insects. An example is Arsenophonus sp. in the brown planthopper (Nilaparvata lugens), an endosymbiotic bacterium supplementing the nutritionally poor diet of its sap-feeding host. In this study, we use the genome of Nl Arsenophonus sp. as a reference to facilitate the genome assembly of a closely related Arsenophonus sp. found in the corn planthopper (Peregrinus maidis). Our assembly is one of the largest Arsenophonus genomes reported to date. We also investigated the role of Arsenophonus sp. in P. maidis, in which it appears to provide B vitamins and essential amino acids. The co-evolution between symbionts and their insect hosts has led to intricate functional interdependencies. Advances in DNA-sequencing technologies have not only reduced the cost of sequencing but, with the advent of highly accurate long-read methods, have also enabled facile genome assembly even using mixed genomic input, thereby allowing us to more easily assess the contribution of symbionts to their insect hosts. In this study, genomic data recently generated from Peregrinus maidis was used to assemble the genome of a bacterial symbiont, Pm Arsenophonus sp. This ~4.9-Mb assembly is one of the largest Arsenophonus genomes reported to date. The Benchmarking Universal Single-Copy Orthologs (BUSCO) result indicates that this Pm Arsenophonus assembly has a high degree of completeness, with 96% of the single-copy Enterobacterales orthologs found. The identity of the Pm Arsenophonus sp. was further confirmed by phylogenetic analysis. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicates a major contribution by Pm Arsenophonus sp. to the biosynthesis of B vitamins and essential amino acids in P. maidis, where threonine and lysine production is carried out solely by Pm Arsenophonus sp. This study not only provides deeper insights into the evolutionary relationships between symbionts and their insect hosts, but also adds to our understanding of insect biology, potentially guiding the development of novel pest control methods. [ABSTRACT FROM AUTHOR]

Simple Summary: The brown planthopper (BPH, Nilaparvata lugens Stål) is the most destructive pest in rice. Understanding the endosymbiont communities hosted by this insect is a prerequisite for controlling BPH rice infestations. This study reveals the diversity and dynamics of endosymbiotic fungi in the developmental stages and various tissues of BPH by means of circular consensus sequencing (CCS), and we found three dominant yeast-like symbionts (YLSs) in almost all samples and the significant biomarkers between female and male adults. This suggests that these endosymbionts are necessary for BPH survival. This study provides a comprehensive survey of symbiotic fungi in the BPH and offers new strategies for pest management in rice. Endosymbiotic fungi play an important role in the growth and development of insects. Understanding the endosymbiont communities hosted by the brown planthopper (BPH; Nilaparvata lugens Stål), the most destructive pest in rice, is a prerequisite for controlling BPH rice infestations. However, the endosymbiont diversity and dynamics of the BPH remain poorly studied. Here, we used circular consensus sequencing (CCS) to obtain 87,131 OTUs (operational taxonomic units), which annotated 730 species of endosymbiotic fungi in the various developmental stages and tissues. We found that three yeast-like symbionts (YLSs), Polycephalomyces prolificus, Ophiocordyceps heteropoda, and Hirsutella proturicola, were dominant in almost all samples, which was especially pronounced in instar nymphs 4–5, female adults, and the fat bodies of female and male adult BPH. Interestingly, honeydew as the only in vitro sample had a unique community structure. Various diversity indices might indicate the different activity of endosymbionts in these stages and tissues. The biomarkers analyzed using LEfSe suggested some special functions of samples at different developmental stages of growth and the active functions of specific tissues in different sexes. Finally, we found that the incidence of occurrence of three species of Malassezia and Fusarium sp. was higher in males than in females in all comparison groups. In summary, our study provides a comprehensive survey of symbiotic fungi in the BPH, which complements the previous research on YLSs. These results offer new theoretical insights and practical implications for novel pest management strategies to understand the BPH–microbe symbiosis and devise effective pest control strategies. [ABSTRACT FROM AUTHOR]

Calcium (Ca2+) is a versatile intracellular second messenger that regulates several signaling pathways involved in growth, development, stress tolerance, and immune response in plants. Autoinhibited Ca2+-ATPases (ACAs) play an important role in the regulation of cellular Ca2+ homeostasis. Here, we systematically analyzed the putative OsACA family members in rice, and according to the phylogenetic tree of OsACAs, OsACA9 was clustered into a separated branch in which its homologous gene in Arabidopsis thaliana was reported to be involved in defense response. When the OsACA9 gene was knocked out by CRISPR/Cas9, significant accumulation of reactive oxygen species (ROS) was detected in the mutant lines. Meanwhile, the OsACA9 knock out lines showed enhanced disease resistance to both rice bacterial blight (BB) and bacterial leaf streak (BLS). In addition, compared to the wild-type (WT), the mutant lines displayed an early leaf senescence phenotype, and the agronomy traits of their plant height, panicle length, and grain yield were significantly decreased. Transcriptome analysis by RNA-Seq showed that the differentially expressed genes (DEGs) between WT and the Osaca9 mutant were mainly enriched in basal immune pathways and antibacterial metabolite synthesis pathways. Among them, multiple genes related to rice disease resistance, receptor-like cytoplasmic kinases (RLCKs) and cell wall-associated kinases (WAKs) genes were upregulated. Our results suggest that the Ca2+-ATPase OsACA9 may trigger oxidative burst in response to various pathogens and synergically regulate disease resistance and leaf senescence in rice. [ABSTRACT FROM AUTHOR]

