Antimicrobial Activity of Various Parts of Tomato Plants Varied with Different Solvent Extracts

Tomato pomace food waste from different variants as a high antioxidant potential resource

Pomaces obtained from three San Marzano tomato genotypes including the wild type (WT), Sun Black (SB), and colorless fruit epidermis (CL) were dried at 50 °C and analyzed for nutritional composition, total polyphenol (TPC), flavonoid (TFC) content, polyphenol qualitative profile, total antioxidant capacity (TAC), and antimicrobial activity. Commercial dried tomato powder (CTRP) was included as a control. No differences were detected nutritionally, in TPC and antimicrobial activity, but significant changes were observed for TFC and TAC, underlying variation in the phenolic profile. SB pomace (SBP) had the highest TFC and TAC. LC-HRMS analysis showed a flavonoid-enriched profile in SBP besides the exclusive presence of anthocyanins, with petanin and negretein as the most abundant. Among flavonoids, quercetin-hexose-deoxyhexose-pentose, naringenin, and rutin were the major. Overall, we showed the potential of dried tomato pomace, especially SBP, as an extremely valuable waste product to be transformed into a functional ingredient, reducing the food industry waste.

Use of Trichoderma culture filtrates as a sustainable approach to mitigate early blight disease of tomato and their influence on plant biomarkers and antioxidants production

Introduction

Alternaria solani is a challenging pathogen in the tomato crop globally. Chemical control is a rapid approach, but emerging fungicide resistance has become a severe threat. The present study investigates the use of culture filtrates (CFs) of three species of Trichoderma spp. to control this disease.

Methods

Highly virulent A. solani strain and three Trichoderma fungal strains viz., T. harzianum (Accession No: MW590687), T. atroviride (Accession No: MW590689) and T. longibrachiatum (Accession No: MW590688) previously isolated by authors were used in this study. The efficacy of culture filtrates (CFs) to mitigate early blight disease were tested under greenhouse and field conditions, experiments were conducted in different seasons of 2020 using a tomato variety "doucen".

Results and discussion

The CFs of T. harzianum, T. longibrachiatum, and T. atroviride significantly inhibited the in vitro mycelial growth of A. solani (62.5%, 48.73%, and 57.82%, respectively, followed by control 100%). In the GC-MS analysis of Trichoderma CF volatile compounds viz., harzianic acid (61.86%) in T. harzianum, linoleic acid (70.02%) in T. atroviride, and hydroxymethylfurfural (68.08%) in the CFs of T. longibrachiatum, were abundantly present. Foliar application of CFs in the greenhouse considerably reduced the disease severity (%) in all treatments, viz., T. harzianum (18.03%), T. longibrachiatum (31.91%), and T. atroviride (23.33%), followed by infected control (86.91%), and positively affected the plant biomarkers. In the greenhouse, the plants treated with CFs demonstrated higher flavonoids after 6 days of inoculation, whereas phenolic compounds increased after 2 days. The CF-treated plants demonstrated higher antioxidant enzymes, i.e., phenylalanine ammonia-lyase (PAL) and peroxidase (POD), after 4 days, whereas polyphenol oxidase (PPO) was higher after 6 days of inoculation, followed by healthy and infected controls. In open field conditions, disease severity in CF-treated plants was reduced in both seasons as compared to naturally infected plants, whereas CF-treated plants exhibited a higher fruit yield than controls. The present results conclude that CFs can be a potential biocontrol candidate and a promising alternative to the early blight pathogen for sustainable production.

Trichoderma pubescens Elicit Induced Systemic Resistance in Tomato Challenged by Rhizoctonia solani

Rhizoctonia solani causes severe diseases in many plant species, particularly root rot in tomato plants. For the first time, Trichoderma pubescens effectively controls R. solani in vitro and in vivo. R. solani strain R11 was identified using the ITS region (OP456527); meanwhile, T. pubescens strain Tp21 was characterized by the ITS region (OP456528) and two genes (tef-1 and rpb2). The antagonistic dual culture method revealed that T. pubescens had a high activity of 76.93% in vitro. A substantial increase in root length, plant height, shoot fresh and dry, and root fresh and dry weight was indicated after applying T. pubescens to tomato plants in vivo. Additionally, it significantly increased the chlorophyll content and total phenolic compounds. The treatment with T. pubescens exhibited a low disease index (DI, 16.00%) without significant differences with Uniform^® fungicide at a concentration of 1 ppm (14.67%), while the R. solani-infected plants showed a DI of 78.67%. At 15 days after inoculation, promising increases in the relative expression levels of three defense-related genes (PAL, CHS, and HQT) were observed in all T. pubescens treated plants compared with the non-treated plants. Plants treated with T. pubescens alone showed the highest expression value, with relative transcriptional levels of PAL, CHS, and HQT that were 2.72-, 4.44-, and 3.72-fold higher in comparison with control plants, respectively. The two treatments of T. pubescens exhibited increasing antioxidant enzyme production (POX, SOD, PPO, and CAT), while high MDA and H₂O₂ levels were observed in the infected plants. The HPLC results of the leaf extract showed a fluctuation in polyphenolic compound content. T. pubescens application alone or for treating plant pathogen infection showed elevated phenolic acids such as chlorogenic and coumaric acids. Therefore, the ability of T. pubescens to inhibit the growth of R. solani, enhance the development of tomato plants, and induce systemic resistance supports the application of T. pubescens as a potential bioagent for managing root rot disease and productivity increase of crops.

