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1.
Annu Rev Cell Dev Biol ; 28: 489-521, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22559264

RESUMEN

Plant hormones have pivotal roles in the regulation of plant growth, development, and reproduction. Additionally, they emerged as cellular signal molecules with key functions in the regulation of immune responses to microbial pathogens, insect herbivores, and beneficial microbes. Their signaling pathways are interconnected in a complex network, which provides plants with an enormous regulatory potential to rapidly adapt to their biotic environment and to utilize their limited resources for growth and survival in a cost-efficient manner. Plants activate their immune system to counteract attack by pathogens or herbivorous insects. Intriguingly, successful plant enemies evolved ingenious mechanisms to rewire the plant's hormone signaling circuitry to suppress or evade host immunity. Evidence is emerging that beneficial root-inhabiting microbes also hijack the hormone-regulated immune signaling network to establish a prolonged mutualistic association, highlighting the central role of plant hormones in the regulation of plant growth and survival.


Asunto(s)
Enfermedades de las Plantas/inmunología , Reguladores del Crecimiento de las Plantas/fisiología , Inmunidad de la Planta , Plantas/inmunología , Animales , Herbivoria , Interacciones Huésped-Patógeno , Humanos , Plantas/metabolismo , Plantas/microbiología , Transducción de Señal
2.
Plant Dis ; 2024 Aug 29.
Artículo en Inglés | MEDLINE | ID: mdl-39207337

RESUMEN

Post-harvest diseases like fruit crown rot (CR) on bananas (Musa spp.) worldwide are mainly attributed to Colletotrichum gloeosporioides (Berk. & Curt.) von Arx and Lasiodiplodia theobromae (Pat.) Griff. & Maubl (Sangeetha et al., 2012; Riera et al., 2019). In April 2019, at a banana farm (cultivar Williams) located in El Oro province (location at 79° 54' 05" W; 03° 17' 16" S), thirty hands were randomly collected from the postharvest process and further placed in a humid chamber at 20 ºC until signs of the disease progressed and became more evident (from 3 days to 20 days). Ten hands presented initial symptoms related to CR during the postharvest process, which included crown or peduncle rot with mycelial development on the crown's surface, leading to the blackening of tissues at the site of the wound left when the cluster was cut. Crown fruit fragments (~0.5 cm) from the edge of healthy tissue and diseased tissue underwent a series of disinfection steps, initially in ethanol (70%) for 1 min, followed by sodium hypochlorite (1%) for 1 min, rinsed three times with sterile distilled water, and dried on sterile filter paper for 10 min. The fragments were placed onto Potato dextrose agar (PDA) + chloramphenicol (100 mg L-1) and incubated at 25°C in darkness for five days. Five isolates with different colony morphologies were obtained. An initial screen of the pathogenicity of all isolates showed that only one isolate showed disease activity in banana crowns. This isolate, C1, showed grayish-white aerial mycelium in culture as described above and, after ten days, became black. We did a full pathogenicity test with C1 using ten individual banana fruits (cv. Williams Cavendish). Briefly, one disc (Ø of 5 mm) of the fungus with agar was placed on the acropetal part of the banana fruit (on the peel) and another piece in the crown without wounding. Inoculated fruit were in a humid chamber at 20 °C for 20 days. Uninoculated fruits constituted the control. Isolate C1 caused 100% of the fruit and crowns to rot, with symptoms similar to those initially observed from fruit collected at the postharvest process (Fig. S1d). The fungus was re-isolated from symptomatic tissue, and its identity was confirmed through morphological characteristics consistent with Lasiodiplodia sp. Matured conidia of all mono hyphal strains (Fig. S1b) appeared dark brown with a single septum, having an ovate shape, and displayed longitudinal striations along their thickened walls (Fig. S1c). The dimensions of the mature conidia ranged from 16.02 - 26.85 x 11.09 - 16.74 µm (n = 60). Morphological characteristics showed similarity to Lasiodiplodia sp. (Alves et al., 2008). Microscopic observations were further confirmed by sequencing three loci: the internal transcribed spacer (ITS), ß-tubulin, and partial translation elongation factor-1α (TEF-1α). Fungal genomic DNA from the C1 isolate was PCR amplified using ITS5/ITS4, EF1-728F/986R, and Bt2A/Bt2B primers, respectively, according to Glass & Donaldson (1995) and Bautista-Cruz et al. (2019). The resulting amplicons were sequenced, and those sequences were deposited in GenBank with the accession numbers ITS: PP532861, TEF-1α: PP551938, and ß-tubulin: PP537587. Sequence alignment was conducted using ClustalW under the MEGA 11.0 software package (Tamura et al., 2021). Subsequently, phylogenetic analysis was performed using Bayesian inference using the BEAST v1.8.4 program (Drummond & Rambaut, 2007). The concatenated sequence of the isolate revealed clustering to the Lasiodiplodia theobromae clade, confirming its identity. To our knowledge, this is the first report of this pathogen causing CR on banana fruit in Ecuador. Based on the report of CR in the country, banana exporters and the Ecuadorian government should consider developing disease management methods that include the cultivation, shipping, ripening, and storage processes of the fruit.

