Agrobacterium is widely considered, when suitably modified, to be the most effective vector for gene transfer into plant cells. For a long time, many cereals crops (monocotyledonous plants) were recalcitrant species to genetic modification, mainly as a result of their recalcitrance to in-vitro regeneration and their resistance to Agrobacterium infection. However, recently Agrobacterium-mediated transformation has been used to transform monocot crops such as maize (Zea mays) but with severe restrictions on genotype suitability. This study was carried out to evaluate the transformation amenability of 2 Syrian maize varieties and 2 hybrids in comparison with the hybrid line Hi II by the Agrobacterium tumefaciens-mediated transformation technique using a callus induction based system from immature zygotic embryos IZEs. A. tumefaciens strains EHA101, harbouring the standard binary vector pTF102, and the EHA105 containing the pBINPLUS/ARS:PpCBF1 vector were used. The effects of genotypes and the size of IZEs explants on callus induction and development were investigated. Results showed that callus induction and subsequent callus growth were significantly affected by the initial explant size. Calli induction from IZEs explants sized 1.5-2.00mm was 76%. Callus weight however decreased to 8.2g, compared with 11.7g of callus derived from IZEs >2.00mm. Callus induction ranged between 73.6-78.9% for varieties and hybrids respectively. Calli derived from varieties weighed significantly more than those initiated from the hybrids. Results demonstrated that Syrian maize genotypes were efficiently transformed via the A. tumefaciens strains but there was variation in transformation frequency. A transformation frequency of 3.7-4.2% was achieved for hybrids and varieties respectively confirming that the transformation frequency was genotype-dependent. The transformation frequency averaged between 3.2-5.6% for the EHA105 and EHA101 respectively. Fertile transgenic plants were regenerated from mature somatic embryos with an average regeneration frequency of 59.2 and 17% respectively for varieties and hybrids. Transgenic seeds of R0 and R1 progenies were produced from 74% of the outcrosses attempted and more than 98% of transgenic plants were normal in morphology. Fertile transgenic maize plants carrying the transferred gene CBF were produced using the Agrobacterium EHA105/PpCBF1 and these plants were shown to be more salt tolerant. Transient expression of the GUS gene was confirmed in transgenic calli, shoots, leaves, roots and floral parts of transgenic R0 and R1 progenies using histochemical GUS assays. The presence of the introduced bar and CBF genes in the genomic DNA of the transformants was confirmed by the PCR amplification. Further, the stable expression of the CBF and bar transgenes in the maize genome of transgenic R1 progeny was confirmed by qRT-PCR. The transformation protocol developed using an A. tumefaciens standard binary vector system was an effective and reproducible method to transform Syrian maize with an anti-stress gene in which fertile salt-resistant transgenic plants were routinely produced. This approach has great potential for development of Syrian maize breeding programmes for abiotic stress resistance for application in many areas in Syrian maize production.

Many systems for field-based, high-throughput phenotyping (FB-HTP) quantify and characterize the reflected radiation from the crop canopy to derive phenotypes, as well as infer plant function and health status. However, given the technology's nascent status, it remains unknown how biophysical and physiological properties of the plant canopy impact downstream interpretation and application of canopy reflectance data. In that light, we assessed relationships between leaf thickness and several canopy-associated traits, including normalized difference vegetation index (NDVI), which was collected via active reflectance sensors carried on a mobile FB-HTP system, carbon isotope discrimination (CID), and chlorophyll content. To investigate the relationships among traits, two distinct cotton populations, an upland (Gossypium hirsutum L.) recombinant inbred line (RIL) population of 95 lines and a Pima (G, barbaderise L.) population composed of 25 diverse cultivars, were evaluated under contrasting irrigation regimes, water-limited (WL) and well-watered pm conditions, across 3 years. We detected four quantitative trait loci (QTL) and significant variation in both populations for leaf thickness among genotypes as well as high estimates of broad-sense heritability (on average, above 0.7 for both populations), indicating a strong genetic basis for leaf thickness. Strong phenotypic correlations (maximum r = -0.73) were observed between leaf thickness and NDVI in the Pima population, but not the RIL population. Additionally, estimated genotypic correlations within the RIL population for leaf thickness with CID, chlorophyll content, and nitrogen discrimination (r(gij) = -0.32, 0.48, and 0.40, respectively) were all significant under WW but not WL conditions. Economically important fiber quality traits did not exhibit significant phenotypic or genotypic correlations with canopy traits. Overall, our results support considering variation in leaf thickness as a potential contributing factor to variation in NDVI or other canopy traits measured via proximal sensing, and as a trait that impacts fundamental physiological responses of plants.

