Search

Aims and background: Pests and diseases of plants often threaten the availability and safety of plants for human consumption. To face these challenges, a new agricultural revolution is underway (agriculture 4.0). This agrarian revolution dramatically benefits from new digital technologies and artificial intelligence (AI). Methods: The farmers need a reliable tool for an early disease diagnosis. Imaging is a promising technique for diagnosing and quantifying the disease plot. Easily automated and non-intrusive, imaging allows, with low costs in instrumentation and human resources, to account for much agricultural priority's local mics on large production areas. The main purpose paper is to develop a hybrid model for tomato disease detection based on image data collection. We apply transfer learning and fine-tuning strategies to improve the performance of different pre-trained models. Two models have been selected to develop our hybrid model for plant disease identification among these CNN models. We used the plant village dataset, which contains nine classes of tomato diseases. Results: First, we evaluate the performance of seven different architectures including VGG16, ResNet50, EfficientNetB0, EfficientNetB1, EfficientNetB2, EfficientNetB3 and EfficientNetB4. We applied the transfer learning technique. Then, the best two pre-trained models were selected and used to implement a weighted average ensemble. The proposed model achieves an accuracy of 0.981. Conclusion: Many diseases can affect tomato plants and cause yield losses. Therefore, plant pathogens should be given more importance. Furthermore, this study can be adapted to cover other types of crops in future research. [ABSTRACT FROM AUTHOR]

Purpose: Plant microbial biostimulants, such as arbuscular mycorrhizal fungi (AMF), enhance nutrient concentration in fruits, including tomato. However, field studies on tomato AMF inoculation are scarce. AMF species belonging to Gigasporaceae and Glomeraceae families known to vary in life-history strategies may determine differential effects on plant nutrient benefits and residue decomposition. Despite this, the effect of different life-history strategies on nutrient acquisition of tomato fruits has not been investigated yet. Methods: We studied the effect of inoculation of two tomato varieties with four AMF species belonging to Glomeraceae and Gigasporaceae. Fungal colonization, yield, fruit nutrient concentration, litter decomposition, and bacterial and fungal abundances in soil were assessed in the field under organic agriculture. Results: Overall Gigasporaceae promoted the concentration of nutrients in tomato fruits compared to Glomeraceae. A variability in AM fungal colonization and fruit nutrient concentration was detected within Glomeraceae. Scutellospora pellucida increased the yield (+ 27%) of var. Rio Grande with respect to Gigaspora gigantea. In var. Rio Grande, inoculation with Funneliformis mosseae did not change litter decomposition as compared to non-inoculated controls, whereas it was lower than in Sclerocystis sinuosa and Gigasporaceae species, which showed the highest decomposition rates. AMF inoculation promoted soil total bacterial and fungal abundance and fungal:bacterial (F:B) ratio compared to controls, and members of Gigasporaceae had the highest F:B ratio. Conclusion: These findings pointed at the inclusion of AM fungal life-history strategy within the selection criteria for the development of biofertilizers able to enhance the nutritional value of vegetables under organic farming systems. [ABSTRACT FROM AUTHOR]

Background and aims: The plant growth promoting rhizobacteria have been repeatedly addressed in improving plant growth and resistance against pathogens. This study explored the role of Paraburkholderia sp. GD17 in improving tomato plant growth and resistance to Botrytis cinerea (Bc). Methods: Tomato roots were treated with GD17 strain, and then the leaves were inoculated with Bc. Physiological and biochemical parameters, and gene expression were analyzed. Results: In the absence of Bc, GD17 efficiently improved plant growth, and increased photosynthetic efficiency. In the presence of Bc, GD17-bacterized plants exhibited an enhanced resistance, as indicated by 67% of disease index in non-bacterized plants, while by 24% in bacterized ones. In response to Bc, the defense reaction was reinforced in bacterized plants, as shown by enhanced antioxidative capacity and mitigated oxidative damage, as well as increased PR gene expression in bacterized plants compared with control. Photosynthesis was inhibited by Bc inoculation, to a greater degree in non-bacterized plants than in bacterized ones. In the presence of Bc, soluble sugar contents significantly increased in non-bacterized plants, while it was controlled in bacterized plants. The carbohydrate catabolism-related genes, including starch degradation, photorespiration, and pentose phosphate pathway, generally presented a higher expression in bacterized plants under Bc attack. Conclusions: GD17 strain improved tomato plant growth by increasing the photosynthetic efficiency. GD17 enhanced plant resistance against Bc-induced disease by increasing defense and alleviating oxidative damage. Additionally, GD17 optimized the trade-off between plant growth and defense by strengthening carbohydrate metabolic regulation. [ABSTRACT FROM AUTHOR]

