Project description:Arabidopsis thaliana plants were infested i) with sucking insect herbivores (the generalist aphid Myzus persicae and the specialist aphid Brevicoryne brassicae), ii) with chewing insect herbivores (generalist caterpillars of Spodoptera exigua and specialist caterpillars of Pieris rapae) or iii) were treated by wounding. For each treatment, rosette leaves were harvested at two time points (6h and 24h) after removal of insects. For chewing herbivores and wounding both local, i.e. immediately damaged leaves, and systemic, i.e. undamaged leaves from the same plant, were collected. Control plants were uninfested, but otherwise equally treated and harvested in parallel. We tested the hypothesis that Arabidopsis can recognize and respond differentially to insect species at the transcriptional level using a genome wide microarray. Transcriptional reprogramming was characterized using co-expression analysis in damaged and undamaged leaves at two times in response to mechanical wounding and four insect species. In all, 2778 (10.6%) of annotated genes on the array were differentially expressed in at least one treatment. Responses differed mainly between aphid and caterpillar and sampling times. Responses to aphids and caterpillars shared only 10% of up-regulated and 8% of down-regulated genes. Responses to two caterpillars shared 21% and 12% of up- and down-regulated genes, whereas responses to the two aphids shared only 7% and 4% of up-regulated and down-regulated genes. Overlap in genes expressed between 6h and 24h was 3-15%, and depended on the insect species. Responses in attacked and unattacked leaves differed at 6h but converged by 24h. Genes responding to the insects are also responsive to many stressors and included primary metabolism. Aphids down-regulated amino acid catabolism; caterpillars stimulated production of amino acids involved in glucosinolate synthesis. Co-expression analysis revealed 17 response networks. Transcription factors were a major portion of differentially expressed genes throughout and responsive genes shared most of the known or postulated binding sites.

Project description:Purpose: Brassica. juncea is vulnerable to abiotic stresses at specific stages in its life cycle. However, till date no attempts have been made to elucidate the genome-wide changes in the transcriptome of B. juncea subjected to either high temperature or drought stress. Hence, to gain global insights into genes, transcription factors and kinases regulated by these stresses and to provide basic information on coding transcripts that are associated with traits of agronomic importance, we utilized a combinatorial approach of next generation sequencing and de novo assembly to discover B. juncea transcriptome associated with high temperature and drought. Results: We constructed and sequenced three transcriptome libraries namely Brassica control (BC), Brassica high temperature stress (BHS) and Brassica drought stress (BDS) from control, high temperature treated and drought treated seedlings of Brassica juncea. More than 180 million purity filtered reads were generated which were processed through quality parameters and high quality reads were assembled de-novo using SOAPde-novo assembler. A total of 77750 unique transcripts were identified out of which 69,245 (89%) were annotated with high confidence. We established a subset of 19110 transcripts, which were differentially regulated by either high temperature and/or drought stress. Furthermore, 886 and 2834 transcripts that code for transcription factors and kinases, respectively, were also identified. Investigation of identified transcription factors revealed that 92 responded to high temperature, 72 exhibited alterations in expression during drought stress, and 60 were commonly associated with both the stresses. Similarly, 217, 259 and 193 kinases were responsive to high temperature, drought or both stresses, respectively. Maximum number of up-regulated transcription factors in high temperature and drought stress belonged to heat shock factors (HSFs) and dehydration responsive element-binding (DREB) families respectively. We also identified 239 metabolic pathways, which were perturbed during high temperature and drought treatments. Analysis of gene ontologies associated with differentially regulated genes forecasted their involvement in diverse biological processes. Conclusions: Our study provides first comprehensive discovery of B. juncea transcriptome under high temperature and drought stress conditions. Transcriptome resources generated in this study will enhance our understanding on the molecular mechanisms involved in defining the response of B. juncea against two important abiotic stresses. Furthermore this information would benefit designing of efficient crop improvement strategies for tolerance against conditions of high temperature regimes and water scarcity. Total three RNA-Seq libraries were prepared and sequenced independently [B. juncea control (BC), B. juncea high temperature stressed (BHS) and B. juncea drought stressed (BDS) on Illumina GAIIx sequencer].

Project description:Purpose: Brassica. juncea is vulnerable to abiotic stresses at specific stages in its life cycle. However, till date no attempts have been made to elucidate the genome-wide changes in the transcriptome of B. juncea subjected to either high temperature or drought stress. Hence, to gain global insights into genes, transcription factors and kinases regulated by these stresses and to provide basic information on coding transcripts that are associated with traits of agronomic importance, we utilized a combinatorial approach of next generation sequencing and de novo assembly to discover B. juncea transcriptome associated with high temperature and drought. Results: We constructed and sequenced three transcriptome libraries namely Brassica control (BC), Brassica high temperature stress (BHS) and Brassica drought stress (BDS) from control, high temperature treated and drought treated seedlings of Brassica juncea. More than 180 million purity filtered reads were generated which were processed through quality parameters and high quality reads were assembled de-novo using SOAPde-novo assembler. A total of 77750 unique transcripts were identified out of which 69,245 (89%) were annotated with high confidence. We established a subset of 19110 transcripts, which were differentially regulated by either high temperature and/or drought stress. Furthermore, 886 and 2834 transcripts that code for transcription factors and kinases, respectively, were also identified. Investigation of identified transcription factors revealed that 92 responded to high temperature, 72 exhibited alterations in expression during drought stress, and 60 were commonly associated with both the stresses. Similarly, 217, 259 and 193 kinases were responsive to high temperature, drought or both stresses, respectively. Maximum number of up-regulated transcription factors in high temperature and drought stress belonged to heat shock factors (HSFs) and dehydration responsive element-binding (DREB) families respectively. We also identified 239 metabolic pathways, which were perturbed during high temperature and drought treatments. Analysis of gene ontologies associated with differentially regulated genes forecasted their involvement in diverse biological processes. Conclusions: Our study provides first comprehensive discovery of B. juncea transcriptome under high temperature and drought stress conditions. Transcriptome resources generated in this study will enhance our understanding on the molecular mechanisms involved in defining the response of B. juncea against two important abiotic stresses. Furthermore this information would benefit designing of efficient crop improvement strategies for tolerance against conditions of high temperature regimes and water scarcity.

Dataset Information

Brassica juncea isolate:insect chewing

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