Rosa Hermosa Prieto - Academia.edu (original) (raw)

Papers by Rosa Hermosa Prieto

Research paper thumbnail of Salicylic acid prevents<i>Trichoderma harzianum</i>from entering the vascular system of roots

Molecular Plant Pathology, May 7, 2014

Trichoderma is a soil-borne fungal genus that includes species with a significant impact on agric... more Trichoderma is a soil-borne fungal genus that includes species with a significant impact on agriculture and industrial processes. Some Trichoderma strains exert beneficial effects in plants through root colonization, although little is known about how this interaction takes place. To better understand this process, the root colonization of wild-type Arabidopsis and the salicylic acid (SA)impaired mutant sid2 by a green fluorescent protein (GFP)-marked Trichoderma harzianum strain was followed under confocal microscopy. Trichoderma harzianum GFP22 was able to penetrate the vascular tissue of the sid2 mutant because of the absence of callose deposition in the cell wall of root cells. In addition, a higher colonization of sid2 roots by GFP22 compared with that in Arabidopsis wild-type roots was detected by real-time polymerase chain reaction. These results, together with differences in the expression levels of plant defence genes in the roots of both interactions, support a key role for SA in Trichoderma early root colonization stages. We observed that, without the support of SA, plants were unable to prevent the arrival of the fungus in the vascular system and its spread into aerial parts, leading to later collapse.

Research paper thumbnail of Trichoderma: a multipurpose, plant-beneficial microorganism for eco-sustainable agriculture

Nature Reviews Microbiology

Research paper thumbnail of Are species concepts outdated for fungi? Intraspecific variation in plant-pathogenic fungi illustrates the need for subspecific categorization

Trends in the systematics of bacteria and fungi

Abstract Precise naming of a species is very important for phytopathogenic fungi because names ma... more Abstract Precise naming of a species is very important for phytopathogenic fungi because names may carry key information for the management of the fungal diseases. Naming fungal species based on morphological traits or biological properties is outdated and unreliable. This chapter provides the classification of some plant pathogenic fungi including Rhizoctonia solani, Colletotrichum, Fusarium oxysporum, and Verticillum based on morphological, pathogenicity, molecular and phylogenetic analysis. Debate on species identification is no longer a question of being in favour of 'splitters' rather than of 'lumpers', but defining phytopathogenic species is particularly complicated and requires further consideration of subspecific categorizations.

Research paper thumbnail of The use of Trichoderma spp. to control plant diseases

Microbial bioprotectants for plant disease management, 2021

Trichoderma is one of the most studied genera of ascomycetous fungi due to the beneficial effects... more Trichoderma is one of the most studied genera of ascomycetous fungi due to the beneficial effects it has on plants. Trichoderma spp. are involved in the production of cell wall-degrading enzymes and metabolites with antimicrobial activity. It also produces volatile compounds that act together as direct biocontrol agents to protect plants against phytopathogenic fungi, oomycetes, nematodes and bacteria. Trichoderma spp. can also compete in the rhizosphere for space and nutrients while it can also protect plants by activating systemic immune responses that result in a faster and stronger induction of plant basal resistance mechanisms against biotic and abiotic stresses. The possibility that Trichoderma can also promote plant growth opens new opportunities to register strains as biostimulants. Adequate registration procedures are urgently needed as there is no appropriate legal framework for registering Trichoderma as both plant protection products and as biofertilizers.

Research paper thumbnail of Rapeseed Overexpressing the  Trichoderma Thkel1 Gene Can Be Colonized by Arbuscular Mycorrhizal Fungi With Increases in Seed Yield and Oil Quality

SSRN Electronic Journal, 2021

Research paper thumbnail of Interactions between Trichoderma harzianum and defoliating Verticillium dahliae in resistant and susceptible wild olive clones

Plant Pathology, 2018

Verticillium wilt (VW) in olive is best managed by an integrated disease management strategy, of ... more Verticillium wilt (VW) in olive is best managed by an integrated disease management strategy, of which use of host resistance is a key element. The widespread occurrence of a highly virulent defoliating (D) Verticillium dahliae pathotype has jeopardized the use of commercial olive cultivars lacking sufficient resistance to this pathogen. However, the combined use of resistant wild olive rootstocks and Trichoderma spp. effective in the biocontrol of VW can improve the management of VW in olive. In vivo interactions between D V. dahliae and Trichoderma harzianum were studied in olive and wild olive plants displaying different degrees of resistance against this pathogen using confocal microscopy. This multitrophic system included wild olive clones Ac‐4 and Ac‐15, olive cv. Picual, and the fungal fluorescent transformants T. harzianum GFP22 and V. dahliae V138I‐YFP, the latter being obtained in this study. In planta observations indicated that V138I‐YFP colonizes the roots and stems of ...