3.
Environ Microbiol ; 25(8): 1377-1392, 2023 08.
Artículo en Inglés | MEDLINE | ID: mdl-36883264

RESUMEN

Understanding the drivers that affect soil bacterial and fungal communities is essential to understanding and mitigating the impacts of human activity on vulnerable ecosystems like those on the Galápagos Islands. The volcanic slopes of these Islands lead to steep elevation gradients that generate distinct microclimates across small spatial scales. Although much is known about the impacts of invasive plant species on the above-ground biodiversity of the Galápagos Islands, little is known about their resident soil microbial communities and the factors shaping them. Here, we investigate the bacterial and fungal soil communities associated with invasive and native plant species across three distinct microclimates on San Cristóbal Island (arid, transition zone and humid). At each site, we collected soil at three depths (rhizosphere, 5 cm and 15 cm) from multiple plants. Sampling location was the strongest driver of both bacterial and fungal communities, explaining 73% and 43% of variation in the bacterial and fungal community structure, respectively, with additional minor but significant impacts from soil depth and plant type (invasive vs. native). This study highlights the continued need to explore microbial communities across diverse environments and demonstrates how both abiotic and biotic factors impact soil microbial communities in the Galápagos archipelago.


Asunto(s)
Microbiota , Suelo , Humanos , Suelo/química , Microclima , Biodiversidad , Plantas , Especies Introducidas , Bacterias/genética , Microbiología del Suelo
4.
Plant Dis ; 2023 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-37261874

RESUMEN

In Ecuador, broccoli (Brassica oleracea var. italica) production is located in the Andean region, specifically Cotopaxi-Ecuador (INEC, 2019). A leaf pathogen has been constantly observed in this area, showing brown circular necrosis surrounded by yellowish halo-like spots causing leaf death (Fig. 1a). This pathogen was believed to be Alternaria sp.; however, the species was not determined either using classical or molecular tools. In 2021, ten leaves showing similar symptoms were collected in Cotopaxi and sent for pathogen identification. Here, leaf explants (0.25 cm2) showing disease symptoms were surface sterilized with 2% sodium hypochlorite (NaClO) and 70% ethanol (C2H6O), rinsed with sterile water, and transferred to Potato Dextrose Agar (PDA) media. Petri dishes were incubated in darkness at 25°C for five days. The single hyphal tip method was used to purify the cultures on PDA. Fifteen pure isolates were obtained after incubating for 14 days. Isolates were incubated under blacklight for two days to induce fungal sporulation. All isolates presented early white cotton-like mycelium that later became dark green (Fig 1b). Under the microscope, we observed straight primary conidia in simple or branched chains. Also, the conidia were obclavate, long ellipsoids, moderate in size (19.5-43.9 µm in length, 7.1-17.2 µm in width), and septate with few longitudinal septa. Lastly, the conidium body can narrow itself into a secondary conidia (Fig 1c) (Woudenberg et al., 2013). According to colony and conidia morphology, isolates were identified as Alternaria sp. (Woudenberg et al., 2013). Five isolates were randomly selected for DNA extraction and sequencing of ITS (internal transcribed spacer; Chou, H.H. and Wu, W.S. 2002), TEF (translation elongation factor; O'Donnell et al., 1998), and RPB2 (RNA polymerase II second largest subunit; Liu et al., 1999) gene regions. DNA sequences obtained from each marker were identical for all isolates. Consensus sequences and alignment were built using ClustalX in MEGA X (Kumar et al., 2018). Consensus sequences were deposited in GenBank with the following accession numbers: ITS, ON982232; TEF, ON983964; RPB2, ON983963. A multilocus Bayesian inference phylogenetic tree was constructed in Beast software (version 1.8.4) using the concatenated sequences (Drummond et al., 2012; Maharachchikumbura et al., 2014). The isolates in our study clustered with isolates of Alternaria alternata, confirming their identity (Figure 2). For Koch's postulates, healthy broccoli plants were grown in sterile soil for six weeks. The fungal conidia were suspended in sterile distilled water (1×106 conidia/ml), and the leaves were inoculated by spraying the spore solution. The control treatment was sprayed with sterile distilled water alone. Plants were maintained at 28°C and had more than 85% relative humidity (Sigillo et al., 2020). Seven days after inoculation, plants showed chlorosis and necrosis. Ten days later, 100% of the treated leaves presented brown circular necrosis (Fig. 1d). Control plants showed no disease symptoms. Re-isolation of the pathogen from the diseased leaf tissue was performed as previously described. The isolates presented the exact morphology of pure cultures obtained from field-diseased leaves. The pathogenicity test was performed twice. To our knowledge, this is the first report on A. alternata being the causal agent of leaf spot on broccoli in Ecuador. Disease diagnosis contributes to providing strategies against this pathogen. Further investigations are needed to find biological/chemical techniques or cultivar resistance to control this pathogen in broccoli.

