Project description:Plants defend themselves against herbivores by activating a plethora of genetic and biochemical mechanisms aimed at reducing plant damage and insect survival. The short-term plant response to insect attack is well understood, but less is known about the maintenance of this response over time. We performed transcriptomic and metabolomics analyses in order to identify genes and metabolites involved in the long-term response of maize to attack by the corn borer Sesamina nonagrioides. To determine the role of elicitors present in caterpillar secretions, we also evaluated the response of maize stem challenged with insect regurgitates. The integrative analysis of the omics results revealed that the long-term response in maize is characterized by repression of the primary metabolism and a strong redox response, mainly mediated by germin-like proteins to produce anti-nutritive and toxic compounds that reduce insect viability, and with the glutathione–ascorbate cycle being crucial to minimize the adverse effects of reactive oxygen species (ROS) on the plant. Our results suggest that different defense mechanisms are involved in the long-term response compared to those reported during the early response. We also observed a marginal effect of the caterpillar regurgitates on the long-term defensive response.
Project description:Plants defend themselves against herbivores by activating a plethora of genetic and biochemical mechanisms aimed at reducing plant damage and insect survival. The short-term plant response to insect attack is well understood, but less is known about the maintenance of this response over time. We performed transcriptomic and metabolomics analyses in order to identify genes and metabolites involved in the long-term response of maize to attack by the corn borer Sesamina nonagrioides. To determine the role of elicitors present in caterpillar secretions, we also evaluated the response of maize stem challenged with insect regurgitates. The integrative analysis of the omics results revealed that the long-term response in maize is characterized by repression of the primary metabolism and a strong redox response, mainly mediated by germin-like proteins to produce anti-nutritive and toxic compounds that reduce insect viability, and with the glutathione–ascorbate cycle being crucial to minimize the adverse effects of reactive oxygen species (ROS) on the plant. Our results suggest that different defense mechanisms are involved in the long-term response compared to those reported during the early response. We also observed a marginal effect of the caterpillar regurgitates on the long-term defensive response.
Project description:The metabolome of a cell is the integration point of an organism's environment, genetics, and gene expression pattern. The metabolic phenotype can be under selection and is known to contribute to adaption. However, the metabolome's inherent networked and convoluted nature makes relating mutations, metabolic changes, and effects on fitness challenging. To overcome this challenge, we use the Long Term Evolution Experiment (LTEE) as a model to understand how mutations can transduce themselves through a cellular network, eventually affecting metabolism and perhaps fitness. We used mass-spectropscopy to broadly survey the metabolomes of both ancestors and all 12 evolved lines and combined this with genomic and expression data to suggest how mutations that alter specific reaction pathways, such as the biosynthesis of nicotinamide adenine dinucleotide, might increase fitness in the system. Our work brings the field closer to a complete genotype-phenotype map for the LTEE and a better understanding of how mutations might affect fitness through the metabolome. We used mass-spectroscopy to profile metabolic changes in the Long Term Evolution Experiment and link these change to upstream changes in gene expression and mutations.
Project description:Managing production environments in ways that promote weed community diversity may enhance both crop production and the development of a more sustainable agriculture. This study analyzed data of productivity of maize (corn) and soybean in plots in the Main Cropping System Experiment (MCSE) at the W. K. Kellogg Biological Station Long-Term Ecological Research (KBS-LTER) in Michigan, USA, from 1996 to 2011. We used models derived from population ecology to explore how weed diversity, temperature, and precipitation interact with crop yields. Using three types of models that considered internal and external (climate and weeds) factors, with additive or non-linear variants, we found that changes in weed diversity were associated with changes in rates of crop yield increase over time for both maize and soybeans. The intrinsic capacity for soybean yield increase in response to the environment was greater under more diverse weed communities. Soybean production risks were greatest in the least weed diverse systems, in which each weed species lost was associated with progressively greater crop yield losses. Managing for weed community diversity, while suppressing dominant, highly competitive weeds, may be a helpful strategy for supporting long term increases in soybean productivity. In maize, there was a negative and non-additive response of yields to the interaction between weed diversity and minimum air temperatures. When cold temperatures constrained potential maize productivity through limited resources, negative interactions with weed diversity became more pronounced. We suggest that: (1) maize was less competitive in cold years allowing higher weed diversity and the dominance of some weed species; or (2) that cold years resulted in increased weed richness and prevalence of competitive weeds, thus reducing crop yields. Therefore, we propose to control dominant weed species especially in the years of low yield and extreme minimum temperatures to improve maize yields. Results of our study indicate that through the proactive management of weed diversity, it may be possible to promote both high productivity of crops and environmental sustainability.
Project description:We used microarrays to study the evolution of gene expression in two bacterial ecotypes that coexisted for more than 35000 generations of experimental evolution in an extremely simple environment We sampled four clones from each of two lineages at generations 6,500, 17,000 and 40,000 from the polymorphic Ara-2 population of the E. coli long-term evolution experiment. The four clones from each lineage and generation were mixed equally and used for global expression profiling, growth assays and competition experiments. Global expression profiles and growth assays were also performed on the ancestral strain. RNA extractions were done using cells in mid-exponential growth in the same glucose-limited minimal medium used in the evolution experiment. Global expression profiles were obtained by using Affymetrix arrays, with 5 or 6 biological replicates for each lineage-generation sample.
Project description:Variation in transciptomic patterns between shallow and mesophotic corals was assessed using tag-based RNA-Seq (Tag-Seq) through analysis of natural populations across four regions in the Gulf of Mexico. Additionally, colonies were fate-tracked and repeatedly sampled to assess changes in gene expression through time in a transplant experiment between shallow and mesophotic depth zones at West and East Flower Garden Banks. This repository contains the raw .fastq.gz files for all sequenced samples.
Project description:Endogenous small RNAs (sRNAs) contribute to gene regulation and genome homeostasis but their activities and functions are incompletely known. The maize genome has a high number of transposable elements (TEs; almost 85%), some of which spawn abundant sRNAs. We performed sRNA and total RNA sequencing from control and abiotically stressed B73 wild-type (wt) plants and rmr6-1 mutants. RMR6 encodes the largest subunit of the RNA polymerase IV (Pol IV) complex, and is responsible for accumulation of most 24 nucleotide (nt) small interfering RNA (siRNAs). We identified novel MIRNA loci and verified miR399 target conservation in maize. RMR6-dependent 23-24 nt siRNA loci were specifically enriched in the upstream region of the most highly expressed genes. Most genes mis-regulated in rmr6-1 did not show a significant correlation with loss of flanking siRNAs, but we identified one gene supporting existing models of direct gene regulation by TE-derived siRNAs. Long-term drought correlated with changes of miRNA and sRNA accumulation, in particular inducing down-regulation of a set of sRNA loci in the wt leaf. sRNA profile of maize leaf and shoot apical meristematic area, of wt and rmr6-1 mutant plants grown under 1) control conditions 2) salt stress 3) drought stress 4) salt+drought stress. Each condition was replicated two/three times, after 10 days of treatment and after 7 days of recovery.