Research paper thumbnail of Effect of tyrosol and trichoderma parareesei chorismate mutase silenced mutants in light perception by arabidopsis plants

Research paper thumbnail of Biodiversity of Trichoderma strains in Tunisia

Canadian Journal of Microbiology, 2009

Trichoderma strains were sampled in 4 different bioclimatic zones of Tunisia, a Mediterranean Nor... more Trichoderma strains were sampled in 4 different bioclimatic zones of Tunisia, a Mediterranean North African country with strong climatic and edaphic variability from north to south, to assess the genetic diversity of endemic species of Trichoderma and their relationship to the bioclimatic zones. In all, 53 strains were isolated and identified at the species level by analysis of their internal transcribed spacers regions 1 and 2 (ITS1 and ITS2) of the rDNA cluster and (or) a fragment of the translation elongation factor 1 (tef1) gene, using an online interactive key for species identification in Trichoderma and ex-type strains and taxonomically established isolates of Trichoderma as references. At least 2 different species were observed in each ecosystem. Trichoderma harzianum clade VI and Trichoderma longibrachiatum were present in forest soils in north Tunisia; Trichoderma atroviride and Trichoderma hamatum were found in cultivated fields in northeast Tunisia; T. harzianum clade VI...

Research paper thumbnail of Effect of Trichoderma asperellum on Wheat Plants’ Biochemical and Molecular Responses, and Yield under Different Water Stress Conditions

International Journal of Molecular Sciences, Jun 17, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Research paper thumbnail of Microbiological Evaluation of the Disinfecting Potential of UV-C and UV-C Plus Ozone Generating Robots

Microorganisms, Jan 15, 2021

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Research paper thumbnail of Deciphering Biocontrol Qualities and Other Plant Beneficial Traits in Trichoderma

Progress in biological control, 2020

Research paper thumbnail of Transcriptomic response of Arabidopsis thaliana after 24h incubation with the biocontrol fungus Trichoderma harzianum

Journal of Plant Physiology, Apr 1, 2012

Trichoderma harzianum is a fungus used as biocontrol agent using its antagonistic abilities again... more Trichoderma harzianum is a fungus used as biocontrol agent using its antagonistic abilities against phytopathogenic fungi, although it has also direct effects on plants, increasing or accelerating their growth and resistance to diseases and the tolerance to abiotic stresses. We analyzed Arabidopsis thaliana gene expression changes after 24 h of incubation in the presence of T. harzianum T34 using the Affymetrix GeneChip Arabidopsis ATH1. Because this microarray contains more than 22,500 probe sets representing approximately 24,000 genes, we were able to construct a global picture of the molecular physiology of the plant at 24 h of T. harzianum-Arabidopsis interaction. We identified several differentially expressed genes that are involved in plant responses to stress, regulation of transcription, signal transduction or plant metabolism. Our data support the hypothesis that salicylic acid- and jasmonic acid-related genes were down-regulated in A. thaliana after 24 h of incubation in the presence of T. harzianum T34, while several genes related to abiotic stress responses were up-regulated. These systemic changes elicited by T. harzianum in Arabidopsis are discussed.

Research paper thumbnail of Trichoderma harzianum Volatile Organic Compounds Regulated by the THCTF1 Transcription Factor Are Involved in Antifungal Activity and Beneficial Plant Responses

Journal of Fungi

The transcription factor THCTF1 from Trichoderma harzianum, previously linked to the production o... more The transcription factor THCTF1 from Trichoderma harzianum, previously linked to the production of 6-pentyl-2H-pyran-2-one (6-PP) derivatives and antifungal activity against Fusarium oxysporum, has been related in this study to conidiation, production of an array of volatile organic compounds (VOCs) and expression of methyltransferase genes. VOCs emitted by three T. harzianum strains (wild type T34, transformant ΔD1-38 that is disrupted in the Thctf1 gene encoding the transcription factor THCTF1, and ectopic integration transformant ΔJ3-16) were characterized by Proton Transfer Reaction-Quadrupole interface-Time-Of-Flight-Mass Spectrometry (PTR-Qi-TOF-MS). Thctf1 disruption affected the production of numerous VOCs such as the antifungal volatiles 2-pentyl furan and benzaldehyde which were under-emitted, and acetoine, a plant systemic defense inductor, which was over-emitted. Biological assays show that VOCs regulated by THCTF1 are involved in the T. harzianum antifungal activity aga...

