Tomato Research Articles

Exploring the Potential of Bacillus subtilis IS1 and B. amyloliquificiens IS6 to Manage Salinity Stress and Fusarium Wilt Disease in Tomato Plants by Induced Physiological Responses.

The intensified concerns related to agrochemicals' ecological and health risks have encouraged the exploration of microbial agents as eco-friendly alternatives. Some members of Bacillus spp. are potential plant-growth-promoting agents and benefit numerous crop plants globally. This study aimed to explore the beneficial effects of two Bacillus strains (B. subtilis strain IS1 and B. amyloliquificiens strain IS6) capable of alleviating the growth of tomato plants against salinity stress and Fusarium wilt disease. These strains were able to significantly promote the growth of tomato plants and biomass accumulation in pot trials in the absence of any stress. Under salinity stress conditions (150 mM NaCl), B. subtilis strain IS1 demonstrated superior performance and significantly increased shoot length (45.74%), root length (101.39%), fresh biomass (62.17%), and dry biomass (49.69%) contents compared to control plants. Similarly, B. subtilis strain IS1 (63.7%) and B. amyloliquificiens strain IS6 (32.1%) effectively suppressed Fusarium wilt disease and significantly increased plant growth indices compared to the pathogen control. Furthermore, these strains increased the production of chlorophyll, carotenoid, and total phenolic contents. They significantly affected the activities of enzymes involved in antioxidant machinery and the phenylpropanoid pathway. Hence, this study effectively demonstrates that these Bacillus strains can effectively alleviate the growth of tomato plants under multiple stress conditions and can be used to develop bio-based formulations for use in the fields.

Biofeedback-Based Closed-Loop Phytoactuation in Vertical Farming and Controlled-Environment Agriculture.

This work focuses on biohybrid systems-plants with biosensors and actuating mechanisms that enhance the ability of biological organisms to control environmental parameters, to optimize growth conditions or to cope with stress factors. Biofeedback-based phytoactuation represents the next step of development in hydroponics, vertical farming and controlled-environment agriculture. The sensing part of the discussed approach uses (electro)physiological sensors. The hydrodynamics of fluid transport systems, estimated electrochemically, is compared with sap flow data provided by heat-based methods. In vivo impedance spectroscopy enables the discrimination of water, nutrient and photosynthates in the plant stem. Additionally to plant physiology, the system measures several air/soil and environmental parameters. The actuating part includes a multi-channel power module to control phytolight, irrigation, fertilization and air/water preparation. We demonstrate several tested in situ applications of a closed-loop control based on real-time biofeedback. In vertical farming, this is used to optimize energy and water consumption, reduce growth time and detect stress. Biofeedback was able to reduce the microgreen production cycle from 7 days to 4-5 days and the production of wheatgrass from 10 days to 7-8 days, and, in combination with biofeedback-based irrigation, a 30% increase in pea biomass was achieved. Its energy optimization can reach 25-30%. In environmental monitoring, the system performs the biological monitoring of environmental pollution (a low concentration of O3) with tomato and tobacco plants. In AI research, a complex exploration of biological organisms, and in particular the adaptation mechanisms of circadian clocks to changing environments, has been shown. This paper introduces a phytosensor system, describes its electrochemical measurements and discusses its tested applications.

The Modulation of Growth and Metabolism in Solanum lycopersicum Contrast With the Leaf-Specific Regulation of Wild Tomato Species.

Plant organs harbour diverse components that connect their physiology to the whole organism. The turnover of metabolites may be higher in some organs than in others, triggering differential growth patterns throughout the organism. We revealed that Solanum lycopersicum exhibits more coordinated growth and physiology across the entire plant compared to wild tomato species. Specifically, young leaves of S. lycopersicum develop more slowly than mature leaves, whereas wild species do not exhibit this pattern. Wild tomato Solanum pennellii displays young leaves with higher photosynthetic rates than mature leaves. Consequently, sucrose metabolism in S. pennellii is quite similar between young and mature leaves, while expression patterns of circadian clock genes differ significantly between leaves of different ages. Additionally, we demonstrated that introducing alleles related to tomato domestication into the wild tomato Solanum pimpinellifolium promotes coordinated growth between young and mature leaves, resulting in similar patterns to those observed in S. lycopersicum. Collectively, S. lycopersicum appears to exhibit more coordinated regulation of growth and metabolism, and understanding this process is likely fundamental to explaining its elevated harvest index.