Rice which is a staple food crop in most Asian countries mainly suffers from higher yield loss due to different factors, and one of the common factors that affect rice yield is rice leaf disease. Many countries do not allow the plantation of new rice varieties unless they are disease-resistant. Hence, disease control serves as an important factor for rice production and this can be effectively accomplished by identifying the rice disease at an early stage which is required for timely pesticide application and disease control. The rice leaf diseases are mainly inspected by the farmers with their naked eye which is error-prone, time-consuming, and often leads to huge yield loss if predicted wrong. This process is effectively handled by different researchers via the use of computer vision and machine learning techniques. To overcome the drawbacks associated with manual processing and low recognition accuracy of different statistical and machine learning techniques, this paper presents a novel concept that uses 3D 2D CNN for feature extraction and an improved backtracking search (IBS) algorithm-optimized deep generative adversarial network (DGAN) for classification. The 3D2D deep convolutional neural network (DCNN) is formed by integrating the 3D fast-learning block with a 2DCNN for extracting the rice disease features such as lesions and shape. The IBS algorithm-optimized GAN architecture is used for rice disease classification and the IBS algorithm is mainly adopted to overcome the instability and overfitting issues that arise in the DGAN. The proposed IBS-optimized GAN architecture offers improved accuracy of 98.7% which is relatively higher than the existing techniques such as extreme gradient boosting (XGBoost), transfer learning techniques, and support vector machine (SVM). [ABSTRACT FROM AUTHOR]

Rice bacterial leaf streak (BLS), caused by Xanthomonas oryzae pv. oryzicola (Xoc), is a worldwide destructive rice bacterial disease, and seriously affects the global rice industry. Effective integrated management measures for BLS depend on the timely and proper detection of Xoc. Here, two highly specific and super-sensitive monoclonal antibodies (MAbs) against Xoc were first prepared using the cultured Xoc RS105 as an immunogen. Then, two serological assays, Dot enzyme-linked immunosorbent assay (Dot-ELISA) and Colloidal gold immunochromatographic strip (CGICS), were developed for the super-sensitive and broad-spectrum detection of Xoc in homogenates prepared from field-collected rice plants. The newly created Dot-ELISA and CGICS assays can detect ten different Xoc strains from various provinces in China and other countries without cross-reactivity with the other ten tested plant bacteria. Furthermore, Dot-ELISA and CGICS can detect Xoc in bacterial suspensions diluted up to 9.78 × 103 CFU/mL and 4.88 × 103 CFU/mL, respectively, or in rice plant tissue homogenates diluted up to 1:51,200 (w/v, g/mL). Surprisingly, both Dot-ELISA and CGICS serological assays were more sensitive than the conventional PCR. Additionally, analysis results using field-collected rice samples showed that the newly created Dot-ELISA and CGICS were reliable in detecting Xoc in rice tissues. Thus, the two serological assays were highly valuable and effective for the diagnosis of rice bacterial leaf streak in rice-grown areas and for inspection and quarantine of Xoc. [ABSTRACT FROM AUTHOR]

Rice bakanae disease (RBD), caused primarily by Fusarium fujikuroi in China, is a destructive seed-borne fungal disease. The sensitivity of 102 F. fujikuroi isolates to a novel demethylase inhibitor (DMI) mefentrifluconazole was measured using mycelial growth rate and spore germination methods. Besides, the effect of mefentrifluconazole on the morphology of mycelia and spores, cell membrane permeability, the integrity of cell wall and membrane, ergosterol and toxins biosynthesis of F. fujikuroi were studied. The results showed that the EC50 values of mefentrifluconazole in inhibiting mycelial growth and spore germination of F. fujikuroi ranged from 0.0305 to 0.7579 μg/mL and 0.1091 to 1.6870 μg/mL, with average EC50 values of (0.2469 ± 0.0167) μg/mL and (0.6397 ± 0.0324) μg/mL, respectively. The mycelia of F. fujikuroi were distorted, and the spores were wrinkled and flatted under the treatment of mefentrifluconazole at a concentration of corresponding EC50. Furthermore, mefentrifluconazole increased the relative conductivity of the cell membrane, disrupted the integrity of the cell wall and membrane, reduced the ergosterol content, and affected the toxins biosynthesis in F. fujikuroi. Overall, this study confirmed the biological activity of mefentrifluconazole against F. fujikuroi, providing a basis for the field control of RBD, and the scientific and rational use of mefentrifluconazole. [ABSTRACT FROM AUTHOR]

Transcription factors (TFs) play essential roles in transcriptional reprogramming during activation of plant immune responses to pathogens. OsSPL10 (SQUAMOSA promoter binding protein-like10) is an important TF regulating trichome development and salt tolerance in rice. Here we report that knockout of OsSPL10 reduces whereas its overexpression enhances rice resistance to blast disease. OsSPL10 positively regulates chitin-induced immune responses including reactive oxygen species (ROS) burst and callose deposition. We show that OsSPL10 physically associates with OsJAmyb, an important TF involved in jasmonic acid (JA) signaling, and positively regulates its protein stability. We then prove that OsJAmyb positively regulates resistance to blast. Our results reveal a molecular module consisting of OsSPL10 and OsJAmyb that positively regulates blast resistance. [ABSTRACT FROM AUTHOR]

