While the great majority of plant herbivore relations is investigated using insect herbivores, in... more While the great majority of plant herbivore relations is investigated using insect herbivores, interactions with gastropods get far less attention. In my PhD project I explore the mechanisms and variation in feeding resistance of bittersweet nightshade to the grey field slug.
In natural environments, plants have to deal with a wide range of different herbivores whose comm... more In natural environments, plants have to deal with a wide range of different herbivores whose communities vary in time and space. It is believed that the chemical diversity within plant species has mainly arisen from selection pressures exerted by herbivores. So far, the effects of chemical diversity on plant resistance have mostly been assessed for arthropod herbivores. However, also gastropods, such as slugs, can cause extensive damage to plants. Here we investigate to what extent individual Solanum dulcamara plants differ in their resistance to slug herbivory and whether this variation can be explained by differences in secondary metabolites. We performed a series of preference assays using the grey field slug (Deroceras reticulatum) and S. dulcamara accessions from eight geographically distinct populations from the Netherlands. Significant and consistent variation in slug preference was found for individual accessions within and among populations. Metabolomic analyses showed that...
Solanum dulcamara (Bittersweet nightshade) shows significant intraspecific variation in glycoalka... more Solanum dulcamara (Bittersweet nightshade) shows significant intraspecific variation in glycoalkaloid (GA) composition and concentration. We previously showed that constitutive differences in overall GA levels are correlated with feeding preference of the grey field slug (GFS; Deroceras reticulatum). One particularly preferred accession, ZD11, contained low GA levels, but high levels of previously unknown structurally related uronic acid conjugated compounds (UACs). Here we test whether different slug species as well as insect herbivores show similar feeding preferences among six S. dulcamara accessions with different GA chemotypes. In addition, we investigate whether slug feeding can lead to induced changes in the chemical composition and affect later arriving herbivores. A leaf disc assay using greenhouse-grown plants showed that three slug species similarly preferred accessions with low GA levels. Untargeted metabolomic analyses showed that previous slug feeding consistently incr...
Temporal flooding is a common environmental stress for terrestrial plants. Aquatic adventitious r... more Temporal flooding is a common environmental stress for terrestrial plants. Aquatic adventitious roots (aquatic roots) are commonly formed in flooding-tolerant plant species and are generally assumed to be beneficial for plant growth by supporting water and nutrient uptake during partial flooding. However, the actual contribution of these roots to plant performance under flooding has hardly been quantified. As the investment into aquatic root development in terms of carbohydrates may be costly, these costs may - depending on the specific environmental conditions - offset the beneficial effects of aquatic roots. This study tested the hypothesis that the balance between potential costs and benefits depends on the duration of flooding, as the benefits are expected to outweigh the costs in long-term but not in short-term flooding. The contribution of aquatic roots to plant performance was tested in Solanum dulcamara during 1-4 weeks of partial submergence and by experimentally manipulati...
SYNOPSIS. Many plants display a characteristic suite of developmental ‘‘shade avoidance’ ’ respon... more SYNOPSIS. Many plants display a characteristic suite of developmental ‘‘shade avoidance’ ’ responses, such as stem elongation and accelerated reproduction, to the low ratio of red to far-red wavelengths (R:FR) reflected or transmitted from green vegetation. This R:FR cue of crowding and vegetation shade is perceived by the phytochrome family of photoreceptors. Phytochrome-mediated responses provide an ideal system for investigating the adaptive evolution of phenotypic plasticity in natural environments. The molecular and developmental mechanisms underlying shade avoidance responses are well studied, and testable ecological hypotheses exist for their adaptive significance. Experimental manipulation of phenotypes demonstrates that shade avoidance responses may be adaptive, resulting in phenotypes with high relative fitness in the envi-ronments that induce those phenotypes. The adaptive value of shade avoidance depends upon the competitive environment, resource availability, and the re...
