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Bacterial stalk rot (BSR), caused by Dickeya zeae (syn. Erwinia chrysanthemi pv. zeae), has emerged as a significant disease affecting maize crops worldwide. In this study, symptomatic maize plants were collected from diverse agroclimatic zones in India over the period of kharif 2019–2021. Various approaches, including pathogenicity tests, cultural characteristics, biochemical profiling and molecular analysis, were employed to accurately identify the collected bacterial isolates as Dickeya. Pathogenicity assessments were conducted on 40‐day‐old maize plants, following Koch's postulates, as well as through potato maceration assays. Furthermore, cross‐infectivity studies were conducted on rice, potato, tomato and banana plants. Phenotypic and biochemical characterization confirmed that all the isolates belonged to the Dickeya genus. Additionally, PCR amplification of a pel gene fragment, specific to the genus Dickeya, further verified the pathogenic isolates as Dickeya. Molecular characterization studies were performed on four isolates (UKMDZ‐3, PBMDZ‐7, TSMDZ‐11 and HPMDZ‐16), selected to represent distinct maize agroclimatic zones and four states of India, and which caused severe infections on susceptible maize cv. Early Composite. Amplification of six characteristic genome regions (16S rRNA, recN, gyrB, dnaX, recA and dnaJ) from these isolates facilitated individual and concatenated gene phylogenetic analyses, confirming their resemblance to Dickeya zeae. This study represents the first comprehensive molecular analysis of D. zeae isolates from India, providing valuable insights for future crop improvement strategies. The findings contribute to our understanding of the genetic basis of BSR in maize and offer potential avenues for genetic enhancement to mitigate the disease's impact on maize cultivation. [ABSTRACT FROM AUTHOR]

Since time immemorial organic amendments have been an important strategy for improving soil fertility and suppressing a wide range of soil-borne pathogens. Biochar, a charcoal-like amendment has true potential in managing phytopathogens with an eco-friendly approach. It is produced by subjecting plant materials and agricultural waste to high temperatures of around 900°C in limited oxygen conditions. Biochar is considered to be an excellent carbon sequester and has an undeniably imperative role in improving soil properties. Biochar has innumerable applications in the remediation of environmental pollutants by immobilizing heavy metals such as Cadmium and Arsenic and degradation of dyes and pesticides. One of the most significant advantages of biochar in addition to mitigating environmental pollution is effectively managing plant pathogens by altering soil physical and chemical properties and promoting antagonistic microorganisms. Biochar directly suppresses plant pathogens by priming plant defense mechanisms. For instance, sugarcane bagasse biochar remediates Cd from contaminated soil, and citrus wood biochar induces systemic resistance against Botrytis cinerea in host-Lycopersicon esculentum, Capsicum annuum L. cv. Maccabi and Fragaria ananassa. Nevertheless, it is essential to acknowledge its limitations, such as the potential to absorb and enhance the residual activity of harmful chemicals. Further research is needed to develop a deeper understanding of biochar's properties and mechanisms for more effective results. Advanced techniques like meta-transcriptomics and metaproteomics hold the potential to provide invaluable insights into this field. The review provides a comprehensive overview of current information regarding biochar, covering its production techniques and highlighting its agricultural benefits, with a particular focus on its role in plant disease management. Furthermore, the associated risks and concerns are also discussed. [ABSTRACT FROM AUTHOR]