Aims: Since producing more with less is required for increasing agricultural sustainability and reducing its environmental impact, breeding varieties with increased yield stability under reduced fertilizer application is an important goal, particularly in high valued horticultural crops such as tomato (Solanum lycopersicum L.). However, because of the difficulties to conciliate yield and fertilizer use efficiency through breeding, the graft-compatible genetic biodiversity existing in horticultural species offers the possibility to directly approach this objective in high-yielding elite varieties through improving nutrient capture and promoting ecosystem services such as insect pollination. We hypothesized that rootstocks affect pollinator foraging decisions through the nutritional status that impacts yield. Methods: Fifteen genetically diverse experimental rootstocks were grafted to a scion tomato variety and cultivated under optimal and reduced (25% of optimal) P and NPK fertilization in the presence of managed bumblebee pollinators (Bombus terrestris). Results: Up to twofold yield variability between rootstocks was associated with leaf nutrition and photosynthesis of the scion. Interestingly, fertilization regime and the rootstock genotype influenced the pollinator foraging decisions since bumblebees showed feeding preference for plants cultivated under low P, and for the most yielding and nutritious graft combinations under reduced but not under optimal fertilization. Bumblebees can sense plant nutritional status through source-sink relations, as supported by the consistent relationship between pollinator preferences and leaf carbon concentration. Conclusions: This study opens new perspectives for using pollinators as "phenotypers" to select the most resilient plants under suboptimal conditions and/or genotypes that synergistically increase crop productivity by promoting the ecosystem service provided by the insects. [ABSTRACT FROM AUTHOR]

Aims: Selenium (Se) has been reported to mitigate the harmful effects of salt stress on plants; however, the internal mechanisms remain unknown. Here, the effects of Se supplementation on tomato plants under salt stress were investigated. Methods: The biomass, relative electrical conductivity (REC), relative water content (RWC), photosynthetic parameter, inorganic ion contents, malondialdehyde (MDA), soluble sugar and proline contents, as well as the regulation of plant hormones of Se application in tomato plants were investigated after exposure to Se and salt stress treatments. Results: Exogenous Se application improved photosynthesis and the water use efficiency (WUE) of tomato plants under salt stress, thereby promoting the growth of tomato plants under salt stress. Se supplementation also maintained the K+ and Na+ homeostasis, reduced the REC, decreased MDA, H2O2 and O2•− contents, and mitigated the oxidative damage caused by salt stress. In addition, exogenous Se increased the salicylic acid (SA) content in tomato leaves and roots via up-regulating the PAL or ICS pathways involved in SA biosynthesis. After pre-treatment with the SA inhibitor 1-aminobenzotriazole, the photosynthetic efficiency of tomato plants decreased, plant growth was weakened, and the REC was increased, indicating that the alleviating role of Se on salt stress was abolished. Conclusions: Our results clarified the roles of Se and its regulation mechanisms in plant salt stress tolerance and the critical involvement of SA in this process. The study of Se in plant abiotic stress tolerance will give a more theoretical foundation for using exogenous Se in agricultural production to enhance crop growth and yield under adversity stresses. [ABSTRACT FROM AUTHOR]

