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A unique genetic variation with respect to blast resistance was clarified in 201 rice accessions from Vietnam. These accessions were classified into three clusters—A, B1, and B2—based on their reactions to 26 standard differential blast isolates selected in Vietnam. Cluster A was the dominant cultivar group in Vietnam and the most susceptible of the three clusters. Cluster B1 was the smallest group and the most resistant. Cluster B2 was the second-most dominant group and of intermediate resistance between clusters A and B1. The percentages of accessions comprising each cluster varied by region and area. Accessions in cluster A were distributed widely throughout Vietnam and had the highest frequencies in both the Central and North regions. Accessions in cluster B2 were found with highest frequencies in the mountainous and intermediate areas of the North region. Accessions in cluster B1 were found with highest frequencies in the Central region and Red River Delta area (North region). These results suggest that rice accessions in Vietnam were basically susceptible (cluster A) or of intermediate resistance (cluster B2), and that high-resistance cultivars were mainly distributed in the low altitude areas, such as the Red River Delta area and Central region.

Plant growth-promoting endophytic microbes have drawn the attention of researchers owing to their ability to confer fitness benefits in many plant species. Here, we report agriculturally beneficial traits of rice-leaf-adapted endophytic Microbacterium testaceum. Our polyphasic taxonomic investigations revealed its identity as M. testaceum. The bacterium displayed typical endophytism in rice leaves, indicated by the green fluorescence of GFP-tagged M. testaceum in confocal laser scanning microscopy. Furthermore, the bacterium showed mineral solubilization and production of IAA, ammonia, and hydrolytic enzymes. Tobacco leaf infiltration assay confirmed its non-pathogenic nature on plants. The bacterium showed antifungal activity on Magnaporthe oryzae, as exemplified by secreted and volatile organic metabolome-mediated mycelial growth inhibition. GC-MS analysis of the volatilome of M. testaceum indicated the abundance of antimicrobial compounds. Bacterization of rice seedlings showed phenotypic traits of MAMP-triggered immunity (MTI), over-expression of OsNPR1 and OsCERK, and the consequent blast suppressive activity. Strikingly, M. testaceum induced the transcriptional tradeoff between physiological growth and host defense pathways as indicated by up- and downregulated DEGs. Coupled with its plant probiotic features and the defense elicitation activity, the present study paves the way for developing Microbacterium testaceum-mediated bioformulation for sustainably managing rice blast disease.

Rice is the most important food crop and directly feeding more people than any other crop in the world.The blast disease caused by Pyricularia oryzae is a major and foremost constraint in rice production.Use of tricyclazole fungicide is one of the best and cost effective ways to quickly manage the disease. Considering the extensive use of fungicide has adverse effects for environment, the present study has been conducted to know the effect of Tricyclazole and Pseudomonas fluorescens alone and various combinations during rabi 2015-2016 and 2016-2017. From the two years data, the results indicated that a spray schedule consisting of tricyclazole followed by an alternate spray of Pseudomonas fluorescens (T + P + T + P), as well as either seed treatment with tricyclazole at 0.1 percent or root dipping with P. fluorescens at 1%, effectively reduced both leaf blast and neck blast with increasing grain yield.

Magnaporthe oryzae is the causal agent of rice blast disease resulting in yield losses in rice-growing regions worldwide, particularly in Vietnam. Up-regulation of osa-miR7695 was observed in blast resistant rice cultivars in comparison with blast non-resistant rice cultivars. The OsNramp6 gene is a target for osa-miR7695, and considered a factor involved in rice immunity but scant evidence has demonstrated systematic expression profiles of OsNramp6 transcript variants involving M. oryzae susceptibility and resistance of rice plants. In this study, a real-time qPCR (qRT-PCR) approach was used to evaluate the expression levels of eight OsNramp6 transcript variants in various Vietnamese rice cultivars. Results indicated that OsNramp6.1 and OsNramp6.4 transcript variants showed decreased expression levels at 24 hpi in M. oryzae resistant rice cultivars and vice versa in the rice group of M. oryzae resistance, suggesting that both could be used as potential markers for discrimination between blast resistant and non-resistant Vietnamese rice cultivars. Identification of potential microRNAs in rice that contribute to the regulation of OsNramp6 transcripts-mediated facilitation of infection by M. oryzae has still to be confirmed for elucidating their roles in rice immunity against M. oryzae.