Bio-control agents are the best alternative to chemicals for the successful management of plant diseases. Among them, Trichoderma is commonly used as a biological control agent in plant disease management due to its ability to suppress soil-borne plant pathogens. In the present study, 20 Trichoderma asperellum isolates were collected from different geographical locations and confirmed using morphological characteristics and molecular phylogenetic inferences based on combined ITS and β-tubulin sequences. All twenty isolates were screened for their antagonism against the collar rot pathogen under in vitro and in planta conditions. The isolates were evaluated through dual culture and volatile methods in an in vitro study. Isolate A10 inhibited the test pathogen Agroathelia rolfsii at 94.66% in a dual culture assay and 70.95% in a volatile assay, followed by the isolates A11 and A17, which recorded 82.64% and 81.19% in dual culture assay and 63.75% and 68.27% in the volatile assay respectively. An in planta study was conducted under greenhouse conditions in tomato var. pusa ruby by pre- and post-inoculation of T. asperellum isolates in the A. rolfsii infected soil to evaluate their antagonistic potential against the disease. The A10 isolate was found effective under both pre- and post-inoculation conditions, with a disease inhibition percent of 86.17 and 80.60, respectively, followed by the isolates A11 and A17, which exhibited inhibition of 77.80% and 75.00% in pre-inoculation and 72.22% and 69.44% in post-inoculation, respectively. Further, biochemical analysis was conducted to determine the specific activity of hydrolytic enzymes produced by T. asperellum during interaction with A. rolfsii. We found that isolate A10 produces more hydrolytic enzymes with the specific activity of 174.68 IU/mg of β-1,3 glucanase, 183.48 IU/mg of β-1, 4 glucanase, 106.06 IU/mg of protease, followed by isolate A17, A11 respectively. In GC-MS analysis, we observed maximum anti-microbial volatile organic compounds from the isolate A10, including 2H-Pyran-2-one (17.39%), which was found to be most abundant, followed by dienolactone (8.43%), α-pyrone (2.19%), and harziandione (0.24%) respective retention time of 33.48, 33.85, 33.39, and 64.23 min, respectively, compared to other isolates. In the TLC assay, we observed that a greater number of bands were produced by the A10 and A17 isolates in the Hexane: Ethyl Acetate (1:1) solvent system than in the 9:1 solvent system, which represents the presence of major metabolites in the ethyl acetate extract. [ABSTRACT FROM AUTHOR]

Various nanotechnology advancements are used to protect crops and the safety concerns of nanopesticides for soil quality need to be addressed. Soil enzymes and certain beneficial bacteria play a vital role in preserving soil health by carrying out required biochemical reactions. In the present study, clotrimazole, econazole nitrate, and miconazole nitrate based nano-fungicides were investigated for their antifungal efficacy followed by their biosafety assessment. Antifungal studies of all the test nano-fungicides demonstrated their effectiveness against Rhizoctonia solani. The relative lesion heights were 29–38% under field conditions and they ranged from 17% to 33% in pot experiments. Impact of these nano-fungicides on urease activity in soil was comparable with the conventional fungicide hexaconazole, as evident from the presence of 0.5–2.7 mg/kg urea-nitrogen after 24 h of 200 mg/kg urea-nitrogen application. In all the treatments, the activity of soil nitrifiers was not adversely affected after application of these nano-fungicides. After 21 days of incubation, the nitrate-N contents were in the range of 150–180 mg/kg in nano-fungicide treated soils as compared to 180 mg/kg of nitrate-N in urea control. Virtual risk assessment using docking of these imidazole derivatives on soil enzymes revealed their behavior similar to that of hexaconazole. [ABSTRACT FROM AUTHOR]

Sustainable food production is necessary to meet the demand of the incessantly growing human population. Phytopathogens pose a major constraint in food production, and the use of conventional fungicides to manage them is under the purview of criticismdue to their numerous setbacks. In the present study, essential oil-grafted copper nanoparticles (EGC) were generated, characterized, and evaluated against the maize fungal pathogens, viz., Bipolaris maydis, Rhizoctonia solani f. sp. sasakii, Macrophomina phaseolina, Fusarium verticillioides, and Sclerotium rolfsii. The ED50 for the fungi under study ranged from 43 to 56 μg ml-1, and a significant inhibition was observed at a low dose of 20 μg ml-1 under in vitro conditions. Under net house conditions, seed treatment + foliar spray at 250 and 500mg L-1 of EGC performed remarkably against maydis leaf blight (MLB), with reduced percent disease index (PDI) by 27.116 and 25.292%, respectively, in two Kharif seasons (May-Sep, 2021, 2022). The activity of enzymatic antioxidants, viz., β-1, 3-glucanase, PAL, POX, and PPO, and a non-enzymatic antioxidant (total phenolics) was increased in treated maize plants, indicating host defense was triggered. The optimumconcentrations of EGC (250mg L-1 and 500mg L-1) exhibited improved physiological characteristics such as photosynthetic activity, shoot biomass, plant height, germination percentage, vigor index, and root system traits. However, higher concentrations of 1,000mg L-1 rendered phytotoxicity, reducing growth, biomass, and copper bioaccumulation to high toxic levels, mainly in the foliar-sprayed maize leaves. In addition, EGC and copper nanoparticles (CuNPs) at 1,000mg L-1 reduced the absorption and concentration of manganese and zinc indicating a negative correlation between Cu andMn/Zn. Our study proposes that the CuNPs combined with EO (Clove oil) exhibit astounding synergistic efficacy against maize fungal pathogens and optimized concentrations can be used as an alternative to commercial fungicides without any serious impact on environmental health. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

