Biology subjects

Frost, C.

Publications and source records attributed to Frost, C..

7 recordsLinked to original sources

bioRxiv2025

Identification of a volatile chemotype associated with resilience to water stress in domesticated varieties of Cotton

Volatile organic compounds (VOCs) mediate plant responses to environmental stresses, yet their chemotypic variation and drought responsiveness remain poorly characterized in domesticated crops. Here, we identify a previously undocumented binary chemotype structure in cultivated upland cotton (Gossypium hirsutum), defined by the mutually exclusive production of either bisabolene or guaiene sesquiterpenes. Across 24 genotypes grown under field conditions, genotypes consistently produced one of these compounds, but never both, revealing a cryptic chemotypic polymorphism with physiological consequences. While drought stress reduced leaf water content across all plants, plants in the guaiene chemotype exhibited disproportionately greater losses. Water limitation also reduced total monoterpene and sesquiterpene concentrations, with the bisabolene chemotype showing stronger declines despite higher constitutive levels. Chemotypes further diverged in their biosynthesis of key damage-induced green leaf volatiles (GLVs). While the guaiene chemotype reduced GLV biosynthetic capacity under prolonged drought, the bisabolene chemotype showed transient increases in GLVs and pathway-specific enzyme activity under short-term stress, suggesting differential physiological resilience. Notably, all genotypes in this study fell within the low {gamma}-terpinene category previously described in wild cotton, indicating that this bisabolene/guaiene variation represents a novel axis of chemical diversity distinct from known wild chemotypes. These findings position chemotypic variation as a promising, non-destructive biomarker for drought response in cotton breeding programs. By linking chemotype to constitutive VOCs and water status, our work provides new tools for identifying stress-resilient cultivars and advances understanding of phytochemical strategies for crop management in a changing climate.

plant biology↗

bioRxiv2021

Tripartite networks show that keystone species can multitask

Keystone species are disproportionately important for ecosystem functioning (1,2). However, while all species engage in multiple interaction types with other species, the importance of keystone species is often defined based on a single dimension of their Eltonian niche (3), that is, one type of interaction (e.g., keystone predator). Therefore, it remains unclear whether the importance of keystone species is unidimensional or if it extends across interaction types. We conducted a meta-analysis of tripartite interaction networks to examine whether species importance in one dimension of their niche is mirrored in other niche dimensions, and whether this is associated with interaction outcome, intimacy, or species richness. We show that keystone species importance is positively associated across multiple ecological niche dimensions, independently of species abundance, and find no evidence that multidimensionality of keystone species is influenced by the explanatory variables. We propose that the role of keystone species extends across multiple ecological niche dimensions, with important implications for ecosystem resilience and conservation. Significance StatementKeystone species are often identified by focusing on a single type of interaction (e.g., predation, pollination, herbivory) which contrasts with the multiple roles that species play in biological communities. We conducted a meta-analysis of 18 tripartite interaction networks to explore if keystonness is correlated across the multiple dimensions of species Eltonian niches. Our results suggest that species importance tends to span across multiple interaction types, independently from abundance, which can be key to understand community resilience and collapse in face of multiple threats.

ecology↗

bioRxiv2021

Plasma amyloid beta ratios in autosomal dominant Alzheimers disease: the influence of genotype

In-vitro studies of autosomal dominant Alzheimers disease (ADAD) implicate longer A{beta} peptides in pathogenesis, however less is known about the behaviour of ADAD mutations in-vivo. In this cross-sectional cohort study, we used liquid chromatography-tandem mass spectrometry to analyse 66 plasma samples from ADAD family members who were at-risk of inheriting a mutation or were already symptomatic. We tested for differences in plasma A{beta}42:38, 38:40 and 42:40 ratios between Presenilin1 (PSEN1) and Amyloid Precursor Protein (APP) carriers. We examined the relationship between plasma and in-vitro models of A{beta} processing and, among PSEN1 carriers, tested for associations with parental age at onset (AAO). 39 participants were mutation carriers (28 PSEN1 and 11 APP). Age- and sex-adjusted models showed marked differences in plasma A{beta} between APP and PSEN1: higher A{beta}42:38 in PSEN1 versus APP (p<0.001) and non-carriers (p<0.001); higher A{beta}38:40 in APP versus PSEN1 (p<0.001) and non-carriers (p<0.001), while A{beta}42:40 was higher in APP and PSEN1 compared to non-carriers (both p<0.001). A{beta} profiles were reasonably consistent in plasma and cell lines. Within PSEN1, sex-adjusted models demonstrated negative associations between (i)A{beta}42:40 (ii)A{beta}42:38 and parental AAO. In-vivo differences in A{beta} processing between APP and PSEN1 provide insights into ADAD pathophysiology which can inform therapy development.

neuroscience↗

bioRxiv2020

Predicting direct and indirect non-target impacts of biocontrol agents using machine-learning approaches

