Project description:Summary: Multi-toxins Bt-crops carrying insecticidal toxins with similar host spectrum and different mode of action e.g. Cry and Vip, are expected to improve resistance management in target pests. Control failure has been informed for Cry toxins but not for Vip3A, of which no mechanism of resistance has yet been identified. Here we applied HT-SuperSAGE to analyze the transcriptome profiling in the midgut tissue of a tobacco budworm Heliothis virescens (F.) strain laboratory-selected for Vip3A resistance. A total of 1324252 26-bp tags were sequenced representing 17751 unique transcripts (UniTags) from genetically similar Vip3A-resistant (Vip-Sel) strain and susceptible control (Vip-Unsel) strain. Differential expression was found significant (≥ 2.5-fold or ≤ 0.4) for 1845 unigenes that constitute 10.4% of the total number of UniTags, where 277 represented overexpressed (OE) and 1568 underexpressed (UE) genes in Vip-Sel compared to Vip-Unsel. BLASTN searches mapped 1141 of these UniTags to H. virescens EST sequences, of which, 816 (143 OE and 673 UE) were unambiguously annotated to proteins in NCBI non-redundant protein databases. Gene ontology revealed Vip3A adaptation induced major constitutive transcriptional differences in serine-proteases (SP)-mediated proteolysis, ribosome biogenesis and metabolic processes. Several unigenes homologous to a particular member of the REsponse to PAThogen (REPAT) family were found to be predominantly OE. Since UniTags related to SP and ribosomal proteins (RP) were the most represented in the libraries, they were further analyzed in details. Interestingly, UniTags related to the putative Vip3A-binding protein RpS2 were underexpressed, while, the tumorigenesis suppressor RpL37 accounted for the 35% of total overexpressed RP. A subset of unigenes was chosen to confirm the HT-SuperSAGE data by qRT-PCR. The present study is the first providing a lepidopteran gut transcriptome associated with Vip3A resistance and a foundation for future attempts to elucidate the resistance mechanism. Methods: Midgut transcriptional profiles of third-instar larvae from genetically similar Vip3A-resistant (Vip-Sel) and susceptible control (Vip-Unsel) strains were generated by HT-SuperSAGE. RNA pools of Vip-Sel and Vip-Unsel samples (five RNA preparations each) were prepared and used for the construction of SuperSAGE libraries HvR_GCCT and HvS_GCAC, respectively, according to the procedure described by [Matsumura et al., 2010]. Purified PCR products were mixed and applied to Illumina Genome Analyzer II sequencing with GEX (DpnII) primer in the sequencing reactions as recommended by the manufacturer. Sorting of sequence reads based on index sequences and the subsequent extraction of sequence tags from reads was conducted using a script written in Perl. Fold-change for each tag was calculated as in [Gilardoni et al., 2010]. qRT–PCR validation was performed using TaqMan and SYBR Green assays.

Project description:Host-pathogen interactions result in complex relationship, many aspects of which are not completely understood. Vip proteins, which are Bacillus thuringensis (Bt) insecticidal toxins produced during the vegetative stage, are selectively effective against specific insect pests. This new group of Bt proteins represents an interesting alternative to the classical Bt Cry toxins because current data suggests that they do not share the same mode of action. We have designed and developed a genome-wide microarray for the beet armyworm Spodoptera exigua, a serious lepidopteran pest of many agricultural crops, and used it to better understand how Lepidopteran larvae respond to the treatment with the insecticidal protein Vip3Aa. With this approach, the goal of our study was to evaluate the changes in gene expression levels caused by treatment with sublethal doses (causing 99% growth inhibition) of Vip3Aa at 8 and 24 h after treatment. Results indicated that the toxin provoked a wide transcriptional response, with 19% of unigenes in the microarray responding significantly to treatment. The number of up- and down-regulated unigenes was very similar.. The number of genes whose expression was regulated at 8 h was similar to the number of genes whose expression was regulated after 24 h of treatment. The up-regulated sequences were enriched for genes involved in innate immune response and in pathogen response such as antimicrobial peptides (AMPs) and repat genes. The down-regulated sequences were mainly unigenes with homology to genes involved in metabolism. Genes related to the mode of action of Bt Cry proteins were found, in general, to be slightly overexpressed. The present study is the first genome-wide analysis of the response of lepidopteran insects to Vip3Aa intoxication. An insight into the molecular mechanisms and components related to Vip intoxication will allow designing of more effective management strategies for pest control. Changes in gene expression levels caused by treatment with sublethal doses (causing 99% growth inhibition) of Vip3Aa were measured at 8 and 24 h after treatment by means of custom Spodoptera exigua microarray. Six to seven larvae were used for each time point and three independent experiments were performed at each time point.

