Impact of Trichoderma asperellum on Chilling and Drought Stress in Tomato (Solanum lycopersicum)

Bioprospecting the roles of Trichoderma in alleviating plants' drought tolerance: Principles, mechanisms of action, and prospects

Drought-induced stress represents a significant challenge to agricultural production, exerting adverse effects on both plant growth and overall productivity. Therefore, the exploration of innovative long-term approaches for addressing drought stress within agriculture constitutes a crucial objective, given its vital role in enhancing food security. This article explores the potential use of Trichoderma, a well-known genus of plant growth-promoting fungi, to enhance plant tolerance to drought stress. Trichoderma species have shown remarkable potential for enhancing plant growth, inducing systemic resistance, and ameliorating the adverse impacts of drought stress on plants through the modulation of morphological, physiological, biochemical, and molecular characteristics. In conclusion, the exploitation of Trichoderma's potential as a sustainable solution to enhance plant drought tolerance is a promising avenue for addressing the challenges posed by the changing climate. The manifold advantages of Trichoderma in promoting plant growth and alleviating the effects of drought stress underscore their pivotal role in fostering sustainable agricultural practices and enhancing food security.

Spectroscopic Investigation of Tomato Seed Germination Stimulated by Trichoderma spp

Seed germination is a complex process that can be negatively affected by numerous stresses. Trichoderma spp. are known as effective biocontrol agents as well as plant growth and germination stimulators. However, understanding of the early interactions between seeds and Trichoderma spp. remains limited. In the present paper, Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy were used to reveal the nature of tomato seed germination as stimulated by Trichoderma. A rapid response of tomato seeds to Trichoderma spp. was observed within 48 h on Murashige and Skoog medium (MS) substrate, preceding any physical contact. Raman analysis indicated that both Trichoderma species stimulated phenolic compound synthesis by triggering plant-specific responses in seed radicles. The impact of T. harzianum and T. brevicompactum on two tomato cultivars resulted in alterations to the middle lamella pectin, cellulose, and xyloglucan in the primary cell wall. The Raman spectra indicated increased xylan content in NA with T9 treatment as well as increased hemicelluloses in GZ with T4 treatment. Moreover, T4 treatment resulted in elevated conjugated aldehydes in lignin in GZ, whereas the trend was reversed in NA. Additionally, FTIR analysis revealed significant changes in total protein levels in Trichoderma spp.-treated tomato seed radicles, with simultaneous decreases in pectin and/or xyloglucan. Our results indicate that two complementary spectroscopic methods, FTIR and Raman spectroscopy, can give valuable information on rapid changes in the plant cell wall structure of tomato radicles during germination stimulated by Trichoderma spp.

Metabolic changes in tomato plants caused by psychrotolerant Antarctic endophytic bacteria might be implicated in cold stress mitigation

Climate change is responsible for mild winters and warm springs that can induce premature plant development, increasing the risk of exposure to cold stress with a severe reduction in plant growth. Tomato plants are sensitive to cold stress and beneficial microorganisms can increase their tolerance. However, scarce information is available on mechanisms stimulated by bacterial endophytes in tomato plants against cold stress. This study aimed to clarify metabolic changes stimulated by psychrotolerant endophytic bacteria in tomato plants exposed to cold stress and annotate compounds possibly associated with cold stress mitigation. Tomato seeds were inoculated with two bacterial endophytes isolated from Antarctic Colobanthus quitensis plants (Ewingella sp. S1.OA.A_B6 and Pseudomonas sp. S2.OTC.A_B10) or with Paraburkholderia phytofirmans PsJN, while mock-inoculated seeds were used as control. The metabolic composition of tomato plants was analyzed immediately after cold stress exposure (4°C for seven days) or after two and four days of recovery at 25°C. Under cold stress, the content of malondialdehyde, phenylalanine, ferulic acid, and p-coumaric acid was lower in bacterium-inoculated compared to mock-inoculated plants, indicating a reduction of lipid peroxidation and the stimulation of phenolic compound metabolism. The content of two phenolic compounds, five putative phenylalanine-derived dipeptides, and three further phenylalanine-derived compounds was higher in bacterium-inoculated compared to mock-inoculated samples under cold stress. Thus, psychrotolerant endophytic bacteria can reprogram polyphenol metabolism and stimulate the accumulation of secondary metabolites, like 4-hydroxybenzoic and salicylic acid, which are presumably involved in cold stress mitigation, and phenylalanine-derived dipeptides possibly involved in plant stress responses.