One neighborhood investigation was conducted amongst 500 farmers of Nagaon, Golaghat, Jorhat and Dibrugarh districts of Central Brahmaputra valley Zone and Upper Brahmaputra valley Zone of Assam. Only 21.8% of farmers completely practiced the indigenous technology knowhow (ITK) for pest management, though 48.4% were aware about ITKs, whereas 41.8% famers apply synthetic chemical driven approaches. A total of 30 different types of ITKs had been collected which weresorted out crop wise and placed in different groups based on their use i.e. rice (20), pulses (1), tuber crops (3), vegetables (2) and fruits (4). It is speculated that a comprehensive study on different ITKs of Assam and their appropriate validation could be the valuable components for organic farming technology. [ABSTRACT FROM AUTHOR]

Rice sheath blight, caused by Rhizoctonia solani, is one of the increasing concerns in rice causing severe economic losses worldwide. Chemical control measures are already in practice for the management of this disease but approach for discovery of new chemicals with improved disease control potential is essential. The present investigation involves the development of nanoformulations of halogen substituted azomethines as new potent fungicide for the management of sheath blight disease in rice. The halogen substituted azomethines were synthesized and screened for in-vitro bioefficacy. Then the azomethines were nanoformulated for their in-vivo pot culture evaluation against Rhizoctonia solani. Transmission electron microscopy confirmed the particle size of the developed nanoformulations in the range of 1–100 nm. In-vitro inhibition results of test compounds revealed their ED50 values in the range of 11.9 to 22.4 μg/ml with best performer 2,4,5-trichloro-N-(2,4-dichlorobenzylidene)aniline. 3-Chloro-N-(2,6-dichlorobenzylidene)-4-fluoroaniline displayed maximum in-vivo efficacy against R. Solani which was comparable with that of hexaconazole, a standard recommended fungicide. [ABSTRACT FROM AUTHOR]

Tilletia indica is a quarantine fungal pathogen that poses a serious biosecurity threat to wheat-exporting countries. Acquiring genetic data for the pathogenicity characters of T. indica is still a challenge for wheat breeders and geneticists. In the current study, double digest restriction-site associated-DNA genotyping by sequencing was carried out for 39 T. indica isolates collected from different locations in India. The generated libraries upon sequencing were with 3,346,759 raw reads on average, and 151 x 2 nucleotides read length. The obtained bases per read ranged from 87 Mb in Ti 25 to 1,708 Mb in Ti 39, with 505 Mb on average per read. Trait association mapping was performed using 41,473 SNPs, infection phenotyping data, population structure, and Kinship matrix, to find single nucleotide polymorphisms (SNPs) linked to virulence genes. Population structure analysis divided the T. indica population in India into three subpopulations with genetic mixing in each subpopulation. However, the division was not in accordance with the degree of virulence. Trait association mapping revealed the presence of 13 SNPs associated with virulence. Using sequences analysis tools, one gene (g4132) near a significant SNP was predicted to be an effector, and its relative expression was assessed and found upregulated upon infection. [ABSTRACT FROM AUTHOR]

Bipolaris maydis is pathogen of maize which causes maydis leaf blight disease. In India major losses occur due to the B. maydis race "O" pathogen, whereas in other parts of the world, major losses are due to the race "T" pathogen. In the present study, we conducted an in planta transcriptomics study of the B. maydis race "O" pathogen after infection on non-CMS maize resistant and susceptible genotypes by mRNA sequencing to understand the molecular basis of pathogenicity for better management of the pathogen. Approximately 23.4 GB of mRNA-seq data of B. maydis were obtained from both resistant and susceptible maize backgrounds for fungus. Differentially expressed genes (DEGs) analysis of B. maydis in two different genetic backgrounds suggested that the majority of highly DEGs were associated with mitochondrial, cell wall and chitin synthesis, sugar metabolism, peroxidase activity, mitogen-activated protein kinase (MAPK) activity, and shikimate dehydrogenase. KEGG analysis showed that the biosynthetic pathways for secondary metabolism, antibiotics, and carbon metabolism of fungus were highly enriched, respectively, in susceptible backgrounds during infection. Previous studies in other host pathogen systems suggest that these genes play a vital role in causing disease in their host plants. Our study is probably the first transcriptome study of the B. maydis race "O" pathogen and provides in-depth insight of pathogenicity on the host. [ABSTRACT FROM AUTHOR]