The brown planthopper (BPH), Nilaparvata lugens (Stål), a rice-specific pest, has risen to the top of the list of significant pathogens and insects in recent years. Host plant-mediated resistance is an efficient strategy for BPH control. Nonetheless, BPH resistance in rice cultivars has succumbed to the emergence of distinct virulent BPH populations. Circular RNAs (circRNAs) play a pivotal role in regulating plant–environment interactions; however, the mechanisms underlying their insect-resistant functions remain largely unexplored. In this study, we conducted an extensive genome-wide analysis using high-throughput sequencing to explore the response of rice circRNAs to BPH infestations. We identified a total of 186 circRNAs in IR56 rice across two distinct virulence groups: IR-IR56-BPH (referring to IR rice infested by IR56-BPH) and IR-TN1-BPH, along with a control group (IR-CK) without BPH infestation. Among them, 39 circRNAs were upregulated, and 43 circRNAs were downregulated in the comparison between IR-IR56-BPH and IR-CK. Furthermore, in comparison with IR-CK, 42 circRNAs exhibited upregulation in IR-TN1-BPH, while 42 circRNAs showed downregulation. The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed that the targets of differentially expressed circRNAs were considerably enriched in a multitude of biological processes closely linked to the response to BPH infestations. Furthermore, we assessed a total of 20 randomly selected circRNAs along with their corresponding expression levels. Moreover, we validated the regulatory impact of circRNAs on miRNAs and mRNAs. These findings have led us to construct a conceptual model that circRNA is associated with the defense regulatory network in rice, which is likely facilitated by the mediation of their parental genes and competing endogenous RNA (ceRNA) networks. This model contributes to the understanding of several extensively studied processes in rice-BPH interactions. [ABSTRACT FROM AUTHOR]

BACKGROUND: Vibrational signal plays a crucial role in courtship communication in many insects. However, it remains unclear whether insect vibrational signals exhibit daily rhythmicity in response to changes in environmental cues. RESULTS: In this study, we observed daily rhythms of both female vibrational signals (FVS) and male vibrational signals (MVS) in the brown planthopper (BPH), Nilaparvata lugens (Stål), one of the most notorious rice pests across Asia. Notably, oscillations of FVS and MVS in paired BPHs were synchronized as part of male–female duetting interactions, displaying significant day‐night rhythmicity. Furthermore, we observed light dependency of FVS emissions under different photoperiodic regimes (18 L:6 D and 6 L:18 D) and illumination intensity levels (>300 lx, 50 lx, and 25 lx). Subsequently, the potential role of circadian clock genes cryptochromes (Nlcry1 and Nlcry2) in regulating FVS daily oscillations was examined using gene knockdown via RNA interference. We observed sharp declines and disrupted rhythms in FVS frequencies when either of the Nlcrys was downregulated, with Nlcry2 knockdown showing a more prominent effect. Moreover, we recorded a novel FVS variant (with a dominant frequency of 361.76 ± 4.31 Hz) emitted by dsNlcry1‐treated BPH females, which significantly diminished the impact of courtship stimuli on receptive males. CONCLUSION: We observed light‐dependent daily rhythms of substrate‐borne vibrational signals (SBVS) in BPH and demonstrated essential yet distinct roles of the two Nlcrys. These findings enhanced our understanding of insect SBVS and illustrated the potential of novel precision physical control strategies for disrupting mating behaviors in this rice pest. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa) being among the most important food crops in the world is also susceptible to various bacterial and fungal diseases that are the major stumbling blocks in the way of increased production and productivity. The bacterial leaf blight caused by Xanthomonas oryzae pv. oryzae and the sheath blight disease caused by Rhizoctonia solani are among the most devastating diseases of the rice crop. In spite of the availability of array of chemical control, there are chances of development of resistance. Thus, there is a need for the nanotechnological intervention for management of disease in the form of copper and silver nano-composites. The copper (CuNPs) and silver nanoparticles (AgNPs) were synthesized using green route and characterized using different high throughput techniques, i.e., UV–Vis, FT-IR, DLS, XRD, FE-SEM, TEM. The particle size and zeta potential of synthesized CuNPs and AgNPs were found 273 nm and − 24.2 mV; 95.19 nm and − 25.5 mV respectively. The nanocomposite of CuNPs and AgNPs were prepared having particle size in the range of 375–306 nm with improved stability (zeta potential − 54.7 to − 39.4 mV). The copper and silver nanoparticle composites evaluated against Xanthomonas oryzae pv. oryzae and Rhizoctonia solani were found to have higher antibacterial (inhibition zone 13 mm) and antifungal activities (77%) compared to only the copper nanoparticle (8 mm; 62% respectively). Net house trials of nano-composite formulations against the bacterial blight of rice also corroborated the potential of nanocomposite formulation. In silico studies were carried out selecting two disease-causing proteins, peptide deformylase (Xanthomonas oryzae) and pectate lyase (Rhizoctonia solani) to perform the molecular docking. Interaction studies indicatedthat both of these proteins generated better complex with CuNPs than AgNPs. The study suggested that the copper and silver nano-composites could be used for developing formulations to control these devastating rice diseases. [ABSTRACT FROM AUTHOR]

