Role of Trichoderma aggressivum f. europaeum as Plant-Growth Promoter in Horticulture

Biocompatibility of Brazilian native yeast-derived sophorolipids and Trichoderma harzianum as plant-growth promoting bioformulations

The replacement of agrochemicals by biomolecules is imperative to mitigate soil contamination and inactivation of its core microbiota. Within this context, this study aimed at the interaction between a biological control agent such as Trichoderma harzianum CCT 2160 (BF-Th) and the biosurfactants (BSs) derived from the native Brazilian yeast Starmerella bombicola UFMG-CM-Y6419. Thereafter, their potential in germination of Oryza sativa L. seeds was tested. Both bioproducts were produced on site and characterized according to their chemical composition by HPLC-MS and GC-MS for BSs and SDS-PAGE gel for BF-Th. The BSs were confirmed to be sophorolipids (SLs) which is a well-studied compound with antimicrobial activity. The biocompatibility was examined by cultivating the fungus with SLs supplementation ranging from 0.1 to 2 g/L in solid and submerged fermentation. In solid state fermentation the supplementation of SLs enhanced spore production, conferring the synergy of both bioproducts. For the germination assays, bioformulations composed of SLs, BF-Th and combined (SLT) were applied in the germination of O. sativa L seeds achieving an improvement of up to 30% in morphological aspects such as root and shoot size as well as the presence of lateral roots. It was hypothesized that SLs were able to regulate phytohormones expression such as auxins and gibberellins during early stage of growth, pointing to their novel plant-growth stimulating properties. Thus, this study has pointed to the potential of hybrid bioformulations composed of biosurfactants and active endophytic fungal spores in order to augment the plant fitness and possibly the control of diseases.

Insights into the molecular mechanism of Trichoderma stimulating plant growth and immunity against phytopathogens

Trichoderma species have received significant interest as beneficial fungi for boosting plant growth and immunity against phytopathogens. By establishing a mutualistic relationship with plants, Trichoderma causes a series of intricate signaling events that eventually promote plant growth and improve disease resistance. The mechanisms contain the indirect or direct involvement of Trichoderma in enhancing plant growth by modulating phytohormones signaling pathways, improving uptake and accumulation of nutrients, and increasing soil bioavailability of nutrients. They contribute to plant resistance by stimulating systemic acquired resistance through salicylic acid, jasmonic acid, and ethylene signaling. A cascade of signal transduction processes initiated by the interaction of Trichoderma and plants regulate the expression of defense-related genes, resulting in the synthesis of defense hormones and pathogenesis-related proteins (PRPs), which collectively improve plant resistance. Additionally, advancements in omics technologies has led to the identification of key pathways, their regulating genes, and molecular interactions in the plant defense and growth promotion responses induced by Trichoderma. Deciphering the molecular mechanism behind Trichoderma's induction of plant defense and immunity is essential for harnessing the full plant beneficial potential of Trichoderma. This review article sheds light on the molecular mechanisms that underlie the positive effects of Trichoderma-induced plant immunity and growth and opens new opportunities for developing environmentally friendly and innovative approaches to improve plant immunity and growth.

Assessment of halotolerant bacterial and fungal consortia for augmentation of wheat in saline soils

Adaptations of green technologies to counter abiotic stress, including salinity for crops like wheat by using halotolerant microbes, is a promising approach. The current study investigated 17 salt-affected agroecological zones from the Punjab and Sindh provinces of Pakistan to explore the potential of indigenous microbial flora, with their multiple biochemical characteristics in addition to plant growth promoting (PGP) traits, for enhanced wheat production in saline areas. Initially, 297 isolated pure bacterial colonies were screened for salt tolerance, biochemical, and PGP traits. Three bacterial strains belonging to Pantoea spp. and Erwinia rhaphontici with possession of multiple characteristics were selected for the development of the halotolerant bacterial consortium. Inoculation of two local wheat varieties, Faisalabad 2008 and Galaxy 2013, with the consortium for in vitro seed germination assay and sand microcosm experiments exhibited significant improvement of selected plant growth parameters like germination percentage and root structure. Two previously reported PGP fungal strains of Trichoderma harzianum and T. viridae were also used as fungal consortium separately for pot experiments and field trials. The pot experiments exhibited a positive correlation of consortia with metabolic viz. catalase, peroxidase, and proline and agronomical parameters including shoot length, dry weight, number of spikes, spike length, and 100 grain weight. To evaluate their performance under natural environmental conditions, field trials were conducted at three salt-affected sites. Agronomical attributes including days of flowering and maturity, flag leaf weight, length and width, shoot length, number of spikes, spike length, spike weight, number of seeds spike-1, 1,000 grain weight, and plot yield indicated the efficiency of these microbes to enhance wheat growth. Concisely, the bacterial consortium showed better performance and Faisalabad 2008 was a more resistant variety as compared to Galaxy 2013. Initial promising results indicate that further extensive research on indigenous microbes might lead to the development of Pakistan's first saline-specific biofertilizers and sustainable eco-friendly agriculture practices.