Perbaikan galur padi gogo dihadapkan pada adanya keragaman sifat fisik dan ekobiologis lahan kering, antara lain lahan kering masam. Alternatif pendekatan optimalisasi budidaya padi gogo di lahan kering masam adalah dengan pemilihan varietas yang adaptif. Tujuan penelitian ini untuk memperoleh sejumlah galur padi gogo yang memiliki keragaan dan hasil unggul di lahan kering masam, serta bermutu beras baik. Sebanyak 36 galur padi gogo dan empat varietas pembanding diseleksi di Kebun Percobaan Tamanbogo, Lampung pada musim hujan November 2017-Maret 2018. Pendugaan parameter genetik menunjukkan keragaman genetik luas berbanding lurus dengan nilai heritabilitas tinggi. Umur berbunga, umur panen, bobot 1,000 butir gabah dan hasil dapat dijadikan sebagai kriteria seleksi galur padi gogo di lahan kering masam. Berdasarkan kriteria seleksi tersebut terpilih empat galur, yaitu B15231-MR-10-1, B15053F-PWR-2, B14908C-MR-1-25-1-3 dan B15344B-TB-34. Galur-galur tersebut memiliki hasil gabah yang tidak berbeda nyata dengan varietas pembanding terbaik Inpago 8 (3.84 ton ha-1), rata-rata tahan terhadap blas daun (skor 1), sangat tahan terhadap blas leher (skor 0), dan agak toleran Al, . Keempat galur terpilih memiliki bentuk beras sedang dengan pengapuran sedikit sampai sedang (MMS-LMM), kadar amilosa 20-23% dengan tekstur nasi pulen-sedang. Satu galur terpilih, yaitu B15344B-TB-34 teridentifikasi sebagai galur beras merah. Kata kunci: kekeringan, keracunan aluminium, kriteria seleksi, mutu beras, penyakit blas

Magnaporthe oryzae, causative agent of the rice blast disease, is a major concern for the loss in yield of rice crop across the globe. It is known for its characteristic melanised dome-shaped appressorium containing a dense melanin layer. The melanised layer is of considerable importance as it is required to generate turgor pressure for initiating peg formation, consequently rupturing the plant cuticle. Various virulence factors play an important role in the disease progression as well as pathogenesis of the fungus. Some of the proteins encoded by virulence genes are associated with signalling, secondary metabolism, protein deprivation, defence responses and conidiation. The purpose of this review is to describe various fungal virulence determinants and provide insights into the molecular mechanisms that are involved in progression of the disease. Besides, the recent molecular approaches being employed to combat the rice blast have also been elaborated.

The rice blast infection triggered by Pyricularia oryzae Cav. is a grave issue restraining rice yields globally. Biological regulation has been seen as an encouraging option to such chemical fungicides. The biological control proficiency of 24 isolates of Streptomyces against P. oryzae (KT693184.1) has been examined. Analysis of defense enzymes such as polyphenol, peroxidase (PO), and total protein and phenol content was performed. The Streptomyces isolate that was determined to have maximum effectiveness was determined to be Streptomyces xantholiticus. The sequence was sent to the NCBI vide accession number MW029942. The S. xantholiticus isolate inhibited P. oryzae 92% using dual culture tests. The greenhouse experiments showed that the disease gravity in rice plants with S. xantholiticus isolate was considerably lower compared to plants sans the treatment. The S. xantholiticus isolate was analyzed for its effects concerning the activity of polyphenol and Po enzymes as well as the total protein content present in rice leaves under greenhouse conditions in both presence and absence of P. oryzae. It was found that rice species treated with the S. xantholiticus isolate had enhanced resistance to the rice blast pathogen along with increasing activity levels of the polyphenol and PO enzymes. There was a direct impact on pathogen growth along with the defense response triggered in the plants as a result of the treatment.

Blast of rice caused by Pyricularia grisea (Cooke.) Sacc. (Teleomorph :Magnaporthe oryzae) is a serious disease of rice and causes considerable reduction in yield. Overdose and untimely application of chemical fungicides disturb the rice ecosystem, pollute the environment and induce resistant mutants of the pathogen. An ecofriendly integrated disease management programme should be implemented to avoid overuse of a single control method and fight against genetic resistance. Salicylic acid (0.01ml/ l) and Benzoic acid (0.01ml/ l) proved superior in inducing disease resistance among different inducers tested at Regional Agricultural Research Station, Pattambi, Palakkdad district, under Kerala Agricultural University under green house conditions. As an integrated approach, Palmarosa oil + Carbendazim and Palmarosa oil+ Salicylic acid were the most effective treatments .Compatibility studies under in vitro conditions showed that Trichoderma harzianum and fluorescent pseudomonad were compatible to each other, and also palmarosa oil and Neemazal were compatible with Trichoderma harzianum and Fluorescent pseudomonad. For the management of blast disease under field conditions with high B:C ratio, Palmarosa oil (0.1%) + Carbendazim (0.1%)was the best treatment followed by Trichoderma (2%) + Fluorescent pseudomonad (2%)+ Palmarosa oil (0.1%).

Blast, a disease caused by Magnaporthe oryzae, is a major constraint for rice production worldwide. Introgression of durable blast resistance genes into high-yielding rice cultivars has been considered a priority to control the disease. The blast resistance Pik locus, located on chromosome 11, contains at least six important resistance genes, but these genes have not been widely employed in resistance breeding since existing markers hardly satisfy current breeding needs due to their limited scope of application. In this study, two PCR-based markers, Pikp-Del and Pi1-In, were developed to target the specific InDel (insertion/deletion) of the Pik-p and Pi-1 genes, respectively. The two markers precisely distinguished Pik-p, Pi-1, and the K-type alleles at the Pik locus, which is a necessary element for functional genes from rice varieties. Results also revealed that only several old varieties contain the two genes, of which nearly half carry the K-type alleles. Therefore, these identified varieties can serve as new gene sources for developing blast resistant rice. The two newly developed markers will be highly useful for the use of Pik-p, Pi-1 and other resistance genes at the Pik locus in marker-assisted selection (MAS) breeding programs.