Choline supplementation reduces cadmium uptake and alleviates cadmium toxicity in Solanum lycopersicum seedlings

Sustainable plant production in soil polluted with heavy metals requires that novel strategies are developed for the benefit of humans and other living things. Cadmium (Cd) is a common heavy metal pollutant for plants, and there is limited information on the use of exogenous bio-regulators to reduce the accumulation and toxic effects of Cd pollution in plants. Choline is an endogenous quertarnary amine that is known to improve stress tolerance in plants, while its mechanism of action in certain conditions is yet to be determined. This study investigated the effects of foliar choline supplementation (10 mM) on Solanum lycopersicum seedlings exposed to Cd application (50 mg/L in soil). The seedlings were randomized to five groups: Control (E1), Cd stress (E2), Choline supplementation after Cd stress (E3), Choline (E4), and Choline supplementation before Cd stress (E5). Following the applications, the Cd content, growth and development parameters (chlorophyll content, fresh and dry weight), oxidative stress parameters (H2O2 and MDA contents), as well as antioxidative defense system (SOD, GSH, AsA, and TPC contents) were analyzed. Choline supplementation after Cd stress reduced the enhanced Cd content in roots by 38% but did not alter it in leaves (p > 0.05) compared to the Cd group. Choline supplementation before Cd stress decreased Cd content both in roots by 87.5% and in leaves by 50%. Choline supplementation after and before Cd stress increased fresh and dry weights in both roots and leaves. While the Cd group (E2) increased the H2O2 level and SOD activity, no remarkable change was observed in H2O2 levels in all choline supplementations (E3, E4, E5). Therefore, lipid peroxidation (MDA) was not observed in choline supplementation before Cd stress (E5), however, when the choline was applied after Cd stress (E3) MDA content was reduced by 40% compared with the Cd stress group (E2). Choline supplementations after and before Cd stress (E3, E5) increased AsA content by 30%, while the Cd group (E2) decreased it by 60% compared with the control group (E1). Choline supplementations before Cd stress (E5) increased TPC by 33%, while the Cd group (E2) decreased it by 18%, moreover, when choline was applied after Cd stress (E3), no change was observed compared to the control group. These data suggest that choline prevents inhibition of plant growth due to Cd toxicity by reducing Cd uptake. The results provided in the present study are likely to enhance the quality and efficiency of crop production in heavy metal-polluted areas.

The Differential Impacts of Tuta absoluta Infestations on Some Nutrient and Pigments contents of Tomato Plant Leaves

The Differential Impacts of Tuta absoluta Infestations on Some Nutrient and Pigments contents of Tomato Plant Leaves

Evaluating the Lethal Dose (LD50) and Mutagenic Effects of Sodium Azide on Germination and Quality Traits in Two Varieties of Tomato (Solanum lycopersicum)

Study’s Excerpt Lethal dose (LD50) of sodium azide for two distinct tomato varieties, Beefsteak and San Marzano was quantified. The optimal mutagen doses that can be leveraged for enhancing quality traits in tomatoes is determined. Sodium azide has potential to improve crop resistance and productivity in tomato breeding programs. Full Abstract Sodium azide is a chemical mutagen that has been used to produce resistance in various susceptible crops to improve their yield and quality traits against harmful pathogens. The lethal dose and mutagenic effects of sodium azide on the germination percentage of two varieties of tomatoes (Beefsteak and San Marzano) were investigated with the aim of optimizing a suitable mutagen concentration with variability that could be exploited in the improvement of quality traits in Tomato plants. This study was carried out in the Green House at the Department of Biotechnology, Alex Ekwueme Federal University Ndufu-Alike, Ebonyi State (AE-FUNAI). The two varieties of tomato seeds were collected locally as fresh seeds from the taxonomic department and were treated with sodium azide at different concentrations of 0.0%, 0.2%, 0.4%, and 0.6% w/v. The seed was sown and monitored for 30 days with everyday documentation of germination percentage, survival percentage, and lethal dose. Statistical analysis using significant difference (LSD) at 95% probability level was employed to analyze the effects. The results obtained from this study show that there is a steady decrease in germination and survival percentage with increased concentration of sodium azide in both varieties of tomatoes when compared with the control. The lethal dose (LD50) was determined upon germination and survival of the tomato varieties. The highest LD50 was calculated by linear regression to be 0.950 for the beefsteak variety, which was significantly higher than 0.794 for the san marzano variety at 50% germination was recorded under treatment 0.6% NaN3. These concentrations are therefore considered as the LD50 values. Sodium azide via mutation at low concentrations improves some important quality traits of tomatoes.