Biocontrol of Diseases Caused by Phytophthora capsici and P. parasitica in Pepper Plants

The main objective of this study was to evaluate the ability of Trichoderma aggressivum f. europaeum, T. longibrachiatum, Paecilomyces variotii, and T. saturnisporum as biological control agents (BCAs) against diseases caused by P. capsici and P. parasitica in pepper. For this purpose, their antagonistic activities were evaluated both in vitro and in vivo. We analysed the expression patterns of five defence related genes, CaBGLU, CaRGA1, CaBPR1, CaPTI1, and CaSAR8.2, in leaves. All BCAs showed a high in vitro antagonistic activity, significantly reducing the mycelial growth of P. capsici and P. parasitica. The treatments with T. aggressivum f. europaeum, T. longibrachiatum, and P. variotii substantially reduced the severity of the disease caused by P. capsici by 54, 76, and 70%, respectively, and of the disease caused by P. parasitica by 66, 55, and 64%, respectively. T. saturnisporum had the lowest values of disease reduction. Reinoculation with the four BCAs increased the control of both plant pathogens. Markedly different expression patterns were observed in the genes CaBGLU, CaRGA1, and CaSAR8.2. Based on the results, all four BCAs under study could be used as a biological alternative to chemicals for the control of P. capsici and P. parasitica in pepper with a high success rate.

Entomopathogenic Fungi-Mediated Solubilization and Induction of Fe Related Genes in Melon and Cucumber Plants

Endophytic insect pathogenic fungi have a multifunctional lifestyle; in addition to its well-known function as biocontrol agents, it may also help plants respond to other biotic and abiotic stresses, such as iron (Fe) deficiency. This study explores M. brunneum EAMa 01/58-Su strain attributes for Fe acquisition. Firstly, direct attributes include siderophore exudation (in vitro assay) and Fe content in shoots and in the substrate (in vivo assay) were evaluated for three strains of Beauveria bassiana and Metarhizium bruneum. The M. brunneum EAMa 01/58-Su strain showed a great ability to exudate iron siderophores (58.4% surface siderophores exudation) and provided higher Fe content in both dry matter and substrate compared to the control and was therefore selected for further research to unravel the possible induction of Fe deficiency responses, Ferric Reductase Activity (FRA), and relative expression of Fe acquisition genes by qRT-PCR in melon and cucumber plants.. In addition, root priming by M. brunneum EAMa 01/58-Su strain elicited Fe deficiency responses at transcriptional level. Our results show an early up-regulation (24, 48 or 72 h post inoculation) of the Fe acquisition genes FRO1, FRO2, IRT1, HA1, and FIT as well as the FRA. These results highlight the mechanisms involved in the Fe acquisition as mediated by IPF M. brunneum EAMa 01/58-Su strain.

Trichoderma as a powerful fungal disease control agent for a more sustainable and healthy agriculture: recent studies and molecular insights

