Open Access
Agronomic and metabolomic side-effects of a divergent selection for indol-3-ylmethylglucosinolate content in kale (Brassica oleracea var. acephala)
(MDPI, 2021) Poveda Arias, Jorge; Velasco, Pablo; Haro, Antonio de; Johansen, Tor J.; McAlvay, Alex C.; Möllers, Christian; Mølmann, Jorgen A.B.; Ordiales, Elena; Rodríguez, Víctor Manuel; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura
Brassica oleracea var. acephala (kale) is a cruciferous vegetable widely cultivated for its leaves and flower buds in Europe and a food of global interest as a 'superfood'. Brassica crops accumulate phytochemicals called glucosinolates (GSLs) which play an important role in plant defense against biotic stresses. Studies carried out to date suggest that GSLs may have a role in the adaptation of plants to different environments, but direct evidence is lacking. We grew two kale populations divergently selected for high and low indol-3-ylmethylGSL (IM) content (H-IM and L-IM, respectively) in different environments and analyzed agronomic parameters, GSL profiles and metabolomic profile. We found a significant increase in fresh and dry foliar weight in H-IM kale populations compared to L-IM in addition to a greater accumulation of total GSLs, indole GSLs and, specifically, IM and 1-methoxyindol-3-ylmethylGSL (1MeOIM). Metabolomic analysis revealed a significant different concentration of 44 metabolites in H-IM kale populations compared to L-IM. According to tentative peak identification from MS interpretation, 80% were phenolics, including flavonoids (kaempferol, quercetin and anthocyanin derivates, including acyl flavonoids), chlorogenic acids (esters of hydroxycinnamic acids and quinic acid), hydroxycinnamic acids (ferulic acid and p-coumaric acid) and coumarins. H-IM kale populations could be more tolerant to diverse environmental conditions, possibly due to GSLs and the associated metabolites with predicted antioxidant potential.
Open Access
Filamentous fungi as biocontrol agents in olive (Olea europaea L.) diseases: mycorrhizal and endophytic fungi
(Elsevier, 2021) Poveda Arias, Jorge; Baptista, Paula; Institute for Multidisciplinary Research in Applied Biology - IMAB
Olive (Olea europaea) is a crop of great agronomic, economic and cultural interest for the Mediterranean Basin, although the increase in world demand for olive oil is expanding its cultivation by other countries in the southern hemisphere. The main olive pathogens include bacteria (Pseudomonas savastanoi pv. savastanoi, Xylella fastidiosa), fungi (Colletotrichum spp., Verticillium dahliae, Fusarium spp. Rhizoctonia solani), oomycetes (Phytophthora spp.) and nematodes (Meloidogyne spp.). To combat these pathogens, different biocontrol strategies have been developed with bacteria and yeasts, although its capacity for establishment in the field entails several difficulties. In this sense, filamentous fungi represent an efficient and effective alternative in the control of the different pathogens of the olive tree. The present review compiles all the studies existing so far in the biocontrol of these pathogens through the use of mycorrhizal and endophytic filamentous fungi, making a separate section for the genus Trichoderma due to the special interest that their use has generated. The mechanisms used by these fungi include competition for space and nutrients, parasitism, antibiosis or activation of the plant's defensive responses, among others.
Open Access
Trichoderma as biocontrol agent against pests: new uses for a mycoparasite
(Elsevier, 2021) Poveda Arias, Jorge; Institute for Multidisciplinary Research in Applied Biology - IMAB
Insects are the main pest in agricultural systems, causing significant losses in crop productivity and storage. During the last decades the control of pest insects has been carried out through the uncontrolled and massive use of chemical insecticides, very harmful to the environment and health, which requires the development of new efficient and safe alternatives. Numerous fungal species have been described as entomopathogens of insect pests, as well as plant endophytic fungi. In this sense, Trichoderma is a genus of filamentous fungi widely studied and used as a biocontrol agent in agriculture on pathogenic fungi due to its ability to parasitize them (mycoparasitism), among other mechanisms of action. In recent years, the possibility of using Trichoderma as a biocontrol agent for insect pest has been considered, both directly and indirectly. The studies carried out to date have reported that Trichoderma is capable of controlling insect pest directly through parasitism and the production of insecticidal secondary metabolites, antifeedant compounds and repellent metabolites. And indirectly through the activation of systemic plant defensive responses, the attraction of natural enemies or the parasitism of insectsymbiotic microorganisms. Therefore, the use of Trichoderma in agriculture is not only effective against plant pathogens, but also against insect pests, representing a future alternative in the development of sustainable agriculture.