Global food security is threatened by rice blast disease caused by the filamentous fungus Magnaporthe oryzae. An understanding of rice resistance mechanisms is fundamental to developing strategies for disease control. In this review, we summarize recent advances in pathogen-associated molecular pattern-triggered immunity, effector-triggered immunity, defense regulator-mediated immunity, and effects of nutrient elements on rice blast resistance. We outline strategies used for breeding rice cultivars with improved disease resistance. We also present the major research challenges for rice blast disease resistance and propose approaches for future investigation.

Rice blast disease caused by a fungus, Magnaporthe grisea, is one of the most destructive diseases in rice production worldwide, and salicylic acid (SA) can efficiently decrease the damage of M. grisea. Here, we combined the 2-Dimensional-Liquid Chromatography and the Matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (2D-LC-MALDI-TOF-TOF MS) techniques to compare and identify differentially expressed labelled proteins by the isobaric tags for relative and absolute quantitation (iTRAQ) between the blast-resistant cultivar Minghui and the susceptible rice cultivar Nipponbare in response to blast fungus infection. The group samples were treated with salicylic acid and compared to control samples. A total of 139 DEPs from the two cultivars showed either more than a two-fold change or alternating regulation patterns. Protein functionality analysis also exhibited that these proteins are involved in a wide range of molecular functions including: energy-related activity (30%), signal transduction (11%), redox homeostasis (15%), amino acid and nitrogen metabolism (4%), carbohydrate metabolism (5%), protein folding and assembly (10%), protein hydrolysis (9%), protein synthesis (12%), and other unknown functions (4%). Specifically, we demonstrated that exogenous treatment with salicylic acid promoted recovery in both rice cultivars from Magnaporthe grisea infection by enhancing: the regulation of signal transduction, increasing energy conversion and production through the regulation of the glycolytic pathway, and other various biochemical processes. These findings may facilitate future studies of the molecular mechanisms of rice blast resistance.

The study into the outbreak of the blast disease in the oil palm plantation in Akamkpa local government of Cross River state was carried out with the aim of identifying the possible sources of contamination of the oil palm seedlings and also the physicochemical parameters of the soil samples. Fungi associated with the blast disease were isolated using the direct plating and bait methods while the physicochemical parameters of the soil were determined using standard methods. The symptoms of the blast disease in the palms begins with rotting of the tips of the roots and then further spreads into the media zone of the cortex resulting in the eventual death of the palm. Fungi isolated from different portion of the affected seedlings, water and soil samples include Pythium, Phytothora, Macrophomina, Aspergillus and Penicillium spp. The results of the soil physical properties of the soil samples showed the particle size analyses of the soils samples to range from 835 gkg1 to 840 gkg1 respectively. The soil texture was sandy loam with an acidic pH ranging from 5.3 to 5.8. The contents of organic matter ranged from 6.10g kg-1 to 14.25 g kg-1, total nitrogen 1.58 g kg-1 to 2.25 g kg-1, available phosphorus 5.08 mg kg-1 to 6.10 mg kg-1 and potassium 1.16 cmol kg-1 to 2.18 cmol kg-1. The result of this study has indicated that the source of water used for the watering of the oil palm nursery serve as the possible source of introduction of pathogenic pathogens to the oil palm seedlings.

This article presents the results of the development of a methodology for describing the main morphological and cultural traits of the Pyricularia oryzae Cav. strains widespread in the south of Russia. At the same time, the types of traits are identified and listed, which make it possible to unambiguously determine the uniqueness and variety of the pathogen. The relationships and patterns established using cluster and statistical analysis make it possible to identify the conditions for the development of a pathogen that determine its predominant forms. Thus, research shows that leaf forms of P. oryzae strains isolated from rice plants with leaf form of blast disease have an equally directional growth pattern of a colony with a felt structure, and strains isolated from neck-affected plant form often produce a zone of a colony with a clumpy structure. The classification of cultural traits will make it possible to obtain scientifically grounded and comparable data that can be used in the analysis of the interaction of P. oryzae strains with rice plants on various varieties and in various agro-technological conditions in order to improve and rationalize agricultural activities. The study opens up the possibility of using data in breeding, making it possible to identify forms of a pathogen that infect certain varieties.

The study was conducted to know the knowledge and adoption level of plant protection measures against blast disease among 80 respondent paddy growers in the blocks of North and South 24 Parganas of Sundarbans. About 48.75% of the respondents had medium knowledge. Majority of the respondents (75%) knew about blast disease of rice and its key identifying symptom. The 67.5% farmers were having the knowledge about the fungicides used against the disease (Tricyclazole 75 WP, Carbendazim 50 WP, Hexaconazole 5EC), and 22.5% of the farmers knowing about the recommended dose of fungicide application. The 28.75% of the respondents also knew that the fungicide should be applied at the first appearance of the disease. Further, it has been found that the adoption level of plant protection measures against blast disease of rice was medium (47.5%). Nearly 53.75% of the respondents practicing rice cultivation were in the middle age group of 31-50 years. Most of the respondent had either 0.13-0.27ha (22.5%) or 0.40-0.67ha (37.5%) landholding wherein they were practicing rice cultivation. Almost all the respondents (100%) possessed Knapsack or hand sprayer for fungicide application. Climatic vagaries, lack of knowledge about to the number of sprays and concerning technology application, non-availability of fungicide on time, lack of facility at the nearby place were the major constraints as expressed by 95, 83.75, 85, 90, and 95 per cent of respondents, respectively. The high cost of chemicals and expensiveness and non-availability of labour during peak cropping period were also the major constraints as expressed by 60 and 83.75 per cent of the respondents, respectively. There was a significant relationship between age, education, landholding, social, mass media and participation in extension activities with knowledge and adoption levels of the farmers of the Indian Sundarbans.

