Intermittent exposure to traces of green leaf volatiles triggers a plant response

Plants are known to mount a defensive response when exposed to volatile chemicals from other plants, but the critical concentration required for this response is not known. We showed that intermittent exposure over a period of 3 weeks to trace amounts (less than 140 pptV) of green leaf volatiles emitted by a freshly damaged Arabidopsis plant induced physiological (defensive) responses in undamaged neighbouring plants. These results demonstrated that plants can respond to long-term repeated exposures to subcritical amounts of chemical signals

Utilizing associational resistance for biocontrol: impacted by temperature, supported by indirect defence

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Diverse Roles of Eph/ephrin Signaling in the Mouse Lens

Recent genetic studies show that the Eph/ephrin bidirectional signaling pathway is associated with both congenital and age-related cataracts in mice and humans. We have investigated the molecular mechanisms of cataractogenesis and the roles of ephrin-A5 and EphA2 in the lens. Ephrin-A5 knockout (-/-) mice often display anterior polar cataracts while EphA2(-/-) lenses show very mild cortical or nuclear cataracts at weaning age. The anterior polar cataract of ephrin-A5(-/-) lenses is correlated with multilayers of aberrant cells that express alpha smooth muscle actin, a marker for mesenchymal cells. Only select fiber cells are altered in ephrin-A5(-/-) lenses. Moreover, the disruption of membrane-associated β-catenin and E-cadherin junctions is observed in ephrin-A5(-/-) lens central epithelial cells. In contrast, EphA2(-/-) lenses display normal monolayer epithelium while disorganization is apparent in all lens fiber cells. Immunostaining of ephrin-A5 proteins, highly expressed in lens epithelial cells, were not colocalized with EphA2 proteins, mainly expressed in lens fiber cells. Besides the previously reported function of ephrin-A5 in lens fiber cells, this work suggests that ephrin-A5 regulates β-catenin signaling and E-cadherin to prevent lens anterior epithelial cells from undergoing the epithelial-to-mesenchymal transition while EphA2 is essential for controlling the organization of lens fiber cells through an unknown mechanism. Ephrin-A5 and EphA2 likely interacting with other members of Eph/ephrin family to play diverse functions in lens epithelial cells and/or fiber cells

Transcriptional Analysis of Arabidopsis thaliana Response to Lima Bean Volatiles

Exposure of plants to herbivore-induced plant volatiles (HIPVs) alters their resistance to herbivores. However, the whole-genome transcriptional responses of treated plants remain unknown, and the signal pathways that produce HIPVs are also unclear.Time course patterns of the gene expression of Arabidopsis thaliana exposed to Lima bean volatiles were examined using Affymetrix ATH1 genome arrays. Results showed that A. thaliana received and responded to leafminer-induced volatiles from Lima beans through up-regulation of genes related to the ethylene (ET) and jasmonic acid pathways. Time course analysis revealed strong and partly qualitative differences in the responses between exposure at 24 and that at 48 h. Further experiments using either A. thaliana ET mutant ein2-1 or A. thaliana jasmonic acid mutant coi1-2 indicated that both pathways are involved in the volatile response process but that the ET pathway is indispensable for detecting volatiles. Moreover, transcriptional comparisons showed that plant responses to larval feeding do not merely magnify the volatile response process. Finally, (Z)-3-hexen-ol, ocimene, (3E)-4,8-dimethyl-1,3,7-nonatriene, and (3E,7E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene triggered responses in A. thaliana similar to those induced by the entire suite of Lima bean volatiles after 24 and 48 h.This study shows that the transcriptional responses of plants to HIPVs become stronger as treatment time increases and that ET signals are critical during this process

The molecular phylogeny of eph receptors and ephrin ligands

<p>Abstract</p> <p>Background</p> <p>The tissue distributions and functions of Eph receptors and their ephrin ligands have been well studied, however less is known about their evolutionary history. We have undertaken a phylogenetic analysis of Eph receptors and ephrins from a number of invertebrate and vertebrate species.</p> <p>Results</p> <p>Our findings indicate that Eph receptors form three major clades: one comprised of non-chordate and cephalochordate Eph receptors, a second comprised of urochordate Eph receptors, and a third comprised of vertebrate Eph receptors. Ephrins, on the other hand, fall into either a clade made up of the non-chordate and cephalochordate ephrins plus the urochordate and vertebrate ephrin-Bs or a clade made up of the urochordate and vertebrate ephrin-As.</p> <p>Conclusion</p> <p>We have concluded that Eph receptors and ephrins diverged into A and B-types at different points in their evolutionary history, such that primitive chordates likely possessed an ancestral ephrin-A and an ancestral ephrin-B, but only a single Eph receptor. Furthermore, ephrin-As appear to have arisen in the common ancestor of urochordates and vertebrates, whereas ephrin-Bs have a more ancient bilaterian origin. Ancestral ephrin-B-like ligands had transmembrane domains; as GPI anchors appear to have arisen or been lost at least 3 times.</p

Volatile exchange between undamaged plants - a new mechanism affecting insect orientation in intercropping

Changes in plant volatile emission can be induced by exposure to volatiles from neighbouring insect-attacked plants.However, plants are also exposed to volatiles from unattacked neighbours, and the consequences of this have not beenexplored. We investigated whether volatile exchange between undamaged plants affects volatile emission and plant-insectinteraction. Consistently greater quantities of two terpenoids were found in the headspace of potato previously exposed tovolatiles from undamaged onion plants identified by mass spectrometry. Using live plants and synthetic blends mimickingexposed and unexposed potato, we tested the olfactory response of winged aphids, Myzus persicae. The altered potatovolatile profile deterred aphids in laboratory experiments. Further, we show that growing potato together with onion in thefield reduces the abundance of winged, host-seeking aphids. Our study broadens the ecological significance of thephenomenon; volatiles carry not only information on whether or not neighbouring plants are under attack, but alsoinformation on the emitter plants themselves. In this way responding plants could obtain information on whether theneighbouring plant is a competitive threat and can accordingly adjust their growth towards it. We interpret this as aresponse in the process of adaptation towards neighbouring plants. Furthermore, these physiological changes in theresponding plants have significant ecological impact, as behaviour of aphids was affected. Since herbivore host plants arepotentially under constant exposure to these volatiles, our study has major implications for the understanding of howmechanisms within plant communities affect insects. This knowledge could be used to improve plant protection andincrease scientific understanding of communication between plants and its impact on other organisms