Project description:Tomato plants are commonly attacked by herbivorous mites, including by generalist Tetranychus urticae and specialists Tetranychus evansi and Aculops lycopersici. Mite feeding induces plant defense responses that reduce mite performance. However, via poorly understood mechanisms, T. evansi and A. lycopersici suppress plant defenses and, consequently, maintain a high performance on tomato. Accordingly, on a shared host, non-adapted T. urticae can be facilitated by either of the specialist mites, likely via the suppression of plant defenses. To better understand defense suppression and indirect plant-mediated interactions between herbivorous mites, we used microarrays to analyze transcriptomic changes in tomato after attack by either a single mite species (T. urticae, T. evansi, A. lycopersici) or two species simultaneously (T. urticae plus T. evansi or T. urticae plus A. lycopersici). Additionally, we assessed mite-induced changes in defense-associated phytohormones using LC-MS/MS. Compared to non-infested controls, jasmonates (JAs) and salicylate (SA) accumulated to higher amounts upon all mite-infestation treatments, but lowest increases were detected after single infestations with defense-suppressors. Strikingly, whereas 8 to 10% of tomato genes was differentially expressed upon single infestations with T. urticae or A. lycopersici, only 0.1% was altered in T. evansi-infested plants. Transcriptome analysis of dual-infested leaves revealed that T. evansi dampened T. urticae-triggered host responses on a genome-wide scale, while A. lycopersici primarily suppressed T. urticae-induced JA defenses. Our results provide valuable new insights into the mechanisms underlying host defense suppression and the plant-mediated facilitation of competing herbivores.
Project description:Genome annotation of the chelicerate Tetranychus urticae revealed the absence of many canonical immunity genes. T. urticae either does not mount an immune response or it induces uncharacterized immune pathways. To disentangle these two hypotheses, we performed transcriptomic analysis of mites injected with bacteria vs mites injected with LB-buffer. Two types of bacteria were injected: E. coli and B. megaterium and transcriptomes were sampled 3, 6 and 12 hrs after injection. We found no consistent differential expression after bacterial infection, supporting the hypothesis that spider mites do not mount an immune response. We hypothesize that the apparent absence of inducable immunity pathways in T. urticae is a result of relaxed selective pressure due to ecological factors.
Project description:While performing mitochondrial isolations and recently developed tRNA-seq methods (AlkB treatment and YAMAT-Seq) in plant tissue, we inadvertently sequenced the mitochondrial tRNAs from a common plant pest, the acariform mite Tetranychus urticae, to a high enough coverage to detect all previously annotated T. urticae tRNA regions. The results not only confirm expression, CCA-tailing and post-transcriptional base modification of these highly divergent tRNAs, but also revealed paired sense and antisense expression of multiple T. urticae mitochondrial tRNAs.
Project description:Generalist arthropod herbivores rapidly adapt to a broad range of host plants. However, the extent of transcriptional reprogramming in the herbivore and its hosts associated with adaptation remains poorly understood. Using the spider mite Tetranychus urticae and tomato as models with available genomic resources, we investigated the reciprocal genome-wide transcriptional changes in both spider mite and tomato as a consequence of mite’s adaptation to tomato We used microarray to assess global gene expression in Solanum lycopersicum cv. Moneymaker upon Tetranychus urticae attack by tomato-adapted and non-adapted spider mite lines.
Project description:Investigating essential physiological processes in diapausing mites by analyzing genome wide gene expression changes using custom-built microarray. We investigated the molecular biology of facultative reproductive diapause in the chelicerate Tetranychus urticae (Acari: Tetranychidae) by analyzing genome-wide gene expression differences in diapausing and non diapausing T. urticae, using an Agilent custom-built two color gene expression microarray. Analysis of this dataset showed that a remarkable number, 11% of the total number of predicted T. urticae genes, were differentially expressed. Gene Ontology analysis revealed that many metabolic pathways were affected in diapausing females. Genes related to digestion and detoxification, cryo-protection, carotenoid synthesis and the organization of the cytoskeleton were profoundly influenced by the state of diapause. We also further confirmed the importance of horizontally transferred carotenoid synthesis genes in diapause and different color morphs of T. urticae. We made one comparison: diapausing mites (DIA) vs non-diapausing mites (NON-DIA), in 4 replicates. Both types of mites belonged to the T. urticae LS-VL strain. In this strain, approximately 30% of mites enter diapause under the experimental conditions applied. Hence, we were able to sample RNA of mites with similar genetic background that were reared under identical environmental conditions. The labeled cRNA samples were pooled and hybdrized to a custom Sureprint genome wide G3 Gene Expression 8x60K microarray. Data was normalized by Agilent Feature Extraction software (using protocol GE2_107_SEP09). Genespring software (Agilent technologies) was used for the statistical analysis of the data.
Project description:The extreme generalist two-spotted spider mite, Tetranychus urticae, which is documented to feed on more than 1100 plant hosts, is becoming an increasingly important agricultural pest. Historically, as studies of plant-herbivore interactions have focused largely on insects, considerably less research has investigated plant responses to spider mite herbivores, especially in grasses. To identify intraspecific differences in maize response to T. urticae, we collected RNA-seq data from three maize (Zea mays) inbred lines (B73, B75 and B49) as well as two F1 lines arising from crosses between B73 x B75 and B73 x B96. For each maize line, RNA-seq data was collected from uninfested leaves (control) and leaves infested with T. urticae for 24 hours.