Blast disease is an important disease that affects many rice plants. Blasts can damage rice leaves (leaf blasts), nodes (node blasts), neck blasts, colar blasts and rice grains. Symptoms on the leaves are rhombic-shaped spots with a tapered tip. The center of the patch is gray surrounded by brown to reddish brown on the edge of the spot. The color of the spots at the beginning of the symptoms is white or gray, surrounded by green-brown. Based on market demand, agricultural products that are safe and healthy for consumers as well as environmentally friendly are increasing, therefore controlling plant pathogens by using antagonistic microorganisms is one of the ways that must be considered. A number of microbes have been widely tested and are quite effective in controlling plant pathogens. PGPR and Streptomyces are biological agents that are able to reduce the level of attack of plant diseases, especially in rice blast disease. This study used a comparative method between rice cultivation and biological agent applications and rice cultivation without biological agents or control plant applications. The results obtained indicate that the application of biological agents can reduce the percentage of disease severity, reduce the percentage of infected leaves, the biological agents are also able to extend the incubation period, increase plant height growth, number of tillers and also the number of grains per panicle.

Fluorescent Pseudomonads (Pseudomonas fluorescens and P. putida) were formulated in talc, bentonite, palm oil and coconut oil for the management of blast disease of rice. The formulated products sh...

Paddy blast has become most epidemic disease in many rice growing countries. Various statistical methods have been used for the prediction of paddy blast but previously used methods failed in predicting diseases with good accuracy. However the need to develop new model that considers both weather factors and non weather data called blast disease data that influences paddy disease to grow. Given this point we developed ensemble classifer based paddy disease prediction model taking weather data from January 2013 to December 2019 from Agricultural and Horticulture Research Station Kathalgere Davangere District. For the predictive model we collected 7 kinds of weather data and 7 kinds of disease related data that includes Minimum Temperature, Maximum Temperature, Temperautre Difference,Relative Humidity, Stages of Paddy Cultivation, Varities of seeds, Season of cropping and so on. It is observed and analyzed that Minimum Temperature, Humidity and Rainfall has huge correlation with occurrence of disease. Since some of the variables are non numeric to convert them to numeric data one hot encoding approach is followed and to improve efficiency of ensemble classifiers 4 different filter based features selection methods are used such as Pearson’s correlation, Mutual information, ANNOVA F Value, Chi Square. Three different ensemble classifiers are used as predictive models and classifiers are compared it is observed that Bagging ensemble technique has achieved accuracy of 98% compared to Adaboost of 97% and Voting classifier of 88%. Other classification metrics are used evaluate different classifiers like precision, recall, F1 Score, ROC and precision recall score. Our proposed ensemble classifers for paddy blast disease prediction has achieved high precision and high recall but when the solutions of model are closely looked bagging classifier is better compared to other ensemble classifers that are proposed in predicting paddy blast disease.

Blast disease is one of the most important diseases of rice with the fungus Magnaporthe oryzae as the causal agent. This research was carried out to evaluate the blast resistance in aerobic rice genotypes in comparison with Iranian lowland rice cultivars as a randomized complete block design by measuring area under the disease progress curve (AUDPC) on 53 rice genotypes with three replications in 2017 and 2018 years. Furthermore, molecular evaluation was done using 30 genes-based markers and linked SSR markers along with 60 random SSR markers. According to the results, aerobic rice genotypes, IR82310-B-B-67-2, IR82589-B-B-114-3, IR82616-B-B-64-3, IR82589-B-B-84-3, and IR82635-B-B-143–1 (ranged from 4.11 to 5.96) and Iranian rice cultivars Nemat, Sange-Tarom and Sepidroud (ranged from 4.46 to 4.72) had the lowest AUDPC, indicating they had the least infection severity during different stages of the experiment. Iranian native rice cultivars showed the most susceptibility, and association analysis via stepwise regression showed a significant relationship between some of the markers and AUDPC. Two gene-based markers of Pi5 and Pib and RM259 were detected in accordance with previous studies, and eight SSR markers (RM12091, RM217, and RM3498 with positive effect along with RM234, RM276 RM1300, RM8007 and RM480 with negative effect) were identified as informative markers in relationship with AUDPC for the first time. RM12091 and Pi5 had the highest adjusted R2, accounting for 30.2% and 25.2% of AUDPC variation, respectively. The most effective identified markers could be considered in marker-assisted selection after final validation using different environments and genetic backgrounds. In addition, the results of this study can help demonstrate the significant potential of aerobic rice genotypes for resistance to blast disease.

