Biology subjects

Glauser, G.

Publications and source records attributed to Glauser, G..

24 records · Page 2Linked to original sources

bioRxiv2020

VAPYRIN attenuates defence by repressing PR gene induction and localized lignin accumulation during arbuscular mycorrhizal symbiosis of Petunia hybrids

O_LIThe intimate association of host and fungus in arbuscular mycorrhizal (AM) symbiosis can potentially trigger induction of host defence mechanisms against the fungus, implying that successful symbiosis requires suppression of defence. C_LIO_LIWe addressed this phenomenon by using AM-defective vapyrin (vpy) mutants in Petunia hybrida, including a new allele (vpy-3) with a transposon insertion close to the ATG start codon. We explore whether abortion of fungal infection in vpy mutants is associated with the induction of defence markers such as cell wall alterations, accumulation of reactive oxygen species (ROS), defence hormones, and induction of pathogenesis-related (PR) genes. C_LIO_LIWe show that vpy mutants exhibit a strong resistance against intracellular colonization, which is associated with the generation of thick cell wall appositions (papillae) with lignin impregnation at fungal entry sites, while no accumulation of defence hormones, ROS, or callose was observed. Systematic analysis of PR gene expression revealed that several PR genes are induced in mycorrhizal roots of the wild type, and even more in vpy plants. Some PR genes are induced exclusively in vpy mutants. C_LIO_LITaken together, these results suggest that VPY is involved in avoiding or suppressing the induction of a cellular defence syndrome that involves localized lignin deposition and PR gene induction. C_LI

plant biology↗

bioRxiv2020

Two distinct phases of chloroplast biogenesis during de-etiolation in Arabidopsis thaliana

Light triggers chloroplast differentiation whereby the etioplast transforms into a photosynthesizing chloroplast and the thylakoid rapidly emerges. However, the sequence of events during chloroplast differentiation remains poorly understood. Using Serial Block Face Scanning Electron Microscopy (SBF-SEM), we generated a series of chloroplast 3D reconstructions during differentiation, revealing chloroplast number and volume and the extent of envelope and thylakoid membrane surfaces. Furthermore, we used quantitative lipid and whole proteome data to complement the (ultra)structural data, providing a time-resolved, multi-dimensional description of chloroplast differentiation. This showed two distinct phases of chloroplast biogenesis: an initial photosynthesis-enabling Structure Establishment Phase followed by a Chloroplast Proliferation Phase during cell expansion. Moreover, these data detail thylakoid membrane expansion during de-etiolation at the seedling level and the relative contribution and differential regulation of proteins and lipids at each developmental stage. Altogether, we establish a roadmap for chloroplast differentiation, a critical process for plant photoautotrophic growth and survival.

plant biology↗

bioRxiv2020

Tissue-specific volatile-mediated defense regulation in maize leaves and roots

O_LIPlant leaves that are exposed to herbivore induced plant volatiles (HIPVs) respond by increasing their defenses. Whether this phenomenon also occurs in the roots is unknown. C_LIO_LIUsing maize (Zea mays), whose leaves respond strongly to leaf HIPVs, we measured the impact of root HIPVs, emanating from plants infested by the banded cucumber beetle (Diabrotica balteata), on constitutive and herbivore-induced levels of root soluble sugars, starch, total soluble proteins, free amino acids, volatile and non-volatile secondary metabolites, defense gene expression, growth and root herbivore resistance of neighboring plants. C_LIO_LIHIPV exposure did not alter constitutive or induced levels of any of the measured root traits. Furthermore, HIPV exposure did not reduce the performance and survival of banded cucumber beetle larvae on maize or teosinte. Cross-exposure experiments revealed that maize roots, in contrast to maize leaves, neither emit nor respond strongly to defense-regulating HIPVs. C_LIO_LITogether, these results demonstrate that volatile-mediated defense regulation is restricted to the leaves of maize and teosinte, a finding which is in line with the lower diffusibility of volatiles in the soil and the availability of other, potentially more efficient information conduits below ground. C_LI

plant biology↗

bioRxiv2018

Variable Effects on Growth and Defence Traits for Plant Ecotypic Differentiation and Phenotypic Plasticity along Elevation Gradients