5.
Plant Cell ; 25(2): 744-61, 2013 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-23435661

RESUMEN

Antagonism between the defense hormones salicylic acid (SA) and jasmonic acid (JA) plays a central role in the modulation of the plant immune signaling network, but the molecular mechanisms underlying this phenomenon are largely unknown. Here, we demonstrate that suppression of the JA pathway by SA functions downstream of the E3 ubiquitin-ligase Skip-Cullin-F-box complex SCF(COI1), which targets JASMONATE ZIM-domain transcriptional repressor proteins (JAZs) for proteasome-mediated degradation. In addition, neither the stability nor the JA-induced degradation of JAZs was affected by SA. In silico promoter analysis of the SA/JA crosstalk transcriptome revealed that the 1-kb promoter regions of JA-responsive genes that are suppressed by SA are significantly enriched in the JA-responsive GCC-box motifs. Using GCC:GUS lines carrying four copies of the GCC-box fused to the ß-glucuronidase reporter gene, we showed that the GCC-box motif is sufficient for SA-mediated suppression of JA-responsive gene expression. Using plants overexpressing the GCC-box binding APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) transcription factors ERF1 or ORA59, we found that SA strongly reduces the accumulation of ORA59 but not that of ERF1. Collectively, these data indicate that the SA pathway inhibits JA signaling downstream of the SCF(COI1)-JAZ complex by targeting GCC-box motifs in JA-responsive promoters via a negative effect on the transcriptional activator ORA59.


Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Ciclopentanos/metabolismo , Oxilipinas/metabolismo , Ácido Salicílico/metabolismo , Factores de Transcripción/metabolismo , Acetatos/farmacología , Arabidopsis/efectos de los fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Sitios de Unión , Ciclopentanos/farmacología , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/metabolismo , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Motivos de Nucleótidos , Oxilipinas/farmacología , Factores de Terminación de Péptidos/genética , Factores de Terminación de Péptidos/metabolismo , Plantas Modificadas Genéticamente , Regiones Promotoras Genéticas , Ácido Salicílico/farmacología , Transducción de Señal/efectos de los fármacos , Factores de Transcripción/genética
6.
Exp Parasitol ; 171: 49-56, 2016 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-27769720

RESUMEN

Tapeworms Taenia solium and Taenia saginata are the causative agents of taeniasis/cysticercosis. These are diseases with high medical and veterinary importance due to their impact on public health and rural economy in tropical countries. The re-emergence of T. solium as a result of human migration, the economic burden affecting livestock industry, and the large variability of symptoms in several human cysticercosis, encourage studies on genetic diversity, and the identification of these parasites with molecular phylogenetic tools. Samples collected from the Ecuadorian provinces: Loja, Guayas, Manabí, Tungurahua (South), and Imbabura, Pichincha (North) from 2000 to 2012 were performed under Maximum Parsimony analyses and haplotype networks using partial sequences of mitochondrial DNA, cytochrome oxidase subunit I (COI) and NADH subunit I (NDI), from Genbank and own sequences of Taenia solium and Taenia saginata from Ecuador. Both species have shown reciprocal monophyly, which confirms its molecular taxonomic identity. The COI and NDI genes results suggest phylogenetic structure for both parasite species from south and north of Ecuador. In T. solium, both genes gene revealed greater geographic structure, whereas in T. saginata, the variability for both genes was low. In conclusion, COI haplotype networks of T. solium suggest two geographical events in the introduction of this species in Ecuador (African and Asian lineages) and occurring sympatric, probably through the most common routes of maritime trade between the XV-XIX centuries. Moreover, the evidence of two NDI geographical lineages in T. solium from the north (province of Imbabura) and the south (province of Loja) of Ecuador derivate from a common Indian ancestor open new approaches for studies on genetic populations and eco-epidemiology.


Asunto(s)
ADN Mitocondrial , Variación Genética , Taenia saginata/genética , Taenia solium/genética , Teniasis/parasitología , Animales , Ecuador/epidemiología , Complejo IV de Transporte de Electrones/genética , Flujo Génico , Haplotipos , NADH Deshidrogenasa/genética , Filogenia , Reacción en Cadena de la Polimerasa , Polimorfismo de Longitud del Fragmento de Restricción , Taenia saginata/clasificación , Taenia solium/clasificación , Teniasis/epidemiología
7.
Biology (Basel) ; 12(7)2023 Jul 11.
Artículo en Inglés | MEDLINE | ID: mdl-37508415

