Plants can alter nutritional availability, structure, and chemistry of the soil they grow in. These soil changes can positively or negatively influence the growth and metabolism of other plants that ...co-occur or grow later in the conditioned soil. Plant-soil feedbacks could affect community interactions and dynamics but also be applied in sustainable agriculture to promote plant growth and resistance to pests. In this study, we use a maize companion cropping system, commonly known as “push-pull,” as a model to investigate soil-mediated effects of functional biodiversity, on maize plant growth, and resistance against insect herbivores. We grew maize in soils collected from push-pull (polyculture) and non-push-pull (monoculture) fields. We evaluated maize performance by measuring plant growth, as well as resistance traits (herbivore oviposition and larval feeding, production of defense-related volatile, and non-volatile secondary defense metabolites). Maize plants grown in soil conditioned by push-pull companion cropping had a higher growth rate compared to those grown in soil from non-push-pull monoculture fields. In addition, soil from push-pull fields induced a constitutively higher and qualitatively different emission of volatile organic compounds than soil from non-push-pull fields. Moreover, secondary defense metabolites such as 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA), were produced in larger quantities in plants grown in soil from push-pull fields compared to those from monoculture fields. These soil-mediated alterations in plant secondary metabolism were associated with reduced herbivory by larvae of the stemboring pest Chilo partelllus. This study provides novel evidence that plant-soil feedbacks can affect plant metabolism, growth, and resistance to pests. The observed soil-mediated effects on maize plant secondary metabolism can be viewed as emergent properties of plant community composition as well as a potent mechanism of associational resistance. In addition, these soil-conditioning effects provide a novel pest control mechanism of push-pull companion cropping.
Zu et al (Science, 19 Jun 2020, p. 1377) propose that an ‘information arms-race’ between plants and herbivores explains plant-herbivore communication at the community level. However, the analysis ...presented here shows that key assumptions of the proposed model either a) conflict with standard evolutionary theory or b) with our current understanding of plant-insect interactions and phytochemical evolution. We investigate whether specific conditional information might be more suitable as a fitness proxy than the community averages proposed by Zu et al. Finally, we show that the presented statistical patterns can be explained more parsimoniously (e.g. through a null model) without invoking an unlikely process of community selection.
The production of complex mixtures of secondary metabolites is a ubiquitous feature of plants. Several evolutionary hypotheses seek to explain how phytochemical diversity is maintained, including the ...synergy hypothesis, the interaction diversity hypothesis, and the screening hypothesis. We experimentally tested a set of predictions derived from these hypotheses by manipulating the richness and structural diversity of phenolic metabolites in the diets of eight plant consumers. Across 3940 total bioassays, there was clear support for the interaction diversity hypothesis over the synergy or screening hypotheses. The number of consumers affected by a particular phenolic composition increased with increasing richness and structural diversity of compounds. Furthermore, the bioactivity of phenolics was consumer‐specific. All compounds tested reduced the performance of at least one consumer, but no compounds affected all consumers. These results show how phytochemical diversity may be maintained in nature by a complex selective landscape exerted by diverse communities of plant consumers.
In this study, we test several hypotheses that explain the origins of phytochemical diversity by manipulating phenolic diversity in the diets of eight plant consumers. Our results show phytochemical diversity benefits plants by providing simultaneous defense against diverse consumers, rather than by providing more effective defense against any given consumer.
Abstract The perception of airborne chemical signals by plants can trigger reconfigurations of their metabolism that alter their biotic interactions. While plant-to-plant chemical communication has ...primarily been studied in the context of eliciting defenses to herbivores and pathogens, recent work suggests that it can also affect plants’ interactions with their rhizosphere microbiomes. In this perspective, we discuss the potential for integrating the fields of plant-to-plant communication and microbial ecology to understand the chemical ecology of plant−microbiome interactions. As an introduction for microbial ecologists, we highlight mechanistic knowledge gaps in plant volatile organic compound (VOC) perception and provide recommendations for avoiding common experimental errors that have plagued the plant communication field. Lastly, we discuss potential implications of plant VOCs structuring rhizosphere microbiomes, particularly effects on plant community and evolutionary dynamics. As we continue to discover links between plant metabolism and their microbiomes—from molecular to community scales—we hope that this perspective will provide both motivation and words of caution for researchers working at the intersection of these two fields.