Molecular studies have elucidated Trichoderma's biocontrol mechanisms. Since fungicides have limited use, Trichoderma could control disease by new metabolic routes and epigenetic alterations. Due to environmental and health hazards, agrochemicals have been a concern since they were introduced in agriculture. Trichoderma, a well-known fungal genus with different mechanisms of action, is an alternative to pesticides and a great tool to help minimize disease incidence. Trichoderma-treated plants mainly benefit from disease control and growth promotion through priming, and these fungi can modulate plants' gene expression by boosting their immune system, accelerating their response to threats, and building stress tolerance. The latest studies suggest that epigenetics is required for plant priming and could be essential for growth promotion, expanding the possibilities for producing new resistant plant varieties. Trichoderma's propagules can be mass produced and formulated depending on the delivery method. Microsclerotia-based bioproducts could be a promising way of increasing the reliability and durability of marketed products in the field, as well as help guarantee longer shelf life. Developing novel formulations and selecting efficient Trichoderma strains can be tiresome, but patent search indicates an increase in the industrialization and commercialization of technologies and an expansion of companies' involvement in research and development in this field. Although Trichoderma is considered a well-known fungal genus, it still attracts the attention of large companies, universities, and research institutes around the world.

Australian native Glycine clandestina seed microbiota hosts a more diverse bacterial community than the domesticated soybean Glycine max

BACKGROUND

Plant microbiome composition has been demonstrated to change during the domestication of wild plants and it is suggested that this has resulted in loss of plant beneficial microbes. Recently, the seed microbiome of native plants was demonstrated to harbour a more diverse microbiota and shared a common core microbiome with modern cultivars. In this study the composition of the seed-associated bacteria of Glycine clandestina is compared to seed-associated bacteria of Glycine max (soybean).

RESULTS

The seed microbiome of the native legume Glycine clandestina (crop wild relative; cwr) was more diverse than that of the domesticated Glycine max and was dominated by the bacterial class Gammaproteobacteria. Both the plant species (cwr vs domesticated) and individual seed accessions were identified as the main driver for this diversity and composition of the microbiota of all Glycine seed lots, with the effect of factor "plant species" exceeded that of "geographical location". A core microbiome was identified between the two Glycine species. A high percentage of the Glycine microbiome was unculturable [G. clandestina (80.8%) and G. max (75.5%)] with only bacteria of a high relative abundance being culturable under the conditions of this study.

CONCLUSION

Our results provided novel insights into the structure and diversity of the native Glycine clandestina seed microbiome and how it compares to that of the domesticated crop Glycine max. Beyond that, it also increased our knowledge of the key microbial taxa associated with the core Glycine spp. microbiome, both wild and domesticated. The investigation of this commonality and diversity is a valuable and essential tool in understanding the use of native Glycine spp. for the discovery of new microbes that would be of benefit to domesticated Glycine max cultivars or any other economically important crops. This study has isolated microbes from a crop wild relative that are now available for testing in G. max for beneficial phenotypes.

Antagonistic Effect of Trichoderma longibrachiatum (TL6 and TL13) on Fusarium solani and Fusarium avenaceum Causing Root Rot on Snow Pea Plants

Snow pea root rot in China is caused by Fusarium solani (FSH) and Fusarium avenaceum (FAH), which affect snow pea production. The chemical control methods used against FSH and FAH are toxic to the environment and resistance may be developed in persistence applications. Therefore, an alternative approach is needed to control these pathogens. This study focuses on Trichoderma longibrachiatum strains (TL6 and TL13), mycoparasitic mechanisms of FSH and FAH, as well as growth-promoting potentials on snow pea seedlings under FSH and FAH stress at the physiological, biochemical, and molecular levels. The average inhibitory rates of TL6 against FSH and FAH were 54.58% and 69.16%, respectively, on day 7. Similarly, TL13 average inhibitory rates against FSH and FAH were 59.06% and 71.27%, respectively, on day 7. The combined TL13 and TL6 with FSH and FAH reduced disease severity by 86.6, 81.6, 57.60, and 60.90%, respectively, in comparison to the controls. The snow pea plants inoculated with FSH and FAH without TL6 and TL13 increased malondialdehyde (MDA) and hydrogen peroxide (H2O2) contents in the leaves by 64.8, 66.0, 64.4 and 65.9%, respectively, compared to the control. However, the combined FSH and FAH with TL6 and TL13 decreased the MDA and H2O2 content by 75.6, 76.8, 70.0, and 76.4%, respectively, in comparison to the controls. In addition, the combined TL6 + FSH and TL6 + FAH increased the activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) by 60.5, 64.7, and 60.3%, respectively, and 60.0, 64.9, and 56.6%, respectively, compared to the controls. Again, compared to the controls, the combined TL13 + FSH and TL13 + FAH increased the activity of SOD, POD, and CAT by 69.7, 68.6, and 65.6%, respectively, and 70.10, 69.5, and 65.8%, respectively. Our results suggest that the pretreatment of snow pea seeds with TL6 and TL13 increases snow pea seedling growth, controls FSH and FAH root rot, increases antioxidant enzyme activity, and activates plant defense mechanisms. The TL13 strain had the greatest performance in terms of pathogen inhibition and snow pea growth promotion compared to the TL6 strain.

