Ainhoa Martínez-Medina

Institute of Natural Resources and Agrobiology Salamanca (IRNASA-CSIC) · Plant Microbe Interaction

Beneficial root microbes are among the most frequently used biocontrol agents in cropping systems, since they have been shown to promote plant growth and crop yield. Moreover, they are able to enhance protection against pathogens and insect herbivores by activating plant resistance mechanisms. Plant defense responses against herbivorous insects inc...

Arbuscular mycorrhizal (AM) symbiosis modulates plant‐herbivore interactions. Still, how it shapes the overall plant defense strategy and the mechanisms involved remain unclear. We investigated how AM symbiosis simultaneously modulates plant resistance and tolerance to a shoot herbivore, and explored the underlying mechanisms. Bioassays with Medica...

Root mutualistic microbes can modulate the production of plant secondary metabolites affecting plant–herbivore interactions. Still, the main mechanisms underlying the impact of root mutualists on herbivore performance remain ambiguous. In particular, little is known about how changes in the plant metabolome induced by root mutualists affect the ins...

Studies on plant-mediated interactions between root parasitic nematodes and aboveground herbivores are rapidly increasing. However, the outcomes for the interacting organisms vary, and the mechanisms involved remain ambiguous. We hypothesized that the impact of root infection by the root-knot nematode Meloidogyne incognita on the performance of the...

Shoot herbivores may influence the communities of herbivores associated with the roots via inducible defenses. However, the molecular mechanisms and hormonal signaling underpinning the systemic impact of leaf herbivory on root-induced responses against nematodes remain poorly understood. By using tomato (Solanum lycopersicum) as a model plant, we e...

Volatile compounds (VCs) of Trichoderma fungi trigger an induced systemic resistance (ISR) in Arabidopsis that is effective against a broad spectrum of pathogens. The root-specific transcription factor MYB72 is an early regulator of ISR and also controls the activation of iron deficiency responses. Nitric oxide (NO) is involved in the regulation of...

Plants mediate interactions between different herbivores that attack simultaneously or sequentially aboveground (AG) and belowground (BG) organs. The local and systemic activation of hormonal signaling pathways and the concomitant accumulation of defense metabolites underlie such AG-BG interactions. The main plant-mediated mechanisms regulating the...

Plant–fungal interactions are widespread in nature, and their multiple benefits for plant growth and health have been amply demonstrated. Endophytic and epiphytic fungi can significantly increase plant resilience, improving plant nutrition, stress tolerance and defence. Although some of these interactions have been known for decades, the relevance...

Research aimed at understanding the mechanisms underlying the relationship between tree diversity and antagonist infestation is often neglecting resource-use complementarity among plant species. We investigated the effects of tree species identity, species richness, and mycorrhizal type on leaf herbivory and pathogen infestation. We used a tree sap...

Plant–microbe–arthropod (PMA) three-way interactions have important implications for plant health. However, our poor understanding of the underlying regulatory mechanisms hampers their biotechnological applications. To this end, we searched for potential common patterns in plant responses regarding taxonomic groups or lifestyles. We found that most...

The necrotrophic mycoparasite Trichoderma atroviride is a biological pest control agent frequently applied in agriculture for the protection of plants against fungal phytopathogens. One of the main secondary metabolites produced by this fungus is 6-pentyl-α-pyrone (6-PP). 6-PP is an organic compound with antifungal and plant growth-promoting activi...

Three-way Interactions between Plants, Microbes, and Arthropods (PMA): Impacts, Mechanisms, and Prospects for Sustainable Plant Protection (By Maria J. Pozo, Benedicte R. Albrectsen, Eduardo R. Bejarano, Eduardo de la Peña, Salva Herrero, Ainhoa Martinez-Medina, Victoria Pastor, Sabine Ravnskov, Mary Williams and Arjen Biere) Plants constantly inte...

Induced responses to above-ground and below-ground herbivores may interact via systemic signalling in plants. We investigated whether the impact of above-ground herbivory on root-knot nematode-induced responses depends on the nematode's life cycle stages. Tomato plants were infected with the nematode (Meloidogyne incognita) for 5, 15 or 30 days bef...

