15 research outputs found
Pre-exposure of Arabidopsis to the abiotic or biotic environmental stimuli "chilling" or "insect eggs" exhibits different transcriptomic responses to herbivory
Plants can retain information about environmental stress and thus, prepare
themselves for impending stress. In nature, it happens that environmental
stimuli like âcoldâ and âinsect egg depositionâ precede insect herbivory. Both
these stimuli are known to elicit transcriptomic changes in Arabidposis
thaliana. It is unknown, however, whether they affect the plantâs anti-
herbivore defence and feeding-induced transcriptome when they end prior to
herbivory. Here we investigated the transcriptomic response of Arabidopsis to
feeding by Pieris brassicae larvae after prior exposure to cold or
oviposition. The transcriptome of plants that experienced a five-day-chilling
period (4â°C) was not fully reset to the pre-chilling state after
deacclimation (20â°C) for one day and responded differently to herbivory than
that of chilling-inexperienced plants. In contrast, when after a five-day-
lasting oviposition period the eggs were removed, one day later the
transcriptome and, consistently, also its response to herbivory resembled that
of egg-free plants. Larval performance was unaffected by previous exposure of
plants to cold and to eggs, thus indicating P. brassicae tolerance to cold-
mediated plant transcriptomic changes. Our results show strong differences in
the persistence of the plantâs transcriptomic state after removal of different
environmental cues, and consequently differential effects on the
transcriptomic response to later herbivory
Egg Laying of Cabbage White Butterfly (Pieris brassicae) on Arabidopsis thaliana Affects Subsequent Performance of the Larvae
Plant resistance to the feeding by herbivorous insects has recently been found
to be positively or negatively influenced by prior egg deposition. Here we
show how crucial it is to conduct experiments on plant responses to herbivory
under conditions that simulate natural insect behaviour. We used a well-
studied plant â herbivore system, Arabidopsis thaliana and the cabbage white
butterfly Pieris brassicae, testing the effects of naturally laid eggs (rather
than egg extracts) and allowing larvae to feed gregariously as they do
naturally (rather than placing single larvae on plants). Under natural
conditions, newly hatched larvae start feeding on their egg shells before they
consume leaf tissue, but access to egg shells had no effect on subsequent
larval performance in our experiments. However, young larvae feeding
gregariously on leaves previously laden with eggs caused less feeding damage,
gained less weight during the first 2 days, and suffered twice as high a
mortality until pupation compared to larvae feeding on plants that had never
had eggs. The concentration of the major anti-herbivore defences of A.
thaliana, the glucosinolates, was not significantly increased by oviposition,
but the amount of the most abundant member of this class,
4-methylsulfinylbutyl glucosinolate was 1.8-fold lower in larval-damaged
leaves with prior egg deposition compared to damaged leaves that had never had
eggs. There were also few significant changes in the transcript levels of
glucosinolate metabolic genes, except that egg deposition suppressed the
feeding-induced up-regulation of FMOGS-OX2, a gene encoding a flavin
monooxygenase involved in the last step of 4-methylsulfinylbutyl glucosinolate
biosynthesis. Hence, our study demonstrates that oviposition does increase A.
thaliana resistance to feeding by subsequently hatching larvae, but this
cannot be attributed simply to changes in glucosinolate content
The Chemistry of the Postpharyngeal Gland of Female European Beewolves
Females of the European beewolf, Philanthus triangulum, possess a large glove-shaped gland in the head, the postpharyngeal gland (PPG). They apply the content of the PPG to their prey, paralyzed honeybees, where it delays fungal infestation. Here, we describe the chemical composition of the gland by using combined GC-MS, GC-FTIR, and derivatization. The PPG of beewolves contains mainly long-chain unsaturated hydrocarbons (C23âC33), lower amounts of saturated hydrocarbons (C14âC33), and minor amounts of methyl-branched hydrocarbons (C17âC31). Additionally, the hexane-soluble gland content is comprised of small amounts of an unsaturated C25 alcohol, an unknown sesquiterpene, an octadecenylmethylester, and several long-chain saturated (C25, C27) and unsaturated (C23âC27) ketones, some of which have not yet been reported as natural products. Surprisingly, we found a dimorphism with regard to the major component of the PPG with some females having (Z)-9-pentacosene, whereas others have (Z)-9-heptacosene as their predominant component. The biological relevance of the compounds for the prevention of fungal growth on the prey and the significance of the chemical dimorphism are discussed
Data from: Phenotypic plasticity of mate recognition systems prevents sexual interference between two sympatric leaf beetle species