Rice leaf folder, Cnaphalocrocis medinalis (Guenée), is one of the most serious pests on rice. At present, chemical control is the main method for controlling this pest. However, the indiscriminate use of chemical insecticides has non-target effects and may cause environmental pollution. Besides, leaf curling behavior by C. medinalis may indirectly reduce the efficacy of chemical spray. Therefore, it is crucial to cultivate efficient rice varieties resistant to this pest. Previous studies have found that three different rice varieties, Zhongzao39 (ZZ39), Xiushui134 (XS134), and Yongyou1540 (YY1540), had varying degrees of infestation by C. medinalis. However, it is currently unclear whether the reason for this difference is related to the difference in defense ability of the three rice varieties against the infestation of C. medinalis. To explore this issue, the current study investigated the effects of three rice varieties on the growth performance and food utilization capability of the 4th instar C. medinalis. Further, it elucidated the differences in defense responses among different rice varieties based on the differences in leaf physiological and biochemical indicators and their impact on population occurrence. The results showed that the larval survival rate was the lowest, and the development period was significantly prolonged after feeding on YY1540. This was not related to the differences in leaf wax, pigments, and nutritional components among the three rice varieties nor to the feeding preferences of the larvae. The rate of superoxide anion production, hydrogen peroxide content, and the activity of three protective enzymes were negatively correlated with larval survival rate, and they all showed the highest in YY1540 leaves. Compared to other tested varieties, although the larvae feeding on YY1540 had higher conversion efficiency of ingested food and lower relative consumption rate, their relative growth was faster, indicating stronger food utilization capability. However, they had a lower accumulation of protein. This suggests that different rice varieties had different levels of oxidative stress after infestation by C. medinalis. The defense response of YY1540 was more intense, which was not conducive to the development of the larvae population. These results will provide new insights into the interaction mechanism between different rice varieties and C. medinalis and provide a theoretical basis for cultivating rice varieties resistant to this pest. [ABSTRACT FROM AUTHOR]

Reactive oxygen species (ROS) act as a group of signaling molecules in rice functioning in regulation of development and stress responses. Respiratory burst oxidase homologues (Rbohs) are key enzymes in generation of ROS. However, the role of the nine Rboh family members was not fully understood in rice multiple disease resistance and yield traits. In this study, we constructed mutants of each Rboh genes and detected their requirement in rice multiple disease resistance and yield traits. Our results revealed that mutations of five Rboh genes (RbohA, RbohB, RbohE, RbohH, and RbohI) lead to compromised rice blast disease resistance in a disease nursery and lab conditions; mutations of five Rbohs (RbohA, RbohB, RbohC, RbohE, and RbohH) result in suppressed rice sheath blight resistance in a disease nursery and lab conditions; mutations of six Rbohs (RbohA, RbohB, RbohC, RbohE, RbohH and RbohI) lead to decreased rice leaf blight resistance in a paddy yard and ROS production induced by PAMPs and pathogen. Moreover, all Rboh genes participate in the regulation of rice yield traits, for all rboh mutants display one or more compromised yield traits, such as panicle number, grain number per panicle, seed setting rate, and grain weight, resulting in reduced yield per plant except rbohb and rbohf. Our results identified the Rboh family members involved in the regulation of rice resistance against multiple pathogens that caused the most serious diseases worldwide and provide theoretical supporting for breeding application of these Rbohs to coordinate rice disease resistance and yield traits. [ABSTRACT FROM AUTHOR]

Rice straighthead disease substantially reduces crop yield, posing a significant threat to global food security. Dimethylarsinic acid (DMA) is the causal agent of straighthead disease and is highly toxic to the reproductive tissue of rice. However, the precise physiological mechanism underlying DMA toxicity remains unknown. In this study, six rice varieties with varying susceptibility to straighthead were utilized to investigate the growth performance and element distribution in rice panicles under DMA stress through pot experiments, as well as to explore the physiological response to DMA using transcriptomic methods. The findings demonstrate significant variations in both DMA accumulation and straighthead sensitivity among cultivars. The susceptible varieties exhibited higher DMA accumulation indices and displayed typical symptoms of straighthead disease, including erect panicles, deformed rachides and husks, and reduced seed setting rate and grain yield when compared to the resistant varieties. Moreover, DMA addition promoted mineral nutrients to accumulate in rachides and husks but less in grains. DMA showed preferential accumulation in rice grains with a distribution pattern similar to that of Copper (Cu) and zinc (Zn) within the panicle. Transcriptome analyses underscored the substantial impact of DMA on gene expression related to mineral metabolism. Notably, DMA addition significantly up‐regulated the expression of pectin methylesterase, pectin lyase, polygalacturonase, and exogalacturonase genes in Nanjingxiangzhan, while these genes were down‐regulated or weakly expressed in Ruanhuayou 1179. The alteration of pectin metabolic pathways induced by DMA may lead to abnormality of cell wall assembly and modification, thereby resulting in deformed rice panicles. [ABSTRACT FROM AUTHOR]

The rice blast fungus Magnaporthe oryzae devastates cultivated rice (Oryza sativa L.), causing extensive crop losses. Despite being a major pathogen, information on this pathosystem, especially on the proteins associated with fungal pathogenicity and host defense response, is relatively scarce. Utilizing liquid chromatography‐mass spectrometry (LC–MS/MS), we identified 123 in planta‐secreted M. oryzae proteins in rice leaves and screened for their cell death‐inducing activity. Biochemical characterization of these M. oryzae proteins revealed an endo‐1,4‐beta‐xylanase (MoXYL1), which induces cell death in Nicotiana benthamiana leaves and H2O2 accumulation in rice suspension‐cultured cells. Transgenic rice plants (PDUF26::MoXYL1) expressing MoXYL1 driven by rice DOMAIN OF UNKNOWN FUNCTION PROTEIN 26 (DUF26) promoter enhanced expression of pathogen‐responsive and hormone‐related genes, and resistance to the M. oryzae and Cochliobolus miyabeanus. Data‐independent acquisition (DIA) MS‐based proteomics of wild‐type and PDUF26::MoXYL1 rice revealed 1,833 significantly modulated rice proteins upon M. oryzae infection. Among these, 219 proteins showed a significant increased abundance exclusively in PDUF26::MoXYL1 transgenic rice, while 410 proteins showed increased abundance in both wild‐type and PDUF26::MoXYL1. Notably, xylanase inhibitor proteins, pathogenesis‐related proteins, and other proteins associated with jasmonic acid biosynthesis exhibited increased abundance in response to M. oryzae. Based on these results, we proposed a putative signaling network induced by MoXYL1 and M. oryzae. In summary, our findings highlight the crucial role of MoXYL1 in inducing rice defense and in potentially enhancing rice disease resistance against fungal pathogens. [ABSTRACT FROM AUTHOR]