Aboveground interactions between plants and organisms have served as a foundation of ecological and evolutionary theories. Accumulating evidence suggests that interactions that occur belowground can have immense influence on eco-evolutionary dynamics of plants. Despite the increasing awareness among scientists of the importance of belowground inter...

We recently demonstrated that nitric oxide (NO) accumulation and PHYTOGB1 transcriptional regulation are early components of the regulatory pathway that is activated in tomato roots during the onset of the mycorrhizal symbiosis between Rhizophagus irregularis and tomato roots. We further showed that the mycorrhizal interaction was associated with a...

In their complex environments, plants continuously interact with fungi. While many of those interactions are detrimental for plants and challenge plant capability for growth and survival, others are beneficial improving plant growth and stress tolerance. Accordingly, plants have evolved sophisticated mechanisms to restrict pathogenic interactions w...

Plant-parasitic nematodes cause major agricultural losses worldwide. Examining the molecular mechanisms underlying plant-nematode interactions and how plants respond to different invading pathogens is attracting major attention to reduce the expanding gap between agricultural production and the needs of the growing world population. This review sum...

The regulatory role of nitric oxide (NO) and phytoglobins in plant response to pathogenic and mutualistic microbes has been evidenced. However, little is known about their function in the arbuscular mycorrhizal (AM) symbiosis. We investigated whether NO and phytoglobin PHYTOGB1 are regulatory components in the AM symbiosis. Rhizophagus irregularis...

Plants develop responses to abiotic stresses, like Fe deficiency. Similarly, plants also develop responses to cope with biotic stresses provoked by biological agents, like pathogens and insects. Some of these responses are limited to the infested damaged organ, but other responses systemically spread far from the infested organ and affect the whole...

Accumulating evidence supports the importance of belowground interactions for plant performance, ecosystem functioning, and conservation biology. However, studying species interactions belowground has unique challenges relative to the aboveground realm. The structure of the media and spatial scale are among the key aspects that seem to strongly inf...

Plants form mutualistic relationship with a variety of belowground fungal species. Such a mutualistic relationship can enhance plant growth and resistance to pathogens. Yet, we know little about how interactions between functionally diverse groups of fungal mutualists affect plant performance and competition. We experimentally determined the effect...

Research on mycorrhizal interactions has traditionally developed into separate disciplines addressing different organizational levels. This separation has led to an incomplete understanding of mycorrhizal functioning. Integration of mycorrhiza research at different scales is needed to understand the mechanisms underlying context-dependency of mycor...

Phytohormones such as jasmonic acid (JA), salicylic acid (SA), ethylene (ET) and abscisic acid (ABA) play a key role in regulation of plant immune responses to different attackers. Extensive research over recent years has led to the identification of molecular markers for specific hormonal-regulated defence pathways. However, most of our current kn...

We recently found that the beneficial fungus Trichoderma harzianum T-78 primes tomato plants for salicylic acid (SA)- and jasmonic acid (JA)-regulated defences, resulting in enhanced resistance against the root knot nematode Meloidogyne incognita. By using SA- and JA-impaired mutant lines and exogenous hormonal application, here we investigated whe...

Root colonization by Trichoderma fungi can trigger induced systemic resistance (ISR). In Arabidopsis, Trichoderma-ISR relies on the transcription factor MYB72, which plays a dual role in the onset of ISR and the activation of Fe uptake responses. Volatile compounds (VCs) from rhizobacteria are important elicitors of MYB72 in Arabidopsis roots. Here...

Trichoderma spp. are cosmopolitan soil fungi that hold great promise as biocontrol organisms. Their biocontrol capacity was initially thought to be based on their direct suppressive effects on plant pathogens, with most strains showing mycoparasitic potential and producing a large variety of enzymes and secondary metabolites. More recently however...

Beneficial root endophytes such as Trichoderma spp. can reduce infections by parasitic nematodes through triggering host defences. Little is currently known about the complex hormone signalling underlying the induction of resistance. In this study, we investigated whether Trichoderma modulates the hormone signalling network in the host to induce re...

Defense priming conditions diverse plant species for the superinduction of defense, often resulting in enhanced pest and disease resistance and abiotic stress tolerance. Here, we propose a guideline that might assist the plant research community in a consistent assessment of defense priming in plants.