Research paper thumbnail of Combined comparative genomics and molecular biology approaches provide insights into the terpene synthases inventory in Trichoderma

Trichoderma is a fungal genus comprising species used as biocontrol agents in crop plant protecti... more Trichoderma is a fungal genus comprising species used as biocontrol agents in crop plant protection and with high value for industry. The beneficial effects of these species are supported by the secondary metabolites they produced. Terpenoid compounds are key players in the interaction of Trichoderma spp. with the environment and with their fungal and plant hosts, however most of the terpene synthase (TS) genes involved in their biosynthesis have yet not been characterized. Here, we combined comparative genomics of TSs of 21 strains belonging to 17 Trichoderma spp., and gene expression studies on TSs using T. gamsii T6085 as a model. An overview of the diversity within the TS-gene family and the regulation of TS genes is provided. We identified 15 groups of TSs, and the presence of clade-specific enzymes revealed a variety of terpenoid chemotypes evolved to cover different ecological demands. We propose that functional differentiation of gene family members is the driver for the high number of TS genes found in the genomes of Trichoderma. Expression studies provide a picture in which different TS genes are regulated in many ways, a strong indication of different biological functions.

Research paper thumbnail of Why Is the Correct Selection of Trichoderma Strains Important? The Case of Wheat Endophytic Strains of T. harzianum and T. simmonsii

Journal of Fungi, 2021

The search for endophytic fungi in the roots of healthy wheat plants from a non-irrigation field ... more The search for endophytic fungi in the roots of healthy wheat plants from a non-irrigation field trial allowed us to select 4 out of a total of 54 cultivable isolates belonging to the genus Trichoderma, identified as T. harzianum T136 and T139, T. simmonsii T137, and T. afroharzianum T138. In vitro assays against the phytopathogenic fungus Fusarium graminearum showed that the T. harzianum strains had the highest biocontrol potential and that T136 exhibited the highest cellulase and chitinase activities. Production patterns of eight phytohormones varied among the Trichoderma strains. All four, when applied alone or in combination, colonized roots of other wheat cultivars and promoted seed germination, tillering, and plant growth under optimal irrigation conditions in the greenhouse. Apart from T136, the endophytic Trichoderma strains showed plant protection capacity against drought as they activated the antioxidant enzyme machinery of the wheat plants. However, T. simmonsii T137 gave...

Research paper thumbnail of Effectiveness of composts and Trichoderma strains for control of Fusarium wilt of tomato

Phytopathologia Mediterranea, 2015

Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (FOL) is a major limiting disease i... more Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (FOL) is a major limiting disease in tomato production in Morocco. Commercial and locally produced Moroccan composts and peat were found to reduce Fusarium wilt in tomato plants. We explored the presence of Trichoderma strains in these materials, and in six soils sampled in the North West of Morocco, where a low incidence of Fusarium wilt had been previously observed. The most abundant Trichoderma -like fungus was selected from each soil, compost or peat sample. Twelve Trichoderma strains were isolated and identified molecularly. Trichoderma asperellum CT9 and Trichoderma virens ST11 showed the greatest overall antagonistic activity against FOL, Rhizoctonia solani , Botrytis cinerea and Pythium ultimum . The three strains evaluated in in planta tests, CT9, ST11 and T. virens ST10, reduced tomato Fusarium wilt, and strain ST11 also promoted growth of tomato plants.