Aims: Negative interactions in the rhizosphere between entomopathogenic nematodes (EPNs) and plant-parasitic nematodes, such as root-knot nematodes (RKNs), have been documented over the past two decades but the mechanisms and dynamics of such interactions remain largely elusive. Methods: Here, we evaluated the effect of the inoculation position of two EPN species, Steinernema feltiae and Heterorhabditis bacteriophora, as well as different facets of the EPN-bacterial symbiont complex on the migration of RKNs toward tomato roots, both in sand and in Pluronic gel conditions. Results: When EPNs were placed between the position of the RKNs and the roots, the movement of RKNs toward the roots was inhibited. We observed this same pattern both in sand and in Pluronic F-127 (PF-127) gel for two species of EPNs. We also observed that different components of the EPNs/bacterial symbiont complex (bacteria separate from the nematodes vs. the nematode-bacterium complex), and particularly the cell-free supernatant produced by the bacterial culture, displayed inhibitory effects on RKNs. Conclusion: Therefore, the EPNs/bacterial complex, by slowing down the movement of RKNs toward the host plant roots, could partially contribute to RKN control. By screening for the most repulsive strains of EPNs that are also effective against insect pests, the combined target approach should alleviate EPNs application costs in integrated pest management practices. [ABSTRACT FROM AUTHOR]

Aims: Drought stress affects crop growth and productivity by causing morphological, physiological, and molecular changes. Pseudomonas koreensis is a plant-growth-promoting rhizobacterium that has potential for inducing stress tolerance in crops; however, the underlying mechanisms remain unclear. Therefore, this study verified the effects of P. koreensis on drought stress in tomato (Solanum lycopersicum Mill.) and explored the associated mechanisms. Methods: Tomato seedlings that were exposed to the cell-free culture filtrate of P. koreensis GS or not were grown under non-stressed and drought-stressed conditions. Plant and leaf samples subjected to integrated physiological, transcriptomic, and metabolomic analyses. Results: Under drought stress, treatment with cell-free culture filtrate prominently increased plant height (7.7%), root length (17.2%), dry biomass (19.8%), relative water content (19.2%), leaf chlorophyll content (13.6%), and net photosynthesis rate (56.5%) in tomato. The culture filtrate treatment also enhanced catalase and peroxidase activity but decreased malondialdehyde content in drought-stressed leaves. Many differentially expressed genes and accumulated metabolites associated with antioxidant defense were enriched in flavonoid biosynthesis, glutathione metabolism, porphyrin and chlorophyll metabolism, photosynthesis, and fructose and mannose metabolism, which jointly contributed to the alleviation of drought stress. Conclusions: The enhancement of plant antioxidant capacity is the key factor for P. koreensis GS cell-free culture filtrate in alleviating drought stress in tomato. [ABSTRACT FROM AUTHOR]

Aims and methods: This study aimed to evaluate the effects of four AMF inoculation treatments (Funneliformis mosseae, Rhizophagus intraradices, Glomus versiforme and a mixture of these three AMF strains) and Meloidogyne incognita inoculation on the growth and reproductive performance of cherry tomato (Solanum lycopersicum var. cerasiforme), and the effect of AMF on M. incognita density in soil under greenhouse conditions. Results: The results showed that AMF colonization could alleviate the biomass decline of cherry tomato caused by M. incognita and could reduce the density of M. incognita in soil. Moreover, AMF colonization promoted the biomass allocation of aboveground parts to alleviate the consumption of photosynthetic products by belowground parts of cherry tomato. Different AMF inoculation treatments had different effects on the uptake of nitrogen and phosphorus in the aboveground and belowground parts after M. incognita infection and they had interactive effects, indicating that AMF played an important role in regulating nutrient uptake of cherry tomato after M. incognita infection, and there were functional differences among different species. Furthermore, AMF colonization increased flower and fruit weight, and the resource investment to seeds under the stress of M. incognita infection. Conclusion: Our results clearly indicated that AMF significantly increased the growth and nitrogen uptake of cherry tomato inoculated by M. incognita. F. mosseae was the most effective treatment enhancing resistance to RKN and improving reproductive capacity of cherry tomato, indicating its application potential. [ABSTRACT FROM AUTHOR]

