Project description:In most aphid species, facultative parthenogenetic reproduction allows rapid growth and formation of large single-genotype colonies. Upon predator attack, individual aphids emit an alarm pheromone to warn the colony of this danger. (E)-beta-farnesene (EBF) is the predominant constituent of the alarm pheromone in Myzus persicae (green peach aphid) and many other aphid species. Continuous exposure to alarm pheromone in aphid colonies raised on transgenic Arabidopsis thaliana plants that produce EBF leads to habituation of the aphid population. Whereas naïve aphids are repelled by EBF, habituated aphids show no avoidance response. Individual aphids from the habituated colony can revert back to being EBF-sensitive in three generations, indicating that this behavioral change is not caused by a genetic mutation. Instead, DNA microarray experiments comparing gene expression in naïve and habituated aphids treated with EBF demonstrate an almost complete desensitization in the transcriptional response to EBF. Furthermore, EBF-responsive aphids, but not habituated aphids show significantly lower reproduction in the presence of EBF. Although both naïve and habituated aphids emit EBF upon damage, EBF-responsive aphids display a higher survival rate in the presence of coccinellid predators and thus outperform habituated aphids that do not show an avoidance response. These results provide direct evidence that aphid perception of conspecific alarm pheromone aids in predator avoidance and thereby bestows fitness benefits in survivorship and fecundity. Although habituated M. persicae have equal fecundity on control and EBF-producing plants, such transgenics may have practical applications in agriculture because of increased predation of habituated aphids. Log fold-changes (LogFC) were computed and contigs with P-values ≤ 0.05 were considered to be differentially expressed (see Supplementary file at foot of this record).
Project description:In most aphid species, facultative parthenogenetic reproduction allows rapid growth and formation of large single-genotype colonies. Upon predator attack, individual aphids emit an alarm pheromone to warn the colony of this danger. (E)-beta-farnesene (EBF) is the predominant constituent of the alarm pheromone in Myzus persicae (green peach aphid) and many other aphid species. Continuous exposure to alarm pheromone in aphid colonies raised on transgenic Arabidopsis thaliana plants that produce EBF leads to habituation of the aphid population. Whereas naïve aphids are repelled by EBF, habituated aphids show no avoidance response. Individual aphids from the habituated colony can revert back to being EBF-sensitive in three generations, indicating that this behavioral change is not caused by a genetic mutation. Instead, DNA microarray experiments comparing gene expression in naïve and habituated aphids treated with EBF demonstrate an almost complete desensitization in the transcriptional response to EBF. Furthermore, EBF-responsive aphids, but not habituated aphids show significantly lower reproduction in the presence of EBF. Although both naïve and habituated aphids emit EBF upon damage, EBF-responsive aphids display a higher survival rate in the presence of coccinellid predators and thus outperform habituated aphids that do not show an avoidance response. These results provide direct evidence that aphid perception of conspecific alarm pheromone aids in predator avoidance and thereby bestows fitness benefits in survivorship and fecundity. Although habituated M. persicae have equal fecundity on control and EBF-producing plants, such transgenics may have practical applications in agriculture because of increased predation of habituated aphids. Log fold-changes (LogFC) were computed and contigs with P-values ≤ 0.05 were considered to be differentially expressed (see Supplementary file at foot of this record). Agilent 8x15K array previously reported by Ramsey et al., 2007 - BMC Genomics 8: 243. Two-condition experiment using Alexa Fluor 555 and 647 dyes. Biological replicates: 4 control replicates, 4 treated replicates.
Project description:Aphids are phloem-feeding insects that cause yield loss on a wide range of crops, including cereals such as barley. While most aphid species are limited to one or few host species, some are able to reproduce on many plants belonging to different families. Interestingly, aphid probing-behaviour can be observed on both host and non-host species indicating that interactions take place at the molecular level that may impact host range. Here, we aimed to gain insight into the interaction of barley with aphid species differing in their ability to infest this crop by analysing transcriptional responses. First, we determined colonization efficiency, settlement, and probing behaviour for the aphid species Rhopalosiphum padi, Myzus persicae and Myzus cerasi, which defined host, poor-host and non-host interactions, respectively. Analyses of barley transcriptional responses revealed gene sets differentially regulated upon the different barley-aphid interactions and showed that the poor-host interaction with M. persicae resulted in the strongest deregulation of genes. Interestingly, we identified several thionin genes strongly up-regulated upon interaction with M. persicae, and to a lesser extend upon R. padi interaction. Ectopic expression of two of these genes in Nicotiana benthamiana reduced host susceptibility to M. persicae, indicating thionins contribute to defences against aphids.
Project description:Soybean aphid is one of the major limiting factors for soybean production. However, the mechanism for aphid resistance in soybean is remain enigmatic, very little information is available about the different mechanisms between antibiosis and antixenosis genotypes. Here we dissected aphid infestation into three stages and used genome-wide gene expression profiling to investigate the underlying aphid-plant interaction mechanisms. Approximately 990 million raw reads in total were obtained, the high expression correlation in each genotype between infestation and non-infestation indicated that the response to aphid was controlled by a small subset of important genes. Moreover, plant response to aphid infestation was more rapid in resistant genotypes. Among the differentially expressed genes (DEGs), a total of 901 transcription factor (TF) genes categorized to 40 families were identified with distinct expression patterns, of which AP2/ERF, MYB and WRKY families were proposed to playing dominated roles. Gene expression profiling demonstrated that these genes had either similar or distinct expression patterns in genotypes. Besides, JA-responsive pathway was domination in aphid-soybean interaction compared to SA pathway, which was not involved plant response to aphid in susceptible and antixenotic genotypes but played an important role in antibiosis one. Throughout, callose were deposited in all genotypes but it was more rapidly and efficiently in antibiotic one. However, reactive oxygen species were not involved in response to aphid attack in resistant genotypes during aphid infestation. Our study helps uncover important genes associated with aphid-attack response in antibiosis and antixenotic genotypes of soybean.
