Systemic resistance in citrus to Tetranychus urticae induced by conspecifics is transmitted by grafting and mediated by mobile amino acids

Recent research suggests that systemic signalling and communication between roots and leaves plays an important role in plant defence against herbivores. In the present study, we show that the oviposition of the two-spotted spider mite Tetranychus urticae in the systemic leaves of citrus rootstock Citrus aurantium (sour orange) was reduced by 50% when a lower leaf was previously infested with conspecifics. Metabolomic and gene expression analysis of the root efflux revealed a strong accumulation of glutamic acid (Glu) that triggered the expression of the citrus putative glutamate receptor ( GRL ) in the shoots. Additionally, uninfested sour orange systemic leaves showed increased expression of glutamate receptors and higher amounts of jasmonic acid (JA) and 12-oxo-phytodienoic acid in plants that were previously infested. Glu perception in the shoots induced the JA pathway, which primed LOX-2 gene expression when citrus plants were exposed to a second infestation. The spider mite- susceptible citrus rootstock Cleopatra mandarin ( C. unshiu ) also expressed systemic resistance, although the resistance was less effective than the resistance in sour orange. Surprisingly, the mobile signal in Cleopatra mandarin was not Glu, which suggests a strong genotype-dependency for systemic signalling in citrus. When the cultivar Clemenules ( C. clementina ) was grafted onto sour orange, there was a reduction in symptomatic leaves and T. urticae populations compared to the same cultivar grafted onto Cleopatra mandarin. Thus, systemic resistance is transmitted from the roots to the shoots in citrus and is dependent on rootstock resistance

Systemic resistance in citrus to Tetranychus urticae induced by conspecifics is transmitted by grafting and mediated by mobile amino acids

Recent research suggests that systemic signalling and communication between roots and leaves plays an important role in plant defence against herbivores. In the present study, we show that the oviposition of the two-spotted spider mite Tetranychus urticae in the systemic leaves of citrus rootstock Citrus aurantium (sour orange) was reduced by 50% when a lower leaf was previously infested with conspecifics. Metabolomic and gene expression analysis of the root efflux revealed a strong accumulation of glutamic acid (Glu) that triggered the expression of the citrus putative glutamate receptor (GRL) in the shoots. Additionally, uninfested sour orange systemic leaves showed increased expression of glutamate receptors and higher amounts of jasmonic acid (JA) and 12-oxo-phytodienoic acid in plants that were previously infested. Glu perception in the shoots induced the JA pathway, which primed LOX-2 gene expression when citrus plants were exposed to a second infestation. The spider mite-susceptible citrus rootstock Cleopatra mandarin (C. unshiu) also expressed systemic resistance, although the resistance was less effective than the resistance in sour orange. Surprisingly, the mobile signal in Cleopatra mandarin was not Glu, which suggests a strong genotype-dependency for systemic signalling in citrus. When the cultivar Clemenules (C. clementina) was grafted onto sour orange, there was a reduction in symptomatic leaves and T. urticae populations compared to the same cultivar grafted onto Cleopatra mandarin. Thus, systemic resistance is transmitted from the roots to the shoots in citrus and is dependent on rootstock resistance

Defensive plats responses induced by Nesidiocoris tenuis (Hemiptera:Miridae) on tomato plants

In the last decade, biological control programs for greenhouse tomatoes and other crops have been successfully implemented using zoophytophagous plant bugs (Miridae), which can feed on both plant tissues and insect prey. It is well known that plants respond to herbivore attacks by releasing volatile compounds through diverse pathways triggered by phytohormones. These herbivore-induced plant volatiles can alert neighboring plants, repel or attract herbivores, and attract natural enemies of these herbivores. Nevertheless, the possible benefits of induced plant responses by zoophytophagous predators that could add to their usefulness as biocontrol agents have not been studied until now. Here we show that the zoophytophagous predator Nesidiocoris tenuis activated abscisic acid and jasmonic acid (JA) signaling pathways in tomato plants, which made them less attractive to the whitefly Bemisia tabaci, a major tomato pest worldwide, and more attractive to the whitefly parasitoid, Encarsia formosa. We also found that intact tomato plants exposed to volatiles from N. tenuis-punctured plants activated the JA pathway, and as a consequence, E. formosa was also attracted to these intact plants with activated defense systems. Thus, our results demonstrate that N. tenuis not only benefits tomato plants directly by entomophagy but also indirectly by phytophagy, which induces a physiological response in the tomato plant.The research leading to these results was funded by the European Union Seventh Framework Programme (FP7/2007–2013) under grant agreement no. 265865, the Spanish Ministry of Science and Innovation (AGL2011-30538-C03) and the Conselleria d’Agricultura, Pesca i Alimentació de la Generalitat Valenciana. The authors thank Virginia Pedroche (IVIA) and Blas Agut (UJI) for their technical assistance, Javier Calvo (KOPPERT BS) for the supply of insects, Universitat Jaume I-SCIC for technical support and two anonymous reviewers for their valuable comments on a previous version of this manuscript

Could Plant Hormones Provide a Reliable Tool for Early Detection of Rhynchophorus ferrugineus (Coleóptera: Curculionidae) Infested Palms?

Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae) is one of the most important pest of palms worldwide. A serious management problem is the difficulty of detecting early infestation stages, which is critical for successful control. Our main objective has been to characterize the metabolic response of Phoenix canariensis hort. ex Chabaud to R. ferrugineus injury to identify candidate biomarkers for early detection. Mechanical wounding and R. ferrugineus infestation resulted in different patterns of plant hormone and secondary metabolite production: SA and caffeic acid concentrations increased by several orders of magnitude following R. ferrugineus development within the palm 7 days after infestation. These compounds did not change in mechanically wounded palms. Therefore, these substances could be further exploited as early warning signs of infestation

Zoophytophagous mites can trigger plant‐genotype specific defensive responses affecting potential prey beyond predation: the case of Euseius stipulatus and Tetranychus urticae in citrus

Background Zoophytophagous predators can trigger plant defenses affecting prey populations beyond predation. Euseius stipulatus is a presumed zoophytophagous phytoseiid common in citrus. The response of citrus to one of its potential prey, Tetranychus urticae, is genotype dependent, with Citrus reshni and C. aurantium exhibiting extreme susceptibility and resistance, respectively. Volatile blends produced upon infestation affected the behavior of these two mites. We wondered whether E. stipulatus could trigger similar responses. Results Euseius stipulatus triggered genotype‐dependent defense responses in citrus. Whereas C. aurantium upregulated the Jasmonic Acid, Salicylic Acid and flavonoids defensive pathways, C. reshni upregulated JA only. Likewise, different volatile blends were induced. These blends were exploited by E. stipulatus to select less‐defended plants (i.e., those in which higher pest densities are expected) and, interestingly, did not prevent T. urticae from choosing E. stipulatus‐infested plants. To the best of our knowledge, this is the first time that this type of response has been described for a zoophytophagous phytoseiid. Conclusion The observed responses could affect herbivore populations through plant‐mediated effects. Although further research is needed to fully characterize them and include other arthropods in the system, these results open opportunities for more sustainable and effective pest control methods (i.e., combining semiochemicals and biological control

Testing Aleppo pine seed sources response to climate change by using trial sites reflecting future conditions

Large-scale biogeographical shifts in forest tree distributions are predicted in response to the altered precipitation and temperature regimes associated with climate change. Adaptive forest management to climate change experienced in either stable or rapidly changing environments must consider this fact when carrying out reforestation programs or specifically assisted population migration for conservation purposes. The aim of this study was to compare field performance of eleven seed sources of Aleppo pine outplanted in core and marginal habitats and to assess their phenotypic plasticity for further screening under specific conditions in particular reforestation areas. We hypothesize that current marginal habitat due to low temperature is shifting toward conditions found on the core habitat and that current core habitat will shift toward warmer and drier marginal habitat. Our study reproduced real conditions of reforestation in potential future climatic conditions. Results suggest that it is difficult to predict Aleppo pine provenances' performance in different natural sites from their performance at a single location, even though 'Levante interior' and 'La Mancha' seed sources showed the best overall response among sites. On a site basis, provenances were matched in groups according to their survival and growth responses. Seedlings grown from local seed sources or seed orchards performed better on the core habitat. However, as conditions shifted to marginal habitats, seedlings from climatically similar regions performed better than local sources at least in the short term; our findings suggest that new plantations in areas already affected by global change could be better adapted if they use alternative seed sources.This study is a part of two research projects: "Application of molecular biology techniques in forest restoration in Mediterranean environments, PAID-05-11" funded by the Universitat Politecnica de Valencia (UPV), program for supporting R&D of new multidisciplinary research lines; and the contract subscribed between the UPV and the Ministry of Environment, Rural and Marine affairs (Centro Nacional de Recursos Geneticos Forestales de Alaquas) through its public partnership TRAGSA titled: "Study of seedling quality and field performance of 12 seed sources of Pinus halepensis Mill." The authors are grateful to Amparo Pedros-Mari for field work in La Hunde, to the Valencia Regional Government (CMAAUV, Generalitat Valenciana) and VAERSA staff for their support in allowing the use of the experimental forest of La Hunde. We thank Dr. Kasten Dumroese from USDA Forest Service, Rocky Mountain Research Station for his critical and valuable comments on the draft manuscript. Also, we thank the anonymous referees for their comments, which significantly improved the final manuscript.Taïbi, K.; Campo García, ADD.; Mulet Salort, JM.; Flors, J.; Aguado, A. (2014). Testing Aleppo pine seed sources response to climate change by using trial sites reflecting future conditions. New Forests. 45(5):603-624. https://doi.org/10.1007/s11056-014-9423-yS603624455Agúndez ID, Degen B, von Wuehlisch G, Alia R (1997) Genetic variation of Aleppo pine (Pinus halepensis mill.). 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Sistema de gestión de energía para microrredes basado en control predictivo