Climate change has become a serious threat for crop productivity worldwide. The increased frequen... more Climate change has become a serious threat for crop productivity worldwide. The increased frequency of heat waves strongly affects reproductive success and thus yield for many crop species, implying that breeding for thermotolerant cultivars is critical for food security. Insight into the genetic architecture of reproductive heat tolerance contributes to our fundamental understanding of the stress sensitivity of this process and at the same time may have applied value. In the case of tomato (Solanum lycopersicum), germplasm screenings for thermotolerance have often used yield as the main measured trait. However, due to the complex nature of yield and the relatively narrow genetic variation present in the cultivated germplasm screened, there has been limited progress in understanding the genetic basis of reproductive heat tolerance. Extending the screening to wild accessions of related species that cover a range of climatic conditions might be an effective approach to find novel, mor...
Clonal plants can form dense canopies in which plants of different genetic origin are competing f... more Clonal plants can form dense canopies in which plants of different genetic origin are competing for the uptake of essential resources. The competitive relationships among these clones are likely to be affected by extreme environmental conditions, such as prolonged drought spells, which are predicted to occur more frequently due to global climate change. This, in turn, may alter characteristics of the ecological system and its associated functioning. We hypothesized that the relative success of individual clones will depend on the size of the ramets as ramets with larger leaves and longer petioles (large ramets) were predicted to have a competitive advantage in terms of increased light interception over smaller-sized ramets. Under drier conditions the relative performances of genotypes were expected to change leading to a change in genotype ranking. We also hypothesized that increased genotypic and phenotypic diversity will increase stand performance and resistance to drought. These ...
Abstract Shade-induced changes in the branching pat-tern of clonal plants can lead to conspicuous... more Abstract Shade-induced changes in the branching pat-tern of clonal plants can lead to conspicuous modifica-tions of their growth form and architecture. It has been hypothesized that reduced branching in shade may be an adaptive trait, enabling clonal plants to escape from unfavourable ...
While the great majority of plant herbivore relations is investigated using insect herbivores, in... more While the great majority of plant herbivore relations is investigated using insect herbivores, interactions with gastropods get far less attention. In my PhD project I explore the mechanisms and variation in feeding resistance of bittersweet nightshade to the grey field slug.
In natural environments, plants have to deal with a wide range of different herbivores whose comm... more In natural environments, plants have to deal with a wide range of different herbivores whose communities vary in time and space. It is believed that the chemical diversity within plant species has mainly arisen from selection pressures exerted by herbivores. So far, the effects of chemical diversity on plant resistance have mostly been assessed for arthropod herbivores. However, also gastropods, such as slugs, can cause extensive damage to plants. Here we investigate to what extent individual Solanum dulcamara plants differ in their resistance to slug herbivory and whether this variation can be explained by differences in secondary metabolites. We performed a series of preference assays using the grey field slug (Deroceras reticulatum) and S. dulcamara accessions from eight geographically distinct populations from the Netherlands. Significant and consistent variation in slug preference was found for individual accessions within and among populations. Metabolomic analyses showed that...
Solanum dulcamara (Bittersweet nightshade) shows significant intraspecific variation in glycoalka... more Solanum dulcamara (Bittersweet nightshade) shows significant intraspecific variation in glycoalkaloid (GA) composition and concentration. We previously showed that constitutive differences in overall GA levels are correlated with feeding preference of the grey field slug (GFS; Deroceras reticulatum). One particularly preferred accession, ZD11, contained low GA levels, but high levels of previously unknown structurally related uronic acid conjugated compounds (UACs). Here we test whether different slug species as well as insect herbivores show similar feeding preferences among six S. dulcamara accessions with different GA chemotypes. In addition, we investigate whether slug feeding can lead to induced changes in the chemical composition and affect later arriving herbivores. A leaf disc assay using greenhouse-grown plants showed that three slug species similarly preferred accessions with low GA levels. Untargeted metabolomic analyses showed that previous slug feeding consistently incr...