Magister Scientiae - MSc / Stress responsive genes play a key role in shaping the manner in which plants process and respond to environmental stress. Their gene products are linked to DNA transcription and its consequent translation into a response product. However, whilst these genes play a significant role in manufacturing responses to stressful stimuli, transcription factors coordinate access to these genes, specifically by accessing a gene's promoter region which houses transcription factor binding sites. Here transcriptional elements play a key role in mediating responses to environmental stress where each transcription factor binding site may constitute a potential response to a stress signal. Arabidopsis thaliana, a model organism, can be used to identify the mechanism of how transcription factors shape a plant's survival in a stressful environment. Whilst there are numerous plant stress research groups, globally there is a shortage of publicly available stress responsive gene databases. In addition a number of previous databases such as the Generation Challenge Programme's comparative plant stressresponsive gene catalogue, Stresslink and DRASTIC have become defunct whilst others have stagnated. There is currently a single Arabidopsis thaliana stress response database called STIFDB which was launched in 2008 and only covers abiotic stresses as handled by major abiotic stress responsive transcription factor families. Its data was sourced from microarray expression databases, contains numerous omissions as well as numerous erroneous entries and has not been updated since its inception.The Dragon Arabidopsis Stress Transcription Factor database (DASTF) was developed in response to the current lack of stress response gene resources. A total of 2333 entries were downloaded from SWISSPROT, manually curated and imported into DASTF. The entries represent 424 transcription factor families. Each entry has a corresponding SWISSPROT, ENTREZ GENBANK and TAIR accession number. The 5' untranslated regions (UTR) of 417 families were scanned against TRANSFAC's binding site catalogue to identify binding sites. The relational database consists of two tables, namely a transcription factor table and a transcription factor family table called DASTF_TF and TF_Family respectively. Using a two-tier client-server architecture, a webserver was built with PHP, APACHE and MYSQL and the data was loaded into these tables with a PYTHON script. The DASTF database contains 60 entries which correspond to biotic stress and 167 correspond to abiotic stress while 2106 respond to biotic and/or abiotic stress. Users can search the database using text, family, chromosome and stress type search options. Online tools have been integrated into the DASTF, database, such as HMMER, CLUSTALW, BLAST and HYDROCALCULATOR. User's can upload sequences to identify which transcription factor family their sequences belong to by using HMMER. The website can be accessed at http://apps.sanbi.ac.za/dastf/ and two updates per year are envisaged. / South Africa

Bacillus thuringiensis (Bt) is a gram-positive common soil bacterium that produces crystals (Cry) containing proteins that are toxic to certain insects, in particular larvae of Lepidoptera and Diptera. The Bt toxin in the past has been widely used as a bioactive compound for the biological control of mainly lepidopteran pests. Most recently a variety of crops, including cotton and maize, have been genetically modified to express a Bt toxin to confer resistance to lepidopteran pests. However, the effect of abiotic environmental stress, such as drought and heat, which are typical for Africa, on Bt toxin expression in a genetically modified crop has so far not been fully evaluated. This study focuses on the expression and stability of the Cry1Ac insecticidal protein from Bacillus thuringiensis in genetically modified cotton plants under drought and heat stress. These include the physiological and biochemical characterization of the expressed Bt toxin gene under drought stress as well as the biological activity against first-instar larvae of the African cotton bollworm Helicoverpa armigera (Lepidoptera: Noctuidae). Non-genetically modified cotton (Gossypium hirsutum cv. Opal), as well as genetically modified cotton (cv. Nuopal) expressing the Bt toxin Cry1Ac, were exposed to drought and heat stress. Drought stress was induced by withholding watering plants until the soil moisture content reached 25- 30 % of field capacity. Non-stressed control plants were watered and soil moisture content to 80-100 % of field capacity was maintained. For heat stress, plants were grown at 38 to 32 DC during the day and night, respectively, whereas control plants were grown in a growth cabinet at a 28/25 DC day/night cycle. For growth analysis plants were harvested every second week after planting. At each harvest, different parts of the plant were collected and their fresh and dry weight determined. For biochemical analysis and determining biological activity against first-instar larvae of H. armigera, two types of experiments were carried out, the first experiment four weeks after treatment induction and the second experiment eight weeks after treatment induction. Different plant material (leaves, flowers and immature green bolls) were used for Bt detection as well as for determining biological activity against first-instar