Improving storage duration of tomatoes (Solanum lycopersicum) through electron beam technology.

Electron beam (EB) technology typically consists of high-energy electron streams produced by a linear accelerator. Although promising, the use of EB irradiation as a technique to delay ripening and prevent spoilage in tomatoes has not been extensively investigated. In this study, the effectiveness of EB irradiation in prolonging the shelf life of tomatoes postharvest was investigated. The results indicated that EB irradiation successfully reduced microbial contamination and decay, preserved key quality attributes (such as total soluble solids, titratable acidity, pH, and firmness), and significantly minimized weight loss. Notably, the treatment delayed the biosynthesis of lycopene, a key indicator of ripening, without adversely affecting phenolic content and antioxidant activity, which remained consistent regardless of irradiation. Additionally, different methods for detecting irradiation were evaluated. Thermoluminescence analysis proved to be the most dependable technique, especially for doses exceeding 600Gy, due to its high sensitivity and specificity. In contrast, photostimulated luminescence and electron spin resonance analyses showed limitations in accurately identifying the irradiation status of foods with high moisture content, such as tomatoes. This study confirms that EB irradiation, while maintaining postharvest quality, extends the shelf life of tomatoes by 5-10days, suggesting its potential for commercial application in food preservation.

Plant Growth Optimization Using Amber Light Supplemented with Different Blue Light Spectra

Blue (400–500 nm) and red (600–700 nm) light regions have been investigated for their effects on photosynthesis and plant growth, yet evidence for specific blue light wavelengths in plant research is lacking. Investigations into amber (595 nm) light are similarly limited. To ‘shed light’ on these two important wavelengths, this study investigated the combined effects of blue and amber light on plant growth and development in two model plants: tomato (Solanum lycopersicum cv. Beefsteak) and lettuce (Lactuca sativa cv. Breen). Plant growth responses were determined with four light treatments: B+BA (blue + broad amber, 455–602 nm), RB-NA (royal blue + narrow amber, 430–602 nm), RB-BA (royal blue + broad amber, 423–595 nm), and high-pressure sodium at a PPFD of 250 µmol m−2 s−1. After 21 days, the highest fresh and dry mass for both plant species was obtained under the RB-BA light treatment. Shifting the blue wavelength from 430 nm to 455 nm with broad amber lighting led to 40% less fresh mass for tomatoes, whereas only an approximate 5% reduction in fresh mass was observed for lettuce plants. Our findings demonstrate that an alternate and combined blue + amber light spectrum is effective for optimizing plant productivity.

Prone to loss: Senescence-regulated protein degradation leads to lower protein extractability in aging tomato leaves

The utilization of proteins extracted from tomato (Solanum lycopersicum) leaves as cost-effective resources for human consumption or animal feed has gained interest. Thus, increasing protein extractability from tomato leaves became a new breeding target. However, the genetic factors influencing this trait remains poorly understood. In this study, we analyzed changes in leaf protein content, protein composition, and extraction yield across developmental stages, which are vegetative growth, flowering, fruit-forming, and mature fruit. Moreover, tomato gene expression across developmental stages was also studied, to identify genes underlying variability in leaf protein extraction. Protein extraction yield decreased from 0.51 g/g to 0.01 g/g leaf protein from the vegetative to mature stage. However, total protein content inferred with Dumas combustion analysis did not change over the developmental stages tested, while the protein-to-peptide ratio decreased significantly. To further analyze potential causes underlying the decline of protein-to-peptide ratio, the enzymatic activity of proteases – i.e. the enzymes responsible for protein degradation – and the expression of genes encoding these enzymes was studied along plant development. The overall specific activity of proteases did not change significantly throughout plant development. On the contrary, the gene expression of distinct members of the aspartic, cysteine, and subtilase protease families increased. Overall, our findings suggest that extraplastidic protein degradation likely underlies the protein degradation observed during senescence. In the future, the reduction of the activity of extraplastidic proteases through biotechnology could represent an effective strategy to develop tomato varieties with improved protein extraction yields.