RESUMEN

This study aimed to compare microscopic counting, culture, and quantitative or real-time PCR (qPCR) to quantify sulfate-reducing bacteria in environmental and engineered sludge samples. Four sets of primers that amplified the dsrA and apsA gene encoding the two key enzymes of the sulfate-reduction pathway were initially tested. qPCR standard curves were constructed using genomic DNA from an SRB suspension and dilutions of an enriched sulfate-reducing sludge. According to specificity and reproducibility, the DSR1F/RH3-dsr-R primer set ensured a good quantification based on dsrA gene amplification; however, it exhibited inconsistencies at low and high levels of SRB concentrations in environmental and sulfate-reducing sludge samples. Ultimately, we conducted a qPCR method normalized to dsrA gene copies, using a synthetic double-stranded DNA fragment as a calibrator. This method fulfilled all validation criteria and proved to be specific, accurate, and precise. The enumeration of metabolically active SRB populations through culture methods differed from dsrA gene copies but showed a plausible positive correlation. Conversely, microscopic counting had limitations due to distinguishing densely clustered organisms, impacting precision. Hence, this study proves that a qPCR-based method optimized with dsrA gene copies as a calibrator is a sensitive molecular tool for the absolute enumeration of SRB populations in engineered and environmental sludge samples.

8.
Biology (Basel) ; 12(5)2023 Apr 27.
Artículo en Inglés | MEDLINE | ID: mdl-37237477

RESUMEN

The root microbiome is vital in plant development and health and is highly influenced by crop cultural practices. Rose (Rosa sp.) is the most popular cut flower worldwide. Grafting in rose production is a standard practice to increase yield, improve flower quality, or reduce root-associated pests and diseases. 'Natal Brier' is a standard rootstock used in most commercial operations in Ecuador and Colombia, leading countries in producing and exporting ornamentals. It is known that the rose scion genotype affects root biomass and the root exudate profile of grafted plants. However, little is known about the influence of the rose scion genotype on the rhizosphere microbiome. We examined the influence of grafting and scion genotype on the rhizosphere microbiome of the rootstock 'Natal Brier'. The microbiomes of the non-grafted rootstock and the rootstock grafted with two red rose cultivars were assessed using 16S rRNA and ITS sequencing. Grafting changed microbial community structure and function. Further, analysis of grafted plant samples revealed that the scion genotype highly influences the rootstock microbiome. Under the presented experimental conditions, the rootstock 'Natal Brier' core microbiome consisted of 16 bacterial and 40 fungal taxa. Our results highlight that the scion genotype influences root microbe's recruitment, which might also influence the functionality of assembled microbiomes.

9.
Planta ; 235(4): 677-85, 2012 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-22009062

RESUMEN

Upward leaf movement (hyponastic growth) is adopted by several plant species including Arabidopsis thaliana, as a mechanism to escape adverse growth conditions. Among the signals that trigger hyponastic growth are, the gaseous hormone ethylene, low light intensities, and supra-optimal temperatures (heat). Recent studies indicated that the defence-related phytohormones jasmonic acid (JA) and salicylic acid (SA) synthesized by the plant upon biotic infestation repress low light-induced hyponastic growth. The hyponastic growth response induced by high temperature (heat) treatment and upon application of the gaseous hormone ethylene is highly similar to the response induced by low light. To test if these environmental signals induce hyponastic growth via parallel pathways or converge downstream, we studied here the roles of Methyl-JA (MeJA) and SA on ethylene- and heat-induced hyponastic growth. For this, we used a time-lapse camera setup. Our study includes pharmacological application of MeJA and SA and biological infestation using the JA-inducing caterpillar Pieris rapae as well as mutants lacking JA or SA signalling components. The data demonstrate that MeJA is a positive, and SA, a negative regulator of ethylene-induced hyponastic growth and that both hormones repress the response to heat. Taking previous studies into account, we conclude that SA is the first among many tested components which is repressing hyponastic growth under all tested inductive environmental stimuli. However, since MeJA is a positive regulator of ethylene-induced hyponastic growth and is inhibiting low light- and heat-induced leaf movement, we conclude that defence hormones control hyponastic growth by affecting stimulus-specific signalling pathways.


Asunto(s)
Arabidopsis/fisiología , Ciclopentanos/farmacología , Oxilipinas/farmacología , Salicilatos/farmacología , Arabidopsis/efectos de los fármacos , Arabidopsis/crecimiento & desarrollo , Arabidopsis/metabolismo , Ciclopentanos/metabolismo , Etilenos/metabolismo , Calor , Oxilipinas/metabolismo , Reguladores del Crecimiento de las Plantas/metabolismo , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/metabolismo , Hojas de la Planta/fisiología , Salicilatos/metabolismo , Transducción de Señal , Tropismo/efectos de los fármacos
10.
Oecologia ; 170(2): 433-44, 2012 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-22526939