larvae of H. armigera. Under drought stress conditions a reduction in leaf area and leaf dry weight were found in both Bt toxin expressing and non-expressing cotton plants, but no significant difference in physiological performance between Bt-expressing and non-expressing cotton plants was found. This study shows that the Bt toxin (Cry1Ac) level decreases in senescent plants and that drought stress did not affect the growth and development of genetically modified Bt plants when compared to non-Bt plants. Although the expression of Bt toxin (Cry1Ac) in Bt cotton plants decreased under drought stress no effect on the efficacy of the toxin against H. armigera was observed. In addition, no significant decrease of Bt toxin content was found in Bt cotton leaves after exposure to heat stress when compared to leaves from nonheat stressed plants. / Dissertation (MSc)--University of Pretoria, 2008. / Plant Science / unrestricted

Plant cysteine proteinase inhibitors or also called phytocystatins inhibit the action of cysteine proteinases in plants. These proteinases are involved in many developmental processes by degrading proteins. In this study possible effects of an exogenous oryzacystatin-I (OC-I) expressed in transformed tobacco has been investigated. By challenging OC-I expressing and non-expressing tobacco with drought and heat stress, OC-I transcription and translation were not affected in OC-I expressing plants and plant extracts from stressed plants containing the inhibitor inhibited papain activity in vitro. Further, plant growth and photosynthesis was not greatly different under the selected growth conditions in both plant types under stress and non-stress conditions. However, OC-I expressing plants showed slightly lower photosynthetic rate, were shorter and had a higher lower dry mass production under non-stress condition. By applying cDNA Representational Difference Analysis (cDNA-RDA) to detect differentially expressed genes in the two types of plants, a gene coding for the light harvesting chlorophyll a/b binding protein gene (lhcb1) of photosystem II (LHC II) was isolated from non-OCI expressing plants. Northern blot analysis showed lower transcript accumulation of the lhcb gene in OCI-expressing plants both under non-stress and stress conditions, which was accompanied by lower chlorophyll content in OC-I expressing plants. Furthermore, plants benefited from OC-I expression by protection of a variety of expressed proteins against degradation. Identification of possible target cysteine proteinases for OC-I in tobacco resulted in the isolation, cloning and characterization of two new papain-like cysteine proteinases from tobacco designated NtCP1 and NtCP2. NtCP1 was expressed only in senescent leaves and it was not induced in mature green leaves upon exposure to drought or heat stress. NtCP1 has therefore a possible potential as a developmental senescence marker in tobacco. In contrast, NtCP2, which was expressed in mature green leaves, has a high similarity to KDEL-tailed cysteine proteinases that are involved in programmed cell death. Both drought and heat decreased NtCP2 transcript abundance in mature green leaves. Overall, this study has provided evidence that expression of exogenous OC-I does not significantly improve plant performance in tobacco in terms of physiological traits under drought and heat stress but provides protection in terms of stability of protein expression by possibly interacting with endogenous tobacco cysteine proteinases. Further detailed studies are suggested on the interaction of endogenous cysteine proteinases and exogenous phytocystatins to elucidate in more detail the type of interaction. Copyright 2006, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Beyene, G 2006, Gene expression and plant performance in oryzacystatin-I expressing transformed tobacco (Nicotiana tabacum L. cv Samsun) plants under abiotic stress, PhD thesis, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-12052006-144409 / > / Thesis (PhD (Botany))--University of Pretoria, 2006. / Plant Science / unrestricted

Higher plants represent an important source of valuable substances, so called secondary metabolites, which can be obtained through explant cultures of plants. Elicitation is a method of increasing the secondary metabolites production. This study aims to evaluate the secondary metabolites production in Fagopyrum esculentum variety Spacinska cultures in vitro after abiotic elicitor treatment. The experiment was focused on alteration of rutin production in callus and suspension cultures of F. esculentum var. Spacinska after selenium application. Murashige and Skoog nutrient medium supplemented with 1 mg l-1 2,4-dichlorophenoxyacetic acid was used for the cultivation. Selenium solutions of various concentrations (c1 = 9.012×10-3 mol l-1 , c2 = 9.012×10-4 mol l-1 , c3 = 9.012×10-5 mol l-1 ) were affecting the cultures for 6, 12, 24, 48, 72 and 168 hours. The content of rutin was determined by HPLC. The release of secondary metabolites into the nutrient medium was studied as well. After elicitor application, the rutin production increased in both callus and suspension cultures. Higher levels of rutin content were detected in callus culture. The maximum rutin content (0.6 mg g-1 DW) was reached after 12 h of elicitor treatment of c2 concentration in callus culture. Concerning suspension culture, the...