Rice blast is a disastrous fungal disease affecting rice (Oryza sativa L.) and undermines world food security. Different ecological conditions and genetic backgrounds altered the effectiveness of rice blast resistance genes. Anhui (China) is a high‐incidence area and has long been affected by rice blast. Despite chemical or other control methods of rice blast, analyzing the effects of specific rice blast resistance genes within the Anhui region, identifying favorable genes (combinations), and incorporating them into the process of new variety selection and breeding programs are effective ways to improve rice blast resistance. This research study examined the distribution of 16 rice blast resistance genes (i.e., Pi‐ta, Pi5, Pi1, Pia, etc.) in a recombinant self‐cross population of japonica rice and analyzed their correlation to panicle neck blast resistance. Five genes, Pit, Pi‐ta, Pik, Pb1, and Pi54, were identified and evaluated as dominant genes to improve panicle neck blast resistance. Further comparisons of the neck blast resistance levels between various gene combinations revealed that Pi54, when combined with Pb1/Pi‐ta (Pi54 + Pb1, Pi54 + Pi‐ta), could further increase resistance to panicle neck blast; and the highest resistance level was found with the three‐gene combination of Pi54 + Pi‐ta + Pb1. Meanwhile, the neck blast resistance capacity of Pi54 and Pb1 was significantly improved after polymerization with Pit and Pik (Pik + Pi54, Pit + Pi54, Pit + Pb1). Therefore, gene polymerization is widely regarded as a successful strategy to breed varieties with long‐lasting and broad‐spectrum resistance. It is anticipated that rice blast tolerance capacity will be considerably improved by gene polymerization of dominant genes. [ABSTRACT FROM AUTHOR]

Rice is a staple meal that helps people worldwide access sufficient food. However, this crop has several illnesses, significantly lowering its production and quality. Because of this, it is imperative to conduct early disease detection to halt the spread of infections. Because of this, it is desirable to develop an automatic system that will help agronomists, pathologists, and indeed growers in directly diagnosing rice diseases. This would allow for preventative measures to be done as quickly as feasible. In this day and age of artificial intelligence, researchers have experimented with various learning approaches to discover diseases that can affect rice plants. Deep learning has recently seen considerable use in many computer vision and image analysis fields, becoming one of the most prominent machine learning algorithms. Deep learning has also recently found substantial usage in many computer vision and picture analysis fields. On the other hand, deep learning methods have seen very little application in plant disease recognition, except for some ongoing research centered on the problem and using a public dataset of pictures magnified to show plant leaves. Because of their high computational complexity, which requires a huge memory cost, and the complexity of experimental materials' backgrounds, which makes it difficult to train an efficient model, deep learning methods have only seen limited use in plant disease recognition. This is due to several factors, including the following: The Inception module was improved to recognise and detect rice plant illnesses in this research by substituting the original convolutions with architecture based on modified-Xception (M-Xception). In addition, ResNet extracts features by prioritising logarithm calculations over softmax calculations to get more consistent classification outcomes. The model's training utilised a two-stage transfer learning process to produce an effective model. The results of the experiments reveal that the suggested approach can achieve the specified level of performance, with an average recognition fineness of 99.73% on the public dataset and 98.05% on the domestic dataset, respectively. Our proposed work is better as per existing methods and models. [ABSTRACT FROM AUTHOR]

The development and commercialization of new chemical classes of insecticides are important for efficient crop protection, particularly for combatting insecticide resistance and providing sustainable agricultural production. This study reports on oxazosulfyl, a novel "sulfyl" class of insecticide, against a wide range of insect pests of rice. In the laboratory assay, oxazosulfyl showed insecticidal activity against all developmental stages of the brown planthopper Nilaparvata lugens (Stål). Phosphor imaging assays and soil drench bioassays demonstrated good systemic distribution in rice plants. Oxazosulfyl showed insecticidal activity against imidacloprid- and fipronil-resistant field populations of N. lugens, the white-backed planthopper Sogatella furcifera (Horváth), and the small brown planthopper Laodelphax striatellus (Fallén), as well as the respective susceptible strains. No cross-resistance was observed among oxazosulfyl, imidacloprid, and fipronil. Oxazosulfyl with a wide insecticidal spectrum is a potentially useful pest management tool for sustainable rice production. [ABSTRACT FROM AUTHOR]

Stability and delivery are major challenges associated with exogenous double‐stranded RNA (dsRNA) application into plants. We report the encapsulation and delivery of dsRNA in cationic poly‐aspartic acid‐derived polymer (CPP6) into plant cells. CPP6 stabilizes the dsRNAs during long exposure at varied temperatures and pH, and protects against RNase A degradation. CPP6 helps dsRNA uptake through roots or foliar spray and facilitates systemic movement to induce endogenous gene silencing. The fluorescence of Arabidopsis GFP‐overexpressing transgenic plants was significantly reduced after infiltration with gfp‐dsRNA‐CPP6 by silencing of the transgene compared to plants treated only with gfp‐dsRNA. The plant endogenous genes flowering locus T (FT) and phytochrome interacting factor 4 (PIF4) were downregulated by a foliar spray of ft‐dsRNA‐CPP6 and pif4‐dsRNA‐CPP6 in Arabidopsis, with delayed flowering and enhanced biomass. The rice PDS gene targeted by pds‐dsRNA‐CPP6 through root uptake was effectively silenced and plants showed a dwarf and albino phenotype. The NaCl‐induced OsbZIP23 was targeted through root uptake of bzip23‐dsRNA‐CPP6 and showed reduced transcripts and seedling growth compared to treatment with naked dsRNA. The negative regulators of plant defence SDIR1 and SWEET14 were targeted through foliar spray to provide durable resistance against bacterial leaf blight disease caused by Xanthomonas oryzae pv. oryzae (Xoo). Overall, the study demonstrates that transient silencing of plant endogenous genes using polymer‐encapsulated dsRNA provides prolonged and durable resistance against Xoo, which could be a promising tool for crop protection and for sustaining productivity. [ABSTRACT FROM AUTHOR]