Maydis leaf blight, caused by Bipolaris maydis, is a serious foliar disease of maize distributed widely throughout the world and causing significant yield losses. The study aimed to describe stages of the infection process of B. maydis on maize leaves. The adaxial surfaces of maize leaves were inoculated with a conidial suspension of B. maydis and leaf samples were collected from 24 to 120 hrs after inoculation (hai). At 24 hai, the germ tubes from the germinated conidia and fungal hyphae attempted to penetrate the leaf through the stomata. These results provide new insight into the infection process of B. maydis on maize leaves and may contribute to the development of more effective management of maydis leaf blight. [ABSTRACT FROM AUTHOR]

Bipolaris maydis causing maydis leaf blight (MLB) is an aggressive fungal pathogen of maize. The present study focused on the responses of certain defence genes in the resistant and susceptible maize inbred lines viz., SC-7 and CM 119, respectively, against MLB and symptom development in the host. Biochemical activity of the PR protein ß-1, 3-glucanase and phenylalanine ammonia lyase (PAL) assay, with total chlorophyll content was recorded for both the inbred lines before and after pathogen inoculation. Gene expression was studied by quantitative polymerase chain reaction (qPCR) at different time intervals post inoculation. Differential expression pattern was observed even at the same time point in both the inbred lines. Enhanced expression of the pathogenesis related (PR) protein and phenylalanine ammonia lyase (PAL) enzyme at different time points in resistant lines indicated their association with infection stages of B. maydis and response of the resistant line against disease establishment. Down regulated gene expression of pheophytinase suggests reduced enzyme activity linked with less chlorophyll degradation in the resistant line compared to the susceptible line. This fact directly correlates with symptom development of MLB disease. The present study thus revealed that the expression of defence related genes is aligned with developmental stages of the pathogen to restrict its growth and gene expression of constitutive genes also changes differentially during the disease development in resistant and susceptible lines. [ABSTRACT FROM AUTHOR]

Knowledge on the genetics of maydis leaf blight (MLB) is crucial to breed the resistant maize cultivars to combat disease epidemics as a sustainable and cost-effective approach. The present investigation was framed to understand the genetics of MLB resistance in subtropical maize. Two contrasting genotypes CM119 (susceptible) and SC-7-2-1-2-6-1 (resistant) were used to generate six genetic populations, namely P1, P2, F1, F2, BC1P1 and BC1P2, and evaluated in three target environments for MLB resistance under artificial epiphytotic condition. The CM119 and SC-7-2-1-2-6-1 showed susceptible and resistant reactions with mean disease reaction of 3.89–3.98 and 1.88–2.00, respectively. The derived generations, namely F1, F2, BC1P1 and BC1P2 showed mean disease reaction of 2.15–2.28, 2.44–2.51, 2.19–2.24 and 2.22–2.28, respectively in the test locations. The segregating generations (F2: 0.35–0.37; BC1P1: 0.24–0.29 and BC1P2: 0.17–0.20) showed variation for MLB disease resistance over the parental and first filial generations (P1: 0.11–0.17; P2: 0.08–0.13 and F1: 0.12–0.14). The genetic analysis of MLB resistance revealed the nonallelic interactions of duplicate epistasis type across the test locations. Among the gene interactions, dominance × dominance [l] effect was predominant over additive × additive [i] and additive × dominance [j] effects. The segregation analysis and the prediction of the number of major loci revealed at least two major genes associated with MLB tolerance in subtropical maize. Our investigation paved the foundation for the improvement of subtropical maize germplasm of MLB resistance. [ABSTRACT FROM AUTHOR]