Electrochemical detection of tellurium is interfered with arsenic due to their similar redox potentials. Gold electrodes modified by benzenedithiols (BDT) self‐assembled monolayers (SAMs) were ...explored to determine Te(IV) in the presence of extra As(III) in this work. SAMs of benzenedithiols on the gold surface allows for selective extraction of Te (IV) over As(III), while blocking the redox of As(III). It provides potential applications to tellurium toxicity analysis, biological membrane study and identification of geochemistry samples.
Intercropping is drawing increasing attention as a strategy to increase crop yields and manage pest pressure, however the mechanisms of associational resistance in diversified cropping systems remain ...controversial. We conducted a controlled experiment to assess the impact of co-planting with silverleaf Desmodium (
Desmodium uncinatum
) on maize secondary metabolism and resistance to herbivory by the spotted stemborer (
Chilo partellus
). Maize plants were grown either in the same pot with a
Desmodium
plant or adjacent to it in a separate pot. Our findings indicate that co-planting with
Desmodium
influences maize secondary metabolism and herbivore resistance through both above and below-ground mechanisms. Maize growing in the same pot with a
Desmodium
neighbor was less attractive for oviposition by spotted stemborer adults. However, maize exposed only to above-ground
Desmodium
cues generally showed increased susceptibility to spotted stemborer herbivory (through both increased oviposition and larval consumption). VOC emissions and tissue secondary metabolite titers were also altered in maize plants exposed to
Desmodium
cues, with stronger effects being observed when maize and
Desmodium
shared the same pot. Specifically, benzoxazinoids were strongly suppressed in maize roots by direct contact with a
Desmodium
neighbor while headspace emissions of short-chain aldehydes and alkylbenzenes were increased. These results imply that direct root contact or soil-borne cues play an important role in mediating associational effects on plant resistance in this system.
In this paper, we report the obtention of tellurium modified with self-assembled monolayers of benzenedithiol on a gold surface as a molecular gate. The switching and electronic transport ...characteristics of the modified gold surface were investigated by cyclic voltammetry (CV). The CV results indicate that the switching of benzenedithiol gates is controlled by the oxidation state of tellurium, which is regulated by the applied potentials.
We have studied a series of human acetyl‐CoA carboxylase (ACC) 1 and ACC2 proteins with deletions and/or Ser to Ala substitutions of the known phosphorylation sites. In vitro ...dephosphorylation/phosphorylation experiments reveal a substantial level of phosphorylation of human ACCs produced in insect cells. Our results are consistent with AMPK phosphorylation of Ser29, Ser80, Ser1,201, and Ser1,216. Phosphorylation of the N‐terminal regulatory domain decreases ACC1 activity, while phosphorylation of residues in the ACC central domain has no effect. Inhibition of the activity by phosphorylation is significantly more profound at citrate concentrations below 2 mm. Furthermore, deletion of the N‐terminal domain facilitates structural changes induced by citrate, including conversion of ACC dimers to linear polymers. We have also identified ACC2 amino acid mutations affecting specific inhibition of the isozyme by compound CD‐017‐0191. They form two clusters separated by 60–90 Å: one located in the vicinity of the BC active site and the other one in the vicinity of the ACC1 phosphorylation sites in the central domain, suggesting a contribution of the interface of two ACC dimers in the polymer to the inhibitor binding site.
The molecular clock maintains energy constancy by producing circadian oscillations of rate-limiting enzymes involved in tissue metabolism across the day and night. During periods of feeding, ...pancreatic islets secrete insulin to maintain glucose homeostasis, and although rhythmic control of insulin release is recognized to be dysregulated in humans with diabetes, it is not known how the circadian clock may affect this process. Here we show that pancreatic islets possess self-sustained circadian gene and protein oscillations of the transcription factors CLOCK and BMAL1. The phase of oscillation of islet genes involved in growth, glucose metabolism and insulin signalling is delayed in circadian mutant mice, and both Clock and Bmal1 (also called Arntl) mutants show impaired glucose tolerance, reduced insulin secretion and defects in size and proliferation of pancreatic islets that worsen with age. Clock disruption leads to transcriptome-wide alterations in the expression of islet genes involved in growth, survival and synaptic vesicle assembly. Notably, conditional ablation of the pancreatic clock causes diabetes mellitus due to defective -cell function at the very latest stage of stimulus-secretion coupling. These results demonstrate a role for the -cell clock in coordinating insulin secretion with the sleep-wake cycle, and reveal that ablation of the pancreatic clock can trigger the onset of diabetes mellitus.
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