Auxin plays a pivotal role in the co‐evolution of plants and microorganisms. Xanthomonas oryzae pv. oryzicola (Xoc) stands as a significant factor that affects rice yield and quality. However, the current understanding of Xoc's capability for indole 3‐acetic acid (IAA) synthesis and its mechanistic implications remains elusive. In this study, we performed a comprehensive genomic analysis of Xoc strain RS105, leading to the identification of two nitrilase enzyme family (NIT) genes, designated as AKO15524.1 and AKO15829.1, subsequently named NIT24 and NIT29, respectively. Our investigation unveiled that the deletion of NIT24 and NIT29 resulted in a notable reduction in IAA synthesis capacity within RS105, thereby impacting extracellular polysaccharide production. This deficiency was partially ameliorated through exogenous IAA supplementation. The study further substantiated that NIT24 and NIT29 have nitrilase activity and the ability to catalyse IAA production in vitro. The lesion length and bacterial population statistics experiments confirmed that NIT24 and NIT29 positively regulated the pathogenicity of RS105, suggesting that NIT24 and NIT29 may regulate Xoc invasion by affecting IAA synthesis. Furthermore, our analysis corroborated mutant strains, RS105_ΔNIT24 and RS105_ΔNIT29, which elicited the outbreak of reactive oxygen species, the deposition of callose and the upregulation of defence‐related gene expression in rice. IAA exerted a significant dampening effect on the immune responses incited by these mutant strains in rice. In addition, the absence of NIT24 and NIT29 affected the growth‐promoting effect of Xoc on rice. This implies that Xoc may promote rice growth by secreting IAA, thus providing a more suitable microenvironment for its own colonization. In summary, our study provides compelling evidence for the existence of a nitrilase‐dependent IAA biosynthesis pathway in Xoc. IAA synthesis‐related genes promote Xoc colonization by inhibiting rice immune defence response and affecting rice growth by increasing IAA content in Xoc. [ABSTRACT FROM AUTHOR]

Rhizoctonia solani AG‐1 IA causes a necrotrophic rice disease and is a serious threat to rice production. To date, only a few effectors have been characterized in AG‐1 IA. We previously identified RsIA_CtaG/Cox11 and showed that infiltration of the recombinant protein into rice leaves caused disease‐like symptoms. In the present study, we further characterized the functionality of RsIA_CtaG/Cox11. RsIA_CtaG/Cox11 is an alternative transcript of cytochrome c oxidase copper chaperone Cox11 that starts from the second AUG codon, but contains a functional secretion signal peptide. RNA interference with RsIA_CtaG/Cox11 reduced the pathogenicity of AG‐1 IA towards rice and Nicotiana benthamiana without affecting its fitness or mycelial morphology. Transient expression of the RsIA_CtaG/Cox11‐GFP fusion protein demonstrated the localization of RsIA_CtaG/Cox11 to mitochondria. Agro‐infiltration of RsIA_CtaG/Cox11 into N. benthamiana leaves inhibited cell death by BAX and INF1. In contrast to rice, agro‐infiltration of RsIA_CtaG/Cox11 did not induce cell death in N. benthamiana. However, cell death was observed when it was coinfiltrated with Os_CoxVIIa, which encodes a subunit of cytochrome c oxidase. Os_CoxVIIa appeared to interact with RsIA_CtaG/Cox11. The cell death triggered by coexpression of RsIA_CtaG/Cox11 and Os_CoxVIIa is independent of the leucine‐rich repeat receptor kinases BAK1/SOBIR1 and enhanced the susceptibility of N. benthamiana to AG‐1 IA. Two of the three evolutionarily conserved cysteine residues at positions 25 and 126 of RsIA_CtaG/Cox11 were essential for its immunosuppressive activity, but not for cell death induction. This report suggests that RsIA_CtaG/Cox11 appears to have a dual role in immunosuppression and cell death induction during pathogenesis. [ABSTRACT FROM AUTHOR]

Rice stripe disease caused by the rice stripe virus (RSV), which infects many Poaceae species in nature, is one of the most devastating plant viruses in rice that causes enormous losses in production. Ailanthone is one of the typical C20 quassinoids synthesized by the secondary metabolism of Ailanthus altissima, which has been proven to be a biologically active natural product with promising prospects and great potential for use as a lead structure for pesticide development. Based on the achievement of the systemic infection and replication of RSV in Nicotiana benthamiana plants and rice protoplasts, the antiviral properties of Ailanthone were investigated by determining its effects on viral-coding RNA gene expression using reverse transcription polymerase chain reaction, and Western blot analysis. Ailanthone exhibited a dose-dependent inhibitory effect on RSV NSvc3 expression in the assay in both virus-infected tobacco plants and rice protoplasts. Further efforts revealed a potent inhibitory effect of Ailanthone on the expression of seven RSV protein-encoding genes, among which NS3, NSvc3, NS4, and NSvc4 are the most affected genes. These facts promoted an extended and greater depth of understanding of the antiviral nature of Ailanthone against plant viruses, in addition to the limited knowledge of its anti-tobacco mosaic virus properties. Moreover, the leaf disc method introduced and developed in the study for the detection of the antiviral activity of Ailanthone facilitates an available and convenient screening method for anti-RSV natural products or synthetic chemicals. [ABSTRACT FROM AUTHOR]