Open Access
Activation of sweet pepper defense responses by novel and known biocontrol agents of the genus Bacillus against Botrytis cinerea and Verticillium dahliae
(Springer, 2022) Poveda Arias, Jorge; Calvo, Javier; Barquero, Marcia; González Andrés, Fernando; Institute for Multidisciplinary Research in Applied Biology - IMAB; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The Fresno-Benavente Pepper (F-BP) Protected Geographical Indication (PGI) is a horticultural crop characterized by its great agronomic, economic and cultural importance in the region of Castilla y León (Spain). Field production is threatened by verticillium wilt caused by Verticillium dahliae and postharvest losses due to grey mould caused by Botrytis cinerea. Eight Bacillus spp. strains endophytically isolated from F-BP roots were used in the study. By conducting an in vitro antagonism study, we found that all Bacillus strains were effective against B. cinerea and five of them showed high antagonism against V. dahliae, with B. siamensis and B. proteolyticus strains being the most effective against both pathogens. Eight Bacillus strains were used for an infection test in F-BP fruits and plants to test their activity against both fungal pathogens. We report that Bacillus thuringiensis, B. siamensis and B. pumilus (SCFC 1–2) could control B. cinerea in pepper fruits through direct action and local activation of plant defences. In the case of V. dahliae root infection, plant roots inoculated with B. siamensis and B. proteolyticus were able to significantly decrease the occurrence of disease through direct action and local activation of jasmonic acid as a defence response. Therefore, we propose that B. siamensis could be used to control B. cinerea and V. dahliae in F-BP fruits and plants, respectively, through direct antagonism as well as the induction of local plant defence responses.
Open Access
Overview of the use of biochar from main cereals to stimulate plant growth
(Carnegie Institution por Science, 2022) Martínez Gómez, Ángela; Poveda Arias, Jorge; Escobar, Carolina; Institute for Multidisciplinary Research in Applied Biology - IMAB
The total global food demand is expected to increase up to 50% between 2010 and 2050; hence, there is a clear need to increase plant productivity with little or no damage to the environment. In this respect, biochar is a carbon-rich material derived from the pyrolysis of organic matter at high temperatures with a limited oxygen supply, with different physicochemical characteristics that depend on the feedstock and pyrolysis conditions. When used as a soil amendment, it has shown many positive environmental effects such as carbon sequestration, reduction of greenhouse gas emissions, and soil improvement. Biochar application has also shown huge benefits when applied to agri-systems, among them, the improvement of plant growth either in optimal conditions or under abiotic or biotic stress. Several mechanisms, such as enhancing the soil microbial diversity and thus increasing soil nutrient-cycling functions, improving soil physicochemical properties, stimulating the microbial colonization, or increasing soil P, K, or N content, have been described to exert these positive effects on plant growth, either alone or in combination with other resources. In addition, it can also improve the plant antioxidant defenses, an evident advantage for plant growth under stress conditions. Although agricultural residues are generated from a wide variety of crops, cereals account for more than half of the world¿s harvested area. Yet, in this review, we will focus on biochar obtained from residues of the most common and relevant cereal crops in terms of global production (rice, wheat, maize, and barley) and in their use as recycled residues to stimulate plant growth. The harvesting and processing of these crops generate a vast number and variety of residues that could be locally recycled into valuable products such as biochar, reducing the waste management problem and accomplishing the circular economy premise. However, very scarce literature focused on the use of biochar from a crop to improve its own growth is available. Herein, we present an overview of the literature focused on this topic, compiling most of the studies and discussing the urgent need to deepen into the molecular mechanisms and pathways involved in the beneficial effects of biochar on plant productivity.