Aims : Many studies have reported beneficial effects of yeasts on the colonization and development of arbuscular mycorrhizae, thought a few studies have also shown neutral effects. All these studies have in common that the mechanism, by which yeasts and mycorrhizae interact, is little understood. Here, we explore how plant growth-promoting yeasts affect the colonization of tomato plants by beneficial mycorrhizal fungi. Methods: We tested the influence of the soil yeasts Candida saitoana, Tausonia pullulans, and Saccharomyces eubayanus on colonization of tomato roots by the mycorrhizal fungus Rhizophagus irregularis. We analyzed mycorrhizal parameters and the expression pattern of mycorrhiza-specific genes. In plants co-inoculated with S. eubayanus and R. irregularis, we measured the root accumulation pattern of jasmonic acid, oxo-phytodienoic acid, abscisic acid and salicylic acid, and the expression of genes related to plant hormone signaling and metabolism. Results: The three yeasts had distinct effects on mycorrhizal colonization: C. saitoana had no effect on mycorrhizal parameters, T. pullulans delayed mycorrhizal colonization at an early stage, and S. eubayanus slowed colonization down throughout the entire trial. In plants co-inoculated with S. eubayanus and R. irregularis, we observed a sustained increase in jasmonic acid and up-regulation of the JA biosynthesis related genes LOXD, OPR3, and AOS1. Conclusion: Co-inoculation with yeast affected mycorrhizal colonization and altered the expression pattern of mycorrhizal and plant defense-related genes. In particular, the yeast S. eubayanus modified plant defense hormones such as jasmonic acid, which is linked to mycorrhizal-induced resistance in tomato plants. [ABSTRACT FROM AUTHOR]

Background and aims: Phosphorus (P) is an essential nutrient for plant growth, but is also one of the least accessible in soil. Plants have evolved several strategies to cope with P deficiency and recently the role of the phytohormones strigolactones (SLs) in modulating tomato plants acclimation to P shortage has been described. How SLs regulate the use of P from sparingly accessible P sources, such as organic P or precipitated metal-P systems, is however still unknown in tomato. Methods: In this study, we compared P acquisition strategies of wild-type (WT) and SL-depleted tomato plants grown hydroponically in the presence of dissolved inorganic phosphate (Pi), dissolved myo-inositol hexaphosphate (myoInsP6), or their coprecipitated form following Fe(II) oxidative precipitation. Results: Irrespective of the P treatment, SL-depleted plants accumulated more P in their tissues than the WT, possibly due to the constitutively higher expression of high-affinity P transporters and activity of P-hydrolyzing enzymes. Wild-type plants were conversely more effective at acidifying their growth medium and exuding more organic compounds in the presence of dissolved myoInsP6 or coprecipitated forms of P, but this behaviour did not translate into a higher P acquisition. Conclusions: The two genotypes activated different subsets of responses to bypass low P bioavailability, although the P acquisition efficiency (PAE) was not effectively increased. Strigolactone-depleted plants achieved higher PAE values than WT plants regardless of the applied P form, highlighting a central role of SLs in controlling P uptake and optimizing the cost/benefit ratio of P acquisition. [ABSTRACT FROM AUTHOR]