The rice blast fungus Magnaporthe oryzae is a devastating plant pathogen that threatens rice production worldwide. Host‐induced gene silencing (HIGS) has been effectively applied to study pathogenic gene function during host–microbe interactions and control fungal diseases in various crops. In this study, the HIGS system of M. oryzae was established using transgenic fungus expressing green fluorescence protein (GFP), KJ201::eGFP and 35S::dsRNAi plants, which produce small interfering RNAs targeting fungal genes. Through this system, we verified the HIGS of rice blast fungus quantitatively and qualitatively in both Arabidopsis and rice. Then, we showed that the HIGS of M. oryzae's pathogenic genes, including RGS1, MgAPT2 and LHS1, significantly alter its virulence. Both 35S::dsRNAi_MgAPT2 and 35S::dsRNAi_LHS1 plants showed a considerably enhanced fungal resistance, characterized by the formation of H2O2‐containing defensive granules and induction of rice pathogenesis‐related (PR) genes. In addition, the enhanced susceptibility of 35S::dsRNAi_RGS1 plants to blast fungus suggested a novel mode of action of this gene during fungal infection. Overall, the results of this study demonstrate that HIGS is a very effective and efficient biological tool not only to accurately characterize the functions of fungal pathogenic genes during rice‐M. oryzae interactions, but also to control fungal disease and ensure a successful rice production. Summary statement: This study demonstrates that host‐induced gene silencing (HIGS) is effective in generating fungus‐resistant crops and characterizing the biological functions of fungal pathogenic genes during plant–microbe interactions. We verified the cross‐kingdom movement of small interfering RNAs from host plants to Magnaporthe oryzae and the silencing of fungal genes. The HIGS of three M. oryzae pathogenic genes, RGS1, MgAPT2 and LHS1, significantly modified the virulence of the fungus suggesting that the functions of these genes are involved in determining the types of plant–microbe interactions, that is, whether they are compatible or incompatible. [ABSTRACT FROM AUTHOR]

South Sulawesi is one of the largest rice production centers in Indonesia. Several important diseases of rice plants, such as those caused by viruses and phytoplasmas, can be transmitted by insect vectors, especially leafhoppers and planthoppers. Symptoms of diseases caused by viruses and phytoplasmas are quite diverse but visually similar and difficult to distinguish. This study aimed to analyze the presence of phytoplasma associated with whitebacked planthopper which are commonly found in rice plantations. The research was done by conducting surveys and explorations of insect samples from six villages in Sidrap District. White-back planthoppers found on rice plantations showing symptoms of yellowing and stunted leaves were sampled for further analysis, including total DNA isolation of insects, standard PCR amplification for insect and Nested-PCR for phytoplasma identification, gene sequencing for both amplicons, and nucleotide analysis. The PCR with CO1 primer successfully amplified a 700 bp amplicon from insects, whereas nested-PCR using fP1/rP7 primers followed by m23SR/R16F2n amplified around 1800 bp and 1250 bp of supposedly 16S RNA gene of phytoplasma, respectively. Results of DNA sequencing analysis identified the insect samples as Sogatella vibix based on 83% homology using BLAST and Mega X Program. As for the phytoplasma, it leans towards the 16SrI group or Candidatus phytoplasma asteris (Aster yellows phytoplasma) with a homology percentage of 99%. [ABSTRACT FROM AUTHOR]

Villosiclava virens (anamorph: Ustilaginoidea virens) is the pathogen of rice false smut (RFS), which is a destructive rice fungal disease. The albino strain LN02 is a natural white-phenotype mutant of V. virens due to its incapability to produce toxic ustilaginoidins. In this study, three strains including the normal strain P1, albino strain LN02, and complemented strain uvpks1C-1 of the LN02 strain were employed to investigate the activation of the ustilaginoidin biosynthesis gene uvpks1 in the albino strain LN02 to influence sporulation, conidia germination, pigment production, stress responses, and the inhibition of rice seed germination. The activation of the ustilaginoidin biosynthesis gene uvpks1 increased fungal tolerances to NaCl-induced osmotic stress, Congo-red-induced cell wall stress, SDS-induced cell membrane stress, and H2O2-induced oxidative stress. The activation of uvpks1 also increased sporulation, conidia germination, pigment production, and the inhibition of rice seed germination. In addition, the activation of uvpks1 was able to increase the mycelial growth of the V. virens albino strain LN02 at 23 °C and a pH from 5.5 to 7.5. The findings help in understanding the effects of the activation of uvpks1 in albino strain LN02 on development, pigment production, stress responses, and the inhibition of rice seed germination by controlling ustilaginoidin biosynthesis. [ABSTRACT FROM AUTHOR]