Seed bio-priming with beneficial Trichoderma harzianum alleviates cold stress in maize

Maize is one of the major crops in the world and the most productive member of the Gramineae family. Since cold stress affects the germination, growth, and productivity of corn seeds, the present study aimed to investigate the effect of seed biopriming with Trichoderma harzianum on the tolerance of two genotypes of maize seedlings to cold stress. This study was conducted in triplicates in factorial experiment with a complete randomized block design (CRBD). The study was conducted in the greenhouse and laboratory of the University of Mohaghegh Ardabili, Ardabil, Iran. Experimental factors include two cultivars (AR68 cold-resistant and KSC703 cold-sensitive maize cultivars), four pretreatment levels (control, biopriming with T. harzianum, exogenous T. harzianum, and hydropriming), and two levels of cold stress (control and cold at 5 °C) in a hydroponic culture medium. The present study showed that maize leaves' establishment rate and maximum fluorescence (Fm) are affected by triple effects (C*, P*, S). The highest establishment (99.66%) and Fm (994 units) rates were observed in the KP3 control treatment. Moreover, among the pretreatments, the highest (0.476 days) and the lowest (0.182 days) establishment rates were related to P0 and P3 treatments, respectively. Cultivar A showed higher chlorophyll a and b, carotenoid content, and establishment rate compared to cultivar K in both optimal and cold conditions. The highest root dry weight (11.84 units) was obtained in cultivar A with P3 pretreatment. The pretreatments with T. harzianum increased physiological parameters and seedling emergence of maize under cold and optimal stress conditions. Pretreatment and cultivar improved catalase activity in roots and leaves. Higher leaf and root catalase activity was observed in the roots and leaves of cultivar K compared to cultivar A. The cold treatment significantly differed in peroxidase activity from the control treatment. Cultivar K showed higher catalase activity than cultivar A. The main effects of pretreatment and cold on polyphenol oxidase activity and proline content showed the highest polyphenol oxidase activity and proline content in hydropriming (H) treatment. Cold treatment also showed higher polyphenol oxidase activity and proline content than cold-free conditions.

Trichoderma longibrachiatum Inoculation Improves Drought Resistance and Growth of Pinus massoniana Seedlings through Regulating Physiological Responses and Soil Microbial Community

Drought stress poses a serious threat to Pinus massoniana seedling growth in southern China. Trichoderma species, as beneficial microorganisms, have been widely used in agriculture to enhance plant growth and drought tolerance, but the interaction mechanisms remain unclear. To investigate the effect of drought-resistant Trichoderma longibrachiatum inoculation on P. massoniana growth under drought stress, the plant physiological indicators and rhizosphere microbiome diversity were measured to identify Trichoderma-activated mechanisms. Trichoderma longibrachiatum inoculation significantly promoted P. massoniana growth under drought treatment, and enhanced nitrogen, phosphorus, and potassium absorption compared with those of non-inoculated seedlings. Trichoderma longibrachiatum treatment alleviated the damage to cell membranes and needle tissue structure, and significantly increased antioxidant enzyme activities, osmotic substance contents, and photosynthesis in P. massoniana in response to drought stress. Soil nutrient contents, activities of sucrase, phosphatase, and urease as well as the relative abundances of the dominant genera Burkholderia, Rhodanobacter, and Trichoderma were elevated in the rhizosphere soil of P. massoniana inoculated with T. longibrachiatum under drought stress. A network analysis showed that certain crucial dominant taxa driven by T. longibrachiatum inoculation, including Penicillium, Trichoderma, Simplicillium, Saitozyma, Burkholderia, Bradyrhizobium, Sinomonas, and Mycobacterium, had more correlations with other microorganisms in the soil. Trichoderma longibrachiatum enhanced P. massoniana seedling growth under drought stress by regulating physiological responses and soil microbial community.