Research paper thumbnail of Trichoderma and the Plant Heritable Priming Responses

Journal of Fungi, 2021

There is no doubt that Trichoderma is an inhabitant of the rhizosphere that plays an important ro... more There is no doubt that Trichoderma is an inhabitant of the rhizosphere that plays an important role in how plants interact with the environment. Beyond the production of cell wall degrading enzymes and metabolites, Trichoderma spp. can protect plants by inducing faster and stronger immune responses, a mechanism known as priming, which involves enhanced accumulation of dormant cellular proteins that function in intracellular signal amplification. One example of these proteins is the mitogen-activated protein kinases (MAPK) that are triggered by the rise of cytosolic calcium levels and cellular redox changes following a stressful challenge. Transcription factors such as WRKYs, MYBs, and MYCs, play important roles in priming as they act as regulatory nodes in the transcriptional network of systemic defence after stress recognition. In terms of long-lasting priming, Trichoderma spp. may be involved in plants epigenetic regulation through histone modifications and replacements, DNA (hypo...

Research paper thumbnail of Phytohormone Production Profiles in Trichoderma Species and Their Relationship to Wheat Plant Responses to Water Stress

Pathogens, 2021

The production of eight phytohormones by Trichoderma species is described, as well as the 1-amino... more The production of eight phytohormones by Trichoderma species is described, as well as the 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase (ACCD) activity, which diverts the ethylene biosynthetic pathway in plants. The use of the Trichoderma strains T. virens T49, T. longibrachiatum T68, T. spirale T75 and T. harzianum T115 served to demonstrate the diverse production of the phytohormones gibberellins (GA) GA1 and GA4, abscisic acid (ABA), salicylic acid (SA), auxin (indole-3-acetic acid: IAA) and the cytokinins (CK) dihydrozeatin (DHZ), isopenteniladenine (iP) and trans-zeatin (tZ) in this genus. Such production is dependent on strain and/or culture medium. These four strains showed different degrees of wheat root colonization. Fresh and dry weights, conductance, H2O2 content and antioxidant activities such as superoxide dismutase, peroxidase and catalase were analyzed, under optimal irrigation and water stress conditions, on 30-days-old wheat plants treated with four-day-old ...

Research paper thumbnail of A Split-Root Method to Study Systemic and Heritable Traits Induced by Trichoderma in Tomato Plants

Methods in Rhizosphere Biology Research, 2019

The split-root methodology constitutes an excellent tool to study local versus systemic plant-ind... more The split-root methodology constitutes an excellent tool to study local versus systemic plant-induced responses. In the most common approach, two different organisms coinfect the two separated root halves of a same plant. Split-root plants have been used to study the biocontrol potential of fungi and bacteria by the induction of systemic defenses in the plant against bacterial, fungal, oomycete, and nematode diseases and insect pests. In our particular case study, we applied this methodology to demonstrate the systemic and heritable effects induced by the biocontrol strain Trichoderma atroviride T11 in tomato plants which were tested against the root-knot nematode (RKN) Meloidogyne javanica (Mj), a major tomato pathogen worldwide. This approach allows Trichoderma and the root pathogen to be kept separate for the analysis of the T11 effects on the penetration, development, and reproduction of Mj in tomato roots upon activating plant systemic responses. The method also enables the plant green mass and nematode infection parameters to be determined and the gene expression analysis related to systemic responses and heritable traits, in terms of defense and growth, induced by T11 when plants are infected with Mj in the progeny of split-root plants.

Research paper thumbnail of Differential Response of Tomato Plants to the Application of Three Trichoderma Species When Evaluating the Control of Pseudomonas syringae Populations

Plants, 2020

Trichoderma species are well known biocontrol agents that are able to induce responses in the hos... more Trichoderma species are well known biocontrol agents that are able to induce responses in the host plants against an array of abiotic and biotic stresses. Here, we investigate, when applied to tomato seeds, the potential of Trichoderma strains belonging to three different species, T. parareesei T6, T. asperellum T25, and T. harzianum T34, to control the fully pathogenic strain Pseudomonas syringae pv. tomato (Pst) DC3000, able to produce the coronatine (COR) toxin, and the COR-deficient strain Pst DC3118 in tomato plants, and the molecular mechanisms by which the plant can modulate its systemic defense. Four-week old tomato plants, seed-inoculated, or not, with a Trichoderma strain, were infected, or not, with a Pst strain, and the changes in the expression of nine marker genes representative of salicylic acid (SA) (ICS1 and PAL5) and jasmonic acid (JA) (TomLoxC) biosynthesis, SA- (PR1b1), JA- (PINII and MYC2) and JA/Ethylene (ET)-dependent (ERF-A2) defense pathways, as well as the ...

