Project description:To characterize the PTI response of tomato and the effect of the delivery of a subset of effectors, we performed an RNA-seq analysis of tomato Rio Grande prf3 leaves challenged with either the flgII-28 peptide or the following bacterial strains: Agrobacterium tumefaciens GV2260, Pseudomonas fluorescens 55, Pseudomonas putida KT2440, Pseudomonas syringae pv. tomato (Pst) DC3000, Pst DC3000 deltahrcQ-U deltafliC and Pst DC3000 deltaavrPto deltaavrPtoB. NOTE: Samples in SRA were assigned the same sample accession. This is incorrect as there are different samples, hence âSource Nameâ was replaced with new values. Comment[ENA_SAMPLE] contains the original SRA sample accessions.
Project description:Plants are attacked by diverse herbivores and respond with manifold defense responses. To study transcriptional and other early regulation events of these plant responses, herbivory is often mimicked to standardize the temporal and spatial dynamics that vary tremendously for natural herbivory. Yet to what extent such mimics of herbivory are able to elicit the same plant response as real herbivory remains largely undetermined. We examined the transcriptional response of a new model plant to herbivory by a lepidopteran larva and to a commonly used herbivory mimic by applying the larvae’s oral secretions to standardized wounds. We designed a microarray for Solanum dulcamara and showed that the transcriptional response to real and to simulated herbivory by Spodoptera exigua overlapped moderately by about 40%. Interestingly, certain responses were mimicked better than others; 60% of the genes up-regulated but not even a quarter of the genes down-regulated by herbivory were similarly affected by application of oral secretions to wounds. While the regulation of genes involved in signaling, defense and water stress were mirrored well by the herbivory mimic, most of the genes related to photosynthesis, carbohydrate- and lipid metabolism were exclusively regulated by real herbivory. Thus, wounding and elicitor application decently mimics herbivory-induced defense responses but likely not the re-allocation of primary metabolites induced by real herbivory.
Project description:In plants, an increase in resource allocation to growth (primary metabolism) associated with the presence of neighbors is likely to reduce defense-related production (secondary metabolism), making plants more vulnerable to herbivory. Even though there is increasing evidence supporting this “trade-off hypothesis”, the underlying mechanisms are still unclear. Far red (FR) radiation reflected from plant tissues serves as an early warning signal of future competition, triggering a suite of plastic morphological adjustments that improve plant’s ability to compete for light in crowded populations. Recent evidence from our lab showed that, when competition signals are present, plant defenses are severely reduced. Besides direct effects of herbivory and competition signals on target plants, second order effects occurs on neighboring plants through plant volatiles (PVs) communication. PVs play a key role in plant-plant and plant-insect interactions, changing its content and composition in response to environmental conditions. To increase our understanding of the molecular mechanisms underlying those interacting signaling webs, we performed a field study with tomato plants (cv Moneymaker), in which plants of EMITTER plots (six plants plot-1) were subjected to herbivory (nine larvae of Spodoptera eridania plant-1) and competition signals (increased FR radiation) in a factorial design. Light treatment started 28 days after sowing (DAS), and herbivory treatment and volatiles conduction started 34 DAS. Volatiles were conducted from EMITTER to RECEIVER plots (five plants plot-1) using a 5 inch, 1.4 m long tube fitted with a computer-type fan. 40 and 45 DAS, larval performance was measured on EMITTER plots as well as naturally-occurring insect colonization on RECEIVER plots. Finally (46 DAS), samples for bulk phenolic content were taken on every plot, and plant material from 4th and 5th leaves was collected for microarray analysis. There were three real biological replicates. Keywords: Reference design