Aims: Plant Growth-Promoting Rhizobacteria (PGPR) support plant growth by alleviating plant stresses, among which those triggered by saline soils. We isolated Stenotrophomonas sp. SRS1 from salt-resistant Carex distans (distant sedge) roots to understand how this growth promotion was enabled and whether an active contribution of the bacteria and/or plant was required. Methods: Various growth assays were used to analyze the effect of bacterial inoculation on Arabidopsis thaliana and Solanum lycopersicum (cherry tomato MicroTom) growth. Furthermore, droplet microfluidics, bacterial genome mining, and bacterial and plant gene expression analysis combined with plant mutant analysis were used for in-depth analysis. Results: SRS1 application enhanced plant growth in both saline and nonsaline environments. The fresh weight of SRS1-inoculated plants was higher than that of noninoculated plants, whereas the fresh weight ratio between SRS1-inoculated and noninoculated plants differed whether the plants were grown on agar plates, white sand or in soil. We demonstrated that the strain grew well in high salt-containing media and that, besides plant-growth-promotion-related genes, the bacterium contained various active stress genes. Interestingly, inoculation with the strain increased the induction of plant genes related to abscisic acid and auxin signaling pathways under saline conditions. Conclusions: SRS1 inoculation promoted the growth of Arabidopsis and MicroTom tomato under saline and nonsaline conditions, also when the plants were grown in white sand and potting soil. Overall, genetic traits related to stress alleviation, derived from both the bacteria and the plants, play a crucial role in the impact of this novel PGPR strain on plant performance. [ABSTRACT FROM AUTHOR]

Background and aims: Crop diversification usually increase nutrient use efficiency and productivity of crops, but we still lack deeper understandings of the underlying mechanisms. Here we aimed to study the role of root exudates and soil microbial communities in mobilization of soil P during an intercropping system. Methods: Different barrier treatments were used to separate tomato and potato onion, and different P forms, that makes most of the plant sparingly available P in the soil (i.e., Al-P, Fe-P, Ca-P, Organic P), were applied in a pot experiment. In addition, we studied the effects of monoculture and/or intercropped tomato root exudates in vitro on soil available P and soil microbial community composition using quantitative PCR and high throughput sequencing. Results: Compared with solid barrier, the 30 μm barrier increased belowground tomato biomass in presence of Ca-P, O-P and no P, soil available P in presence of Al-P, Fe-P and Ca-P, increased abundance of Bacillus spp. in presence of Fe-P, Ca-P and O- P, Pseudomonas spp. in presence of all P forms, and Trichoderma spp. in presence of Al-P, Ca-P and O-P. Compared with control, in vitro root exudates of intercropped tomato activated all P forms examined in this study, and increased soil available P was positively correlated with abundances of Bacillus, Pseudomonas and Trichoderma spp., and relative abundances of Massilia and Planomicrobium. The bacterial community structure and diversity was altered in intercropped tomato root exudates treatment as compared to rest of the treatments. Conclusions: These findings suggest the key role of root exudates in increased bioavailability of soil P in the intercropping of tomato and potato onion. [ABSTRACT FROM AUTHOR]

Aims : Pseudomonas koreensis, a subgroup of the P. fluorescens complex, is a potential plant growth-promoting rhizobacterium. This study explored the mechanisms of plant growth promotion by P. koreensis and its potential to induce stress tolerance in tomato. Methods: Tomato plants in pots were inoculated with P. koreensis GS and cultured for 60 days. RNA sequencing and gas chromatography-mass spectrometry were used to detect global transcriptomic and metabolomic changes in tomato leaves. Liquid chromatography-mass spectrometry was used for quantification of plant hormones. Results: The inoculated plants showed more vigorous growth, with higher leaf chlorophyll content and shoot biomass compared with uninoculated controls. The activities of several defense enzymes (e.g., phenylalanine ammonia-lyase) were enhanced in the leaves of inoculated plants. A total of 737 differentially expressed genes were identified, which were related to plant hormone biosynthesis, MAPK signaling transduction, and polyphenol biosynthesis. The contents of specific metabolites related to plant growth and stress tolerance, including polyphenols (phenylpropanoids) and amino acids (tryptophanand and proline), were increased after inoculation. Plant hormones such as indole-3-acetic acid participated in plant growth promotion by P. koreensis. Conclusions: P. koreensis promoted plant growth and showed potential to induce stress tolerance in tomato by enhancing auxin and polyphenol-related pathways. [ABSTRACT FROM AUTHOR]