Trichoderma: The Current Status of Its Application in Agriculture for the Biocontrol of Fungal Phytopathogens and Stimulation of Plant Growth

Rhizosphere filamentous fungi of the genus Trichoderma, a dominant component of various soil ecosystem mycobiomes, are characterized by the ability to colonize plant roots. Detailed knowledge of the properties of Trichoderma, including metabolic activity and the type of interaction with plants and other microorganisms, can ensure its effective use in agriculture. The growing interest in the application of Trichoderma results from their direct and indirect biocontrol potential against a wide range of soil phytopathogens. They act through various complex mechanisms, such as mycoparasitism, the degradation of pathogen cell walls, competition for nutrients and space, and induction of plant resistance. With the constant exposure of plants to a variety of pathogens, especially filamentous fungi, and the increased resistance of pathogens to chemical pesticides, the main challenge is to develop biological protection alternatives. Among non-pathogenic microorganisms, Trichoderma seems to be the best candidate for use in green technologies due to its wide biofertilization and biostimulatory potential. Most of the species from the genus Trichoderma belong to the plant growth-promoting fungi that produce phytohormones and the 1-aminocyclopropane-1-carboxylate (ACC) deaminase enzyme. In the present review, the current status of Trichoderma is gathered, which is especially relevant in plant growth stimulation and the biocontrol of fungal phytopathogens.

Mineral Biofortification and Growth Stimulation of Lentil Plants Inoculated with Trichoderma Strains and Metabolites

Biofortification of crops via agricultural interventions represents an excellent way to supply micronutrients in poor rural populations, who highly suffer from these deficiencies. Soil microbes can directly influence plant growth and productivity, e.g., by contrasting plant pathogens or facilitating micronutrient assimilation in harvested crop-food products. Among these microbial communities, Trichoderma fungi are well-known examples of plant symbionts widely used in agriculture as biofertilizers or biocontrol agents. In this work, eleven Trichoderma strains and/or their bioactive metabolites (BAMs) were applied to lentil plants to evaluate their effects on plant growth and mineral content in greenhouse or field experiments. Our results indicated that, depending upon the different combinations of fungal strain and/or BAM, the mode of treatment (seed and/or watering), as well as the supplementary watering with solutions of iron (Fe) and zinc (Zn), the mineral absorption was differentially affected in treated plants compared with the water controls. In greenhouse conditions, the largest increase in Fe and Zn contents occurred when the compounds were applied to the seeds and the strains (in particular, T. afroharzianum T22, T. harzianum TH1, and T. virens GV41) to the soil. In field experiments, Fe and Zn contents increased in plants treated with T. asperellum strain KV906 or the hydrophobin HYTLO1 compared with controls. Both selected fungal strains and BAMs applications improved seed germination and crop yield. This biotechnology may represent an important challenge for natural biofortification of crops, thus reducing the risk of nutrient deficiencies.

Biological Control of Fungal Diseases by Trichoderma aggressivum f. europaeum and Its Compatibility with Fungicides

Our purpose was to evaluate the ability of Trichoderma aggressivum f. europaeum as a biological control agent against diseases from fungal phytopathogens. Twelve isolates of T. aggressivum f. europaeum were obtained from several substrates used for Agaricus bisporus cultivation from farms in Castilla-La Mancha (Spain). Growth rates of the 12 isolates were determined, and their antagonistic activity was analysed in vitro against Botrytis cinerea, Sclerotinia sclerotiorum, Fusarium solani f. cucurbitae, Pythium aphanidermatum, Rhizoctonia solani, and Mycosphaerella melonis, and all isolates had high growth rates. T. aggressivum f. europaeum showed high antagonistic activity for different phytopathogens, greater than 80%, except for P. aphanidermatum at approximately 65%. The most effective isolate, T. aggressivum f. europaeum TAET1, inhibited B. cinerea, S. sclerotiorum, and M. melonis growth by 100% in detached leaves assay and inhibited germination of S. sclerotiorum sclerotia. Disease incidence and severity in plant assays for pathosystems ranged from 22% for F. solani to 80% for M. melonis. This isolate reduced the incidence of Podosphaera xanthii in zucchini leaves by 66.78%. The high compatibility by this isolate with fungicides could allow its use in combination with different pest management strategies. Based on the results, T. aggressivum f. europaeum TAET1 should be considered for studies in commercial greenhouses as a biological control agent.