Research paper thumbnail of Salicylic acid prevents<i>Trichoderma harzianum</i>from entering the vascular system of roots

Molecular Plant Pathology, May 7, 2014

Trichoderma is a soil-borne fungal genus that includes species with a significant impact on agric... more Trichoderma is a soil-borne fungal genus that includes species with a significant impact on agriculture and industrial processes. Some Trichoderma strains exert beneficial effects in plants through root colonization, although little is known about how this interaction takes place. To better understand this process, the root colonization of wild-type Arabidopsis and the salicylic acid (SA)impaired mutant sid2 by a green fluorescent protein (GFP)-marked Trichoderma harzianum strain was followed under confocal microscopy. Trichoderma harzianum GFP22 was able to penetrate the vascular tissue of the sid2 mutant because of the absence of callose deposition in the cell wall of root cells. In addition, a higher colonization of sid2 roots by GFP22 compared with that in Arabidopsis wild-type roots was detected by real-time polymerase chain reaction. These results, together with differences in the expression levels of plant defence genes in the roots of both interactions, support a key role for SA in Trichoderma early root colonization stages. We observed that, without the support of SA, plants were unable to prevent the arrival of the fungus in the vascular system and its spread into aerial parts, leading to later collapse.

Research paper thumbnail of Trichoderma: a multipurpose, plant-beneficial microorganism for eco-sustainable agriculture

Nature Reviews Microbiology

Research paper thumbnail of Are species concepts outdated for fungi? Intraspecific variation in plant-pathogenic fungi illustrates the need for subspecific categorization

Trends in the systematics of bacteria and fungi

Abstract Precise naming of a species is very important for phytopathogenic fungi because names ma... more Abstract Precise naming of a species is very important for phytopathogenic fungi because names may carry key information for the management of the fungal diseases. Naming fungal species based on morphological traits or biological properties is outdated and unreliable. This chapter provides the classification of some plant pathogenic fungi including Rhizoctonia solani, Colletotrichum, Fusarium oxysporum, and Verticillum based on morphological, pathogenicity, molecular and phylogenetic analysis. Debate on species identification is no longer a question of being in favour of 'splitters' rather than of 'lumpers', but defining phytopathogenic species is particularly complicated and requires further consideration of subspecific categorizations.

Research paper thumbnail of The use of Trichoderma spp. to control plant diseases

Microbial bioprotectants for plant disease management, 2021

Trichoderma is one of the most studied genera of ascomycetous fungi due to the beneficial effects... more Trichoderma is one of the most studied genera of ascomycetous fungi due to the beneficial effects it has on plants. Trichoderma spp. are involved in the production of cell wall-degrading enzymes and metabolites with antimicrobial activity. It also produces volatile compounds that act together as direct biocontrol agents to protect plants against phytopathogenic fungi, oomycetes, nematodes and bacteria. Trichoderma spp. can also compete in the rhizosphere for space and nutrients while it can also protect plants by activating systemic immune responses that result in a faster and stronger induction of plant basal resistance mechanisms against biotic and abiotic stresses. The possibility that Trichoderma can also promote plant growth opens new opportunities to register strains as biostimulants. Adequate registration procedures are urgently needed as there is no appropriate legal framework for registering Trichoderma as both plant protection products and as biofertilizers.

Research paper thumbnail of Rapeseed Overexpressing the  Trichoderma Thkel1 Gene Can Be Colonized by Arbuscular Mycorrhizal Fungi With Increases in Seed Yield and Oil Quality

SSRN Electronic Journal, 2021

Research paper thumbnail of Interactions between Trichoderma harzianum and defoliating Verticillium dahliae in resistant and susceptible wild olive clones

Plant Pathology, 2018

Verticillium wilt (VW) in olive is best managed by an integrated disease management strategy, of ... more Verticillium wilt (VW) in olive is best managed by an integrated disease management strategy, of which use of host resistance is a key element. The widespread occurrence of a highly virulent defoliating (D) Verticillium dahliae pathotype has jeopardized the use of commercial olive cultivars lacking sufficient resistance to this pathogen. However, the combined use of resistant wild olive rootstocks and Trichoderma spp. effective in the biocontrol of VW can improve the management of VW in olive. In vivo interactions between D V. dahliae and Trichoderma harzianum were studied in olive and wild olive plants displaying different degrees of resistance against this pathogen using confocal microscopy. This multitrophic system included wild olive clones Ac‐4 and Ac‐15, olive cv. Picual, and the fungal fluorescent transformants T. harzianum GFP22 and V. dahliae V138I‐YFP, the latter being obtained in this study. In planta observations indicated that V138I‐YFP colonizes the roots and stems of ...