Aims: This study aims to understand the mechanism by which grafting tomato (Solanum lycopersicum) onto Torubamu (Solanum melongena) reduces cadmium (Cd) accumulation in tomato. Methods: Tomato plants were grafted onto Torubamu rootstocks, and both the un-grafted and grafted tomato plants were grown in the control soil and soil that contained 2.0 or 5.0 mg•kg−1 Cd for 30 d. Results: Grafting onto Torubamu rootstock markedly reduced the accumulation of both Cd and total sulfur in the leaves of tomato plants to 4.1–11.7% and 25.0–36.7% of the values in the un-grafted tomato plants, respectively. Moreover, the expression of miR166a and miR395b markedly increased in tomato scions. Tobacco dual-luciferase (LUC) assays and Agrobacterium-mediated tomato genetic transformation verified that miR166a and miR395b targeted Phavoluta (PHV), Revolute (REV), Class III Homeodomain Leucine Zipper (HD-ZIP), Sulfate transporter 2;1 (SULTR2;1), ATP sulfurylase (APS) (APS1/3), and High-affinity sulfate transporter (HAST) genes, which are directly or indirectly responsible for sulfate transport. Conclusions: Based on the correlations between the Cd and sulfur accumulation in the tomato scions (r2 = 0.91) and in the miR166a/395b-transformed tomato scions (r2 = 0.96–0.98) grown in the soil with 2.0 mg•kg−1 Cd, we conclude that tomato grafting onto Torubamu rootstock can reduce Cd accumulation because of the sulfate transport regulatory ability of miR166a and miR395b. Understanding this mechanism can be of great benefit for Cd tolerance breeding. [ABSTRACT FROM AUTHOR]

Background and aim: Vermicompost leachate (VCL) produced by earthworms is a valuable biostimulant but its hormonal impact on salt-treated plants remains elusive. Methods: Plants of Solanum lycopersicum L. were cultivated in nutrient solution and exposed during 7 days to 125 mM NaCl in the presence or absence of VCL (18 mL.L−1). Mineral nutrition, water and hormonal status were quantified in roots, young and old leaves and analyzed in relation to phytohormone content of VCL. Results: VCL improved plant growth and reduced Na+ accumulation in salt-stressed plants. It delayed senescence in young leaves through a decrease in ethylene synthesis and an increase in proline and anthocyanin contents. VCL contains high amounts of salicylic acid, benzoic acid and aminocyclopropane carboxylic acid (ACC) but low concentrations of jasmonates, cytokinins and proline. VCL did not increase abscisic acid content in salt-stressed plants and did not lead to ACC accumulation while it increased jasmonate accumulation and modified the pattern of cytokinin profile with an increase in dihydrozeatin-types in old leaves and N6-(∆2-isopentenyl)adenine-types in young ones. Conclusion: VCL reduces the impact of salinity on leaf senescence, which is related to its impact on endogenous phytohormones rather than to a passive absorption of exogenous hormonal compounds. [ABSTRACT FROM AUTHOR]

