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Author

Georgios Valsamakis

Bio: Georgios Valsamakis is an academic researcher from Free University of Berlin. The author has contributed to research in topics: Pieris brassicae & Hatching. The author has an hindex of 2, co-authored 3 publications receiving 18 citations.
Topics: Pieris brassicae, Hatching, Elicitor, Camalexin

Papers
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Journal ArticleDOI
TL;DR: It is concluded that glandular secretions rather than egg-associated microbes act in a dose-dependent manner as elicitor of the egg-mediated enhancement of the plant's defence against insect larvae.
Abstract: Plants can enhance their defence against herbivorous insects by responding to insect egg depositions preceding larval feeding. The similarity of plant responses to insect eggs with those to phytopathogens gave rise to the hypothesis that egg-associated microbes might act as elicitors. We tested this hypothesis by investigating first if elimination of microbes in the butterfly Pieris brassicae changes the responses of Brassica nigra and Arabidopsis thaliana to eggs and larvae of this insect species. An antibiotic treatment of butterflies mitigated the plant transcriptional response to the eggs and the egg-mediated enhancement of the plant's defence against larvae. However, application of cultivated microbial isolates from the eggs onto Arabidopsis thaliana did not enhance the plant's anti-herbivore defence. Instead, application of an egg-associated glandular secretion, which is attaching the eggs to the leaves, elicited the enhancing effect on the plant's defence against larvae. However, this effect was only achieved when the secretion was applied in similar quantities as released by control butterflies, but not when applied in the reduced quantity as released by antibiotic-treated butterflies. We conclude that glandular secretions rather than egg-associated microbes act in a dose-dependent manner as elicitor of the egg-mediated enhancement of the plant's defence against insect larvae.

19 citations

Journal ArticleDOI
TL;DR: The results show that larvae gained less biomass the longer the eggs had previously been on the plant, and Arabidopsis thaliana adjusts the kinetics of its egg-primed response to the time point of larval hatching, ensuring that the plant is optimally prepared just in time prior to larvals hatching.
Abstract: Plants can respond to eggs laid by herbivorous insects on their leaves by preparing (priming) their defense against the hatching larvae. Egg-mediated priming of defense is known for several plant species, including Brassicaceae. However, it is unknown yet for how long the eggs need to remain on a plant until a primed defense state is reached, which is ecologically manifested by reduced performance of the hatching larvae. To address this question, we used Arabidopsis thaliana, which carried eggs of the butterfly Pieris brassicae for 1-6 days prior to exposure to larval feeding. Our results show that larvae gained less biomass the longer the eggs had previously been on the plant. The strongest priming effect was obtained when eggs had been on the plant for 5 or 6 days, i.e., for (almost) the entire development time of the Pieris embryo inside the egg until larval hatching. Transcript levels of priming-responsive genes, levels of jasmonic acid-isoleucine (JA-Ile), and of the egg-inducible phytoalexin camalexin increased with the egg exposure time. Larval performance studies on mutant plants revealed that camalexin is dispensable for anti-herbivore defense against P. brassicae larvae, whereas JA-Ile - in concert with egg-induced salicylic acid (SA) - seems to be important for signaling egg-mediated primed defense. Thus, A. thaliana adjusts the kinetics of its egg-primed response to the time point of larval hatching. Hence, the plant is optimally prepared just in time prior to larval hatching.

16 citations

Journal ArticleDOI
TL;DR: This work aimed to elucidate whether the DNA extraction kit and bacteria therein affect the characterization of bacterial communities associated with butterfly samples harbouring different bacterial abundancies.
Abstract: Aims We aimed to elucidate whether the DNA extraction kit and bacteria therein affect the characterization of bacterial communities associated with butterfly samples harbouring different bacterial abundancies. Methods and results We analysed bacteria associated with eggs of Pieris brassicae and with adults of this butterfly, which were either untreated or treated with antibiotics (ABs). Three DNA extraction kits were used. Regardless of the extraction kit used, PCR amplification of the bacterial 16S rRNA gene detected very low bacterial presence in eggs and AB-treated butterflies. In untreated butterflies, bacterial signal intensity varied according to the kit and primers used. Sequencing (MiSeq) of the bacterial communities in untreated and AB-treated butterflies revealed a low alpha diversity in untreated butterflies because of the dominance of few bacteria genera, which were detectable regardless of the kit. However, a significantly greater alpha diversity was found in AB-treated butterflies, evidencing a true bias of the results due to bacterial contaminants in the kit. Conclusions The so-called 'kitome' can impact the profiling of Lepidoptera-associated bacteria in samples with low bacterial biomass. Significance and impact of the study Our study highlights the necessity of method testing and analysis of negative controls when investigating Lepidoptera-associated bacterial communities.

6 citations


Cited by
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Journal ArticleDOI
TL;DR: This review focuses on the machinery of herbivory-sensing and on cellular and systemic/airborne signaling via elicitors, exemplified by the model case of interactions between Arabidopsis hosts and moths of the genus Spodoptera.