Rice blast disease is one of the major constraints to rice production, threatening food security globally. Rice grain production losses due to the disease leads economic losses to the farmers, and to an increase in global rice price as a result of the supply that is far below the consumer demand. The losses from the disease annually was estimated to feed over 60 million individual. The disease has been studied comprehensively by researchers due to the importance attached to rice and its vast spread and destructiveness across the globe. A good understanding of the pathogen causing the disease, its life cycle and development, epidemiology, symptoms, management strategy will offer a good insight into the disease incidence and give an appropriate and effective decision-making in its management. Different control measures have been adopted managing the disease, including the use of resistant varieties. Integrated disease management strategies coupled with good agronomy practices are required for successful control of rice blast for food security. This review, therefore, examined the fundamentals of rice blast disease (Magnaporthe oryzae) and offered strategies to minimize the disease activities to ensure proper production and increase the supply of rice grains.

Finger millet is a food crop that provides nutritional security and is climatically resilient for farming and agricultural diversification. However, its quality and yield remain low due to biotic and abiotic factors, the greatest of which is blast disease caused by Magnaporthe oryzae. We surveyed the occurrence, distribution and severity of finger millet blast in five counties, namely, Busia, Bungoma, Kisii, Machakos and Makueni, in Kenya. Blast disease occurrence was determined by observing disease symptoms of different plant parts on each farm, and symptoms were recorded as either present or absent. Severity was evaluated based on the disease symptoms on plant fingers, leaves and necks and generally at the whole farm scale. Distribution was assessed based on the number of farms sampled for blast per county, and global positioning systems coordinates were recorded. Blast occurrence was 100%, with a uniform distribution pattern on all the farms surveyed across all the counties. Busia County had the highest disease severity at 82.3%, while Makueni had the lowest severity at 61%. Pearson’s correlation test revealed no statistically significant correlation between blast severity and plant parts infected (p< 0.05), with Busia (74.2%) having the highest number of plants showing symptoms of blast on fingers, followed by Bungoma (57.1%), Makueni (57%), Machakos (56%) and Kisii, 53.3%. This study reveals that finger millet blast is rampant in all the counties surveyed and is widely distributed in Kenya. This information is helpful in understanding the geographical distribution, occurrence and severity of M. oryzae. Key words: Finger millet blast, occurrence, severity, distribution, Magnaporthe oryzae.

Rice blast caused by Magnaporthe grisea is the major damaging disease in nearly all rice growing nations. Economically relevance with 60 percent of total population of world depending on rice as the main source of calories, may have destructive effects of the disease, however, this pathogen has developed into a pioneering model system for researching host-pathogen interactions. The disease outbreak depends on the weather and climatic conditions of the various regions. The disease's occurrence and symptoms vary from country to country. Susceptible cultivars cause huge rice production loss in yield. The principal cause of resistance breakdown in rice against rice blast disease is pathogenic variability. During sexual hybridization, pathogenic changes may provide evidence of pathogenic variation found at the asexual stage of the fungus. The virulent pathotypes cause severe disease incidence. Only through pathogenicity research the pathotypes can be determined using a collection of different rice varieties that are usually different carrying various resistance genes. Rice breeders now have a number of resistant genes however, most of the breeding programs emphasized upon monogenic resistance. Genetic heterogeneity of M. grisea should be taken into account when screening blast resistant rice genotypes through morphological analysis, pathogenicity and molecular characterization. Knowledge on the virulence of the rice blast and host resistant is essential for managing the disease. Cultivation of resistant varieties with chemical control is highly effective against blast pathogens.

MicroRNAs (miRNAs) are known to fine-tune growth, development, and stress-induced responses. Osa-miR1873 is a rice-specific miRNA targeting LOC_Os05g01790. Here, we show that Osa-miR1873 fine-tunes rice immunity against Magnaporthe oryzae and yield traits via LOC_Os05g01790. Osa-miR1873 was significantly upregulated in a susceptible accession but downregulated in a resistance accession at 24 h post-inoculation (hpi) of M. oryzae. Overexpressing Osa-miR1873 enhanced susceptibility to M. oryzae and compromised induction of defense responses. In contrast, blocking Osa-miR1873 through target mimicry compromised susceptibility to M. oryzae and enhanced induction of defense responses. Altered expression of Osa-miR1873 also resulted in some defects in yield traits, including grain numbers and seed setting rate. Moreover, overexpression of the target gene LOC_Os05g01790 increased rice blast disease resistance but severely penalized growth and yield. Taken together, we demonstrate that Osa-miR1873 fine-tunes the rice immunity-growth trade-off via LOC_Os05g01790, and blocking Osa-miR1873 could improve blast disease resistance without significant yield penalty. Thus, the Osa-miR1873-LOC_Os05g01790 regulatory module is valuable in balancing yield traits and blast resistance.

