Biology subjects

Godinho, D. P.

Publications and source records attributed to Godinho, D. P..

8 recordsLinked to original sources

bioRxiv2025

Inducible tomato defences persist in detached leaves, despite differential plant variety and gene-dependent expression

Herbivore and pathogen attacks often lead to the induction of plant defences. Given the intricate nature of such responses, plant integrity is assumed to be a pre-requisite for the successful mounting of defences, a hypothesis supported by work done in plant-pathogen interactions. However, the relevance of plant integrity in plant-herbivore interactions, particularly in direct plant defences, is unclear and lacks empirical molecular validation. To test this, we measured the expression of plant defence-related genes (PPO-D and PI-IIc, involved in the jasmonate signal pathway and PR-1a, involved in the salicylic acid signal pathway) in intact plants and detached leaves of two tomato varieties infested or not with the herbivorous spider mite Tetranychus urticae. We also tested whether defences persisted in detached leaves after one, four, seven or fourteen days of infestation. We found that tomato defences were induced in both intact plants and detached leaves and that the expression of all three genes in detached leaves increased over time, being the increment higher in the two late-expression genes, PI-IIc and PR-1a. Such results suggests that both intact plants and detached leaves can be used in studies addressing herbivore interactions with plant defences. However, induction levels in intact plants and detached leaves varied with plant variety and the gene assessed, ranging from higher expression in detached leaves than in intact plants to the reverse. Hence, studies aiming at identifying the role of specific genes should account for the differential, variety-dependent, role of plant integrity in their expression.

ecology↗

bioRxiv2023

Spider mites collectively avoid plants with cadmium irrespective of their frequency or the presence of competitors

Accumulation of heavy metals by plants can serve as a defence against herbivory. Herbivores, in turn, may avoid feeding on contaminated tissues. Such avoidance, however, may hinge upon the specific conditions faced by herbivores. Here, we tested whether the spider mite Tetranychus urticae avoids tomato plants contaminated with cadmium in presence of conspecifics or heterospecifics and depending on the frequency of contaminated plants. We show that individual spider mite females do not preferentially move to leaf tissues with or without cadmium, despite clear costs on their performance. However, in a set-up where 200 mites were simultaneously given the choice between four plants with or without cadmium, they collectively avoided plants with cadmium, irrespective of the proportion of plants with cadmium. In addition, T. urticae did not discriminate between plants infested with its competitor T. evansi and other uncontaminated plants but they preferred plants with competitors when the other plants contained cadmium. Our results show that aggregation may facilitate avoidance of contaminated plants. They also indicate that cadmium accumulation in plants is a stronger selective pressure than interspecific competition with T. evansi. Therefore, collective avoidance of metal-accumulating plants by herbivores is robust to environmental conditions and may have important consequences for species distribution and interactions in metal contaminated sites.

ecology↗

bioRxiv2023

Evolution in abiotic environments shapes coexistence between two spider mite species

Adaptation to abiotic stresses generally relies on traits that are not independent from those affecting species interactions. Still, the impact of such evolutionary processes on coexistence remains elusive. Here, we studied two spider mite species evolving separately on tomato plants that hyper-accumulated cadmium, a stressful environment for herbivores, or on plants without cadmium. Through experimental evolution and structural stability theory, we found that both species coexist in the cadmium environment, but evolution of a single species in cadmium leads to exclusion. However, when both species evolve in cadmium they can coexist. This shift occured due to a simultaneous increase in intra and a decrease in interspecific competition in that environment. These predictions were further confirmed with complementary experiments of population dynamics. Therefore, population shifts to novel environments, even in absence of interspecific competitors, may have unforeseen evolutionary consequences for community composition and the maintenance of species diversity.

evolutionary biology↗

bioRxiv2023

Limits to the adaptation of herbivorous spider mites to metal accumulation in homogeneous and heterogeneous environments

Metal accumulation is used by some plants as a defence against herbivores. Yet, herbivores may adapt to these defences, becoming less susceptible. Moreover, ecosystems often contain plants that do and do not accumulate metals, and such heterogeneity may affect herbivore adaptation. Surprisingly, few studies have tested this. Tomato plants accumulate cadmium, affecting the performance of the herbivorous spider mite Tetranychus evansi. Here, we performed experimental evolution to test whether these mites adapt to plants with high cadmium concentrations, in homogeneous (plants with cadmium) or heterogeneous (plants with and without cadmium) environments. We measured fecundity, hatching rate and the number of adult offspring after 12 and 33 generations and habitat choice after 14 and 51 generations, detecting no trait change, which implies absence of adaptation. We then tested whether this absence of adaptation was due to a lack of genetic variation in the traits measured and, indeed, additive genetic variance was low for the measured traits. Possibly, we did not measure the traits that contributed to population persistence on plants with cadmium. Interestingly, despite no signs of adaptation we observed a decrease in fecundity and number of adult offspring produced in cadmium-free plants, in the populations evolving in environments with cadmium. Being this the case, evolving in environments with cadmium may reduce the growth rate of spider mite populations on non-accumulating plants as well. Nevertheless, adaptation to metal accumulation may occur via herbivore traits not commonly measured, which calls for broader studies on this topic.