26 citations

Journal ArticleDOI
TL;DR: The findings suggest that the plants’ egg‐killing trait is a new front on the evolutionary arms‐race between Brassicaceae and pierid butterflies beyond the well‐studied plant toxins that have evolved against their caterpillars.
Abstract: Evolutionary arms-races between plants and insect herbivores have long been proposed to generate key innovations such as plant toxins and detoxification mechanisms that can drive diversification of the interacting species. A novel front-line of plant defence is the killing of herbivorous insect eggs. We test whether an egg-killing plant trait has an evolutionary basis in such a plant-insect arms-race. Within the crucifer family (Brassicaceae), some species express a hypersensitive response (HR)-like necrosis underneath butterfly eggs (Pieridae) that leads to eggs desiccating or falling off the plant. We studied the phylogenetic distribution of this trait, its egg-killing effect on and elicitation by butterflies, by screening 31 Brassicales species, and nine Pieridae species. We show a clade-specific induction of strong, egg-killing HR-like necrosis mainly in species of the Brassiceae tribe including Brassica crops and close relatives. The necrosis is strongly elicited by pierid butterflies that are specialists of crucifers. Furthermore, HR-like necrosis is linked to PR1 defence gene expression, accumulation of reactive oxygen species and cell death, eventually leading to egg-killing. Our findings suggest that the plants' egg-killing trait is a new front on the evolutionary arms-race between Brassicaceae and pierid butterflies beyond the well-studied plant toxins that have evolved against their caterpillars.

24 citations

Book ChapterDOI
01 Jan 2020
TL;DR: An order by order update of symbioses across herbivorous insects is provided, particularly focusing on recent published evidence, and on how symbionts interact with the defensive system of the plant.
Abstract: Microbes play crucial roles in the biology of herbivorous insects, and the last decade has provided exciting new evidence for a prominent role of microbial symbiosis in detoxification of plant toxins, manipulation of plant defences and defence against natural enemies. We provide an order by order update of symbioses across herbivorous insects, particularly focusing on recent published evidence, and on how symbionts interact with the defensive system of the plant. While the hemimetabolous Hemiptera order largely relies on obligatory microbial symbioses, we did not find such a close relationship between symbionts and hosts in the other three orders Orthoptera, Phasmatodea and Thysanoptera. These three orders mostly harbour transient gut symbionts and/or rely on laterally transferred genes from microbes. Despite the radical changes and harsh conditions during metamorphosis, numerous holometabolous species transmit symbionts vertically and show close associations with both intra- and extracellular symbionts. The last section of this book chapter discusses the role that symbionts will play in future scenarios of global warming, but also their implications for the transmission of plant viruses and modern agriculture.

19 citations

Journal ArticleDOI
TL;DR: It is shown that disturbance of the bacterial community in parental butterflies by an antibiotic treatment has a detrimental effect on those offspring larvae feeding on a different host plant than their parents, which shapes how the offspring individuals can adjust themselves to a novel host plant.
Abstract: An insect's phenotype can be influenced by the experiences of the parental generation. However, the effects of the parental symbiotic microbiome and host plant use on the offspring are unclear. We addressed this gap of knowledge by studying Pieris brassicae, a multivoltine butterfly species feeding on different brassicaceous plants across generations. We investigated how disturbance of the parental bacterial community by antibiotic treatment affects F1 larval traits. We tested the effects depending on whether F1 larvae are feeding on the same plant species as their parents or on a different one. The parental treatment alone had no impact on the biomass of F1 larvae feeding on the parental plant species. However, the parental treatment had a detrimental effect on F1 larval biomass when F1 larvae had a different host plant than their parents. This effect was linked to higher larval prophenoloxidase activity and greater downregulation of the major allergen gene (MA), a glucosinolate detoxification gene of P. brassicae Bacterial abundance in untreated adult parents was high, while it was very low in F1 larvae from either parental type, and thus unlikely to directly influence larval traits. Our results suggest that transgenerational effects of the parental microbiome on the offspring's phenotype become evident when the offspring is exposed to a transgenerational host plant shift.IMPORTANCE Resident bacterial communities are almost absent in larvae of butterflies and thus are unlikely to affect their host. In contrast, adult butterflies contain conspicuous amounts of bacteria. While the host plant and immune state of adult parental butterflies are known to affect offspring traits, it has been unclear whether also the parental microbiome imposes direct effects on the offspring. Here, we show that disturbance of the bacterial community in parental butterflies by an antibiotic treatment has a detrimental effect on those offspring larvae feeding on a different host plant than their parents. Hence, the study indicates that disturbance of an insect's parental microbiome by an antibiotic treatment shapes how the offspring individuals can adjust themselves to a novel host plant.

18 citations

Journal ArticleDOI
TL;DR: The results show that larvae gained less biomass the longer the eggs had previously been on the plant, and Arabidopsis thaliana adjusts the kinetics of its egg-primed response to the time point of larval hatching, ensuring that the plant is optimally prepared just in time prior to larvals hatching.
Abstract: Plants can respond to eggs laid by herbivorous insects on their leaves by preparing (priming) their defense against the hatching larvae. Egg-mediated priming of defense is known for several plant species, including Brassicaceae. However, it is unknown yet for how long the eggs need to remain on a plant until a primed defense state is reached, which is ecologically manifested by reduced performance of the hatching larvae. To address this question, we used Arabidopsis thaliana, which carried eggs of the butterfly Pieris brassicae for 1-6 days prior to exposure to larval feeding. Our results show that larvae gained less biomass the longer the eggs had previously been on the plant. The strongest priming effect was obtained when eggs had been on the plant for 5 or 6 days, i.e., for (almost) the entire development time of the Pieris embryo inside the egg until larval hatching. Transcript levels of priming-responsive genes, levels of jasmonic acid-isoleucine (JA-Ile), and of the egg-inducible phytoalexin camalexin increased with the egg exposure time. Larval performance studies on mutant plants revealed that camalexin is dispensable for anti-herbivore defense against P. brassicae larvae, whereas JA-Ile - in concert with egg-induced salicylic acid (SA) - seems to be important for signaling egg-mediated primed defense. Thus, A. thaliana adjusts the kinetics of its egg-primed response to the time point of larval hatching. Hence, the plant is optimally prepared just in time prior to larval hatching.

16 citations