Rice (Oryza sativa L.) is the staple food of the majority of Indians, and India is both the major producer and consumer of rice. Rice cultivation in India is confronted with diverse agro-climatic conditions, varying soil types, and several biotic and abiotic constraints. Among major fungal diseases of Rice in India, the blast caused by Magnaporthe oryzae is the most devastating disease, with the neck blast being the most destructive form. Most of the blast epidemic areas in India have been identified with a mixture of races blast fungus resulting in the resistance breakdown in a short period. At present, a more significant number of the rice varieties cultivated in India were bred by conventional breeding methods with blast resistance conferred by a single resistance gene. Therefore, the blast disease in India is predominantly addressed by the use of ecologically toxic fungicides. In line with the rest of the world, the Indian scientific community has proven its role by identifying several blast resistance genes and successfully pyramiding multiple blast resistance genes. Despite the wealth of information on resistance genes and the availability of biotechnology tools, not a great number of rice varieties in India harbor multiple resistance genes. In the recent past, a shift in the management of blast disease in India has been witnessed with a greater focus on basic research and modern breeding tools such as marker-assisted selection, marker-assisted backcross breeding, and gene pyramiding.

Wheat blast is an emerging threat to wheat production, due to its recent migration to South Asia and Sub-Saharan Africa. Because genomic selection (GS) has emerged as a promising breeding strategy, the key objective of this study was to evaluate it for wheat blast phenotyped at precision phenotyping platforms in Quirusillas (Bolivia), Okinawa (Bolivia) and Jashore (Bangladesh) using three panels: (i) a diversity panel comprising 172 diverse spring wheat genotypes, (ii) a breeding panel comprising 248 elite breeding lines, and (iii) a full-sibs panel comprising 298 full-sibs. We evaluated two genomic prediction models (the genomic best linear unbiased prediction or GBLUP model and the Bayes B model) and compared the genomic prediction accuracies with accuracies from a fixed effects model (with selected blast-associated markers as fixed effects), a GBLUP + fixed effects model and a pedigree relationships-based model (ABLUP). On average, across all the panels and environments analyzed, the GBLUP + fixed effects model (0.63 ± 0.13) and the fixed effects model (0.62 ± 0.13) gave the highest prediction accuracies, followed by the Bayes B (0.59 ± 0.11), GBLUP (0.55 ± 0.1), and ABLUP (0.48 ± 0.06) models. The high prediction accuracies from the fixed effects model resulted from the markers tagging the 2NS translocation that had a large effect on blast in all the panels. This implies that in environments where the 2NS translocation-based blast resistance is effective, genotyping one to few markers tagging the translocation is sufficient to predict the blast response and genome-wide markers may not be needed. We also observed that marker-assisted selection (MAS) based on a few blast-associated markers outperformed GS as it selected the highest mean percentage (88.5%) of lines also selected by phenotypic selection and discarded the highest mean percentage of lines (91.8%) also discarded by phenotypic selection, across all panels. In conclusion, while this study demonstrates that MAS might be a powerful strategy to select for the 2NS translocation-based blast resistance, we emphasize that further efforts to use genomic tools to identify non-2NS translocation-based blast resistance are critical.

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Dispersal Simulation of Rice Blast Disease Using Spatial Multi Criteria Evalution Model: Case Study In District of Karawang and PurwakartaRice blast is caused by Pyricularia oryzae. The potential epidemic of this disease can be spatially simulated using the MCA (Multi Criteria Analysis) method based on geographical characteristics, cultivation practices, and eviromental condition. A software that can be used for MCA is SMCE (Spatial Multi Criteria Evaluation). This study was aimed to predict the spatial dispersal of blast disease using SMCE model, and identify the factors that supports the epidemic. The study was conducted in February - August 2018 in Karawang and Purwakarta District. The research methods include observing the severity of blast disease, cultivation practices and environmental conditions, and analyzing SMCE. The SMCE analysis uses rice crop maps from the Sistem Monitoring Pertanaman Padi (Simotandi), which consists of grouping factors, standardizing factors, and weighting factors. The SMCE results are a simulation map of blast disease dispersal which is then compiled with predictions of its severity. Accuracy of prediction results was evaluated by MAPE (Mean Absolute Percentage Error) based on observational data on actual disease severity. The prediction results for Karawang and Purwakarta showed means of accuration 78.16% and 73.95% respectively. In general, factors that have a strong influence on the development of blast disease include altitude, distance from source of the epidemic, history of disease in the fields, number of spores (inoculum) trapped, irrigation quality, application of herbicides, soil nutrient (N, P, K) contents and the level of soil acidity.

Rice blast disease has become endemic in Purwoasri Village, Gumukmas District, Jember since 2018; this was due to the use of the Ciherang variety planted continuously. The study aimed to use the indigenous microorganisms (IM) suspension from Mimosa invisa roots, made by farmers from Pos Pelayanan Agens Hayati (PPAH, Biological Agent Service Post) in Ambulu District as the control agent for blast pathogens and increased rice production. The roots of rice seeds were dipped in IM suspension at a concentration of 50 mL/L for 2 hours to penetrate to roots. Seedlings with IM were planted in a block of 250 m2, and control was also planted in the same block size. In the IM-treated block, the incidence and severity of blast disease decreased compared to the control. The root treated by IM dipping was also increased the plant growth, including root architecture, root length, root volume, and the number of tillers/plant; furthermore, it improved the rice production. It was found that IM suspension contained pseudomonad fluorescent and Bacillussp. that belong to Plant Growth Promoting Rhizobacteria (PGPR) group.