RESUMEN

Plant pathogens and insect herbivores are prone to share hosts under natural conditions. Consequently, pathogen-induced changes in the host plant can affect herbivory, and vice versa. Even though plant viruses are ubiquitous in the field, little is known about plant-mediated interactions between viruses and non-vectoring herbivores. We investigated the effects of virus infection on subsequent infestation by a non-vectoring herbivore in a natural genotype of Trifolium repens (white clover). We tested whether infection with White clover mosaic virus (WClMV) alters (1) the effects of fungus gnat feeding on plant growth, (2) the attractiveness of white clover for adult fungus gnat females, and (3) the volatile emission of white clover plants. We observed only marginal effects of WClMV infection on the interaction between fungus gnat larvae and white clover. However, adult fungus gnat females clearly preferred non-infected over WClMV-infected plants. Non-infected and virus-infected plants could easily be discriminated based on their volatile blends, suggesting that the preference of fungus gnats for non-infected plants may be mediated by virus-induced changes in volatile emissions. The compound ß-caryophyllene was exclusively detected in the headspace of virus-infected plants and may hence be particularly important for the preference of fungus gnat females. Our results demonstrate that WClMV infection can decrease the attractiveness of white clover plants for fungus gnat females. This suggests that virus infections may contribute to protecting their hosts by decreasing herbivore infestation rates. Consequently, it is conceivable that viruses play a more beneficial role in plant-herbivore interactions than generally thought.


Asunto(s)
Herbivoria , Virus del Mosaico/patogenicidad , Trifolium/virología , Animales , Dípteros , Enfermedades de las Plantas , Plantas Comestibles , Sesquiterpenos Policíclicos , Sesquiterpenos/metabolismo , Trifolium/química , Volatilización
11.
Artículo en Inglés | MEDLINE | ID: mdl-35162506

RESUMEN

Biological treatment using sulfate-reducing bacteria (SRB) is a promising approach to remediate acid rock drainage (ARD). Our purpose was to assess the performance of a sequential system consisting of a limestone bed filter followed by a sulfate-reducing bioreactor treating synthetic ARD for 375 days and to evaluate changes in microbial composition. The treatment system was effective in increasing the pH of the ARD from 2.7 to 7.5 and removed total Cu(II) and Zn(II) concentrations by up to 99.8% and 99.9%, respectively. The presence of sulfate in ARD promoted sulfidogenesis and changed the diversity and structure of the microbial communities. Methansarcina spp. was the most abundant amplicon sequence variant (ASV); however, methane production was not detected. Biodiversity indexes decreased over time with the bioreactor operation, whereas SRB abundance remained stable. Desulfobacteraceae, Desulfocurvus, Desulfobulbaceae and Desulfovibrio became more abundant, while Desulfuromonadales, Desulfotomaculum and Desulfobacca decreased. Geobacter and Syntrophobacter were enriched with bioreactor operation time. At the beginning, ASVs with relative abundance <2% represented 65% of the microbial community and 21% at the end of the study period. Thus, the results show that the microbial community gradually lost diversity while the treatment system was highly efficient in remediating ARD.


Asunto(s)
Microbiota , Sulfatos , Reactores Biológicos/microbiología , Carbonato de Calcio , Cobre , Sulfatos/química , Zinc
12.
Nat Chem Biol ; 5(5): 308-16, 2009 May.
Artículo en Inglés | MEDLINE | ID: mdl-19377457

RESUMEN

Plants live in complex environments in which they intimately interact with a broad range of microbial pathogens with different lifestyles and infection strategies. The evolutionary arms race between plants and their attackers provided plants with a highly sophisticated defense system that, like the animal innate immune system, recognizes pathogen molecules and responds by activating specific defenses that are directed against the invader. Recent advances in plant immunity research have provided exciting new insights into the underlying defense signaling network. Diverse small-molecule hormones play pivotal roles in the regulation of this network. Their signaling pathways cross-communicate in an antagonistic or synergistic manner, providing the plant with a powerful capacity to finely regulate its immune response. Pathogens, on the other hand, can manipulate the plant's defense signaling network for their own benefit by affecting phytohormone homeostasis to antagonize the host immune response.


Asunto(s)
Reguladores del Crecimiento de las Plantas/fisiología , Plantas/inmunología , Plantas/metabolismo , Transducción de Señal
13.
Pest Manag Sci ; 77(12): 5382-5395, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34313385

RESUMEN

BACKGROUND: Andean lupin (Lupinus mutabilis Sweet) is an important leguminous crop from South America with a high protein content. In Ecuador, lupin yields are severely affected by the infestation of Delia platura larvae on germinating seeds. The application of elicitor molecules with activity against herbivorous insects to control D. platura infestation constitutes an unexplored and promising alternative for chemical insecticides. In this study, methyl jasmonate (MeJA), hexanoic acid, menadione sodium bisulfite, and DL-ß-aminobutyric acid were evaluated for their ability to induce resistance against D. platura in three commercial lupin cultivars. RESULTS: Only seeds pretreated with MeJA significantly impaired insect performance during choice and no-choice assays. Additionally, fitness indicators such as seed germination and growth were not affected by MeJA treatment. To investigate the molecular mechanisms behind the MeJA-mediated resistance, RT-qPCR assays were performed. First, RT-qPCR reference genes were validated, showing that LmUBC was the most stable reference gene. Next, expression analysis over time revealed that MeJA application up-regulated the activity of the jasmonic acid biosynthetic genes LmLOX2 and LmAOS, together with other jasmonate-related defense genes, such as LmTPS1, LmTPS4, LmPI2, LmMBL, LmL/ODC, LmCSD1, and LmPOD. CONCLUSION: This study indicates that MeJA can be used as an environmentally friendly elicitor molecule to protect Andean lupin from D. platura attack without fitness cost. MeJA application induces plant defense responses to insects in Andean lupin that may be modulated by the onset of terpenoid biosynthesis, proteinase inhibitors, lectins, polyamines, and antioxidative enzymes. © 2021 Society of Chemical Industry.