Open Access
Editorial: Beneficial effects of fungal endophytes in major agricultural crops
(Frontiers Media, 2022) Poveda Arias, Jorge; Baptista, Paula; Sacristán, Soledad; Velasco, Pablo; Institute for Multidisciplinary Research in Applied Biology - IMAB
Endophytic microorganisms are those that can dwell within plant tissues without any external sign of infection or other harmful effects on the host plants (Burragoni and Jeon, 2021). In recent decades, the important role that both bacterial and fungal endophytes play in plant growth and development, as well as in their ability to survive in their environment, has been identified (Burragoni and Jeon, 2021). Endophytic fungi can be found colonizing any plant organ, presenting a very different distribution and diversity among plants of different species, among plants of the same species, and even among organs of the same plant (Aamir et al., 2020). In crops, endophytic fungi act through different beneficial pathways, as biofertilizers promoting plant growth, as biological control agents of pathogens and pests or as inducers of tolerance under abiotic stresses, having great importance in the development of new strategies for sustainable agriculture (Aamir et al., 2020). These benefits for crops have been studied in the papers published in this Research Topic: promotion of plant growth in tomato (Paradza et al.), cotton (Silva et al.) and wheat (Asim et al.), increased tolerance under salt stress in tritordeum and perennial ryegrass (Toghueo et al.), as biological control agents against pathogenic fungi through antibiosis and mycoparasitism (Silva et al.), or as insecticidal agents through activation of systemic plant defenses (Paradza et al.; Agbessenou et al.), among others.
Open Access
Glucosinolates as an effective tool in plant-parasitic nematodes control: exploiting natural plant defenses
(Elsevier, 2022) Eugui Arrizabalaga, Daniel; Escobar, Carolina; Velasco, Pablo; Poveda Arias, Jorge; Agronomia, Bioteknologia eta Elikadura; Institute for Multidisciplinary Research in Applied Biology - IMAB; Agronomía, Biotecnología y Alimentación
Plant-parasitic nematodes (PPNs) are an important damaging biotic agent for numerous crops around the world, causing serious losses directly and indirectly. Cultural and chemical control strategies were mainly used to PPNs management. However, the choice of chemical nematicides is strictly limited in the agrosystems due to their toxicity, their impact to the environment and, therefore, banning policies. The main lines of action of biological control strategies for nematode control, are based on the development of antagonist microorganism formulations and the use of plant extracts with nematicidal potential. There are many plant secondary metabolites with effective nematicidal potential. In this sense, glucosinolates (GSLs) and, especially, glucosinolate hydrolysis products (GHPs) show relevant nematicidal activity. The effects through which these compounds control nematodes, both direct and indirect are diverse, such as toxicity, anti-hatching effect or promotion of competing saprophytic nematodes or nematophagous bacteria populations. The present work compiles many of the studies that describe the use of GSLs and GHPs as nematicides in agriculture, through very diverse strategies that range from crop rotation with Brassicales to the direct application of GSLs and GHPs to the soil. The authors present GSLs and GHPs as a more sustainable and suitable alternative in nematode control, remarking the need to further research in the modes of action and the impact on environment.
Open Access
Deciphering plant health status: the link between secondary metabolites, fungal community and disease incidence in olive tree
(Frontiers Media, 2023) Gomes, Teresa; Pereira, José Alberto; Moya-Laraño, Jordi; Poveda Arias, Jorge; Lino-Neto, Teresa; Baptista, Paula; Institute for Multidisciplinary Research in Applied Biology - IMAB; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Plant-associated microorganisms are increasingly recognized to play key roles in host health. Among several strategies, associated microorganisms can promote the production of specific metabolites by their hosts. However, there is still a huge gap in the understanding of such mechanisms in plant-microorganism interaction. Here, we want to determine whether different levels of olive leaf spot (OLS) disease incidence were related to differences in the composition of fungal and secondary metabolites (i.e. phenolic and volatile compounds) in leaves from olive tree cultivars with contrasting OLS susceptibilities (ranging from tolerant to highly susceptible). Accordingly, leaves with three levels of OLS incidence from both cultivars were used to assess epiphytic and endophytic fungal communities, by barcoding of cultivable isolates, as well as to evaluate leaf phenolic and volatile composition. Fungal and metabolite compositions variations were detected according to the level of disease incidence. Changes were particularly noticed for OLS-tolerant cultivars, opposing to OLS-susceptible cultivars, suggesting that disease development is linked, not only to leaf fungal and metabolite composition, but also to host genotype. A set of metabolites/fungi that can act as predictive biomarkers of plant tolerance/susceptibility to OLS disease were identified. The metabolites ¿-farnesene and p-cymene, and the fungi Fusarium sp. and Alternaria sp. were more related to disease incidence, while Pyronema domesticum was related to the absence of disease symptoms. Cultivar susceptibility to OLS disease is then suggested to be driven by fungi, volatile and phenolic host leaves composition, and above all to plant-fungus interaction. A deeper understanding of these complex interactions may unravel plant defensive responses.