Sheath blight (ShB) disease, caused by Rhizoctonia solani Kühn, is one of the most serious rice diseases. Rice breeding against ShB has been severely hindered because no major resistance genes or germplasms are available in rice. Here, we report that introduction of Gastrodia antifungal protein (GAFP) genes from Gastrodia elata B1 into rice significantly enhances resistance to rice ShB. Four GAFP genes were cloned from G. elata B1, and all displayed a strong ability to inhibit R. solani growth in plate assays. Two versions, with or without a signal peptide, for each of the four GAFP genes were introduced into XD3 and R6547 rice cultivars, and all transgenic lines displayed stronger ShB resistance than the corresponding wild-type control in both greenhouse and field conditions. Importantly, GAFP2 showed the highest ShB resistance; GAFPs with and without its signal peptide showed no significant differences in enhancing ShB resistance. We also evaluated the agronomic traits of these transgenic rice and found that ectopic expression of GAFPs in rice at appropriate levels did not affect agronomic traits other than enhancing ShB resistance. Together, these results indicate that GAFP genes, especially GAFP2, have great potential in rice breeding against ShB disease. [ABSTRACT FROM AUTHOR]

Summary: Rice false smut caused by Ustilaginoidea virens is a devastating rice (Oryza sativa) disease worldwide. However, the molecular mechanisms underlying U. virens–rice interactions are largely unknown. In this study, we identified a secreted protein, Uv1809, as a key virulence factor. Heterologous expression of Uv1809 in rice enhanced susceptibility to rice false smut and bacterial blight. Host‐induced gene silencing of Uv1809 in rice enhanced resistance to U. virens, suggesting that Uv1809 inhibits rice immunity and promotes infection by U. virens. Uv1809 suppresses rice immunity by targeting and enhancing rice histone deacetylase OsSRT2‐mediated histone deacetylation, thereby reducing H4K5ac and H4K8ac levels and interfering with the transcriptional activation of defence genes. CRISPR‐Cas9 edited ossrt2 mutants showed no adverse effects in terms of growth and yield but displayed broad‐spectrum resistance to rice pathogens, revealing a potentially valuable genetic resource for breeding disease resistance. Our study provides insight into defence mechanisms against plant pathogens that inactivate plant immunity at the epigenetic level. [ABSTRACT FROM AUTHOR]

Sheath rot is a widespread rice disease that affects rice crops worldwide. It is particularly prevalent in Ethiopia, with the Fogera plains exhibiting the highest incidence and severity. However, the lack of reliable molecular‐level identification of rice fungal pathogens in Ethiopia has hindered the development of effective management practices. This study aimed to assess the diversity of fungal agents causing sheath rot disease in rice crops around the Fogera plains, Ethiopia, using both morphology and nucleotide sequences of the ITS1 rDNA region. Additionally, the pathogenicity of the isolates was evaluated using attached tiller assay methods. A total of 16 fungal isolates were recovered from diseased plant samples. Among these, five species; Phoma spp., Phoma herbarium, Epicoccum sorghinum, Epicoccum lantuscollum and Microdochium seminicola were identified and reported as new records of sheath rot disease in rice. The predominant genus was Phoma (75%) followed by Epicoccum (18.75%). The pathogenicity caused by E. sorghinum was particularly severe and significantly different from the symptoms caused by other isolates, resulting in a mean lesion length of 167.7 mm and a disease severity of 55.7%. These findings suggest that E. sorghinum is the most important rice pathogen in the region. Our results have identified the most predominant and pathogenic fungal species associated with sheath rot disease in the region. Importantly, this study marks the first report of sheath rot‐causing fungi identified in rice using the ITS rDNA‐sequencing technique in Ethiopia. Therefore, this research may contribute to the development of fungal disease management strategies in rice and provide evidence to initiate a rice breeding program focused on developing sheath‐rot‐resistant rice varieties. [ABSTRACT FROM AUTHOR]

Deep convolutional neural network (DCNN) has recently made significant strides in the classification and recognition of rice leaf disease. The majority of classification models perform disease image recognitions using collocation patterns including pooling layers, convolutional layers, and fully connected layers, followed by repeating this structure to complete depth increase. However, the key information of the lesion area is locally limited. That is to say, in the case of only performing feature extraction according to the above-mentioned model, redundant and low-correlation image feature information with the lesion area will be received, resulting in low accuracy of the model. For improvement of the network structure and accuracy promotion, here we proposed a double-branch DCNN (DBDCNN) model with a convolutional block attention module (CBAM). The results show that the accuracy of the classic models VGG-16, ResNet-50, ResNet50+CBAM, MobileNet-V2, GoogLeNet, EfficientNet-B1 and Inception-V2 is lower than the accuracy of the model in this paper (98.73%). Collectively, the DBDCNN model here we proposed might be a better choice for classification and identification of rice leaf diseases in the future, based on its novel identification strategy for crop disease diagnosis. [ABSTRACT FROM AUTHOR]

Pantoea dispersa is a plant-associated bacterium that often has beneficial effects on plants. In this study, we demonstrated that P. dispersa BB1, a previously identified potential biocontrol agent against the seedling rot pathogen Burkholderia glumae, could effectively suppress the symptoms of seedling blight caused by Burkholderia plantarii. To facilitate the isolation and utilization of P. dispersa as a biocontrol agent, a comparative genome analysis was performed to develop novel PCR primer sets for specifically detecting P. dispersa genes. Among the developed primer sets, the Pd725 set could detect 0.3 pg of genomic DNA of P. dispersa and evaluate the colonization of P. dispersa in plants. Using this primer set, we demonstrated that the colonization of P. dispersa in rice seeds infected with B. glumae and B. plantarii was significantly higher than that in non-infected seeds. This suggested that infection by Burkholderia pathogens promoted the colonization of P. dispersa. The Pd725 primer set could serve as a valuable tool for monitoring the colonization of P. dispersa in crops and evaluating potential new biocontrol strains. [ABSTRACT FROM AUTHOR]