Asunto(s)
Dípteros , Lupinus , Acetatos/farmacología , Animales , Ciclopentanos/farmacología , Regulación de la Expresión Génica de las Plantas , Oxilipinas/farmacología , Semillas
14.
Plants (Basel) ; 10(6)2021 May 26.
Artículo en Inglés | MEDLINE | ID: mdl-34073325

RESUMEN

Mineral nutrients are essential for plant growth and reproduction, yet only a few studies connect the nutritional status to plant innate immunity. The backbone of plant defense response is mainly controlled by two major hormones: salicylic acid (SA) and jasmonic acid (JA). This study investigated changes in the macronutrient concentration (deficiency/excess of nitrogen, phosphorus, potassium, magnesium, and sulfur) on the expression of PR1, a well-characterized marker in the SA-pathway, and PDF1.2 and LOX2 for the JA-pathway, analyzing plants carrying the promoter of each gene fused to GUS as a reporter. After histochemical GUS assays, we determined that PR1 gene was strongly activated in response to sulfur (S) deficiency. Using RT-PCR, we observed that the induction of PR1 depended on the function of Non-expressor of Pathogenesis-Related gene 1 (NPR1) and SA accumulation, as PR1 was not expressed in npr1-1 mutant and NahG plants under S-deprived conditions. Plants treated with different S-concentrations showed that total S-deprivation was required to induce SA-mediated defense responses. Additionally, bioassays revealed that S-deprived plants, induced resistance to the hemibiotrophic pathogen Pseudomonas syringae pv. DC3000 and increase susceptibility to the necrotrophic Botrytis cinerea. In conclusion, we observed a relationship between S and SA/JA-dependent defense mechanisms in Arabidopsis.

15.
Mol Plant Microbe Interact ; 23(2): 187-97, 2010 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-20064062

RESUMEN

Cross-talk between jasmonate (JA), ethylene (ET), and Salicylic acid (SA) signaling is thought to operate as a mechanism to fine-tune induced defenses that are activated in response to multiple attackers. Here, 43 Arabidopsis genotypes impaired in hormone signaling or defense-related processes were screened for their ability to express SA-mediated suppression of JA-responsive gene expression. Mutant cev1, which displays constitutive expression of JA and ET responses, appeared to be insensitive to SA-mediated suppression of the JA-responsive marker genes PDF1.2 and VSP2. Accordingly, strong activation of JA and ET responses by the necrotrophic pathogens Botrytis cinerea and Alternaria brassicicola prior to SA treatment counteracted the ability of SA to suppress the JA response. Pharmacological assays, mutant analysis, and studies with the ET-signaling inhibitor 1-methylcyclopropene revealed that ET signaling renders the JA response insensitive to subsequent suppression by SA. The APETALA2/ETHYLENE RESPONSE FACTOR transcription factor ORA59, which regulates JA/ET-responsive genes such as PDF1.2, emerged as a potential mediator in this process. Collectively, our results point to a model in which simultaneous induction of the JA and ET pathway renders the plant insensitive to future SA-mediated suppression of JA-dependent defenses, which may prioritize the JA/ET pathway over the SA pathway during multi-attacker interactions.


Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Ciclopentanos/metabolismo , Etilenos/metabolismo , Oxilipinas/metabolismo , Ácido Salicílico/metabolismo , Transducción de Señal , Alternaria/genética , Alternaria/metabolismo , Arabidopsis/genética , Arabidopsis/microbiología , Proteínas de Arabidopsis/genética , Botrytis/genética , Botrytis/metabolismo , Enfermedades de las Plantas/genética , Enfermedades de las Plantas/microbiología
16.
Planta ; 232(6): 1423-32, 2010 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-20839007