Rice blast caused by the fungus Magnaporthe oryzae (syn. Magnaporthe grisea) is one of the most lethal diseases for sustainable rice production worldwide. Blast resistance mediated by major resistance genes is often broken down after a short period of deployment, while minor blast resistance genes, each providing a small effect on disease reactions, are more durable. In the present study, we first evaluated disease reactions of two rice breeding parents ‘Minghui 63’ and ‘M-202’ with 11 blast races, IA45, IB1, IB45, IB49, IB54, IC1, IC17, ID1, IE1, IG1, and IH1, commonly present in the United States, under greenhouse conditions using a category disease rating resembling infection types under field conditions. ‘Minghui 63’ exhibited differential resistance responses in comparison with those of ‘M-202’ to the tested blast races. A recombinant inbred line (RIL) population of 275 lines from a cross between ‘Minghui 63’ and ‘M-202’ was also evaluated with the above-mentioned blast races. The population was genotyped with 156 simple sequence repeat (SSR) and insertion and deletion (Indel) markers. A linkage map with a genetic distance of 1,022.84 cM was constructed using inclusive composite interval mapping (ICIM) software. A total of 10 resistance QTLs, eight from ‘Minghui 63’ and two from ‘M-202’, were identified. One major QTL, qBLAST2 on chromosome 2, was identified by seven races/isolates. The remaining nine minor resistance QTLs were mapped on chromosomes 1, 3, 6, 9, 10, 11, and 12. These findings provide useful genetic markers and resources to tag minor blast resistance genes for marker-assisted selection in rice breeding program and for further studies of underlying genes.

There are important biological process involved in rice blast disease that are now well-studied during the early events in plant infection which include: the cell biology of appressorium formation, the biology of invasive growth and effector secretion, the two distinct mechanisms of effector secretion, the nature of the plant-pathogen interface, PAMP-triggered immunity modulation by secreted effectors and effector-triggered immunity and blast resistance. The devastating losses caused by the blast fungus have been documented in most grasses, but this chapter discusses the use of major resistance genes to rice blast and wheat blast disease as an emerging threat to global food security. This chapter also highlights an emerging approach to breed for durable resistance to plant pathogens using gene editing technologies with an example: CRISPR-Cas9 mutagenesis of dominant S-genes for disease control.

Phyllosphere—the harsh foliar plant part exposed to vagaries of environmental and climatic variables is a unique habitat for microbial communities. In the present work, we profiled the phyllosphere microbiome of the rice plants using 16S rRNA gene amplicon sequencing (hereafter termed metabarcoding) and the conventional microbiological methods (culturomics) to decipher the microbiome assemblage, composition, and their functions such as antibiosis and defense induction against rice blast disease. The blast susceptible rice genotype (PRR78) harbored far more diverse bacterial species (294 species) than the resistant genotype (Pusa1602) that showed 193 species. Our metabarcoding of bacterial communities in phyllomicrobiome revealed the predominance of the phylum, Proteobacteria, and its members Pantoea, Enterobacter, Pseudomonas, and Erwinia on the phyllosphere of both rice genotypes. The microbiological culturomic validation of metabarcoding-taxonomic annotation further confirmed the prevalence of 31 bacterial isolates representing 11 genera and 16 species with the maximum abundance of Pantoea. The phyllomicrobiome-associated bacterial members displayed antifungal activity on rice blast fungus, Magnaporthe oryzae, by volatile and non-volatile metabolites. Upon phyllobacterization of rice cultivar PB1, the bacterial species such as Enterobacter sacchari, Microbacterium testaceum, Pantoea ananatis, Pantoea dispersa, Pantoea vagans, Pseudomonas oryzihabitans, Rhizobium sp., and Sphingomonas sp. elicited a defense response and contributed to the suppression of blast disease. qRT-PCR-based gene expression analysis indicated over expression of defense-associated genes such as OsCEBiP, OsCERK1, and phytohormone-associated genes such as OsPAD4, OsEDS1, OsPR1.1, OsNPR1, OsPDF2.2, and OsFMO in phyllobacterized rice seedlings. The phyllosphere bacterial species showing blast suppressive activity on rice were found non-plant pathogenic in tobacco infiltration assay. Our comparative microbiome interrogation of the rice phyllosphere culminated in the isolation and identification of agriculturally significant bacterial communities for blast disease management in rice farming through phyllomicrobiome engineering in the future.

Rice Leaf Blast Disease and Brown Spot Disease are among the most significant diseases affecting rice cultivation. Monitoring and maintaining rice plants from many diseases are very important to regulate their production. In this study, the key objective was to develop an application that identifies whether a rice leaf has leaf blast or brown spot disease. The You Only Look Once (YOLO) Algorithm was implemented for the development of the system. The YOLO algorithm was trained with a custom dataset of 200 rice leaf images. It was found out that the device’s accuracy for leaf blast disease was 90.00% while the class 2 brown spot disease was at 70.00%. For the third class, which was the unknown disease, the device’s performance resulted in a 100.00% of accuracy. Therefore, it was concluded that the overall accuracy of the device was at 73.33% and the error of commission was only 26.67%.