Research paper thumbnail of Effect of tyrosol and trichoderma parareesei chorismate mutase silenced mutants in light perception by arabidopsis plants

Research paper thumbnail of Biodiversity of Trichoderma strains in Tunisia

Canadian Journal of Microbiology, 2009

Trichoderma strains were sampled in 4 different bioclimatic zones of Tunisia, a Mediterranean Nor... more Trichoderma strains were sampled in 4 different bioclimatic zones of Tunisia, a Mediterranean North African country with strong climatic and edaphic variability from north to south, to assess the genetic diversity of endemic species of Trichoderma and their relationship to the bioclimatic zones. In all, 53 strains were isolated and identified at the species level by analysis of their internal transcribed spacers regions 1 and 2 (ITS1 and ITS2) of the rDNA cluster and (or) a fragment of the translation elongation factor 1 (tef1) gene, using an online interactive key for species identification in Trichoderma and ex-type strains and taxonomically established isolates of Trichoderma as references. At least 2 different species were observed in each ecosystem. Trichoderma harzianum clade VI and Trichoderma longibrachiatum were present in forest soils in north Tunisia; Trichoderma atroviride and Trichoderma hamatum were found in cultivated fields in northeast Tunisia; T. harzianum clade VI...

Research paper thumbnail of Effect of Trichoderma asperellum on Wheat Plants’ Biochemical and Molecular Responses, and Yield under Different Water Stress Conditions

International Journal of Molecular Sciences, Jun 17, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Research paper thumbnail of Microbiological Evaluation of the Disinfecting Potential of UV-C and UV-C Plus Ozone Generating Robots

Microorganisms, Jan 15, 2021

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Research paper thumbnail of Deciphering Biocontrol Qualities and Other Plant Beneficial Traits in Trichoderma

Progress in biological control, 2020

Research paper thumbnail of Transcriptomic response of Arabidopsis thaliana after 24h incubation with the biocontrol fungus Trichoderma harzianum

Journal of Plant Physiology, Apr 1, 2012

Trichoderma harzianum is a fungus used as biocontrol agent using its antagonistic abilities again... more Trichoderma harzianum is a fungus used as biocontrol agent using its antagonistic abilities against phytopathogenic fungi, although it has also direct effects on plants, increasing or accelerating their growth and resistance to diseases and the tolerance to abiotic stresses. We analyzed Arabidopsis thaliana gene expression changes after 24 h of incubation in the presence of T. harzianum T34 using the Affymetrix GeneChip Arabidopsis ATH1. Because this microarray contains more than 22,500 probe sets representing approximately 24,000 genes, we were able to construct a global picture of the molecular physiology of the plant at 24 h of T. harzianum-Arabidopsis interaction. We identified several differentially expressed genes that are involved in plant responses to stress, regulation of transcription, signal transduction or plant metabolism. Our data support the hypothesis that salicylic acid- and jasmonic acid-related genes were down-regulated in A. thaliana after 24 h of incubation in the presence of T. harzianum T34, while several genes related to abiotic stress responses were up-regulated. These systemic changes elicited by T. harzianum in Arabidopsis are discussed.

Research paper thumbnail of Trichoderma harzianum Volatile Organic Compounds Regulated by the THCTF1 Transcription Factor Are Involved in Antifungal Activity and Beneficial Plant Responses

Journal of Fungi

The transcription factor THCTF1 from Trichoderma harzianum, previously linked to the production o... more The transcription factor THCTF1 from Trichoderma harzianum, previously linked to the production of 6-pentyl-2H-pyran-2-one (6-PP) derivatives and antifungal activity against Fusarium oxysporum, has been related in this study to conidiation, production of an array of volatile organic compounds (VOCs) and expression of methyltransferase genes. VOCs emitted by three T. harzianum strains (wild type T34, transformant ΔD1-38 that is disrupted in the Thctf1 gene encoding the transcription factor THCTF1, and ectopic integration transformant ΔJ3-16) were characterized by Proton Transfer Reaction-Quadrupole interface-Time-Of-Flight-Mass Spectrometry (PTR-Qi-TOF-MS). Thctf1 disruption affected the production of numerous VOCs such as the antifungal volatiles 2-pentyl furan and benzaldehyde which were under-emitted, and acetoine, a plant systemic defense inductor, which was over-emitted. Biological assays show that VOCs regulated by THCTF1 are involved in the T. harzianum antifungal activity aga...