Maladaptive sexual interactions among heterospecific individuals (sexual interference) can prevent the coexistence of animal species. Thus, the avoidance of sexual interference by divergence of mate recognition systems is crucial for a stable coexistence in sympatry. Mate recognition systems are thought to be under tight genetic control. However, we demonstrate that mate recognition systems of two closely related sympatric leaf beetle species show a high level of host-induced phenotypic plasticity. Mate choice in the mustard leaf beetles, Phaedon cochleariae and P. armoraciae, is mediated by cuticular hydrocarbons (CHCs). Divergent host plant use causes a divergence of CHC phenotypes, whereas similar host use leads to their convergence. Consequently, both species exhibit significant behavioral isolation when they feed on alternative host species, but mate randomly when using a common host. Thus, sexual interference between these syntopic leaf beetles is prevented by host-induced phenotypic plasticity rather than by genotypic divergence of mate recognition systems
Cuticular hydrocarbon phenotypes of indivudual Phaedon beetles
Relative composition of cuticular hydrocarbons (% total peak area) of individual 21-d-old beetles of Phaedon cochleariae and P. armoraciae. Beetles were either reared on their native host plant species or on Brassica rapa ssp. pekinensis
Divergence of cuticular hydrocarbons in two sympatric grasshopper species and the evolution of fatty acid synthases and elongases across insects
Cuticular hydrocarbons (CHCs) play a major role in the evolution of
reproductive isolation between insect species. The CHC profiles of two closely
related sympatric grasshopper species, Chorthippus biguttulus and C. mollis,
differ mainly in the position of the first methyl group in major methyl-
branched CHCs. The position of methyl branches is determined either by a fatty
acid synthase (FAS) or by elongases. Both protein families showed an expansion
in insects. Interestingly, the FAS family showed several lineage-specific
expansions, especially in insect orders with highly diverse methyl-branched
CHC profiles. We found five putative FASs and 12 putative elongases in the
reference transcriptomes for both species. A dN/dS test showed no evidence for
positive selection acting on FASs and elongases in these grasshoppers.
However, one candidate FAS showed species-specific transcriptional differences
and may contribute to the shift of the methyl-branch position between the
species. In addition, transcript levels of four elongases were expressed
differentially between the sexes. Our study indicates that complex methyl-
branched CHC profiles are linked to an expansion of FASs genes, but that
species differences can also mediated at the transcriptional level
Data from: Divergence of cuticular hydrocarbons in two sympatric grasshopper species and the evolution of fatty acid synthases and elongases across insects
Cuticular hydrocarbons (CHCs) play a major role in the evolution of reproductive isolation between insect species. The CHC profiles of two closely related sympatric grasshopper species, Chorthippus biguttulus and C. mollis, differ mainly in the position of the first methyl group in major methyl-branched CHCs. The position of methyl branches is determined either by a fatty acid synthase (FAS) or by elongases. Both protein families showed an expansion in insects. Interestingly, the FAS family showed several lineage-specific expansions, especially in insect orders with highly diverse methyl-branched CHC profiles. We found five putative FASs and 12 putative elongases in the reference transcriptomes for both species. A dN/dS test showed no evidence for positive selection acting on FASs and elongases in these grasshoppers. However, one candidate FAS showed species-specific transcriptional differences and may contribute to the shift of the methyl-branch position between the species. In addition, transcript levels of four elongases were expressed differentially between the sexes. Our study indicates that complex methyl-branched CHC profiles are linked to an expansion of FASs genes, but that species differences can also mediated at the transcriptional level
Count matrix DE analysis with sra accession numbers
Count matrix DE analysis with sra accession number
Effects of prior egg deposition and egg shell consumption (a typical behaviour of neonate larvae) on larval performance (means ± SE) of <i>Pieris brassicae</i> on <i>Arabidopsis thaliana</i> Col-0 plants<sup>1</sup> (for statistics, see Table 2).
1<p>Batches of 40 freshly hatched larvae either fed upon a plant with prior <i>P. brassicae</i> egg deposition (Egg) or without any eggs (Control) until they were 4 days old; thereafter, batches of 10 larvae where transferred to fresh, undamaged egg-free plants, where they completed their development until pupation. <sup>2</sup> Larvae were allowed to feed upon their egg shells. <sup>3</sup> Larvae were prevented from feeding upon their egg shells during the first 2 days after hatching. <sup>4</sup> Number of batches of larvae (1 batch per plant; <i>N</i>â=â8 for freshly hatched larvae; <i>N</i> â=â initially 4 for elder larvae).</p