Biological pest control (i.e. biocontrol) agents can have direct and indirect non-target impacts, and predicting these effects (especially indirect impacts) remains a central challenge in biocontrol risk assessment. The analysis of ecological networks offers a promising approach to understanding the community-wide impacts of biocontrol agents (via direct and indirect interactions). Independently, species traits and phylogenies have been shown to successfully predict species interactions and network structure (alleviating the need to collect quantitative interaction data), but whether these approaches can be combined to predict indirect impacts of natural enemies remains untested. Whether predictions of interactions (i.e. direct effects) can be made equally well for generalists vs. specialists and across different habitat types is also untested for consumer-prey interactions, though previous work on mutualist networks suggests that interactions among generalists may be more difficult to predict. Here, we used two machine learning techniques (random forest and k-nearest neighbour; KNN) to test whether we could accurately predict empirically-observed quantitative host-parasitoid networks using trait, abundance, and phylogenetic information. Then, we tested whether the accuracy of machine-learning-predicted interactions depended on the generality of the interacting partners or on the source (habitat type) of the training data. Finally, we used these predicted networks to generate predictions of indirect effects via shared natural enemies (i.e. apparent competition), and tested these predictions against empirically observed indirect effects between hosts. We found that random-forest models predicted host-parasitoid pairwise interactions (which could be used to predict attack of non-target host species) more successfully than KNN, and this predictive ability depended on the generality of the interacting partners, but not the source (habitat type) of data used to train the models. Further, although our machine-learning informed methods could significantly predict indirect effects, the explanatory power for both direct and indirect interactions was reasonably low. Combining machine-learning and network approaches provides a starting point for reducing risk in biocontrol.

ecology↗

bioRxiv2020

Invasive freshwater snails form novel microbial symbioses

Resident microbes (microbiota) can shape host organismal function and adaptation in the face of environmental change. Invasion of new habitats exposes hosts to novel selection pressures, but little is known about the impact of invasion on microbiota and the host-microbiome relationship after this transition (e.g., how rapidly symbioses are formed, whether microbes influence invasion success). We used high-throughput 16S rRNA sequencing of New Zealand (native) and European (invasive) populations of the freshwater snail Potamopyrgus antipodarum and found that while invaders do carry over some core microbial taxa from New Zealand, most of their microbial community is distinct. This finding highlights that invasions can result in the formation of novel symbioses. We further show that the native microbiome is composed of fewer core microbes than the microbiome of invasive snails, suggesting that the microbiota is streamlined to essential members. Together, our findings demonstrate that microbiota comparisons across native and invasive populations can reveal the impact of a long coevolutionary history and specialization of microbes in the native host range, as well as new associations occurring after invasion. We lay essential groundwork for understanding how microbial relationships affect invasion success and how microbes may be utilized in the control of invasive hosts.

evolutionary biology↗

bioRxiv2019

Plant seeds are primed by herbivore-induced plant volatiles

Mature plants can detect and respond to herbivore-induced plant volatiles (HIPVs) by priming or directly activating defenses against future herbivores. Whether other plant life stages can respond to HIPVs in similar manners is poorly understood. For example, seeds are known to respond to a variety of environment cues that are essential for proper germination timing and survival. Seeds may also be exposed to HIPVs prior to germination, and such exposure may affect the growth, development, and defense profiles when the seeds grow into mature plants. Here, we investigated the effect of seed exposure to common HIPVs on growth, reproduction and defense characteristics in the model plants Arabidopsis thaliana and Medicago truncatula. Of all the HIPVs tested, indole specifically reduced both beet armyworm growth on A. thaliana and pea 33 aphid fecundity on M. truncatula. Induction of defense genes was not affected by seed exposure to indole in either plant species, suggesting that seed priming operates independently of induced resistance. Moreover, neither species showed any negative effect of seed exposure to HIPVs on vegetative and reproductive growth. Rather, M. truncatula plants derived from seeds exposed to z-3-hexanol and z-3-hexenyl acetate grew faster and produced larger leaves compared to controls. Our results indicate that seeds are sensitive to specific HIPVs, which represents a novel ecological mechanism of plant-to-plant communication.

plant biology↗

bioRxiv2018

Variable costs of eavesdropping a green leaf volatile on two plant species in a common garden experiment

Herbivore-induced plant volatile (HIPV)-mediated eavesdropping by plants is a well-documented, inducible phenomenon that has practical agronomic applications for enhancing plant defense and pest management. However, as with any inducible phenomenon, responding to volatile cues may incur physiological and ecological costs that limit plant productivity. In a common garden experiment, we tested the hypothesis that exposure to a single HIPV would decrease herbivore damage at the cost of reduced plant growth and reproduction. Lima bean (Phaseolus lunatus) and pepper (Capsicum annuum) plants were exposed to a persistent, low-dose ([~]10ng/hour) of the green leaf volatile cis-3-hexenyl acetate (z3HAC), which is an HIPV and damage-associated volatile. z3HAC-treated pepper plants were shorter, had less aboveground and belowground biomass, and produced fewer flowers and fruits relative to controls while z3HAC-treated lima bean plants were taller and produced more leaves and flowers than did controls. Natural herbivory was reduced in z3HAC-exposed lima bean plants, but not in pepper. Cyanogenic potential, a putative direct defense mechanism in lima bean, was lower in young z3HAC-exposed leaves, suggesting a growth-defense tradeoff from z3HAC exposure alone. Plant species-specific responses to an identical volatile cue have important implications for agronomic costs and benefits of volatile-mediated inter-plant communication under field conditions.

ecology↗