Open Access
Mechanisms involved in drought stress tolerance triggered by rhizobia strains in wheat
(Frontiers Media, 2022) Barquero, Marcia; Poveda Arias, Jorge; Laureano Marín, Ana M.; Ortiz Liébana, Noemí; Brañas, Javier; González Andrés, Fernando; Institute for Multidisciplinary Research in Applied Biology - IMAB
Rhizobium spp. is a well-known microbial plant biostimulant in non-legume crops, but little is known about the mechanisms by which rhizobia enhance crop productivity under drought stress. This work analyzed the mechanisms involved in drought stress alleviation exerted by Rhizobium leguminosarum strains in wheat plants under water shortage conditions. Two (LBM1210 and LET4910) of the four R. leguminosarum strains significantly improved the growth parameters (fresh and dry aerial weight, FW and DW, respectively), chlorophyll content, and relative water content (RWC) compared to a non-inoculated control under water stress, providing values similar to or even higher for FW (+4%) and RWC (+2.3%) than the non-inoculated and non-stressed control. Some other biochemical parameters and gene expression explain the observed drought stress alleviation, namely the reduction of MDA, H2O2 (stronger when inoculating with LET4910), and ABA content (stronger when inoculating with LBM1210). In agreement with these results, inoculation with LET4910 downregulated DREB2 and CAT1 genes in plants under water deficiency and upregulated the CYP707A1 gene, while inoculation with LBM1210 strongly upregulated the CYP707A1 gene, which encodes an ABA catabolic enzyme. Conversely, from our results, ethylene metabolism did not seem to be involved in the alleviation of drought stress exerted by the two strains, as the expression of the CTR1 gene was very similar in all treatments and controls. The obtained results regarding the effect of the analyzed strains in alleviating drought stress are very relevant in the present situation of climate change, which negatively influences agricultural production.
Open Access
Effect of volatile and non-volatile metabolites from Leptosphaeria maculans on tomato calli under abiotic stresses
(Global Science Books, 2022) Poveda Arias, Jorge; Institute for Multidisciplinary Research in Applied Biology - IMAB
Drought and salinity can be serious problems for agricultural productivity in certain planet areas. Leptosphaeria maculans is the causative agent of the blackleg in crucifer plants. In this work, a novel methodology for studying the effects of fungal metabolites (volatile and non-volatile) on plant calli in the presence of abiotic stresses is presented, by using L. maculans, tomato calli, and drought and salinity stresses. In this way, this study has reported how, under salinity and drought stresses, the growth and vitality of tomato calli is inhibited, increasing its tissues-oxidation and accumulation of ROS. By applying metabolites from L. maculans, the growth of calli treated with non-volatile metabolites showed and increment under salinity and drought conditions. On the other hand, calli treated with volatile metabolites showed an increment in tissues-vitality under salinity and drought conditions. A series of gene expression analysis was also conducted in order to determine the performance of related genes. Results of this study showed that growth related gene expression was induced, together with abiotic stress tolerance gene in response to abscisic acid, AREB1. In addition, the application of volatile metabolites from L. maculans on tomato calli without abiotic stresses increases its growth and vitality, and reduces its oxidation and accumulation of ROS, in accordance with the results of gene expression obtained. The ability of L. maculans metabolites to increase plant tolerance to abiotic stresses could be related to their ability to produce volatile and non-volatile-metabolites, which induce the antioxidant enzyme activity or accumulation of antioxidant compounds, or their ability to increase the expression of ABA-dependent response genes to abiotic stresses.