The application of Trichoderma strains with biocontrol and plant growth-promoting capacities to plant substrates can help reduce the input of chemical pesticides and fertilizers in agriculture. Some Trichoderma isolates can directly affect plant pathogens, but they also are known to influence the phytohormonal network of their host plant, thus lead...

Arbuscular mycorrhizal (AM) symbioses are mutualistic associations between soil fungi and most vascular plants. Modulation of the hormonal and transcriptional profiles, including changes related to defense signalling, has been reported in many host plants during AM symbioses. These changes have been often related to the improved stress tolerance co...

Plant interaction with beneficial soil microorganisms usually promotes plant growth and increases the plant’s ability to cope with biotic and abiotic stresses. Among these beneficial microorganisms, arbuscular mycorrhizal fungi (AMF) are of major importance because they establish mutualistic symbiosis with most plant species. Profound physiological...

Root colonization by selected Trichoderma isolates can activate in the plant a systemic defense response that is effective against a broad-spectrum of plant pathogens. Diverse plant hormones play pivotal roles in the regulation of the defense signaling network that leads to the induction of systemic resistance triggered by beneficial organisms [ind...

The European Union is promoting a new legislation through the "Proposal for a Directive of the European Parliament and of the Council on spreading of sludge on land", with special interest on human pathogens. Autothermal thermophilic aerobic digestion (ATAD) is described in this Proposal as an advanced treatment capable of producing sanitized sludg...

Symbioses between plants and beneficial soil microorganisms like arbuscular-mycorrhizal fungi (AMF) are known to promote plant growth and help plants to cope with biotic and abiotic stresses. Profound physiological changes take place in the host plant upon root colonization by AMF affecting the interactions with a wide range of organisms below- and...

Trichoderma ssp. have shown to induce systemic resistance to a variety of plant pathogens and to promote plant growth through fungal interactions with phytohormonal signalling. Changes in the concentration of SA, JA, IAA, Ze and ACC in shoots of melon plants grown in seedling nurseries, as a result of inoculation with T. harzianum as well as their...

The objective of this work was to evaluate the interactions between four arbuscular mycorrhizal fungi (AMF) (Glomus intraradices, Glomus mosseae, Glomus claroideum, and Glomus constrictum) and the beneficial fungus Trichoderma harzianum, inoculated in a greenhouse nursery, with regard to their effects on melon crop growth under conventional and int...

Arbuscular mycorrhizal fungi (AMF) and Trichoderma harzianum are known to affect plant growth and disease resistance through interaction with phytohormone synthesis or transport in the plant. Cross-talk between these microorganisms and their host plants normally occurs in nature and may affect plant resistance. Simultaneous quantification in the sh...

The plant hormones salicylic acid (SA), jasmonic acid (JA), ethylene (ET), and abscisic acid (ABA) are known to play crucial roles in plant disease and pest resistance. Changes in the concentrations of these plant hormones in melon plant shoots, as a consequence of the interaction between the plant, the pathogen Fusarium oxysporum, the antagonistic...

Practical use of Trichoderma harzianum requires feasible formulated products. The objective of this study was to investigate the survival and effectiveness of a T. harzianum bentonite-vermiculite formulation against fusarium wilt and its growthpromotion effect on melon plants under nursery conditions compared with the incorporation of this agent as...

BACKGROUND: Biological control through the use of Trichoderma spp. and arbuscular mycorrhizal fungi (AMF) could contribute to a reduction of the inputs of environmentally damaging agrochemical products. The objective of this study was to evaluate the interactions between four AMF (Glomus intraradices, Glomus mosseae, Glomus claroideum and Glomus co...

Dollar spot, caused by Sclerotinia homoeocarpa,. is one of the most devastating diseases of turfgrass worldwide. Many fungi belonging to the genus Sclerotinia produce oxalic acid along with pectolytic cell wall-degrading enzymes. A series of in vitro experiments showed the relationships among temperature, pH, mycelial growth and acid production. My...

Solid product effective for biocontrol of vascular fusariosis of melon, method for preparation thereof and method for use of same. The invention is part of the technical field of conventional and organic agriculture, is applicable both in fields and nurseries and provides a solid product effective for the biological control of vascular fusariosis o...