Considerando (1) a importância da bananicultura no Vale do Ribeira, (2) o destaque da Mata Atlântica no contexto da conservação da fauna e flora mundial, (3) a necessidade da adoção de práticas agrícolas alternativas mais eficientes do ponto de vista ambiental e econômico, (4) o papel dos hormônios etileno, acido indol-3-acético (AIA) e ácido abscísico (ABA) no contexto das respostas dos vegetais a diferentes condições ambientais e nos atributos de qualidade da banana, (5) a falta de metodologias otimizadas para a extração de compostos fenólicos solúveis totais (CFST) em bananeiras e (6) a importância do estudo da relação entre os CFST e fatores de estresse, o presente trabalho teve como objetivo avaliar a influência da proximidade do fragmento florestal de Mata Atlântica com a área de cultivo da banana (Musa acuminata AAA cv. Nanicão) sobre o amadurecimento da fruta e os CFST em folhas de bananeiras, além de otimizar uma técnica para a extração destes últimos. Foi observado que bananas colhidas próxima ao fragmento florestal apresentam vida-verde (período compreendido entre a colheita do fruto e o início do seu amadurecimento) maior quando comparados a frutos com a mesma idade fisiológica, porém colhidos em áreas sem a influência da floresta nativa. Este fato pode ser explicado, pelo menos em parte, pela diferença nos perfis de etileno, ABA e AIA ao longo do amadurecimento das bananas provenientes das diferentes áreas, que também influenciam no metabolismo amido-sacarose. Quanto aos CFST nas folhas, foi observado que a utilização de acetona 80% em água (v/v) e posterior emprego de hexano para a remoção do excesso de clorofilas é capaz de obter um bom rendimento de extração de CFST, sem extrair compostos que interferem significativamente no método de Folin-Ciocalteu. Além disso, a utilização da metodologia otimizada mostrou que bananeiras podem apresentar diferenças na sua composição de fenólicos quando influenciadas ou não pela presença de biodiversidade. Assim, a avaliação dos CFST em folhas pode fornecer informações importantes sobre as condições ambientais da planta. / Considering (1) the importance of banana production in Ribeira Valley, (2) the Atlantic Rainforest in the context of fauna and flora conservation, (3) the need for the adoption of more sustainable agricultural practices, (4) the ethylene, indole 3-acetic acid and abscisic acid responses in acclimation mechanisms of plants and in the quality attributes of the banana, (5) the lack of methodologies optimized for the extraction of total soluble phenolics compounds (TSPC) in banana leaves and (6) the importance of the relationship between the TSPC content and stress factors, the present work aimed to evaluate the influence of the Atlantic Forest fragments proximity in the banana (Musa acuminata AAA cv. Nanicão) crop area on fruit ripening and leaves TSPC levels, using a optimized methodology. It was observed that bananas harvested near to the forest fragment presented a longest greenlife (period between the harvest and the climacteric) when compared with the fruits with the same phisiologycal age, but without the influence of the native forest. This fact can be explained, at least partly, by the difference on ethylene, ABA and IAA profiles in the ripening of bananas from the different areas, which also influence the starch-sucrose metabolism. Moreover, it was observed that the extraction with acetone (80% v/v in water) and posterior hexane cycle to remove chlorophylls excess was able to obtain a good TSPC extraction yield in leaves, without extracting compounds that interfere significantly with Folin-Ciocalteu method. In additional, the use of optimized methodology showed that bananas leaves can present different TSPC amount when influenced by the presence of native forest. Thus, the evaluation of leaves TSPC profile can provide important information about the environmental conditions of the plant.