evolutionary biology↗

bioRxiv2021

Virulence constrains transmission even in the absence of a genetic trade-off

The virulence-transmission trade-off predicts that parasite fitness peaks at intermediate virulence. However, whether this relationship is driven by the environment or genetically determined and if it depends on transmission opportunities remains unclear. We tackled these issues using inbred lines of the macro-parasitic spider-mite Tetranychus urticae. When transmission was not possible during the infection period, we observed a hump-shaped relationship between virulence and parasite fitness, as predicted by theory. This was environmentally driven, as no genetic correlation between traits was detected. However, when transmission to uninfected hosts occurred during the infection period, virulence was positively, environmentally and genetically correlated with parasite fitness. Therefore, the virulence-transmission trade-off depends on within-host dynamics and on the timing of transmission, rather than on a genetic correlation. This fundamental correlation may thus be easier to manipulate than previously thought.

evolutionary biology↗

bioRxiv2020

Creating outbred and inbred populations of haplodiploid mites to measure adaptive responses in the lab

Laboratory studies are often criticized for not being representative of processes occurring in natural populations. This can be partially mitigated by using lab populations that capture large amounts of variation. Additionally, many studies addressing adaptation of organisms to their environment are done with laboratory populations, using quantitative genetics or experimental evolution methodologies. Such studies rely on populations that are either highly outbred or inbred. However, the methodology underlying the generation of such biological resources are usually not explicitly documented. Given their small size, short generation time, amenability to laboratory experimentation and knowledge of their ecological interactions, haplodiploid spider mites are becoming a widely used model organism. Here, we describe the creation of outbred populations of two species of spider mites, Tetranychus urticae and T. evansi, obtained by performing controlled crosses between individuals from field-collected populations. Subsequently, from the outbred population of T. evansi, we derived inbred lines, by performing several generations of sib-mating. These can be used to measure broad-sense heritability as well as correlations among traits. Finally, we outline an experimental evolution protocol that can be widely used in other systems. Sharing these biological resources with other laboratories and combining them with the available powerful genetic tools for T. urticae (and other species) will allow consistent and comparable studies that greatly contribute to our understanding of ecological and evolutionary processes.

evolutionary biology↗

bioRxiv2018

Effect of cadmium accumulation on the performance of plants and of herbivores that cope differently with organic defences

Some plants can accumulate in their shoots metals that are toxic to most other organisms. This ability may serve as a defence against herbivores. Although both metal accumulation and the production of organic defences may be costly to the plant, the two mechanisms may interact on their effect on herbivores. However, this interplay between metal-based and classical organic defences remains overlooked.\n\nTo fill this gap, we studied the interactions between tomato (Solanum lycopersicum), a plant that accumulates cadmium, and two spider-mites, Tetranychus urticae and T. evansi that respectively induce and suppress organic plant defences, measurable via the activity of trypsin inhibitors. We exposed plants to different concentrations of cadmium and measured their effect on mites and plants. The oviposition of both spider-mite species was higher on plants exposed to low concentrations of Cd than on control plants but decreased at concentrations above 0.5 mM. Therefore, herbivores with contrasting responses to organic defences responded similarly to metal accumulation by the plants. On the plant, despite clear evidence for Cd accumulation, we did not detect any effect of Cd on traits that reflect the general response of the plant, such as biomass, water content and carbon/nitrogen ratio. Still, we found an effect of Cd supply upon the quantity of soluble sugars and leaf reflectance changes that may reflect structural modifications in the cells. In turn, these changes in plant traits interfered with the performance of spider mites feeding on those plants.\n\nAdditionally, we show that the induction and suppression of plant defences by spider mites was not affected by Cd supply to the plants. Furthermore, the effect of metal supply on spider-mite performance was not affected by previous infestation. Together, our results suggest no interaction between metal-based and organic plant defences, on our system. This may be useful for plants living in heterogeneous environments, as they may use one or the other defence mechanism, depending on their relative performance in each environment. This may be relevant to studies on the interactions between herbivores and plants, from physiology to ecology.

ecology↗

bioRxiv2018

Wolbachia both aids and hampers the performance of spider mites on different host plants

In the last decades, many studies had revealed the potential role of arthropod bacterial endosymbionts in shaping the host range of generalist herbivores and their performance on different host plants, which, in turn, might affect endosymbiont distribution in herbivores populations. We tested this by measuring the prevalence of endosymbionts in natural populations of the generalist spider mite Tetranychus urticae on different host plants. Focusing on Wolbachia, we then analysed how symbionts affected mite life-history traits on the same host-plants in the laboratory. Overall, the prevalences of Cardinium and Rickettsia were low, whereas that of Wolbachia was high, with the highest values on bean and eggplant and the lowest on purple, tomato and zuchini. Although most mite life-history traits were affected by the plant species only, Wolbachia infection was detrimental for egg hatching rate on purple and zucchini, and led to a more female-biased sex ratio on purple and eggplant. These results suggest that endosymbionts may affect the host range of polyphagous herbivores, both by aiding and hampering their performance, depending on the host plant and on the life-history trait that affects performance the most. Conversely, endosymbiont spread may be facilitated or hindered by the plants on which infected herbivores occur.

ecology↗