Abstract Background In polyhouse cultivation of tomato (Solanum lycopersicum) in root-knot (Meloidogyne incognita) infested soils, several accessions remained free of nematode infection. It was hypothesized that such plants that were free of root-knot infection in the selected polyhouses were possibly harboring potent nematode antagonistic microbes. Therefore, attempts were made to isolate root-associated rhizobacteria from nematode infected and uninfected roots of 7 tomato accessions. Eighty morphologically distinct isolates were multiplied in nutrient broth for 48 h to test the presence of nematotoxic metabolites. Laboratory bioassays were conducted using their cell-free filtrates to observe mortality in M. incognita juveniles (J2s) at 24 h. The most potent ones were identified through molecular characterization (16S rDNA) and assayed for plant growth promotion traits, seed germination and seedling vigor and bioefficacy against M. incognita infecting polyhouse tomato. Results Rhizobacterial densities were estimated from the root samples using 3 media. In all the media, the average numbers of colony forming units (cfu) from uninfected roots were significantly higher than the infected roots. The maximum numbers of colonies were observed in soil plate count agar. The extracellular metabolites caused juvenile mortality in the range of 60.67–100% from isolates associated with nematode uninfected roots of accessions H308, H299 and H266, as compared to isolates from nematode infected roots of accessions H195, BSS99, H178/F4 and H88, which caused mortality in the range of 52.33 to 73.67%. Four isolates (B9, B16, B26 and B31) caused 100% J2 mortality, followed by 13 isolates (B7, B8, B13, B14, B17, B18, B21, B22, B25, B28, B29, B32 and B33) that caused 90–95%, 12 isolates caused 80–85% and 51 isolates caused < 85% J2 mortality, when exposed to bacterial metabolites in cell-free filtrates for 24 h. The isolates B9, B16, B26 and B31 were identified based on 16S rRNA sequence analysis as Bacillus pumilus, B. megaterium, B. subtilis and B. cereus, respectively. These 4 bacterial isolates possessed plant growth promotion traits like production of IAA, ammonia, catalase and chitinase with the ability to solubilize zinc and phosphate. These enhanced tomato seed germination and seedling vigor, and their application in soil resulted in significant increase in root and shoot length of tomato seedlings. Conclusions In the present investigation, the 21% bacterial colonies (17 isolates) that caused nemato toxicity in the range of 90 to 100% and another 15% (12 isolates) that caused juvenile mortality in the range of 80 to 90% were from uninfected tomato accessions, indicating their role in protecting the plants against root-knot nematode (RKN) infection. The 4 bacterial isolates characterized from uninfected plants possessed high nematicidal potential with plant growth promotion (PGP) traits that enhanced tomato seed germination and seedling vigor index. The isolates can be utilized for root-knot nematode pest management in polyhouse cultivation.

Early blight disease caused by Alternaria solani is the most catastrophic disease causing losses both at pre and post-harvest stages in tomato growing places of India. An experiment was conducted for evaluation of tomato hybrids under open field conditions against early blight at College of Agriculture Gwalior Research Field during Rabi 2020-21. Total thirteen tomato hybrids were screened, out of which minimum disease were found in Cherry Tomato (4.21 per cent ) followed by Chenaya, F1 Gold Current Cherry Tomato, Abhiraj, Tomato Oblate Yellow, Deep – S – 22, Satyam, Local Hybrid 4, Tomato S Yellow Pear, Local Hybrid-1, Local Hybrid-2 and F1 hybrid tomato Sachriya while , the maximum disease intensity was found in Selection – 22 ( 58.65 per cent ).

In December 2020, stem and leaf rot symptoms in small-fruited tomato (Solanum lycopersicum) plants were observed in a farmer's vinyl greenhouse located in Pyeongtaek, Gyeonggi Province, Korea. The incidence of diseased plants in the vinyl greenhouse was 2–6%. Seven single-spore isolates of Phoma sp. were obtained from the diseased stems and leaves. All the isolates were identified as Boeremia linicola based on the cultural, morphological and molecular characteristics. Two isolates of B. linicola were tested for pathogenicity on stems and leaves of small-fruited tomato and large-fruited tomato using artificial inoculation. All the tested isolates caused stem and leaf rot symptoms in the inoculated plants. The symptoms were similar to those observed in plants from the vinyl greenhouse investigated. This is the first report of B. linicola causing stem and leaf rot in tomato.

The loss of tomatoes caused by Botrytis cinerea (B. cinerea) is one of the crucial issues restricting the tomato yield. This study screened the elicitor protein phosphopentomutase from Bacillus velezensis LJ02 (BvEP) which improves the tomato resistance to B. cinerea. Phosphatemutase was reported to play a crucial role in the nucleoside synthesis of various microorganisms. However, there is no report on improving plant resistance by phosphopentomutase, and the related signaling pathway in the immune response has not been elucidated. High purity recombinant BvEP protein have no direct inhibitory effect on B. cinerea in vitro,and but induce the hypersensitivity response (HR) in Nicotiana tabacum. Tomato leaves overexpressing BvEP were found to be significantly more resistant to B. cinerea by Agrobacterium-mediated genetic transformation. Several defense genes, including WRKY28 and PTI5 of PAMP-triggered immunity (PTI), UDP and UDP1 of effector-triggered immunity (ETI), Hin1 and HSR203J of HR, PR1a of systemic acquired resistance (SAR) and the SAR related gene NPR1 were all up-regulated in transgenic tomato leaves overexpressing BvEP. In addition, it was found that transient overexpression of BvEP reduced the rotting rate and lesion diameter of tomato fruits caused by B. cinerea, and increased the expression of PTI, ETI, SAR-related genes, ROS content, SOD and POD activities in tomato fruits, while there was no significant effect on the weight loss and TSS, TA and Vc contents of tomato fruits. This study provides new insights into innovative breeding of tomato disease resistance and has great significance for loss reduction and income enhancement in the tomato industry.

