Adaptive plant responses to specific abiotic stresses or biotic agents are fine-tuned by a network of hormonal signaling cascades, including abscisic acid (ABA), ethylene, jasmonic acid (JA) and ...salicylic acid. Moreover, hormonal cross-talk modulates plant responses to abiotic stresses and defenses against insect herbivores when they occur simultaneously. How such interactions affect plant responses under multiple stresses, however, is less understood, even though this may frequently occur in natural environments. Here, we review our current knowledge on how hormonal signaling regulates abiotic stress responses and defenses against insects, and discuss the few recent studies that attempted to dissect hormonal interactions occurring under simultaneous abiotic stress and herbivory. Based on this we hypothesize that drought stress enhances insect resistance due to synergistic interactions between JA and ABA signaling. Responses to flooding or waterlogging involve ethylene signaling, which likely reduces plant resistance to chewing herbivores due to its negative cross-talk with JA. However, the outcome of interactions between biotic and abiotic stress signaling is often plant and/or insect species-dependent and cannot simply be predicted based on general knowledge on the involvement of signaling pathways in single stress responses. More experimental data on non-model plant and insect species are needed to reveal general patterns and better understand the molecular mechanisms allowing plants to optimize their responses in complex environments.
The rhizosphere is densely populated with a variety of organisms. Interactions between roots and rhizosphere community members are mostly achieved via chemical communication. Root exudates contain an ...array of primary and secondary plant metabolites that can attract, deter, or kill belowground insect herbivores, nematodes, and microbes, and inhibit competing plants. Metabolomics of root exudates can potentially help us to better understand this chemical dialogue. The main limitations are the proper sampling of the exudate, the sensitivity of the metabolomics platforms, and the multivariate data analysis to identify causal relations. Novel technologies may help to generate a spatially explicit metabolome of the root and its exudates at a scale that is relevant for the rhizosphere community.
Metabolomics is becoming accepted as a tool for the (untargeted) analysis of metabolites in root exudates.
The importance of the rhizosphere microbiome for the functioning of plants is becoming increasingly clear.
Statistical analysis and genetic mapping are used to establish relations between metabolites and (other) traits.
The increased understanding of metabolic engineering in plants will allow the critical assessment of the role of individual compounds in plant–rhizosphere communication.
Novel chemical-analytical platforms, such as laser-assisted electrospray ionisation (LAESI), will allow for spatial metabolomics on the scale of roots and interacting organisms.
Emerging Targets in Photopharmacology Lerch, Michael M.; Hansen, Mickel J.; van Dam, Gooitzen M. ...
Angewandte Chemie (International ed.),
September 5, 2016, Letnik:
55, Številka:
37
Journal Article
Recenzirano
Odprti dostop
The field of photopharmacology uses molecular photoswitches to establish control over the action of bioactive molecules. It aims to reduce systemic drug toxicity and the emergence of resistance, ...while achieving unprecedented precision in treatment. By using small molecules, photopharmacology provides a viable alternative to optogenetics. We present here a critical overview of the different pharmacological targets in various organs and a survey of organ systems in the human body that can be addressed in a non‐invasive manner. We discuss the prospects for the selective delivery of light to these organs and the specific requirements for light‐activatable drugs. We also aim to illustrate the druggability of medicinal targets with recent findings and emphasize where conceptually new approaches have to be explored to provide photopharmacology with future opportunities to bring “smart” molecular design ultimately to the realm of clinical use.
Spotlight on the patient: The impressive advances made in the field of photopharmacology in recent years are critically reviewed with respect to the “photodruggability” of medicinal targets and prospects for the selective delivery of light to different organs. This Review is meant to provide a stimulus for chemists to enter this exciting field, with fascinating opportunities to bring “smart” molecular design to the realm of clinical use.
Belowground Herbivory and Plant Defenses Dam, Nicole M. van
Annual review of ecology, evolution, and systematics,
12/2009, Letnik:
40, Številka:
1
Journal Article
Recenzirano
Belowground-feeding herbivores may be very destructive to plants. Roots are known to produce various defense compounds to protect themselves against these herbivores, both with direct and ...indirect—inducible—defense compounds. Recent literature reviews reveal no overall pattern for root-shoot defense allocation. Optimal defense allocation patterns within roots may be predicted with an ecophysiological model taking into account the value and vulnerability of root classes. Induced responses elicited by root herbivores are likely to result in systemic responses in the shoots. These systemic responses may affect aboveground herbivores and higher trophic levels. This calls into question whether root-to-shoot systemic induction is an adaptive response. Physiological responses conferring tolerance may co-occur with resistance reponses, depending on the biotic and abiotic environment of the roots. More detailed analyses of root defenses and the feeding sites of herbivores are needed to gain a better understanding of optimal defense allocation in roots.