Background and aims: Root-knot nematodes are major constraints among different pathogens with wide host range and cause severe agricultural loss worldwide. The present study was designed to understand the role of plant growth promoting bacteria (Pseudomonas aeruginosa & Burkholderia gladioli) on growth and antioxidative potential in nematode infected Lycopersicon esculentum seedlings.Methods: An experiment was conducted to assess the levels of superoxide anions, H2O2 and MDA contents generated during nematode infection. Moreover, the contribution of antioxidative enzymes, non-enzymatic antioxidants, total antioxidants and gene expression profiling was also carried out in nematode infected Lycopersicon esculentum seedlings.Results: The results of present study revealed that nematode infection reduced the growth of seedlings which upon inoculation of microbes was improved. Moreover, number of galls were reduced upon supplementation of these strains. Nematode infection also caused accumulation of superoxide anion, H2O2, and malondialdehyde contents along with nuclear damage and loss of cell viability which was reduced upon supplementation of microbes. The oxidative burst generated enhanced various antioxidant enzymes such as SOD (30.6%), POD (3.6%), CAT (18.1%), GPOX (65.9%), APOX (24.8%), GST (5.6%), DHAR (13.9%), GR (11%) and PPO (2.5%) which were further elevated upon application of P. aeruginosa (23.9%, 7.2%, 7%, 66%, 28.9%, 71.3%, 14.5%, 10.6% and 38.3%) and B. gladioli (5.1%, 30.6%, 16.2%, 92.1%, 78.5%, 97.5%, 15.5%, 65.7% and 23.2%). The non-enzymatic antioxidants (glutathione, ascorbic acid and tocopherol) and total antioxidants contents (both water soluble and lipid soluble) were also enhanced upon inoculation of microbes. Confocal microscopy revealed the improvement in nuclear damage and cell viability in microbe inoculated roots. Gene expression profiling revealed the enhanced expression levels of SOD, POD, CAT, GR, GPOX, APOX, PPOgenes in P.aeruginosa inoculated nematode infected seedlings by 53%, 2.7%, 64.1%, 10.4%,19.7%, 29.2%, 38.4% and B. gladioli inoculated seedlings by 18.3%,144%, 67%, 43%, 308%, 151% respectively.Conclusions: The results therefore suggest the favourable aspects of micro-organisms in modulating growth characteristics and antioxidative defense expression of Lycopersicon esculentum to encounter oxidative stress generated under nematode infection. [ABSTRACT FROM AUTHOR]

Aims: The aim of our study was to clarify whether inoculating a soil with Pseudomonas sp. RU47 (RU47) bacteria would stimulate the enzymatic cleavage of organic P compounds in the rhizosphere and bulk soil, promoting plant growth. Adding either viable or heat treated RU47 cells made it possible to separate direct from indirect effects of the inoculum on P cycling in soil and plants.Methods: We performed a rhizobox experiment in the greenhouse with tomato plants (Solanum lycopersicum) under low P soil conditions. Three inoculation treatments were conducted, using unselectively grown soil bacteria (bacterial mix), heat treated (HT-RU47) and viable RU47 (RU47) cells, and one not inoculated, optimally P-fertilized treatment. We verified plant growth, nutrient availability, enzyme activities and microbial community structure in soil.Results: A plant growth promotion effect with improved P uptake was observed in both RU47 treatments. Inoculations of RU47 cells increased microbial phosphatase activity (PA) in the rhizosphere.Conclusions: Plant growth promotion by RU47 cells is primarily associated with increased microbial PA in soil, while promotion of indigenous Pseudomonads as well as phytohormonal effects appear to be the dominant mechanisms when adding HT-RU47 cells. Thus, using RU47 offers a promising approach for more efficient P fertilization in agriculture. [ABSTRACT FROM AUTHOR]

Background and aim: Accumulation of heavy metals in soil causes loss of cover vegetation and increases the production of reactive oxygen species (ROS). ROS accumulation induces the expression of genes encoding antioxidant enzymes and other proteins involved in redox homeostasis. This study aimed to evaluate the interaction between a saprophytic fungal consortium and mycorrhizal Rhizophagus irregularis with regard to the oxidative stress and molecular responses of Solanum lycopersicum L. grown in a soil contaminated with heavy metals. Methods: We determined the effects of the saprophytic fungal consortium ( Bjerkandera adusta and Mortierella sp) and the mycorrhizal fungus Rhizophagus irregularis on the plant antioxidant response and the expression levels of genes encoding metallothioneins (MT), phytochelatins (PC), the NRAMP transporter and heat shock protein (HSP) in Solanum lycopersicum cultivated in a heavy metal-contaminated soil. Results: The fungal consortium increased plant growth, and the co-inoculation with R. irregularis synergistically improved soil biochemical activities. Superoxide dismutase activity decreased in all treatments. Peroxidase activity (ascorbate and guaiacol) increased in plants inoculated with R. irregularis and the fungal consortium. Dual inoculation decreased the malondialdehyde content in the leaves and increased transcription of the NRAMP, GR, MT2b, PCS and HSP90 genes. Conclusions: Our results demonstrate that co-inoculation contributes to reduced plant stress by improving defence mechanisms and homeostasis [ABSTRACT FROM AUTHOR]