En este artículo se presenta un sistema de gestión de energía para microrredes a partir de un control Predictivo basado en Modelos (MPC), el cual tiene como tarea la optimización de las operaciones de una microrred, al tiempo que cumple una serie de restricciones de funcionamiento. Para ello, el problema ha sido formulado empleando Programación Lineal Entera-Mixta (MILP), la cual ha sido resuelta de manera eficiente. Se han estudiado diferentes escenarios, comparando el MPC con una estrategia fija y se han calculado costes de funcionamiento e inversión, mostrando finalmente los resultados.Los autores quieren agradecer a la Universitat Jaume I y a la Generalitat Valenciana el apoyo recibido y materializado en los proyectos P11B2013-34 y GV/2014/117 respectivamente

The olfactive responses of Tetranychus urticae natural enemies in citrus depend on plant genotype, prey presence, and their diet specialization

[EN] Sour orange, Citrus aurantium, displays higher constitutive and earlier inducible direct defenses against the two-spotted spider mite, Tetranychus urticae, than Cleopatra mandarin, Citrus reshni. Moreover, herbivore-induced plant volatiles (HIPVs) produced by sour orange upon infestation can induce resistance in Cleopatra mandarin but not vice versa. Because the role of these HIPVs in indirect resistance remains ignored, we have carried out a series of behavioral assays with three predatory mites with different levels of specialization on this herbivore, from strict entomophagy to omnivory. We have further characterized the volatile blend associated with T. urticae, which interestingly includes the HIPV methyl salicylate, as well as that produced by induced Cleopatra mandarin plants. Although a preference for less defended plants with presumably higher prey densities (i.e., C. reshni) was expected, this was not always the case. Because predators' responses changed with diet width, with omnivore predators responding to both HIPVs and prey-related odors and specialized ones mostly to prey, our results reveal that these responses depend on plant genotype, prey presence and predator diet specialization. As the different volatile blends produced by infested sour orange, induced Cleopatra mandarin and T. urticae itself are attractive to T. urticae natural enemies but not to the herbivore, they may provide clues to develop new more sustainable tools to manipulate these agriculturally relevant species.The research leading to these results was partially funded by the Spanish Ministry of Economy and Competitiveness (AGL2014-55616-C3; AGL2015-64990-2R). The authors thank M. Piquer (UJI) for technical assistance. MC received a pre-doctoral fellowship from the Spanish Ministry of Economy and Competitiveness (BES-2015-074570), and MP was the recipient of a research fellowship from INIA, Spain (subprogram DOC INIA-CCAA).Cabedo López, M.; Cruz-Miralles, J.; Vacas, S.; Navarro-Llopis, V.; Pérez-Hedo, M.; Flors, V.; Jaques, JA. (2019). The olfactive responses of Tetranychus urticae natural enemies in citrus depend on plant genotype, prey presence, and their diet specialization. Journal of Pest Science. 92(3):1165-1177. https://doi.org/10.1007/s10340-019-01107-7S1165117792

Control de la tensión del bus de continua de un filtro activo mediante un convertidor DC-DC

En este artículo se presentan los resultados experimentales obtenidos mediante un sistema compensador generador trabajando de forma aislada de la red eléctrica. Para analizar el funcionamiento del sistema se ha desarrollado un prototipo de un convertidor DC-DC bidireccional el cual permite adaptar el valor de la tensión de las baterías conectadas a su entrada con la tensión del bus de continua a la entrada del filtro activo. Para el control del convertidor DC-DC se ha utilizado un control por realimentación del estado diseñado mediante algoritmos genéticos, y en el caso del filtro activo se ha utilizado un control proporcional con prealimentación. Los resultados experimentales obtenidos muestran el correcto funcionamiento del sistema tanto en estado estacionario, como en régimen transitorio.Los autores quieren agradecer a la Universitat Jaume I y a la Generalitat Valenciana el apoyo recibido y materializado en los proyectos P11B2013-34 y GV/2014/117 respectivamente