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Among the many biotic factors with adverse effects on Solanum lycopersicum (tomato), diseases caused by fungi, viruses and nematodes are notable. Since the genome of S. lycopersicum became available, efforts have continued to identify the genes and proteins associated with the plant defence activity. One such gene family belongs to TIR-NBS- -LRR (TNL), a subfamily of larger NBS-LRR genes. In total, 27 full-length TNLs were identified via genome wide analysis. Four pairs of segmental duplication events were observed involving different pairs of chromosomes, except the pairing of Solyc02g082050-Solyc02g032650, which were both present on chromosome 2. More than twenty nine percent (29.63%) of the genes were localised on chromosome 1 alone. Hormone-mediated biotic stress-responsive cis-regulatory elements were detected for methyl-jasmonate, salicylic acid (TCA motif) and ethylene (ERE motif). Differential gene expression was observed for many genes under different plant tissues and biotic stresses. The upregulation of many genes including SlBS4 was observed against Alternaria solani attacks in the disease tolerant varieties. Altogether, the results suggested that TNLs play a significant role in plant defence under biotic stress. [ABSTRACT FROM AUTHOR]

Early blight (EB), caused by Alternaria solani, is a serious problem in tomato production. Plant growth-promoting rhizobacteria promote plant growth and inhibit plant disease. The present study explored the bio-efficacy of synergistic effect of rhizobacterial isolates and ginger powder extract (GPE) against tomato EB disease, singly and in combination. Six fungal isolates from symptomatic tomato plants were identified as A. solani on the basis of morphological features i.e., horizontal septation (6.96 to 7.93 µm), vertical septation (1.50 to 2.22 µm), conidia length (174.2 to 187.6 µm), conidial width (14.09 to 16.52 µm), beak length (93.06 to 102.26 µm), and sporulation. Five of the twenty-three bacterial isolates recovered from tomato rhizosphere soil were nonpathogenic to tomato seedlings and were compatible with each other and with GPE. Out of five isolates tested individually, three isolates (St-149D, Hyd-13Z, and Gb-T23) showed maximum inhibition (56.3%, 48.3%, and 42.0% respectively) against mycelial growth of A. solani. Among combinations, St-149D + GPE had the highest mycelial growth inhibition (76.9%) over the untreated control. Bacterial strains molecularly characterized as Pseudomonas putida, Bacillus subtilis, and Bacillus cereus and were further tested in pot trials through seed bacterization for disease control. Seeds treated with bacterial consortia + GPE had the highest disease suppression percentage (78.1%), followed by St-149D + GPE (72.2%) and Hyd-13Z + GPE (67.5%). Maximum seed germination was obtained in the bacterial consortia + GPE (95.0 ± 2.04) followed by St-149D + GPE (92.5 ± 1.44) and Hyd-13Z + GPE (90.0 ± 2.04) over control (73.8 ± 2.39) and chemical control as standard treatment (90.0 ± 2). Ginger powder extracts also induce the activation of defence-related enzymes (TPC, PO, PPO, PAL, and CAT) activity in tomato plants. These were highly significant in the testing bacterial inoculants against A. solani infection in tomato crops. [ABSTRACT FROM AUTHOR]

Phytohormones are the key regulators of various developmental and physiological processes in plants. In the present study, we have examined the efficacy of Methyl Jasmonate Methyl Ester (MJME) as a potent elicitor on inducing resistance factors against early blight disease of tomato. Both PKM1 (susceptible) and Arka Rakshak (resistant) cultivars of tomato were sprayed with different concentrations of MJME (1, 5, 10 and 25 μM) and/or infected with A. solani. MJME pre‐treatment followed by A. solani infected leaves showed a higher accumulation of superoxide anion radicals and hydrogen peroxide at the early stages and then decreased gradually in both resistant and susceptible cultivars. A significant increase in antioxidant enzyme activity such as superoxide dismutase, guaiacol peroxidase and catalase was evident in MJME pre‐treatment followed by A. solani infected leaves in susceptible cultivar of tomato compared with control. Manifestation of disease symptoms was reduced to 60% in tomato leaves pre‐treated with higher concentrations of MJME and infected with A. solani in susceptible cultivar on par with resistant cultivar. Quantitative real‐time polymerase chain reaction (qRT‐PCR) analysis revealed an induction of expression of defence‐related genes such as ACO1, EDS1, LoxD, NP24, NPR1 and Sl10EAH30 in tomato leaves pre‐treated with MJME followed by A. solani infection. Interestingly, a two‐fold increase in the expression of EDS1 gene was evident in both susceptible and resistant cultivars after MJME treatment compared with control. The present study showed that MJME could be a potential elicitor of resistance factors against the early blight disease of tomato. [ABSTRACT FROM AUTHOR]

Silver nanoparticles have gained considerable interest in recent decades due to their antimicrobial activity and are used in water disinfection, wound healing, food packaging, and plant protection. This study tested the potential of silver nanoparticles synthesized using the neem (Azadirachta indica) leaf extract against Alternaria solani causes early blight disease in tomato plants. The pathogen was isolated from infected tomato plants and identified using morphological and molecular features. The results showed significant variation among isolates. Isolates, Shk-1 and Ksr-1 were highly pathogenic, causing up to 80% disease incidence. The potential of silver nanoparticles against each isolate was determined using different concentrations of silver nanoparticles. During in vitro and in vivo experiments, the growth inhibition rate of the pathogen was 70–100% at 50 ppm. Lower concentrations of silver nanoparticles (5 and 10 ppm) increased phenolics, PO, PPO, and PAL production by more than 50% as compared to the untreated control. These defensive mechanisms clearly demonstrate the fungicidal potential of AgNPs and recommend their utilization in different crop protection programs. [ABSTRACT FROM AUTHOR]