A nursery comprising 25 elite bread wheat genotypes were evaluated to identify the sources of resistance to wheat blast caused by Magnaporthe oryzae pathotype Triticum (MoT), under artificial and natural infection experiments in three consecutive years from 2018 to 2020 in two different locations of Bangladesh. Seedling evaluation results revealed the absence of resistant and most genotypes displayed moderately susceptible to susceptible reaction. In the adult-plant field testing, six genotypes namely Borlaug 100, BARI Gom 33, BAW 1272, BAW 1280, BAW 1286, and BAW 1297 consistently showed resistant response to wheat head blast (WHB) infection with low levels of disease severity ranging from 0.2 to 8.1%. Among the remaining genotypes, some were moderately resistant, and the others exhibited various levels of susceptibility. The resistant genotypes that were most promising showed good agronomic performance under inoculated field trials. A significant positive correlation was observed between seedling and adult plant resistance. The above mentioned six genotypes also showed resistant reaction to WHB infection under controlled conditions when tested with three selected MoT isolates. The presence of 2NS/2AS translocation conferring WHB resistance was confirmed in four of the tested genotypes. Three (BAW 1272, BAW 1286, and BAW 1297) lines having non-2NS background exhibited good blast resistance under both the field and controlled conditions. These results will be useful for breeders and pathologists in exploiting the 2NS and non-2NS based resistant sources to pyramid and develop broad genetic based resistant germplasm.

Blast disease of rice is caused by Pyricularia oryzae (Cavara), has become a major concern not only in India, but also in almost all rice-growing areas of the world. The fungal pathogen attacks all areal parts of the plants at all stages of growth, although leaves and the neck of the panicle are more commonly affected. The neck of the panicle is infected when the ear emergence. When the grains are set, the panicle breaks at the neck due to weakening of the neck tissue. Such panicle hangs down and can be distinguished at a distance. In severe cases losses to the extent of 70–80%. Application of many nitrogenous fertilizers with intensive measure of rice cultivation results in the severe form of the disease. Now-a-day the disease is managed only by administering prophylactic foliar spray of selected chemical fungicides. Prediction of the disease for its better eco-friendly management needs attention proper management strategies with eco-friendly chemicals, host plant resistance, bio-agents, adoption of cultural practices such as summer plowing, application of moderate nitrogen level, etc., are given priority as important components for implementation of integrated disease management.

Rice (Oryza sativa L.), is one of the most widely cultivated and major food crops of the world. However the productivity of crop was affects by the attack of various fungal as well as bacterial diseases. Among the various diseases the most predominant one was blast disease caused by Pyricularia oryzae which is very severe in hot and humid climate of Konkan region. Eight essential oils along with one fungicide were tested under field condition. The results revealed that, the lowest incidence of blast was recorded in treatment T4 (Nirgundi oil) with disease incidence 52.59% as compare to the control (71.85%).The highest reduction of disease control was 26.80% and was statistically significant over other treatments. This was followed by treatments T2 (Eucalyptus oil), T5 (Lemon grass oil), and T1 (Citronella oil) with disease incidence of 52.9, 52.96 and 57.03 percent respectively as compare to the control and percent disease reduction was in the tune of 26.29%, 26.29% and 20.63% over control. Data also revealed that treatment of Eucalyptus oil (T2) showed highest yield of 49.03q ha-1 as against 39.11 q ha-1 in control and was statistically significant. Treatment T2 recorded 25.36% increase in yield over control. This was followed by T5 (46.85%) and T4 (43.40%).

The in vivo experiment was conducted at Agricultural Research Station, Vizianagaram against pearl millet blast revealed that all the treatments showed significant reduction in blast disease incidence in pearl millet. Among all the treatments T3i.e., foliar application of Pseudomonas fluorescens at 20 DAS and Trifloxystrob in + Tebuconazole at 35 DAS was found effective with least disease intensity of blast (14.1%), highest grain (26.0 q/ha) and fodder yield (60.9 q/ha). While the highest disease intensity (94.8) was noticed in the treatment T6i.e., control with lowest grain (9.3 q/ha) and fodder yiled (26.3 q/ha). The highest cost benefit ratio (2.5) was obtained in treatment T3.

Keeping in view the importance of rice blast disease, an experiment was conducted in the Laboratory of the department of Plant Pathology & Seed Science, Sylhet Agricultural University, and at the field of regional BADC Seed Production farm, Khadimnagar, Sylhet, Bangladesh, to evaluate see health status of the collected samples and effectiveness of fungicides against the blast disease of rice. Treatments viz T1: Edifen 50 EC (Edifenphos), T2: Karisma 28 SC (Azoxystrobin 20% + Cyproconazole 8%), T3: Nativo 75 WP (Tebuconazole 50% +Trifloxystrobin 25%), T4: Trooper 75WP (Tricyclazole), T5: Stanza 75WP (Imidazole), T6: Amister top (Azoxystobin 20% + Difenoconazole 12.5%), T7: Control (water) were used both in laboratory and field condition. In laboratory, different seed borne fungi, like Aspergillus, Fusarium, Curvularia, Penicillium, Pyricularia, Bipolaris, Alternaria, were detected from the collected seed sample by blotter method. In the field, treatments were applied as foliar sprays for three times with ten days interval. The lowest blast disease incidence (34.0%), lowest severity (31.6%) was found in T2: Karisma 28 SC treated plots, and gave best result in term of yield (6.3 ton/ha) in comparison to other treatments. The results of the present studies suggested that use of Karisma 28 SC is the best choice against rice blast with lowest disease incidence and highest yield.