Cette étude vise à explorer les mécanismes de tolérance des plantes aux xénobiotiques organiques de la famille des HAPs (phénanthrène), à travers l’analyse de l’impact des évènements de spéciation par hybridation et duplication génomique (allopolyploïdie). Nous avons pour cela mené une approche comparative sur un modèle de spéciation allopolyploïde récente, constitué des espèces parentales hexaploïdes S. alterniflora et S. maritima, et de l’allopolyploïde S. anglica qui résulte de la duplication du génome de leur hybride F1 S. x townsendii. Une approche intégrative basée sur des analyses physiologiques et moléculaires nous a permis de montrer que chez Spartina l’hybridation et le doublement du génome augmentent la tolérance aux xénobiotiques. Le parent paternel S. maritima se montre particulièrement sensible au phénanthrène par rapport au parent maternel S. alterniflora. Différentes analyses transcriptomiques ont permis l’identification de novo de transcrits spécifiquement exprimés en condition de stress, et l’annotation des petits ARNs (miARNs, leurs gènes cibles, et siARNs) agissant en tant que régulateurs de l’expression des gènes et la régulation des éléments transposables. Les analyses d’expression différentielle en réponse au stress ont permis de générer un modèle de régulation (miARN/gènes cibles) en réponse aux HAPs, testé par validation fonctionnelle en système hétérologue chez Arabidopsis. Un travail exploratoire de profilage du microbiome de la rhizosphère des spartines exposées au phénanthrène a été réalisé pour préciser les mécanismes de dégradation des xénobiotiques dans l’environnement en vue d’une application dans les stratégies de remédiation verte. / We explored mechanisms involved in tolerance to organic xenobiotics belonging to PAHs (phenanthrene), in the context of allopolyploid speciation (hybrid genome duplication). We developed a comparative approach, using a recent allopolyploidization model including the hexaploid parental species S. alterniflora and S. maritima, and the allopolyploid S. anglica, which resulted from genome doubling of the F1 hybrid S. x townsendii. Integrative approach based on physiological and molecular analyses highlights that hybridization and genome doubling enhance tolerance to xenobiotics in Spartina. The paternal parent S. maritima exhibits higher sensitivity compared to the maternal parent S. alterniflora. Various transcriptomic analyses were performed, to identify de novo stress responsive transcripts, and to annotate small RNAs (miRNAs, their target genes, and siRNAs) involved in gene expression and transposable element regulations. Differential expression analyses in response to stress allowed us to develop a putative miRNA regulatory network (miRNA/target genes) in response to PAH, functionally validated in Arabidopsis as heterologous system. An exploratory profiling of Spartina rhizosphere microbiome exposed to phenanthrene was also performed to characterize environmental degradation abilities, in the perspective of optimizing green remediation strategies.

abstract: Nitrous oxide (N2O) is an important greenhouse gas and an oxidant respired by a diverse range of anaerobic microbes, but its sources and sinks are poorly understood. The overarching goal of my dissertation is to explore abiotic N2O formation and microbial N2O consumption across reducing environments of the early and modern Earth. By combining experiments as well as diffusion and atmospheric modeling, I present evidence that N2O production can be catalyzed on iron mineral surfaces that may have been present in shallow waters of the Archean ocean. Using photochemical models, I showed that tropospheric N2O concentrations close to modern ones (ppb range) were possible before O2 accumulated. In peatlands of the Amazon basin (modern Earth), unexpected abiotic activity became apparent under anoxic conditions. However, care has to be taken to adequately disentangle abiotic from biotic reactions. I identified significant sterilant-induced changes in Fe2+ and dissolved organic matter pools (determined by fluorescence spectroscopy). Among all chemical and physical sterilants tested, γ - irradiation showed the least effect on reactant pools. Targeting geochemically diverse peatlands across Central and South America, I present evidence that coupled abiotic and biotic cycling of N2O could be a widespread phenomenon. Using isotopic tracers in the field, I showed that abiotic N2O fluxes rival biotic ones under in-situ conditions. Moreover, once N2O is produced, it is rapidly consumed by N2O-reducing microbes. Using amplicon sequencing and metagenomics, I demonstrated that this surprising N2O sink potential is associated with diverse bacteria, including the recently discovered clade II that is present in high proportions at Amazonian sites based on nosZ quantities. Finally, to evaluate the impact of nitrogen oxides on methane production in peatlands, I characterized soil nitrite (NO2–) and N2O abundances along soil profiles. I complemented field analyses with molecular work by deploying amplicon-based 16S rRNA and mcrA sequencing. The diversity and activity of soil methanogens was affected by the presence of NO2– and N2O, suggesting that methane emissions could be influenced by N2O cycling dynamics. Overall, my work proposes a key role for N2O in Earth systems across time and a central position in tropical microbial ecosystems. / Dissertation/Thesis / Doctoral Dissertation Microbiology 2020