Anti-Fungal Activity of Moutan cortex Extracts against Rice Sheath Blight (Rhizoctonia solani) and Its Action on the Pathogen's Cell Membrane

Rice sheath blight (RSB) caused by Rhizoctonia solani is one of the most destructive diseases of rice (Oryza sativa). Although chemical fungicides are the most important control methods, their long-term unreasonable application has brought about problems such as environmental pollution, food risks, and non-target poisoning. Therefore, considering the extraction of fungistatic substances from plants may be an alternative in the future. In this study, we found that the Moutan cortex ethanol extract has excellent antifungal activity against R. solani, with a 100% inhibition rate at 1000 μg/mL, which aroused our great exploration interest. In-depth exploration found that the antifungal active ingredients of M. cortex were mainly concentrated in the petroleum ether extract of the M. cortex ethanol extract, which still maintained a 100% inhibition rate with 250 μg/mL, and its effective medium concentration (EC₅₀) was 145.33 μg/mL against R. solani. Through the measurement of extracellular relative conductivity and OD₂₆₀, the petroleum ether extract induced leakage of intracellular electrolytes and nucleic acids, indicating that the cell membrane was ruined. Therefore, we preliminarily determined that the cell membrane may be the target of the petroleum ether extract. Moreover, we found that petroleum ether extract reduced the content of ergosterol, a component of the cell membrane, which may be one of the reasons for the cell membrane destruction. Furthermore, the increase of MDA content would lead to membrane lipid peroxidation, further aggravating membrane damage, resulting in increased membrane permeability. Also, the destruction of the cell membrane was observed by the phenomenon of the mycelium being transparent and broken. In conclusion, this is the first report of the M. cortex petroleum ether extract exhibiting excellent antifungal activity against R. solani. The effect of the M. cortex petroleum ether extract on R. solani may be on the cell membrane, inducing the disorder of intracellular substances and metabolism, which may be one of the antifungal mechanisms against R. solani.

Minor tropical fruits as a potential source of bioactive and functional foods

Tropical fruits are defined as fruits that are grown in hot and humid regions within the Tropic of Cancer and Tropic of Capricorn, covering most of the tropical and subtropical areas of Asia, Africa, Central America, South America, the Caribbean and Oceania. Depending on the cultivation area covered, economic value and popularity these tropical fruits are divided into major and minor tropical fruits. There is an annual increment of 3.8% in terms of commercialization of the tropical fruits. In total 26 minor tropical fruits (Kiwifruit, Lutqua, Carambola, Tree Tomato, Elephant apple, Rambutan, Bay berry, Mangosteen, Bhawa, Loquat, Silver berry, Durian, Persimon, Longan, Passion fruit, Water apple, Pulasan, Indian gooseberry, Guava, Lychee, Annona, Pitaya, Sapodilla, Pepino, Jaboticaba, Jackfruit) have been covered in this work. The nutritional composition, phytochemical composition, health benefits, traditional use of these minor tropical fruits and their role in food fortification have been portrayed.

Controlling Alternaria cerealis MT808477 Tomato Phytopathogen by Trichoderma harzianum and Tracking the Plant Physiological Changes

Plant responses during the pathogen infection and the pathogen control reflect its strategies to protect its cells. This work represents the Alternaria cerealis MT808477 as a phytopathogen causing leaf spot disease in tomatoes. A. cerealis was identified morphologically and genetically by 18SrRNA, and its pathogenicity was confirmed by light and scanning electron microscopy. Trichoderma harzianum has the ability to control A. cerealis MT808477 by stimulating various cell responses during the controlling process. The cell behavior during the biological control process was observed by analyses of total phenol, flavonoids, terpenoids, antioxidant, malondialdehyde and antioxidant enzymes (catalase and peroxidase). The extracts of infected tomato leaves were tested against plant and human pathogenic microorganisms. Results showed that the biological control process activates the defense cell strategies by increasing the plant tolerance, and activation of plant defense systems. The total phenol, flavonoids, terpenoids, antioxidant and malondialdehyde were increased after 48 h. Catalase and peroxidase were increased in infected tomato plants and decreased during the biological control process, reflecting the decrease of cell stress. Leaves extract inhibited the growth of nine plant and human pathogenic microorganisms. Biological control represents a safe and effective solution to phytopathogens that decreases plant cell stress by stimulating various defensive agents.

The influence of feedstocks and additives in 23 added-value composts as a growing media component on Pythium irregulare suppressivity

Alternative materials with added-value functions, such as phytopathogen suppression and biostimulant and/or biofertilising activity, have been proposed as peat substitutes in growing media. The aim of this work was to evaluate the effect of 23 agro-industrial composts as components of growing media for baby-leaf lettuce transplant production and their activity against the plant pathogen Pythium irregulare. The composts were produced by mixing different starting feedstocks-tomato waste, leek waste, olive mill cake and vineyard pruning waste-with different additives (coffee, thyme, lavender and rockrose waste), which were incorporated at the beginning of the maturation phase. The results obtained indicated that the composts were mature enough to be used as growing media. The fresh weight of the lettuce plants grown with the different composts was significantly higher than in plants obtained with peat. Composts with the coffee additive produced higher lettuce fresh weight, while those with thyme yielded a lower fresh weight. Moreover, composts as components of growing media showed significantly higher P. irregulare suppressiveness than peat. The composts with additives produced lower lettuce fresh weight than composts without additives, but showed higher suppressiveness. Composts with additives showed opposite results depending on whether they were exposed to pathogens or not. Composts with additives showed opposite results according to pathogen pressure or not. Out of all the composts studied, the compost with tomato waste and leek waste as the initial feedstock, and lavender as an additive, showed the highest suppressive capacity. After lettuce harvesting, the growing media with composts showed significantly lower concentrations of P. irregulare than peat. Principal Component Analysis (PCA) revealed that the growing media with compost can be grouped together according to the additive type.