Temporal flooding is a common environmental stress for terrestrial plants. Aquatic adventitious r... more Temporal flooding is a common environmental stress for terrestrial plants. Aquatic adventitious roots (aquatic roots) are commonly formed in flooding-tolerant plant species and are generally assumed to be beneficial for plant growth by supporting water and nutrient uptake during partial flooding. However, the actual contribution of these roots to plant performance under flooding has hardly been quantified. As the investment into aquatic root development in terms of carbohydrates may be costly, these costs may - depending on the specific environmental conditions - offset the beneficial effects of aquatic roots. This study tested the hypothesis that the balance between potential costs and benefits depends on the duration of flooding, as the benefits are expected to outweigh the costs in long-term but not in short-term flooding. The contribution of aquatic roots to plant performance was tested in Solanum dulcamara during 1-4 weeks of partial submergence and by experimentally manipulati...
SYNOPSIS. Many plants display a characteristic suite of developmental ‘‘shade avoidance’ ’ respon... more SYNOPSIS. Many plants display a characteristic suite of developmental ‘‘shade avoidance’ ’ responses, such as stem elongation and accelerated reproduction, to the low ratio of red to far-red wavelengths (R:FR) reflected or transmitted from green vegetation. This R:FR cue of crowding and vegetation shade is perceived by the phytochrome family of photoreceptors. Phytochrome-mediated responses provide an ideal system for investigating the adaptive evolution of phenotypic plasticity in natural environments. The molecular and developmental mechanisms underlying shade avoidance responses are well studied, and testable ecological hypotheses exist for their adaptive significance. Experimental manipulation of phenotypes demonstrates that shade avoidance responses may be adaptive, resulting in phenotypes with high relative fitness in the envi-ronments that induce those phenotypes. The adaptive value of shade avoidance depends upon the competitive environment, resource availability, and the re...
Climate change has become a serious threat for crop productivity worldwide. The increased frequen... more Climate change has become a serious threat for crop productivity worldwide. The increased frequency of heat waves strongly affects reproductive success and thus yield for many crop species, implying that breeding for thermotolerant cultivars is critical for food security. Insight into the genetic architecture of reproductive heat tolerance contributes to our fundamental understanding of the stress sensitivity of this process and at the same time may have applied value. In the case of tomato (Solanum lycopersicum), germplasm screenings for thermotolerance have often used yield as the main measured trait. However, due to the complex nature of yield and the relatively narrow genetic variation present in the cultivated germplasm screened, there has been limited progress in understanding the genetic basis of reproductive heat tolerance. Extending the screening to wild accessions of related species that cover a range of climatic conditions might be an effective approach to find novel, mor...
Clonal plants can form dense canopies in which plants of different genetic origin are competing f... more Clonal plants can form dense canopies in which plants of different genetic origin are competing for the uptake of essential resources. The competitive relationships among these clones are likely to be affected by extreme environmental conditions, such as prolonged drought spells, which are predicted to occur more frequently due to global climate change. This, in turn, may alter characteristics of the ecological system and its associated functioning. We hypothesized that the relative success of individual clones will depend on the size of the ramets as ramets with larger leaves and longer petioles (large ramets) were predicted to have a competitive advantage in terms of increased light interception over smaller-sized ramets. Under drier conditions the relative performances of genotypes were expected to change leading to a change in genotype ranking. We also hypothesized that increased genotypic and phenotypic diversity will increase stand performance and resistance to drought. These ...
Abstract Shade-induced changes in the branching pat-tern of clonal plants can lead to conspicuous... more Abstract Shade-induced changes in the branching pat-tern of clonal plants can lead to conspicuous modifica-tions of their growth form and architecture. It has been hypothesized that reduced branching in shade may be an adaptive trait, enabling clonal plants to escape from unfavourable ...
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Papers by Heidrun Huber