RESUMEN

Jasmonates (JAs) and salicylic acid (SA) are plant hormones that play pivotal roles in the regulation of induced defenses against microbial pathogens and insect herbivores. Their signaling pathways cross-communicate providing the plant with a regulatory potential to finely tune its defense response to the attacker(s) encountered. In Arabidopsis thaliana, SA strongly antagonizes the jasmonic acid (JA) signaling pathway, resulting in the downregulation of a large set of JA-responsive genes, including the marker genes PDF1.2 and VSP2. Induction of JA-responsive marker gene expression by different JA derivatives was equally sensitive to SA-mediated suppression. Activation of genes encoding key enzymes in the JA biosynthesis pathway, such as LOX2, AOS, AOC2, and OPR3 was also repressed by SA, suggesting that the JA biosynthesis pathway may be a target for SA-mediated antagonism. To test this, we made use of the mutant aos/dde2, which is completely blocked in its ability to produce JAs because of a mutation in the ALLENE OXIDE SYNTHASE gene. Mutant aos/dde2 plants did not express the JA-responsive marker genes PDF1.2 or VSP2 in response to infection with the necrotrophic fungus Alternaria brassicicola or the herbivorous insect Pieris rapae. Bypassing JA biosynthesis by exogenous application of methyl jasmonate (MeJA) rescued this JA-responsive phenotype in aos/dde2. Application of SA suppressed MeJA-induced PDF1.2 expression to the same level in the aos/dde2 mutant as in wild-type Col-0 plants, indicating that SA-mediated suppression of JA-responsive gene expression is targeted at a position downstream of the JA biosynthesis pathway.


Asunto(s)
Arabidopsis/genética , Ciclopentanos/metabolismo , Oxilipinas/metabolismo , Ácido Salicílico/metabolismo , Secuencia de Bases , Northern Blotting , Cartilla de ADN , Genes de Plantas , Mutación , Reacción en Cadena de la Polimerasa , Transducción de Señal
17.
Front Plant Sci ; 11: 1139, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32973821

RESUMEN

The jasmonic acid (JA) signaling pathway is one of the primary mechanisms that allow plants to respond to a variety of biotic and abiotic stressors. Within this pathway, the JAZ repressor proteins and the basic helix-loop-helix (bHLH) transcription factor MYC3 play a critical role. JA is a volatile organic compound with an essential role in plant immunity. The increase in the concentration of JA leads to the decoupling of the JAZ repressor proteins and the bHLH transcription factor MYC3 causing the induction of genes of interest. The primary goal of this study was to identify the molecular basis of JAZ-MYC coupling. For this purpose, we modeled and validated 12 JAZ-MYC3 3D in silico structures and developed a molecular dynamics/machine learning pipeline to obtain two outcomes. First, we calculated the average free binding energy of JAZ-MYC3 complexes, which was predicted to be -10.94 +/-2.67 kJ/mol. Second, we predicted which ones should be the interface residues that make the predominant contribution to the free energy of binding (molecular hotspots). The predicted protein hotspots matched a conserved linear motif SL••FL•••R, which may have a crucial role during MYC3 recognition of JAZ proteins. As a proof of concept, we tested, both in silico and in vitro, the importance of this motif on PEAPOD (PPD) proteins, which also belong to the TIFY protein family, like the JAZ proteins, but cannot bind to MYC3. By mutating these proteins to match the SL••FL•••R motif, we could force PPDs to bind the MYC3 transcription factor. Taken together, modeling protein-protein interactions and using machine learning will help to find essential motifs and molecular mechanisms in the JA pathway.

18.
Sci Rep ; 10(1): 10319, 2020 06 25.
Artículo en Inglés | MEDLINE | ID: mdl-32587286

RESUMEN

The plant hormones salicylic acid (SA) and jasmonic acid (JA) regulate defense mechanisms capable of overcoming different plant stress conditions and constitute distinct but interconnected signaling pathways. Interestingly, several other molecules are reported to trigger stress-specific defense responses to biotic and abiotic stresses. In this study, we investigated the effect of 14 elicitors against diverse but pivotal types of abiotic (drought) and biotic (the chewing insect Ascia monuste, the hemibiotrophic bacterium Pseudomonas syringae DC 3000 and the necrotrophic fungus Alternaria alternata) stresses on broccoli and Arabidopsis. Among the main findings, broccoli pre-treated with SA and chitosan showed the highest drought stress recovery in a dose-dependent manner. Several molecules led to increased drought tolerance over a period of three weeks. The enhanced drought tolerance after triggering the SA pathway was associated with stomata control. Moreover, methyl jasmonate (MeJA) reduced A. monuste insect development and plant damage, but unexpectedly, other elicitors increased both parameters. GUS reporter assays indicated expression of the SA-dependent PR1 gene in plants treated with nine elicitors, whereas the JA-dependent LOX2 gene was only expressed upon MeJA treatment. Overall, elicitors capable of tackling drought and biotrophic pathogens mainly triggered the SA pathway, but adversely also induced systemic susceptibility to chewing insects. These findings provide directions for potential future in-depth characterization and utilization of elicitors and induced resistance in plant protection.