Early blight commonly attacks the tomato leaf. The drone and image processing technologies offer a tool to detect the symptom of the tomato disease. One of the stages in the early blight detection is the segmentation of the tomato leaf. The K-means algorithm is a known image segmentation method which works simply and quickly. However, randomized initialization of centroids causes the K-means algorithm to easily get stuck in the local optimum and, as a result, gives imprecise segmentation. The swarm intelligence-based algorithm can avoid this problem. For this reason, we propose the early blight disease segmentation method on tomato leaves uses K-means algorithm with swarm intelligence-based algorithm. This research uses the Particle Swarm Optimization (PSO) because PSO is one of the swarm intelligence-based algorithms which has a balance in exploration and exploitation. The Hue of the HSV color space is used as input. From the experimental results, we can conclude that the performance of the early blight disease segmentation method using the K-means algorithm with swarm intelligence-based algorithm is much better. [ABSTRACT FROM AUTHOR]

Tomato (Solanum lycopersicum L.), is an important horticulture crop supporting rural economy of Sirmaur district of Himachal Pradesh. Tomato crops in this geographical region are highly susceptible to plant pathogens resulting in significant loss of productivity and yield. In this study, we have determined the prevalence and causative pathogens of early blight disease affecting tomato crops in 18 geographical sites of district Sirmaur. On the basis of colony characteristics, microscopic features and ITS region sequence-based phylogenetic analysis, blight disease-associated isolates exhibited close resemblance to Alternaria alternata and other related species. These findings necessitates an integrated management strategy for effective pathogen control towards minimising the crop losses. [ABSTRACT FROM AUTHOR]

Tomato (Solanum lycopersicum L.) is among the most important vegetable crops worldwide. Early blight disease, caused by Alternaria solani, is a destructive foliar disease of tomato and other Solanaceae species. Herein, we investigated the in vitro antifungal properties of gallic acid and two of its derivatives (syringic and pyrogallic acids) against A. solani during 2019 and 2020 seasons. The physiological and biochemical effects of these compounds on infected tomato plants were also investigated using the whole plant bioassay. The in vitro investigation showed that all tested compounds showed fungistatic action and inhibited the mycelial radial growth of A. solani in a dose-dependent manner. In two separate pot-experiments, those compounds efficiently suppressed the development of the disease symptoms and area under disease progress curve (AUDPC), without any phytotoxic effects on the treated tomato plants. Additionally, all tested compounds positively enhanced the biochemical traits of treated plants including the chlorophyll content, the total soluble phenolics, the total soluble flavonoids, and the enzymatic activities of catalase, peroxidase, and polyphenol oxidase during 2019 and 2020 seasons. Moreover, the treatment with gallic acid and its derivatives significantly increased all yield components of A. solani-infected tomato plants such as the total number of flowers and fruits, and the fruit yield for each tomato plant in both experiments. Considering the fungitoxicity of phenolic acids against A. solani with no phytotoxicity on treated tomato plants, we believe that gallic acid and its derivatives might be a sustainable eco-friendly control strategy to reduce the usage of chemical fungicides partially or entirely against A. solani particularly, and fungal diseases in general. [ABSTRACT FROM AUTHOR]

• Peppermint based nanoemulsion has been synthesized by high energy sonication method. • 1% dose of PNE was able to inhibit the growth of A. solani. • 1% PNE reduce the disease severity caused by A. solani in tomato up to 87.5%. • PNE modulates plant physiology at biochemical, morphological, gene expression level. Early blight, caused by Alternaria solani is one of the most devastating disease affecting to the Solanum lycopersicum (tomato), reducing its productivity by 80%. The present study illustrates the synthesis of nanoemulsion using peppermint oil for potent antimicrobial activity against A. solani. A peppermint oil based nanoemulsion (PNE) was synthesized which was further characterized by Dynamic Light Scattering and Transmission Electron Microscopy. The nano-droplets present in nanoemulsion were spherical in shape with average size <100 nm. In-vitro antimicrobial activity of PNE was examined against A. solani with the carbendazim as positive control. A green-house study was performed to evaluate the antimicrobial efficacy and plant immunity developed by nanoemulsion as well as compared with carbendazim, chemical fungicide. PNE was much competent to reduce the disease severity up to 68.7% at 14th day and 87.5% at 21st day respectively. Physiological modulation was showed in tomato plants against A. solani, they were confirmed by measured the physical parameters, plant physiology, changes in leaf morphology and stress responses. A significant changes were found in proline and lipid peroxidation content in infected plants whereas nanoemulsion treated infected plants was able to cope-up from stress condition. Physical parameters and Scanning Electron Microscopy (SEM) analysis also revealed the similar observations. A reduced photosynthesis rate and transpiration rate were found in diseased plants as compared to other treatments, although stomatal conductance was not much affected. Defence responsive gene expression also up-regulated in PNE treated diseased plants than pathogen alone. Thus, the current study demonstrated the peppermint oil based nanoemulsion was more efficacious than chemical fungicide to early blight disease management in Solanum lycopersicum. [ABSTRACT FROM AUTHOR]