Inoculation of Trichoderma asperelloides ameliorates aluminum stress-induced damages by improving growth, photosynthetic pigments and organic solutes in maize

Excess aluminum (Al) is a stressful condition that affects plant growth and yield quality. This study evaluates growth responses and changes in the contents of photosynthetic pigments and organic solute in maize (Zea mays L.) plants inoculated with Trichoderma asperelloides isolates (T01, T02, T74, T76, or T96) and treated with increasing doses of Al (0, 50, 100, 150, and 200 µM of Al). Uninoculated unstressed plants served as control. Absolute growth rate, root length, dry biomass (shoot, roots and total) and shoot:root ratio were significantly affected in Al-stressed maize plants inoculated with T. asperelloides. Also, chlorophylls (a, b and total) were significantly reduced, whereas carotenoids and anthocyanins increased in those plants. Except for carotenoids, all parameters increased in plants inoculated with T. asperelloides, especially T01 or T02 isolates. Anthocyanins increased by 50% in plants inoculated with T74 and treated with 100 or 150 µM Al as compared to control plants. Total soluble carbohydrates increased by 74% and 101% in plants inoculated with T74 and T76, respectively, and treated with 200 µM Al. Total free amino acids increased more than 50% in plants inoculated with T02 and treated with 150 and 200 µM Al. Free prolines increased by 90%, 145% and 165% in plants inoculated with T74 and treated 100, 150 and 200 µM Al, respectively, in comparison to the unstressed control plants. We concluded that T. asperelloides positively affected growth, photosynthetic pigments, and organic solutes of Al-stressed plants, especially those inoculated with T01, T02, or T74 isolates.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03310-3.

Promotion of Plant Growth in Arid Zones by Selected Trichoderma spp. Strains with Adaptation Plasticity to Alkaline pH

Trichoderma species are filamentous fungi that support plant health and confer improved growth, disease resistance, and abiotic stress tolerance. The objective of this study is to describe the physiological characteristics of the abundance and structure of Trichoderma model strains from arid zones and evaluate and describe their possible adaptation and modulation in alkaline pH. The presence of biotic factors such as phytopathogens forces farmers to take more actions such as using pesticides. In addition, factors such as the lack of water worldwide lead to losses in agricultural production. Therefore, the search for biocontrol microorganisms that support drought opens the door to the search for variations in the molecular mechanisms involved in these phenomena. In our case, we isolated 11 tested Trichoderma fungal strains from samples collected both from the rhizosphere and roots from two endemic plants. We probed their molecular markers to obtain their identity and assessed their resistance to alkaline conditions, as well as their response to mycoparasitism, plant growth promotion, and drought stress. The findings were worthy of being analyzed in depth. Three fungal taxa/species were grouped by phylogenetic/phenotypic characteristics; three T. harzianum strains showed outstanding capabilities to adapt to alkalinity stress. They also showed antagonistic activity against three phytopathogenic fungi. Additionally, we provided evidence of significant growth promotion in Sorghum bicolor seedlings under endemic agriculture conditions and a reduction in drought damage with Trichoderma infection. Finally, beneficial fungi adapted to specific ambient niches use various molecular mechanisms to survive and modulate their metabolism.

Foliar-applied magnesium nanoparticles modulate drought stress through changes in physio-biochemical attributes and essential oil profile of yarrow (Achillea millefolium L.)

Nanoparticles (NPs) are an emerging tool for mitigating environmental stresses. Although beneficial roles of NPs have been reported in some plants, there is little data on magnesium (Mg)-NPs in alleviating drought stress. Therefore, the field experiment was conducted to study changes in biochemical attributes and essential oil (EO) compositions of yarrow (Achillea millefolium L.) plants under drought stress and Mg-NPs in 2016 and 2017. Irrigation regimes were used in two levels as well-watered (irrigation intervals of 7 days) and drought stress (irrigation intervals of 14 days) conditions, and Mg-NPs were sprayed on leaves in four levels (0, 0.1, 0.3, and 0.5 g L-1). The results showed drought stress led to increased electrolyte leakage (EL), proline, carotenoid, anthocyanin, and total flavonoid content (TFC). However, flowers yield and EO yield were lower in plants exposed to drought stress as compared to well-watered conditions. The 0.3 and 0.5 g L-1 Mg-NPs were more effective in alleviating drought stress by enhancing these traits. Heat map results showed that EL and TSS represented the high variability upon different treatments. The GC and GC/MS results represented that α-pinene (8.60-12.20%), 1,8-cineol (9.03-14.02%), camphor (6.84-9.80%), α-bisabolol (8.54-18.81%), chamazulene (14.23-22.50%), and caryophyllene oxide (7.20-9.80%) were the min EO constitutes of yarrow plants. Totally, drought decreased monopertens but increased sesquiterpenes of EO. To sum up, foliar applied Mg-NPs in a range of 0.3-0.5 g L-1 can be recommended as effective tool to improve plant yield through changes in biochemical attributes of yarrow plants.