Fortes chuvas e outros eventos climáticos podem afetar o fitness de plantas e insetos. Estudos recentes têm demonstrado que esses organismos são capazes de detectar súbitas variações da pressão barométrica que antecedem a condição climática adversa. Para os insetos, esta percepção é acompanhada de alterações comportamentais aparentemente adaptativas, como a redução do voo e chamamento para cópula. As plantas, por sua vez, respondem com a abertura dos estômatos, de maneira muito semelhante ao estresse hídrico, devido à ativação de rotas bioquímicas associadas ao ácido abscísico. O longo histórico co-evolutivo entre plantas e insetos herbívoros indica que alterações em um organismo reflete na resposta adaptativa do outro. Assim, mesmo que a variação na pressão barométrica afete apenas um dos organismos, a interação inseto-planta deve ser alterada, porém, esta abordagem nunca foi estudada. Utilizando como modelo o milho, Zea mays L. (Poales: Poaceae) e a lagarta-cartucho-do-milho, Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae), nós investigamos o desempenho alimentar do inseto e defesas induzidas de plantas intactas e com indução pela herbivoria frente a diferentes pressões barométricas. Para isso foram desenvolvidos dispositivos automatizados e os ensaios foram conduzidos dentro de uma câmara barométrica. As lagartas consumiram maiores áreas foliares em pressão baixa do que alta, porém o ganho de peso foi similar nas pressões testadas. Plantas intactas, danificadas pela lagarta e com aplicação do regurgito de S. frugiperda não produziram defesas induzidas pela pressão barométrica, apesar dos tratamentos com indução pelo herbívoro emitirem misturas mais complexa de voláteis comparado às plantas intactas. Além disso, plantas com indução mecânica apresentaram maiores níveis do fitohormônio ácido jasmônico. Nesse contexto, nós hipotetizamos que condições de estresse, como pressão baixa, aumentam o consumo foliar e taxa metabólica das lagartas, resultando em incremento de peso similar a condições não estressantes. Em contrapartida, plantas de milho aparentemente não utilizam a pressão como fator abiótico preditor de alterações climáticas e aumento de herbivoria. Para o melhor do nosso conhecimento, este foi o primeiro estudo a investigar os efeitos da pressão barométrica na interação planta-inseto herbívoro e os resultados obtidos podem repercutir na inclusão da pressão como fator que transmuta ensaios biológicos. / Severe raining and other climatic events can affect plant and insect\'s fitness. Recent studies have shown that these organisms are able to detect sudden barometric pressure variations that generally precede an adverse climatic condition. For insects, this perception is followed by behavioral modifications that are apparently adaptive, as, for instance, the reduction in flights and the calling for mating. Plants, in turn, respond with stomata opening, similar to hydric stress, once biochemical routes associated to the abscisic acid are activated. The historical co-evolutive process between plants and herbivore insects indicate that changes in one organism reflects in the adaptive responses of the other. In that sense, even if the fluctuation of the barometric pressure has direct effects in a single organism, the insect-plant interaction may be altered. However, this approach has never been examined. Taking as models maize plants, Zea mays L. (Poales: Poaceae), and the fall armyworm, Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) we have investigated the feeding performance and induced defences of intact and herbivore-induced plants under different barometric pressures. For that, we developed automated devices and the assays were conducted inside of a barometric chamber. The fall armyworms larvae consumed greater leaf areas under low than high pressures, but the weight gain was similar among the pressures tested. Wound-induced maize did not displayed defenses by the barometric pressure changes, although the treatments with herbivore induction have emitted more complex volatiles blends when compared to intact maize. Besides that, plants with mechanical damage presented higher levels of the phytohormone jasmonic acid. In this context, we have hypothesized that stress conditions by low pressures increase the leaf area consumption by S. frugiperda, possibly associated to higher metabolic rates of armyworms, resulting in a weight gain similar to the non-stress conditions. On the other hand, corn plants apparently do not use the barometric pressure as an abiotic predictor of climatic changes and increase of herbivory. To the best of our knowlegde this is the first study investigating the barometrtic pressure effects on plant-herbivore insect interaction. Our results may potencially impact in the inclusion of pressure as factor that reshape biological assays.