Tomato wilt is a widespread soilborne disease of tomato that has caused significant yield losses in many tomato growing regions of the world. Previously, it was reported that tomato wilt can be caused by many pathogens, such as Fusarium oxysporum, Ralstonia solanacearum, Ralstonia pseudosolanacearum, Fusarium acuminatum, and Plectosphaerella cucumerina. In addition, we have already reported that Fusarium brachygibbosum caused symptomatic disease of tomato wilt for the first time in China. The symptoms of tomato wilt caused by these pathogens are similar, making it difficult to distinguish them in the field. However, F. brachygibbosum specific identification method has not been reported. Therefore, it is of great importance to develop a rapid and reliable diagnostic method for Fusarium brachygibbosum to establish a more effective plan to control the disease. In this study, we designed F. brachygibbosum-specific forward primers and reverse primers with a fragment size of 283bp located in the gene encoding carbamoyl phosphate synthase arginine-specific large chain by whole genome sequence comparison analysis of the genomes of eight Fusarium spp.. We then tested different dNTP, Mg2+ concentrations, and annealing temperatures to determine the optimal parameters for the PCR system. We evaluated the specificity, sensitivity and stability of the PCR system based on the optimized reaction system and conditions. The PCR system can specifically identify the target pathogens from different fungal pathogens, and the lower detection limit of the target pathogens is at concentrations of 10 pg/uL. In addition, we can accurately identify F. brachygibbosum in tomato samples using the optimized PCR method. These results prove that the PCR method developed in this study can accurately identify and diagnose F. brachygibbosum.

Large amounts of processing tomato are grown in Xinjiang, China. Tomato black spot disease, caused by Alternaria spp., and the produced alternaria toxins in tomato products are posing risks to human health. In this study, we isolated a rhizospheric bacterium, XJ-BV2007, from tomato (Solanum lycopersicum) fields, which we identified as Bacillus amyloliquefaciens. We found that this bacterium has a strong antagonistic effect against Alternaria alternata and reduces the accumulation of alternaria toxins in tomatoes. According to the antifungal activity of the bacteria-free filtrate, we revealed that B. amyloliquefaciens XJ-BV2007 suppresses A.&nbsp:alternata by the production of antifungal metabolites. Combining semi-preparative high-performance liquid chromatography, we employed UPLC-QTOF-MS analysis and the Oxford cup experiment to find that fengycin plays an important role in inhibiting A. alternata. This paper firstly reported that B. amyloliquefaciens efficiently controls tomato black spot disease and mycotoxins caused by A.&nbsp:alternata. B. amyloliquefaciens XJ-BV2007 may provide an alternative biocontrol strain for the prevention of tomato black spot disease.

ABSTRACT Bacterial diseases are a major cause of yield loss in tomato plants worldwide, and there is a need to identify strategies for control of these diseases. Bacterial wilt caused by Ralstonia solanacearum (RS) and bacterial spot caused by Xanthomonas axonopodis pv vesicatoria (Xav) are amongst the bacterial diseases affecting tomato crops. The current study investigates Euphorbia hirta (E. hirta) methanol extract (EHM) for its antibacterial activity against RS, and Xav induced diseases in tomato plants, along with its biostimulant potential in increasing fruit yield. EHM at 1280 mg/L exhibited 90% inhibition in the growth of both RS and Xav bacteria. Further, evaluation of EHM on Arka Vikas, a susceptible tomato variety, showed that pre-treatment of 15 days and 45 days tomato plants with 1280 mg/L EHM exhibited moderate resistance to bacterial wilt and spot disease, respectively, with increased tomato yield and improved chlorophyll b levels compared to control plants. The effectiveness of EHM in increasing fruit yield was further confirmed using field evaluation on ‘Namdhari NS 538’ variety of tomato plants. A 3.5-fold increase in numbers and weight of tomato was observed with foliar application of EHM (1280 mg/L). A significant reduction in fruit spoilage along with an increase in mRNA level of ethylene receptor factor (ERF1) was also observed. The study is the first to demonstrate the cost-effective and eco-friendly antibacterial and biostimulant potential of EHM (1280 mg/L) for tomato plants.

Despite the high efficacy of the zoophytophagous Nesidiocoris tenuis as a biological control agent, one of its drawbacks is its ability to cause damage to tomato plants. Confronted with sucking insects, tomato plants trigger defense responses, including the production of antioxidants or the increase of callose depositions to reduce the impact of insect piercing. In this work, we hypothesized that the damage caused by N. tenuis in tomato plants might be reduced by increasing the plant defenses. To do so, N. tenuis was released in defensive-induced tomato plants and non-induced control tomato plants under greenhouse conditions. Tomato plants were defensively induced by exposing them to the green leaf volatile (Z)-3-hexenyl propanoate through polymeric dispensers. Nesidiocoris tenuis established in both groups of plants (induced and non-induced), surprisingly the number of individuals was higher in the induced plants. However, as hypothesized, the damage caused by N. tenuis was significantly lower in the defensive-induced plants. In the defense-induced plants, the total number of necrotic rings was reduced by half, but what was even more interesting was that the number of severe, bent, and aborted rings decreased by almost 70 %. This result can be explained by the increase of callose deposition in the induced plants, which helped in regenerating the plant tissue in areas attacked by N. tenuis. Our results, by minimizing the damage caused by N. tenuis in tomatoes, provide an opportunity for enhancing the management of N. tenuis through the activation of the plant’s defenses.