Objective To evaluate the impact of combinations of lifestyle factors on mortality in middle aged women.Design Prospective cohort study.Setting Nurses’ health study, United States.Participants 77 782 ...women aged 34 to 59 years and free from cardiovascular disease and cancer in 1980.Main outcome measure Relative risk of mortality during 24 years of follow-up in relation to five lifestyle factors (cigarette smoking, being overweight, taking little moderate to vigorous physical activity, no light to moderate alcohol intake, and low diet quality score).Results 8882 deaths were documented, including 1790 from cardiovascular disease and 4527 from cancer. Each lifestyle factor independently and significantly predicted mortality. Relative risks for five compared with zero lifestyle risk factors were 3.26 (95% confidence interval 2.45 to 4.34) for cancer mortality, 8.17 (4.96 to 13.47) for cardiovascular mortality, and 4.31 (3.51 to 5.31) for all cause mortality. A total of 28% (25% to 31%) of deaths during follow-up could be attributed to smoking and 55% (47% to 62%) to the combination of smoking, being overweight, lack of physical activity, and a low diet quality. Additionally considering alcohol intake did not substantially change this estimate.Conclusions These results indicate that adherence to lifestyle guidelines is associated with markedly lower mortality in middle aged women. Both efforts to eradicate cigarette smoking and those to stimulate regular physical activity and a healthy diet should be intensified.
Arthropod herbivory induces plant volatiles that can be used by natural enemies of the herbivores to find their prey. This has been studied mainly for arthropods that prey upon or parasitise ...herbivorous arthropods but rarely for insectivorous birds, one of the main groups of predators of herbivorous insects such as lepidopteran larvae. Here, we show that great tits (Parus major) discriminate between caterpillar‐infested and uninfested trees. Birds were attracted to infested trees, even when they could not see the larvae or their feeding damage. We furthermore show that infested and uninfested trees differ in volatile emissions and visual characteristics. Finally, we show, for the first time, that birds smell which tree is infested with their prey based on differences in volatile profiles emitted by infested and uninfested trees. Volatiles emitted by plants in response to herbivory by lepidopteran larvae thus not only attract predatory insects but also vertebrate predators.
Prospective studies linking dietary pattern and cognitive function in the elderly are limited in Asian populations.
We examined the associations between various healthful dietary patterns and risk of ...cognitive impairment in Chinese adults.
We used data from the Singapore Chinese Health Study of 16,948 men and women who were aged 45–74 y at baseline (1993–1998) and reinterviewed at the third follow-up visit (2014–2016), ∼20 y later. Diet quality at baseline was assessed according to the alternate Mediterranean diet (aMED), the Dietary Approaches to Stop Hypertension (DASH) diet, the alternative Healthy Eating Index (AHEI)-2010, overall plant-based diet index (PDI), and healthful plant-based diet index (hPDI). Cognitive function was evaluated using a Singapore-modified Mini-Mental State Examination during the third follow-up visit when subjects were aged 61–96 y. Multivariable logistic regression models were used to compute ORs and 95% CIs associated with the risk of cognitive impairment defined using education-specific cut-offs.
Cognitive impairment was present in 2443 (14.4%) participants. The OR (95% CI) for cognitive impairment comparing the highest with the lowest quartile of diet quality scores was 0.67 (0.59, 0.77) for aMED, 0.71 (0.62, 0.81) for DASH, 0.75 (0.66, 0.85) for AHEI-2010, 0.82 (0.71, 0.94) for PDI, and 0.78 (0.68, 0.90) for hPDI (all P values for trend <0.001). Each SD increment in different diet quality scores was associated with 7–16% lower risk of cognitive impairment.
These results provide evidence that adherence to healthy dietary patterns in midlife is associated with a lower risk of cognitive impairment in late life in Chinese adults.
• Carbon (C) allocation plays a central role in tree responses to environmental changes. Yet, fundamental questions remain about how trees allocate C to different sinks, for example, growth vs ...storage and defense.
• In order to elucidate allocation priorities, we manipulated the whole-tree C balance by modifying atmospheric CO₂ concentrations CO₂ to create two distinct gradients of declining C availability, and compared how C was allocated among fluxes (respiration and volatile monoterpenes) and biomass C pools (total biomass, nonstructural carbohydrates (NSC) and secondary metabolites (SM)) in well-watered Norway spruce (Picea abies) saplings. Continuous isotope labelling was used to trace the fate of newly-assimilated C.
• Reducing CO₂ to 120 ppm caused an aboveground C compensation point (i.e. net C balance was zero) and resulted in decreases in growth and respiration. By contrast, soluble sugars and SM remained relatively constant in aboveground young organs and were partially maintained with a constant allocation of newly-assimilated C, even at expense of root death from C exhaustion.
• We conclude that spruce trees have a conservative allocation strategy under source limitation: growth and respiration can be downregulated to maintain ‘operational’ concentrations of NSC while investing newly-assimilated C into future survival by producing SM.
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