SlMKK4 is responsible for pollen development in tomato

The development of viable pollen is a determinant of male fertility and plays an essential role in the reproductive process of angiosperms. Mitogen-activated protein kinase (MAPK) cascades modulate diverse aspects of plant growth, but their involvement in post-meiotic pollen development is unclear. In this study, SlMKK4 was identified as a crucial regulator in overseeing pollen development in tomatoes (Solanum lycopersicum). Utilizing CRISPR-associated protein 9 to disrupt SlMKK4 resulted in an obvious decrease in pollen viability. The results of cell biology and transcriptomic analyses demonstrated that SlMKK4 specifically regulates auxin and sugar metabolism as well as signal transduction during post-meiotic pollen development. This is supported by the finding that protein–protein interaction assays and in vitro phosphorylation assays indicate that SlMKK4 serves as the upstream MAPKK for SlMPK20, which exhibits a distinct function in regulating the uninucleate (UN) to binucleate (BN) transition during microgametogenesis in tomatoes. Moreover, pollen from transgenic plants experienced significant arrest predominantly at the BN stage, accompanied by subcellular abnormalities manifesting during the late UN microspore phase. Furthermore, transcriptomic analyses indicated that SlMKK4 knockout remarkably downregulated the expression of numerous genes regulating auxin and sugar metabolism as well as signal transduction in anthers. Therefore, our findings suggest that SlMKK4 may serve as one of the upstream SlMAPKKs of SlMPK20 and also play a pivotal role in modulating post-meiotic pollen development in tomato plants.

Different multicellular trichome types coordinate herbivore mechanosensing and defense in tomato.

Herbivore-induced wounding can elicit a defense response in plants. However, whether plants possess a surveillance system capable of detecting herbivore threats and initiating preparatory defenses before wounding occurs remains unclear. In this study, we reveal that tomato (Solanum lycopersicum) trichomes can detect and respond to the mechanical stimuli generated by herbivores. Mechanical stimuli are preferentially perceived by long trichomes, and this mechanosensation is transduced via intra-trichome communication. This communication presumably involves calcium waves, and the transduced signals activate the jasmonic acid (JA) signaling pathway in short glandular trichomes, resulting in the upregulation of the Woolly (Wo)-SlMYC1 regulatory module for terpene biosynthesis. This induced defense mechanism provides plants with an early warning system against the threat of herbivore invasion. Our findings represent a perspective on the role of multicellular trichomes in plant defense and the underlying intra-trichome communication.

Modified Surface Drip Irrigation and Hydraulic Barrier Impacts on Soil Moisture and Water Productivity for Tomatoes in a Greenhouse

Considerable amounts of irrigation water of vegetable crops grown in homogenous sandy soil profiles could be subjected to deep percolation water losses due to inappropriately designed surface or subsurface drip irrigation methods. This study aimed to investigate the combined influence of implementing clay soil layer in homogenous sandy soil profile of low-tech greenhouse ridges and using modified surface drip irrigation (M-DI) on soil moisture distribution and water productivity of tomatoes. In the greenhouse, a 7.5 cm thick clay soil layer was implemented 15 cm from the soil surface of each ridge as a hydraulic barrier. Three irrigation regimes (100%, 70% and 50% of ETo) were imposed with the M-DI on tomato plants and 100%ETo with surface drip irrigation (DI) as control. Regarding economic valuation, viability was preserved for the M-DI and DI methods. The outcome indicated that soil moisture spreads more horizontally than vertically on the sandy soil above the clay soil layer. The combined effect of the homogenous sandy soil profile amendment and full irrigation (100%ETo) with the M-DI irrigation method increased the tomato fruit yield by 64.5%. Furthermore, the combined influence enhanced water productivity by the M-DI to 54.7 kg/m3 compared to 32 kg/m3 by the DI. However, M-DI demonstrated dominance over DI regarding returns, yield, and profit. Economic-wise, the M-DI requires 50% less of the lateral pipelines needed by the DI in low-tech greenhouses. Adopting the M-DI with a hydraulic barrier can improve soil moisture, water productivity, yield, and returns for tomato crops in low-tech greenhouses under sandy soil conditions. Also, the M-DI with the hydraulic clay barriers was an economically viable investment compared to the DI without clay barriers for growing tomatoes in low-tech greenhouses.