Research paper thumbnail of Combined comparative genomics and molecular biology approaches provide insights into the terpene synthases inventory in Trichoderma

Trichoderma is a fungal genus comprising species used as biocontrol agents in crop plant protecti... more Trichoderma is a fungal genus comprising species used as biocontrol agents in crop plant protection and with high value for industry. The beneficial effects of these species are supported by the secondary metabolites they produced. Terpenoid compounds are key players in the interaction of Trichoderma spp. with the environment and with their fungal and plant hosts, however most of the terpene synthase (TS) genes involved in their biosynthesis have yet not been characterized. Here, we combined comparative genomics of TSs of 21 strains belonging to 17 Trichoderma spp., and gene expression studies on TSs using T. gamsii T6085 as a model. An overview of the diversity within the TS-gene family and the regulation of TS genes is provided. We identified 15 groups of TSs, and the presence of clade-specific enzymes revealed a variety of terpenoid chemotypes evolved to cover different ecological demands. We propose that functional differentiation of gene family members is the driver for the high number of TS genes found in the genomes of Trichoderma. Expression studies provide a picture in which different TS genes are regulated in many ways, a strong indication of different biological functions.

Research paper thumbnail of Why Is the Correct Selection of Trichoderma Strains Important? The Case of Wheat Endophytic Strains of T. harzianum and T. simmonsii

Journal of Fungi, 2021

The search for endophytic fungi in the roots of healthy wheat plants from a non-irrigation field ... more The search for endophytic fungi in the roots of healthy wheat plants from a non-irrigation field trial allowed us to select 4 out of a total of 54 cultivable isolates belonging to the genus Trichoderma, identified as T. harzianum T136 and T139, T. simmonsii T137, and T. afroharzianum T138. In vitro assays against the phytopathogenic fungus Fusarium graminearum showed that the T. harzianum strains had the highest biocontrol potential and that T136 exhibited the highest cellulase and chitinase activities. Production patterns of eight phytohormones varied among the Trichoderma strains. All four, when applied alone or in combination, colonized roots of other wheat cultivars and promoted seed germination, tillering, and plant growth under optimal irrigation conditions in the greenhouse. Apart from T136, the endophytic Trichoderma strains showed plant protection capacity against drought as they activated the antioxidant enzyme machinery of the wheat plants. However, T. simmonsii T137 gave...

Research paper thumbnail of Effectiveness of composts and Trichoderma strains for control of Fusarium wilt of tomato

Phytopathologia Mediterranea, 2015

Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (FOL) is a major limiting disease i... more Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (FOL) is a major limiting disease in tomato production in Morocco. Commercial and locally produced Moroccan composts and peat were found to reduce Fusarium wilt in tomato plants. We explored the presence of Trichoderma strains in these materials, and in six soils sampled in the North West of Morocco, where a low incidence of Fusarium wilt had been previously observed. The most abundant Trichoderma -like fungus was selected from each soil, compost or peat sample. Twelve Trichoderma strains were isolated and identified molecularly. Trichoderma asperellum CT9 and Trichoderma virens ST11 showed the greatest overall antagonistic activity against FOL, Rhizoctonia solani , Botrytis cinerea and Pythium ultimum . The three strains evaluated in in planta tests, CT9, ST11 and T. virens ST10, reduced tomato Fusarium wilt, and strain ST11 also promoted growth of tomato plants.