In recent years, breeding work and planting techniques pursuing high yield and disease resistance, and post-harvest treatments such as low-temperature storage have caused a great decline in tomato flavor quality. How to improve the flavor quality of tomato is an urgent problem to be solved. The flavor quality of tomato mainly involves sweet and sour taste and aroma, which is closely related to sugars, organic acids and volatile flavor substances in the fruit, and losses of volatile flavor substances are the key factor causing the deterioration of tomato flavor quality. In this paper, the flavor composition of tomato, the synthesis pathways of tomato flavor compounds and the factors affecting tomato flavor are systematically reviewed in order to provide theoretical guidance for improving the flavor quality of tomato.

Bacterial, fungal, and viral diseases of tomato (Solanum lycopersicum) are responsible for widespread yield losses, especially in humid growing environments. Chromosome 11 of tomato contains genes that modulate resistance to several prominent tomato pathogens, including bacterial spot caused by Xanthomonas spp., gray leaf spot caused by Stemphylium spp., Fusarium wilt caused by race 2 of Fusarium oxysporum f. sp. lycopersici, and tomato yellow leaf curl virus (TYLCV) caused by begomoviruses. Major resistance loci are quantitative trait locus 11 (QTL-11) and Xv3/Rx4 for bacterial spot, Sm for gray leaf spot, I2 for Fusarium wilt, and Ty-2 for TYLCV. Marker-assisted selection was used to select for rare recombination events that combined these resistance loci into a linked cassette that can be inherited together in future crosses. A pedigree breeding strategy was used with marker-assisted selection and used to identify a novel coupling of Xv3/Rx4 and Ty-2. Recombination between the two genes was estimated as 0.056 cM, demonstrating that effective combinations of resistance can be established using publicly available germplasm. Progeny from the recombinant plants were screened using inoculated seedling trials to confirm resistance. The recombinants identified maintained resistance levels similar to the resistant controls. Trial results suggest that the trait markers on chromosome 11 are tightly linked to the respective resistance loci and are effective for selecting plants with resistance to the target diseases.

Abstract Tomato mosaic disease caused by Tomato mosaic virus (ToMV) reduces tomato crop production globally. Biocontrol measures using various rhizobacteria and algae have been developed to reduce the adverse effects of plant diseases. To this end, two rhizobacteria (probiotic bacteria) including Pseudomonas fluorescens, Bacillus subtilis, and aqueous extract of brown alga (Sargassum angustifolium) were applied. A certain concentration of bacterial suspension was added to the tomato rhizosphere along with the aqueous extract of brown alga and the plants were subsequently inoculated with ToMV. Semi-quantitative indirect-ELISA was performed to estimate the virus titer within inoculated plants. Also, the disease severity index was determined by visual scoring of the plants at 14 and 28 days post-inoculation. Growth indices of plants were evaluated and the data were statistically analyzed. The results showed that multiple treatments of the rhizobacteria and the aqueous extract of brown alga reduced the disease severity to 27.46%, and inhibit the ToMV accumulation up to 86.48% in tomato plants. Moreover, the growth indices of tomato plants pre-treated with a combination of the rhizobacteria and brown alga extract were significantly improved. Taken together, the results suggest that these biocontrol agents have a synergistic effect and their simultaneous application can, therefore, reduce the crop loss caused by ToMV.

Tomato is one of the most important fruits worldwide. It is widely consumed due to its sensory and nutritional attributes. However, like many other industrial crops, it is affected by biotic and abiotic stress factors, reducing its metabolic and physiological processes. Tomato plants possess different mechanisms of stress responses in which hormones have a pivotal role. They are responsible for a complex signaling network, where the antioxidant system (enzymatic and non-enzymatic antioxidants) is crucial for avoiding the excessive damage caused by stress factors. In this sense, it seems that hormones such as ethylene, auxins, brassinosteroids, and salicylic, jasmonic, abscisic, and gibberellic acids, play important roles in increasing antioxidant system and reducing oxidative damage caused by different stressors. Although several studies have been conducted on the stress factors, hormones, and primary metabolites of tomato plants, the effect of endogenous and/or exogenous hormones on the secondary metabolism is still poorly studied, which is paramount for tomato growing management and secondary metabolites production. Thus, this review offers an updated overview of both endogenous biosynthesis and exogenous hormone application in the antioxidant system of tomato plants as a response to biotic and abiotic stress factors.