Effects of foliar spraying with melatonin and chitosan Nano-encapsulated melatonin on tomato (Lycopersicon esculentum L. cv. Falcato) plants under salinity stress

Melatonin has been found to be crucial in the growth and development of plants under stress conditions. In this study, the effects of melatonin and nano melatonin regarding the growth and development of tomato plants, along with their photosynthetic pigment, phenol, and antioxidant activity, were investigated under saline conditions. The study was conducted using a completely randomized design with three replications, and the applied treatments were salt stress and foliar spraying of melatonin at a concentration of 0 (control), melatonin (Mel), and nano capsule-melatonin (Nano-Mel) at 500 µM. Salinity treatments included application of sodium chloride with two concentration of 0 mM NaCl (S1) and 50 mM NaCl (S2). Under saline conditions, Mel and Nano-Mel increased both shoot and root fresh and dry weights, improved relative water content (RWC), and enhanced antioxidant activity and phenolic content. Salinity elevated leaf ABA content, unaffected by Mel or Nano-Mel. Chlorophyll fluorescence and SPAD values demonstrated resilience to salinity with Mel and Nano-Mel applications. Nano-Mel notably mitigated Na + accumulation in leaves under salinity, helping maintain K + homeostasis. Proline levels rise due to salinity but decreased with Mel and Nano-Mel treatments. Electrolyte leakage (EL) increased under salinity but is significantly reduced by Mel, indicating enhanced membrane stability. The findings reveal that salinity stress significantly reduced plasma membrane intrinsic protein (PIP) expression in roots and leaves, whereas Mel and Nano-Mel treatments enhance PIP expression, particularly in roots. The study concludes that Mel and Nano-Mel effectively alleviate salinity-induced stress, promoting growth and maintaining physiological homeostasis in tomato plants.

Enhancing tomato growth and soil fertility under salinity stress using halotolerant plant growth-promoting rhizobacteria

Soil salinization is a critical issue that not only hampers the efficiency and sustainability of global agricultural production but also poses significant challenges to the achievement of sustainable development goals across environmental, economic, and social dimensions. Halotolerant plant growth-promoting rhizobacteria (HPGPR) have the potential to mitigate abiotic stress, foster plant growth, and bolster the stress resistance capabilities of crops. This study conducted the isolation, identification, and characterization of HPGPR originating from a saline-alkali orchard area in northwest China. The efficacy of the isolated bacterial strains was evaluated through potted plant experiments, assessing the growth of tomato plants under in vitro conditions and under varying salinity stress. Ultimately, the study investigated the influence of these HPGPR on soil physicochemical properties, enzymatic activities, and the structure and composition of the microbial community. Upon isolating 12 bacterial strains, we conducted an in vitro assessment of their salt tolerance, ultimately singling out three robust isolates, which exhibited exceptional salt tolerance. Detailed 16S rRNA gene sequencing and meticulous taxonomic evaluation systematically assigned these isolates to Priestia endophyticus GSCK1 (accession number: OR569048), Bacillus atrophaeus GSCK2 (accession number: OR569061), and Serratia fonticola GSCK6 (accession number: OR569062), respectively. These strains exhibited notable biochemical and plant growth-promoting traits, including enzymatic activities and the production of indole-3-acetic acid. They significantly enhanced plant growth metrics and soil fertilities, particularly strain GSCK6, which also reshaped the soil microbial community, augmenting beneficial microbe abundance. The HPGPR treatment notably improved soil pH, nutrient availability, enzymatic activities, and reduced soil electrical conductivity, underscoring their potential in agricultural resilience against salinity. The eco-friendly salt stress mitigation strategy of HPGPR not only enhances soil quality and promotes plant growth by regulating the composition and function of microbial communities, but also provides a novel solution for global agricultural production. This approach is conducive to increasing crop yield and quality, reducing the limitations of saline-alkali land on agricultural production, and promoting food security and sustainable agricultural development.

Characterization of Low-Temperature Sensitivity and Chlorophyll Fluorescence in Yellow Leaf Mutants of Tomato