Research paper thumbnail of Trichoderma and the Plant Heritable Priming Responses

Journal of Fungi, 2021

There is no doubt that Trichoderma is an inhabitant of the rhizosphere that plays an important ro... more There is no doubt that Trichoderma is an inhabitant of the rhizosphere that plays an important role in how plants interact with the environment. Beyond the production of cell wall degrading enzymes and metabolites, Trichoderma spp. can protect plants by inducing faster and stronger immune responses, a mechanism known as priming, which involves enhanced accumulation of dormant cellular proteins that function in intracellular signal amplification. One example of these proteins is the mitogen-activated protein kinases (MAPK) that are triggered by the rise of cytosolic calcium levels and cellular redox changes following a stressful challenge. Transcription factors such as WRKYs, MYBs, and MYCs, play important roles in priming as they act as regulatory nodes in the transcriptional network of systemic defence after stress recognition. In terms of long-lasting priming, Trichoderma spp. may be involved in plants epigenetic regulation through histone modifications and replacements, DNA (hypo...

Research paper thumbnail of Phytohormone Production Profiles in Trichoderma Species and Their Relationship to Wheat Plant Responses to Water Stress

Pathogens, 2021

The production of eight phytohormones by Trichoderma species is described, as well as the 1-amino... more The production of eight phytohormones by Trichoderma species is described, as well as the 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase (ACCD) activity, which diverts the ethylene biosynthetic pathway in plants. The use of the Trichoderma strains T. virens T49, T. longibrachiatum T68, T. spirale T75 and T. harzianum T115 served to demonstrate the diverse production of the phytohormones gibberellins (GA) GA1 and GA4, abscisic acid (ABA), salicylic acid (SA), auxin (indole-3-acetic acid: IAA) and the cytokinins (CK) dihydrozeatin (DHZ), isopenteniladenine (iP) and trans-zeatin (tZ) in this genus. Such production is dependent on strain and/or culture medium. These four strains showed different degrees of wheat root colonization. Fresh and dry weights, conductance, H2O2 content and antioxidant activities such as superoxide dismutase, peroxidase and catalase were analyzed, under optimal irrigation and water stress conditions, on 30-days-old wheat plants treated with four-day-old ...

Research paper thumbnail of A Split-Root Method to Study Systemic and Heritable Traits Induced by Trichoderma in Tomato Plants

Methods in Rhizosphere Biology Research, 2019

The split-root methodology constitutes an excellent tool to study local versus systemic plant-ind... more The split-root methodology constitutes an excellent tool to study local versus systemic plant-induced responses. In the most common approach, two different organisms coinfect the two separated root halves of a same plant. Split-root plants have been used to study the biocontrol potential of fungi and bacteria by the induction of systemic defenses in the plant against bacterial, fungal, oomycete, and nematode diseases and insect pests. In our particular case study, we applied this methodology to demonstrate the systemic and heritable effects induced by the biocontrol strain Trichoderma atroviride T11 in tomato plants which were tested against the root-knot nematode (RKN) Meloidogyne javanica (Mj), a major tomato pathogen worldwide. This approach allows Trichoderma and the root pathogen to be kept separate for the analysis of the T11 effects on the penetration, development, and reproduction of Mj in tomato roots upon activating plant systemic responses. The method also enables the plant green mass and nematode infection parameters to be determined and the gene expression analysis related to systemic responses and heritable traits, in terms of defense and growth, induced by T11 when plants are infected with Mj in the progeny of split-root plants.

Research paper thumbnail of Differential Response of Tomato Plants to the Application of Three Trichoderma Species When Evaluating the Control of Pseudomonas syringae Populations

Plants, 2020

Trichoderma species are well known biocontrol agents that are able to induce responses in the hos... more Trichoderma species are well known biocontrol agents that are able to induce responses in the host plants against an array of abiotic and biotic stresses. Here, we investigate, when applied to tomato seeds, the potential of Trichoderma strains belonging to three different species, T. parareesei T6, T. asperellum T25, and T. harzianum T34, to control the fully pathogenic strain Pseudomonas syringae pv. tomato (Pst) DC3000, able to produce the coronatine (COR) toxin, and the COR-deficient strain Pst DC3118 in tomato plants, and the molecular mechanisms by which the plant can modulate its systemic defense. Four-week old tomato plants, seed-inoculated, or not, with a Trichoderma strain, were infected, or not, with a Pst strain, and the changes in the expression of nine marker genes representative of salicylic acid (SA) (ICS1 and PAL5) and jasmonic acid (JA) (TomLoxC) biosynthesis, SA- (PR1b1), JA- (PINII and MYC2) and JA/Ethylene (ET)-dependent (ERF-A2) defense pathways, as well as the ...