Along ecological gradients, ecotypes generally evolve as the result of local adaptation to a specific environment to maximize organisms fitness. Alongside ecotypic differentiation, phenotypic plasticity, as the ability of a single genotype to produce different phenotypes under different environmental conditions, can also evolve for favouring increased organisms performance in different environments. Currently, there is a lack in our understanding of how varying habitats may contribute to the differential contribution of ecotypic differentiation and plasticity in growth versus defence traits. Using reciprocal transplant-common gardens along steep elevation gradients, we evaluated patterns of ecotypic differentiation and phenotypic plasticity of two coexisting but unrelated plant species, Cardamine pratensis and Plantago major. For both species, we observed ecotypic differentiation accompanied by plasticity in growth related traits. Plants grew faster and produced more biomass when placed at low elevation. In contrast, we observed fixed ecotypic differentiation for defence and resistance traits. Generally, low elevation ecotypes produced higher chemical defences regardless of the growing elevation. Yet, some plasticity was observed for specific compounds, such as indole glucosinolates. We speculate that ecotypic differentiation in defence traits is maintained by costs of chemical defence production, while plasticity in growth traits is regulated by temperature driven growth response maximization.

ecology↗

bioRxiv2018

Molecular dissection of early defense signaling underlying volatile-mediated defense priming and herbivore resistance in rice

Herbivore-induced plant volatiles prime plant defenses and resistance. How volatiles are integrated into early defense signaling is not well understood. Furthermore, whether there is a causal relationship between volatile defense priming and herbivore resistance is unclear. Here, we investigated the impact of indole, a common herbivore-induced plant volatile and known defense priming cue, on early defense signaling and herbivore resistance in rice. We show that rice plants infested by Spodoptera frugiperda caterpillars release up to 25 ng*h-1. Exposure to equal doses of synthetic indole enhances rice resistance to S. frugiperda. Screening of early signaling components reveals that indole directly enhances the expression of the receptor like kinase OsLRR-RLK1. Furthermore, indole specifically primes the transcription, accumulation and activation of the mitogen-activated protein kinase OsMPK3 as well as the expression of the downstream WRKY transcription factor OsWRKY70 and several jasmonate biosynthesis genes, resulting in a higher accumulation of jasmonic acid (JA). Using transgenic plants defective in early signaling, we show that OsMPK3 is required, and that OsMPK6 and OsWRKY70 contribute to indole-mediated defense priming of JA-dependent herbivore resistance. We conclude that volatiles can increase herbivore resistance of plants by priming early defense signaling components.

plant biology↗

bioRxiv2017

Genotype, nitrogen and herbivory shape plant defense: the case of a vitamin-enriched maize

The cultivation of crops with novel traits could interfere with ecosystem services delivered by arthropods through bottom-up effects. Here we tested the hypothesis that a vitamin enriched maize (CarolightR) is similar in terms of plant-arthropod interactions to its wild type when compared in controlled environment and under field conditions. In order to assess the robustness of their equivalence we tested two nitrogen availability regimes. We used arthropod field abundance, the behavior and fitness of a keystone maize herbivore - the leafhopper Zyginidia scutellaris - and above ground chemistry of maize plants (volatile, hormone and metabolite profiling) as indicators of potential changes in plant-insect interactions. Nitrogen availability was the key driver of herbivore abundance and behavior, and determined direct and indirect chemical defense in maize plants. Both genotypes presented similar constitutive and inducible phytohormone profiles independently of the nitrogen regime. However, feeding by the herbivore suppressed the levels of JA-Ile and JA, without impairing the release of induced plant volatiles. CarolightR and M37W differed to some degree in the concentrations of phenolics (hydroxycinnamic acids and lignans) and in the abundance of a volatile compound. Overall the effect of maize genotype on the herbivores was smaller than the effect of nitrogen fertilization.\n\nHIGHLIGHTWe show the separate and interactive effects of nitrogen availability and genotype on the performance and behavior of a herbivore, and related these changes to constitutive and inducible maize defenses.

plant biology↗