Aims: Using Fe- and Mn-deficient Solanum lycopersicum plants, we investigated the effects of Fe and Mn foliar fertilisers, either individually or combined, on plant biomass, leaf chlorophyll and metal micronutrient levels in leaves and roots. Methods: Plants were grown in hydroponics with different combinations of 0 or 45 μM Fe and 0 or 4.6 μM Mn. Foliar fertiliser formulations (9 mM FeSO and/or 3 mM MnSO, supplemented with a surfactant) were applied in three consecutive doses. Fertilisation was applied to the first three leaf levels, while upper leaf levels were left untreated. Results: Iron and Mn deficiency led to characteristic symptoms. Foliar treatments increased concentrations of Fe and Mn, biomass and chlorophyll in treated leaves, although re-greening was incomplete. Approximately 11-12 % of the Fe increase was in roots (likely mediated via phloem transport), but no Fe increase occurred in untreated leaves. Regarding Mn, a 2 % increase occurred in untreated leaves, but no increase occurred in roots. Conclusions: Iron fertilisation was effective not only in leaves treated with the fertiliser but also in roots, whereas Mn fertilisation had major effects on treated leaves and minor effects on untreated ones. The combined application of Fe + Mn was not detrimental to Fe- or Mn-deficient plants. [ABSTRACT FROM AUTHOR]

Aims: This research was to study the capacity of Trichoderma harzianum strain SQR-T037 to colonize tomato roots and how this strain and its bio-organic fertilizer stimulate plant growth and increase yields under field conditions. Methods: Field trials were conducted with a reduced application of chemical fertilizer (75 % of the recommended application) plus Trichoderma-enriched bio-organic fertilizer (BF) or organic fertilizer (OF) or Trichoderma spore suspension (SS), while 100 % of the recommended chemical fertilizer (CF) was used as control. Results: Trichoderma SQR-T037 could efficiently colonize tomato roots and soils based on the reverse transcription-quantitative PCR analysis, and significantly stimulate biomass accumulation at an early stage. The 75 % rates of chemical fertilizer coupled with bio-organic fertilizer (BF) produced tomato yields equivalent to those obtained using the 100 % rates of chemical fertilizer (CF), while inoculation with the Trichoderma alone (SS) or supplement with organic fertilizer alone (OF) would cause 11 and 13 % decreases in yield over the control (CF). The efficacy of BF for maintaining a stable tomato yield may be due to the enhanced soil nutrients availability and the increased abundance of soil microflora, including bacteria, fungi, actinomycetes and Trichoderma communities, which had a positive linear correlation in most of the cases revealed by the Pearson correlation analysis. Conclusions: The results of this study imply that the reason by which the bio-organic fertilizer promotes plant growth and increases the tomato yields can be attributed to the enhancement of the rhizospheric microflora, which promotes nutrient activation. Therefore, T. harzianum could be employed in a combination with composts. In this way, the application rate of chemical fertilizers can be practically decreased by 25 % to obtain maximum benefits. [ABSTRACT FROM AUTHOR]

A correction to the article "Effects of individual and combined metal foliar fertilisers on iron- and manganese-deficient Solanum lycopersicum plants" that was published online on February 20, 2016 is presented.