Bioprospecting of Rhizosphere-Resident Fungi: Their Role and Importance in Sustainable Agriculture

Rhizosphere-resident fungi that are helpful to plants are generally termed as 'plant growth promoting fungi' (PGPF). These fungi are one of the chief sources of the biotic inducers known to give their host plants numerous advantages, and they play a vital role in sustainable agriculture. Today's biggest challenge is to satisfy the rising demand for crop protection and crop yield without harming the natural ecosystem. Nowadays, PGPF has become an eco-friendly way to improve crop yield by enhancing seed germination, shoot and root growth, chlorophyll production, and fruit yield, etc., either directly or indirectly. The mode of action of these PGPF includes the solubilization and mineralization of the essential micro- and macronutrients needed by plants to regulate the balance for various plant processes. PGPF produce defense-related enzymes, defensive/volatile compounds, and phytohormones that control pathogenic microbes' growth, thereby assisting the plants in facing various biotic and abiotic stresses. Therefore, this review presents a holistic view of PGPF as efficient natural biofertilizers to improve crop plants' growth and resistance.

The Influence of Trichoderma harzianum Rifai T-22 and Other Biostimulants on Rhizosphere Beneficial Microorganisms of Carrot

The principles of good agricultural and horticultural practice, which consider both giving environmental protection and high yielding of plants, require modern cultivation methods. Modern cultivation of horticultural plants uses, for example, cover crops, living mulches, plant growth-promoting microorganisms (PGPMs), plant growth regulators (PGRs) and other biostimulants protecting the soil against degradation and plants against phytopathogens and stress. The purpose of field and laboratory studies was to determine the effect of Trianum P (containing Trichoderma harzianum Rifai T-22 spores), Beta-Chikol (a.s.—chitosan), Timorex Gold 24 EC (based on tea tree oil) and fungicide Zaprawa Nasienna T 75 DS/WS (a.s.—tiuram 75%) on the health of carrot (Daucus carota L.) plants and the microorganism population in the rhizosphere of this plant. Moreover, the antagonistic effect of rhizosphere fungi on selected carrot fungal pathogens was determined. Laboratory mycological analysis allowed one to determine the qualitative and quantitative composition of fungi colonizing the underground parts of carrot plants. In addition, the total population of fungi and bacteria was determined (including Bacillus sp. and Pseudomonas sp.) based on the microbiological analysis of the rhizosphere soil. The application of the plant growth-promoting fungus (Trichoderma harzianum T-22), chitosan and tea tree oil positively influenced the growth, development and health status of carrot plants. T. harzianum T-22, chitosan and fungicide most effectively protected carrots against infection by soil-borne fungi from the genus Alternaria, Fusarium, Haematonectria, Sclerotinia and Rhizoctonia. The rhizosphere population of Bacillus sp. and Pseudomonas sp. in the treatments with Trianum P or Zaprawa Nasienna T 75 DS/WS was bigger than in the other experimental treatments. A reverse relationship was observed in the population of rhizosphere fungi. T. harzianum T-22, chitosan and tea tree oil promoted the growth of antagonistic fungi (Albifimbria sp., Clonostachys sp., Penicillium sp., Talaromyces sp. and Trichoderma sp.) in the carrot rhizosphere. Antagonistic activity of these fungi towards Alternaria dauci, Alternaria radicina, Sclerotiniasclerotiorum and Rhizoctonia solani was higher after the application of the preparations compared to control. Consequently, Trianum P, Beta-Chikol and Timorex Gold 24 EC can be recommended as plant biostimulants in ecological agricultural production, including Daucus carota cultivation.