Asunto(s)
Arabidopsis/inmunología , Brassica/inmunología , Resistencia a la Enfermedad , Enfermedades de las Plantas/inmunología , Acetatos/metabolismo , Alternaria/patogenicidad , Animales , Arabidopsis/microbiología , Arabidopsis/parasitología , Brassica/microbiología , Brassica/parasitología , Mariposas Diurnas/patogenicidad , Ciclopentanos/metabolismo , Sequías , Regulación de la Expresión Génica de las Plantas/inmunología , Oxilipinas/metabolismo , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/parasitología , Proteínas de Plantas/metabolismo , Pseudomonas syringae/patogenicidad , Ácido Salicílico/metabolismo
19.
mSphere ; 5(4)2020 08 12.
Artículo en Inglés | MEDLINE | ID: mdl-32817451

RESUMEN

Glyphosate is a commonly used herbicide with a broad action spectrum. However, at sublethal doses, glyphosate can induce plant growth, a phenomenon known as hormesis. Most glyphosate hormesis studies have been performed under microbe-free or reduced-microbial-diversity conditions; only a few were performed in open systems or agricultural fields, which include a higher diversity of soil microorganisms. Here, we investigated how microbes affect the hormesis induced by low doses of glyphosate. To this end, we used Arabidopsis thaliana and a well-characterized synthetic bacterial community of 185 strains (SynCom) that mimics the root-associated microbiome of Arabidopsis We found that a dose of 3.6 × 10-6 g acid equivalent/liter (low dose of glyphosate, or LDG) produced an ∼14% increase in the shoot dry weight (i.e., hormesis) of uninoculated plants. Unexpectedly, in plants inoculated with the SynCom, LDG reduced shoot dry weight by ∼17%. We found that LDG enriched two Firmicutes and two Burkholderia strains in the roots. These specific strains are known to act as root growth inhibitors (RGI) in monoassociation assays. We tested the link between RGI and shoot dry weight reduction in LDG by assembling a new synthetic community lacking RGI strains. Dropping RGI strains out of the community restored growth induction by LDG. Finally, we showed that individual RGI strains from a few specific phyla were sufficient to switch the response to LDG from growth promotion to growth inhibition. Our results indicate that glyphosate hormesis was completely dependent on the root microbiome composition, specifically on the presence of root growth inhibitor strains.IMPORTANCE Since the introduction of glyphosate-resistant crops, glyphosate has become the most common and widely used herbicide around the world. Due to its intensive use and ability to bind to soil particles, it can be found at low concentrations in the environment. The effect of these remnants of glyphosate in plants has not been broadly studied; however, glyphosate 1,000 to 100,000 times less concentrated than the recommended field dose promoted growth in several species in laboratory and greenhouse experiments. However, this effect is rarely observed in agricultural fields, where complex communities of microbes have a central role in the way plants respond to external cues. Our study reveals how root-associated bacteria modulate the responses of Arabidopsis to low doses of glyphosate, shifting between growth promotion and growth inhibition.


Asunto(s)
Arabidopsis/crecimiento & desarrollo , Glicina/análogos & derivados , Herbicidas/farmacología , Hormesis/efectos de los fármacos , Microbiota , Raíces de Plantas/microbiología , Arabidopsis/efectos de los fármacos , Arabidopsis/microbiología , Bacterias/clasificación , Glicina/farmacología , Desarrollo de la Planta/efectos de los fármacos , Glifosato
20.
Plant Cell Environ ; 32(7): 837-50, 2009 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-19220780

RESUMEN

Plants respond to wounding by means of a multitude of reactions, with the purpose of stifling herbivore assault. Phospholipase D (PLD) has previously been implicated in the wounding response. Arabidopsis (Arabidopsis thaliana) AtPLDalpha1 has been proposed to be activated in intact cells, and the phosphatidic acid (PA) it produces to serve as a precursor for jasmonic acid (JA) synthesis and to be required for wounding-induced gene expression. Independently, PLD activity has been reported to have a bearing on wounding-induced MAPK activation. However, which PLD isoforms are activated, where this activity takes place (in the wounded or non-wounded cells) and what exactly the consequences are is a question that has not been comprehensively addressed. Here, we show that PLD activity during the wounding response is restricted to the ruptured cells using (32)P(i)-labelled phospholipid analyses of Arabidopsis pld knock-out mutants and PLD-silenced tomato cell-suspension cultures. pldalpha1 knock-out lines have reduced wounding-induced PA production, and the remainder is completely eliminated in a pldalpha1/delta double knock-out line. Surprisingly, wounding-induced protein kinase activation, AtLOX2 gene expression and JA biosynthesis were not affected in these knock-out lines. Moreover, larvae of the Cabbage White butterfly (Pieris rapae) grew equally well on wild-type and the pld knock-out mutants.


Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiología , Fosfolipasa D/metabolismo , Animales , Arabidopsis/enzimología , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Mariposas Diurnas/fisiología , Células Cultivadas , Ciclopentanos/metabolismo , Regulación de la Expresión Génica de las Plantas , Técnicas de Inactivación de Genes , Larva/fisiología , Solanum lycopersicum/enzimología , Solanum lycopersicum/genética , Solanum lycopersicum/fisiología , Oxilipinas/metabolismo , Ácidos Fosfatidicos/metabolismo , Fosfolipasa D/genética , Proteínas Quinasas/metabolismo
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