Leaf color mutants serve as valuable models for studying the regulation of plant photosynthesis, alternations in chloroplast structure and function, and the analysis of associated gene functions. A yellow leaf mutant, ylm, was separated from the wild tomato M82, with its yellowing intensity influenced by low temperature. To assess the low-temperature sensitivity of this mutant, the photosynthetic and chlorophyll fluorescence responses of ylm and M82 were examined under different temperature conditions. In this study, the ylm mutant and its wild type, M82, were exposed to three temperature levels, 16, 25, and 30 °C, for 48 h. The impact of these temperature treatments on leaf color change, chlorophyll content, photosynthetic performance, and chlorophyll fluorescence characteristics of mutant ylm was investigated. The results revealed the following: (1) After exposure to 16 °C, the ylm mutant exhibited significant yellowing, a marked reduction in chlorophyll content, and a notable increase in carotenoid content. At 25 °C, the differences were less pronounced, and at 30 °C, the differences between ylm and M82 were minimal. (2) The photosynthetic rate of the ylm mutant was lower than that of M82 at 16 °C, with the gap narrowing as temperature increased, eventually converging at higher temperatures. (3) The fluorescence transient curve (OJIP) of the ylm mutant differed significantly from that of M82 at 16 °C, with higher fluorescence intensity at the O point and lower intensity at the J, I, and P points. This difference was decreased at 25 °C and nearly disappeared at 30 °C. Additionally, the Fv/Fm, Fv/Fo, PIabs, PItotal, ABS/CSm, TRo/CSm, and ETo/CSm values of ylm were lower than those of M82 at 16 °C, while the ABS/RC and DIo/RC values were higher, with no significant differences observed at 30 °C. These findings suggest that the ylm mutant is highly sensitive to low temperature, with pronounced yellowing, reduced light energy absorption and capture efficiency, and impaired electron transport at lower temperature.

Endophyte Bacillus vallismortis BL01 to Control Fungal and Bacterial Phytopathogens of Tomato (Solanum lycopersicum L.) Plants

Some strains of Bacillus vallismortis have been reported to be efficient biocontrol agents against tomato pathogens. The aim of our study was to assess the biocontrol ability of the endophytic strain BL01 Bacillus vallismortis through in vitro and field trials, as well as to verify its plant colonization ability and analyze the bacterial genome in order to find genes responsible for the biocontrol activity. We demonstrated in a gnotobiotic system and by confocal laser microscopy that the endophytic strain BL01 was able to colonize the endosphere and rhizosphere of tomato, winter wheat and oilseed rape. In vitro experiments demonstrated the inhibition activity of BL01 against a wide range of phytopathogenic fungi and bacteria. BL01 showed biological efficacy in two-year field experiments with tomato plants against black bacterial spotting by 40–70.8% and against late blight by 47.1% and increased tomato harvest by 24.9% or 10.9 tons per hectare compared to the control. Genome analysis revealed the presence of genes that are responsible for the synthesis of biologically active secondary metabolites, which could be responsible for the biocontrol action. Strain BL01 B. vallismortis can be considered an effective biocontrol agent to control both fungal and bacterial diseases in tomato plants.

A Novel Enterococcus-Based Nanofertilizer Promotes Seedling Growth and Vigor in Wheat (Triticum aestivum L.).

Excessive use of chemical fertilizers poses significant environmental and health concerns. Microbial-based biofertilizers are increasingly being promoted as safe alternatives. However, they have limitations such as gaining farmers' trust, the need for technical expertise, and the variable performance of microbes in the field. The development of nanobiofertilizers as agro-stimulants and agro-protective agents for climate-smart and sustainable agriculture could overcome these limitations. In the present study, auxin-producing Enterococcus sp. SR9, based on its plant growth-promoting traits, was selected for the microbe-assisted synthesis of silver nanoparticles (AgNPs). These microbial-nanoparticles SR9AgNPs were characterized using UV/Vis spectrophotometry, scanning electron microscopy, and a size analyzer. To test the efficacy of SR9AgNPs compared to treatment with the SR9 isolate alone, the germination rates of cucumber (Cucumis sativus), tomato (Solanum lycopersicum), and wheat (Triticum aestivum L.) seeds were analyzed. The data revealed that seeds simultaneously treated with SR9AgNPs and SR9 showed better germination rates than untreated control plants. In the case of vigor, wheat showed the most positive response to the nanoparticle treatment, with a higher vigor index than the other crops analyzed. The toxicity assessment of SR9AgNPs demonstrated no apparent toxicity at a concentration of 100 ppm, resulting in the highest germination and biomass gain in wheat seedlings. This work represents the first step in the characterization of microbial-assisted SR9AgNPs and encourages future studies to extend these conclusions to other relevant crops under field conditions.