The tomato leaf curl New Delhi virus (ToLCNDV), a bipartite begomovirus (family Geminiviridae), poses a significant threat to various horticultural crops in many Asian and Mediterranean countries. Since its identification, the Asian strain of this virus has exhibited severe infectivity and caused high yield loss in tomato and cucurbit production in the Indian subcontinent and other parts of Asia. ToLCNDV-ES, a different strain of ToLCNDV, emerged recently in the Mediterranean Basin and caused significant outbreaks in Cucurbitaceae species but has shown low adaptation to tomatoes. In a field survey, tomato plants infected with this Mediterranean strain were not discovered. Nevertheless, the same field survey revealed that ToLCNDV-ES occurred in natural double infection with tomato yellow leaf curl virus (TYLCV) in tomato plants with an infection ratio of up to 50%. Moreover, results obtained from experiments where tomato plants agro-inoculated simultaneously with infectious clones of ToLCNDV-ES and TYLCV showed that ToLCNDV-ES was detected in tomatoes while synergized with TYLCV with infection ratios similar to those found under field conditions. Quantitative PCR data indicated the highest amount of ToLCNDV in co-infected plants and no significant change in TYLCV titers among the different mixed infections. Moreover, it was ascertained that not all begomoviruses can enhance the infectivity of Mediterranean ToLCNDV isolates in tomato plants. Our study reports a new finding regarding the ToLCNDV-ES response in tomato while synergized with TYLCV with evidence from both field and laboratory conditions.

Abstract Background Tomato plant (Solanum lycopersicum L.) suffers from numerous fungal pathogens that cause damage to yeild production qualitatively and quantitatively. One of the most destructive disease of tomato is Fusarium wilt that caused by soil borne fungus called F. oxysporum. Methods In this study, the anti-Fusarium capabilities of the foliar application of fungal endophytes extracts have been investigated on tomato under Fusarium challenges. Antifungal assay, inhibition of conidial germination, disease severity, photosynthetic pigments, osmolytes, secondary metabolites, oxidative stress, peroxidase (POD) and polyphenol oxidases (PPO) isozymes were tested for potential resistance of tomato growing under Fusarium infection. Results Ethyl acetate extracts of A. flavus MZ045563, A. fumigatus MZ045562 and A. nidulans MZ045561 exhibited antifungal activity toward F. oxysporum where inhibition zone diameters were 15, 12 and 20 mm, respectively. Moreover, extracts of all fungal isolates at concentration 7.5 mg/mL reduced conidia germination from 94.4 to 100%. Fusarium infection caused a destructive effects on tomato plant, high severity desiese index 84.37%, reduction in growth parameters, photosynthetic pigments, and soluble protein. However, contents of proline, total phenol, malondialdehyde (MDA), hydrogen peroxide (H2O2) and antioxidant enzymes activity were increased in tomato plants grown under Fusarium wilt. Treatment of healthy or infected tomato plants by ethyl acetate fungal extracts showed improvements in morphological traits, photosynthetic pigments, osmolytes, total phenol and antioxidant enzymes activity. Besides, the harmful impacts of Fusarium wilt disease on tomato plants have also been reduced by lowering MDA and H2O2 levels. Also, treated tomato plants showed different responses in number and density of POD and PPO isozymes. Conclusion It could be suggested that application of ethyl acetate extracts of tested fungal endophytes especially combination of A. flavus, A. nidulans and A. fumigatus could be commercially used as safe biostimulation of tomato plants as well as biofungicide against tomato Fusarium wilt disease.

Foliar bacterial pathogens have to penetrate the plant tissue and access the interior of the apoplast in order to initiate the pathogenic phase. The entry process is driven by chemotaxis towards plant‐derived compounds in order to locate plant openings. However, information on plant signals recognized by bacterial chemoreceptors is scarce. Here, we show that the perception of GABA and l‐Pro, two abundant components of the tomato apoplast, through the PsPto‐PscC chemoreceptor drives the entry of Pseudomonas syringae pv. tomato into the tomato apoplast. The recognition of both compounds by PsPto‐PscC caused chemoattraction to both amino acids and participated in the regulation of GABA catabolism. Mutation of the PsPto‐PscC chemoreceptor caused a reduced chemotactic response towards these compounds which in turn impaired entry and reduced virulence in tomato plants. Interestingly, GABA and l‐Pro levels significantly increase in tomato plants upon pathogen infection and are involved in the regulation of the plant defence response. This is an example illustrating how bacteria respond to plant signals produced during the interaction as cues to access the plant apoplast and to ensure efficient infection.