Project description:Background: Aphids are economically important pests and that display exceptional variation in host range. The underlying mechanism of diverse aphid host ranges are not well understood, but it is likely that molecular interactions are involved. With significant progress being made towards understanding host responses upon aphid attack, the mechanisms underlying nonhost resistance remain to be elucidated. Here, we investigated and compared Arabidopsis host and nonhost responses to aphids at the transcriptome level using three different aphid species. Results: Gene expression analyses revealed a surprising level of overlap in the overall gene expression changes during host and nonhost interactions with regards to the sets of genes differentially expressed and the direction of expression changes. Despite the overlap in transcriptional responses across interactions, there was a stronger repression of genes involved in metabolism and oxidative responses specifically during the host interaction. In addition we indentified a set of genes with opposite gene expression patterns during host versus nonhost interactions. Aphid performance assays on Arabidopsis mutants selected based on our transcriptome analyses identified genes involved in host and nonhost interactions. Conclusions: Understanding how plants respond to aphid species that differ in their ability to infest plant species, and identifying the genes and signaling pathways involved, is essential for the development of novel and durable aphid control in crop plants. Our work is an important step forward to provide such essential insights in that we identified novel genes contributing to host susceptibility, host defences as well nonhost resistance to aphids.
Project description:Comparison of social dominance phenotypes induced in the cichlid A. burtoni females with the goal of comparing to other gene expression profiles of social dominance Used platform GPL928 In many species, under varying ecological conditions, social interactions among individuals result in the formation dominance hierarchies. Despite general similarities, there are substantial differences across species, populations, environments, life stages, sexes, and individuals. Understanding the proximate mechanisms of this variation is an important step toward understanding the evolution of social behavior. However, physiological changes associated with dominance such as gonadal maturation and somatic growth, often complicate efforts to identify the specific underlying mechanisms. We demonstrate complementary analysis tools to allow a comparative approach to high-throughput expression profiling that allow us to both test a priori hypotheses and generate new hypotheses about the mechanisms and evolution of social dominance. Using experimental manipulation to produce female dominance hierarchies in the cichlid A. burtoni, heralded as a genomic model of social dominance, we generate gene lists, and assess molecular gene modules. We demonstrate a general pattern of “masculinization” of the female neural gene expression profile and compare expression biases between male and female dominance hierarchies. Using a threshold-free approach to identify correlation throughout gene ranked lists, we query previously published datasets from maternal behavior, alternative reproductive tactics, cooperative breeding and sex-role reversal to describe correlations among neural gene expression profiles. These complementary approaches capitalize on the high-throughput gene expression profiling from similar behavioral phenotypes in order to address the mechanism associated with social dominance behavioral phenotypes.
Project description:DNA methylation is an important chromatin modification that is necessary for the structural integrity and proper regulation of the genome for many species. Despite its conservation across the tree of life, little is known about its contribution to complex traits. Reports that differences in DNA methylation between castes in closely related Hymenopteran insects (ants, bees and wasps) contributes to social behaviors has generated hypotheses on the role of DNA methylation in governing social behavior. However, social behavior has evolved multiple times across insecta, and a common role of DNA methylation in social behavior remains outstanding. Using phylogenetic comparative methods we sought to better understand patterns of DNA methylation and social behavior across insects. DNA methylation can be found in social and solitary insects from all orders, except Diptera (flies), which suggests a shared loss of DNA methylation within this order. The lack of DNA methylation is reflected in the absence of the maintenance and de novo DNA methyltransferases (DNMT) 1 and 3, respectively. Interestingly, DNA methylation is found in species without DNMT3. DNA methylation and social behavior (social/solitary) or with division of labor (caste+/caste–) for 123 insect species analyzed from 11 orders are not evolutionary dependent, which is further supported by sequencing of DNA methylomes from 40 species.
Project description:A major goal of molecular evolutionary biology is to understand the fate and consequences of duplicated genes. In this context, aphids are particularly intriguing because the newly sequenced pea aphid genome is characterized by extraordinarily high levels of lineage-specific gene duplication relative to other insect genomes. While analyzing the results of a microarray comparing gene expression between male, sexual female and asexual female Myzus persicae aphids, we unexpectedly found duplicated nutrient amino acid transporters highly upregulated in males. These transporters, homologous to the Drosophila slimfast, belong to an aphid-specific gene family expansion in which other paralogs are thought to have functionally diverged to fill a role in mediating interactions between aphids and their nutrititonally required bacterial symbiont. The lack of a known male role for slimfast in other insects suggests that aphid slimfast paralogs have been retained as a result of functional divergence to fill multiple novel functional roles in symbiosis and in males.
Project description:Social experience influences multiple behaviors of many animal species, including aggression. Social isolation often increases aggressiveness. To investigater the molecular basis of social influences on aggressiveness, we performed comparative gene expression profiling on heads from 6-day-old, single-housed, more aggressive and group-housed, less aggressive male flies. Keywords: social experience