Bacillus amyloliquefaciens strain BaNCT02: An antagonist with multiple mechanisms of action against Meloidogyne incognita

AbstractBacillus species are among the most studied and commercially exploited biocontrol agents of plant‐parasitic nematodes. These antagonists may control nematodes by producing toxic or repellent substances, inducing systemic resistance in plants and disrupting nematode chemotaxis. Understanding the mechanism of action of antagonists increases the likelihood of success for microbiological nematicides under field conditions. Therefore, the objective of this work was to elucidate the mechanisms of action of Bacillus amyloliquefaciens strain BaNCT02 against Meloidogyne incognita. We assessed the potential of this strain for forming biofilm in roots and producing volatile and non‐volatile toxic substances. BaNCT02 did not induce systemic resistance in tomato plants against M. incognita. Scanning electron microscopy and chemotaxis analyses revealed that the bacteria form a biofilm on soybean roots and 67% of second‐stage juveniles of M. incognita are repelled by common bean roots treated with the antagonist. Additionally, BaNCT02 produces substances with toxic effects against eggs and juveniles of M. incognita, including volatile organic compounds such as 2‐undecanone and 2‐heptanone, as well as non‐volatile metabolites like proteases and chitinases. The suppressive effect of these substances on hatching and mortality of juveniles varied from approximately 70% to more than 90%. We concluded that B. amyloliquefaciens BaNCT02 forms a biofilm on root surfaces and produces volatile and non‐volatile metabolites with nematicidal and repellent effects against M. incognita.

A gene cluster for polyamine transport and modification improves salt tolerance in tomato.

Polyamines act as protective compounds directly protecting plants from stress-related damage, while also acting as signaling molecules to participate in serious abiotic stresses. However, the molecular mechanisms underlying these effects are poorly understood. Here, we utilized metabolome genome-wide association study to investigate the polyamine content of wild and cultivated tomato accessions, and we discovered a new gene cluster that drove polyamine content during tomato domestication. The gene cluster contains two polyphenol oxidases (SlPPOE and SlPPOF), two BAHD acyltransferases (SlAT4 and SlAT5), a coumaroyl-CoA ligase (Sl4CL6), and a polyamine uptake transporter (SlPUT3). SlPUT3 mediates polyamine uptake and transport, while the five other genes are involved in polyamine modification. Further salt tolerance assays demonstrated that SlPPOE, SlPPOF, and SlAT5 overexpression lines showed greater phenolamide accumulation and salt tolerance as compared with wild-type (WT). Meanwhile, the exogenous application of Spm to SlPUT3-OE lines displayed salt tolerance compared with WT, while having the opposite effect in slput3 lines, confirms that the polyamine and phenolamide can play a protective role by alleviating cell damage. SlPUT3 interacted with SlPIP2;4, a H2O2 transport protein, to maintain H2O2 homeostasis. Polyamine-derived H2O2 linked Spm to stress responses, suggesting that Spm signaling activates stress response pathways. Collectively, our finding reveals that the H2O2-polyamine-phenolamide module coordinately enhanced tomato salt stress tolerance and provide a foundation for tomato stress-resistance breeding.

Effects of dynamised high dilutions and vegetal extract based on silicon on the growth and induction of resistance in tomato plants against Rhizoctonia solani

ABSTRACT The objective of this study was to study the response of tomato (Solanum lycopersicum) against Rhizoctonia solani using dynamised high dilutions and plant extract based on silicon. The treatments were Silicea terra (ST), Thuya occidentalis (TO), and Equisetum arvense (EA) at 30CH (Centesimal Hahnemannian dilution order), Equisetum arvense leaf extract (LE), and non-dynamised water as the control. Seeds of tomato cv Marmande were treated overnight. The in vitro bioassays involved assessment of R. solani mycelial growth, seed germination, and seedling development. In the greenhouse experiment, the emergence, root and aerial part development, and disease development were evaluated. Leaves were harvested to analyse concentrations of flavonoids, phenolic compounds, chlorophyll, carotenoids, and chitinase activity. In the in vitro bioassay, LE reduced mycelial growth and TO increased the seedling vigour index, dry weight, and length of seedlings. In the greenhouse experiment, TO and ST increased plant emergence. Tomato plants treated with ST improved the fresh weight and the length of the roots. The disease severity was decreased by ST, LE, and TO. The flavonoid concentration was higher in plants treated with TO and LE. Overall, the treatments of TO, EA, and ST improved the content of phenolic compounds. Moreover, endochitinase and chitobiosidase were activated by LE.