Project description:Background Drought is the major constraint to increase yield in chickpea (Cicer arietinum). Improving drought tolerance is therefore of outmost importance for breeding. However, the complexity of the trait allowed only marginal progress. A solution to the current stagnation is expected from innovative molecular tools such as transcriptome analyses providing insight into stress-related gene activity and, combined with molecular markers and expression (e)QTL mapping, may accelerate knowledge-based breeding. SuperSAGE, an improved version of the serial analysis of gene expression (SAGE) technique, currently is the most advanced tool for transcriptome analysis. SuperSAGE generates genome-wide, high-quality transcription profiles from any eukaryote. The method produces 26bp long fragments (SuperTags26bp tags) from defined positions in cDNAs, providing sufficient sequence information to unambiguously characterize the mRNAs. Further, SuperSAGE Tags may be immediately used to produce so called SuperTag microarrays and probes for real-time-PCR thereby overcoming the lack of genomic tools in non-model organisms. Results We applied SuperSAGE to the analysis of gene expression in chickpea roots in response to drought. To this end, we sequenced 80,238 26bp SuperTtags representing 17,493 unique transcripts (UniTags) from drought-stressed and non-stressed control roots. A total of 7,532 (43%) UniTags were more than 2.7-fold differentially expressed , and 880 (5.0%) were regulated more than 8-fold upon stress. Their large size enabled the unambiguous annotation of 2,798 (16.3%) UniTags to genes or proteins in public data bases and thus to stress-response processes. We designed a microSuperTag array carrying 3,000 of these SuperTags26bp tags. The chip data confirmed the SuperSAGE results in 79 % of cases whereas RT-PCR confirmed the SuperSAGE data in all cases. Conclusions This study represents the most comprehensive analysis of the drought-response transcriptome of chickpea available to date. It demonstrates that - inter alias - signal transduction, transcription regulation, osmolyte accumulation, chromosome organization, and ROS scavenging undergo strong transcriptional remodelling in chickpea roots already 6h after drought stress. Certain transcript isoforms characterizing these processes are potential targets for breeding for drought tolerance. We demonstrate that these can be easily accessed by micro-arrays and RT-PCR assays readily produced downstream of SuperSAGE. Our study proves that SuperSAGE has a good potential is best suited for molecular breeding also in non-model crops.

Project description:To gain novel molecular insights into quantitative late blight resistance, we performed a high-resolution quantitative analysis of gene expression using potato cultivars with contrasting SNP alleles at the StAOS2 locus associated with maturity corrected resistance (MCR). SuperSAGE samples were generated from uninfected and infected plants of the selected genotypes under controlled environmental conditions. Genotypes were pooled to reduce the influence of the genetic background on the transcriptome. Nine SuperSAGE samples were prepared from artificially inoculated plants in a growth chamber using total RNA of the pooled 14, 6 and 9 genotypes in groups A1, A2 and B2, respectively, at three infection time points T0, T1 and T2. Combining the tag counts of both NlaIII and DpnII libraries resulted in 1.1 to 6.2 million tags per sample. Of total 266361 unique tags (unitags), 52.6% matched to the potato genome sequence when up to three mismatches per 26 base pairs were allowed, and 23.3% matched without mismatch. Fifteen pair wise comparisons were performed between the nine SuperSAGE samples to identify transcripts that were differentially expressed in response to infection (six comparisons) or between three genotype pools at the infection time points T0, T1 and T2 (nine comparisons). The number of unitags per comparison ranged from 127 000 to 182 000 (average 158 000). Between 2100 and 11800 tags were differentially expressed in pair wise comparisons, depending on arbitrary cut-off p-values for a significant difference. The highest number of differences was observed for the comparison between genotype pools A1 and A2 one day after infection (A1-T1 vs A2-T1), and the lowest between genotype pools A2 and B2 two days after infection (B2-T2 vs A2-T2). The number of differences in response to infection and between genotype pools even before infection (T0) was in the same order of magnitude. Based on the annotations in the DFCI potato gene index, in the potato genome and in few cases by BLASTX searches against the protein database at NCBI, transcripts that showed reproducible differential expression over the infection time course or between genotype pools A1, A2 and B2 were grouped in 16 functional categories, with overlaps between categories. Genes with genotype dependent, constitutive differential expression provide excellent targets for developing novel diagnostic markers for breeding cultivars with improved quantitative resistance to late blight and possibly other biotic and abiotic stresses. Relevant in this respect appear, besides numerous genes of unknown or ill-defined function, genes with known function involved in stress responses, photosynthesis, protein biosynthesis, protein degradation via the 26S proteasome, transport of proteins, lipids, ions and other small molecules, cell wall structure and many others. Eighteen SuperSAGE libraries were constructed based on nine leaf samples from one infection experiment. For each time point (T0, T1 and T2) one leaflet each of 14, 6 and 9 SL genotypes in genotypic groups A1, A2 and B2, respectively, were pooled. Frozen pooled leaf tissue was powdered in a CryoMill. SuperSAGE libraries were generated at GenXPro GmbH (Frankfurt, Germany) essentially as described (Matsumura et al. 2010). To prevent amplification biases the TrueQuant technology was applied as described by B. Rotter (Patent application Nr. WO2009152928). Besides NlaIII (recognition site: 5M-bM-^@M-^Y-CATG-3M-bM-^@M-^Y), DpnII (recognition site: 5M-bM-^@M-^Y-GATC-3M-bM-^@M-^Y) was used as second anchoring enzyme, to capture transcripts without a NlaIII site. Therefore, the 26 bp tags carry either CATG or GATC at their 5M-bM-^@M-^Y end. The libraries were pooled and sequenced by Solexa/Illumina technology (Illumina, Inc., USA).

Project description:To gain novel molecular insights into quantitative late blight resistance, we performed a high-resolution quantitative analysis of gene expression using potato cultivars with contrasting SNP alleles at the StAOS2 locus associated with maturity corrected resistance (MCR). SuperSAGE samples were generated from uninfected and infected plants of the selected genotypes under controlled environmental conditions. Genotypes were pooled to reduce the influence of the genetic background on the transcriptome. Nine SuperSAGE samples were prepared from artificially inoculated plants in a growth chamber using total RNA of the pooled 14, 6 and 9 genotypes in groups A1, A2 and B2, respectively, at three infection time points T0, T1 and T2. Combining the tag counts of both NlaIII and DpnII libraries resulted in 1.1 to 6.2 million tags per sample. Of total 266361 unique tags (unitags), 52.6% matched to the potato genome sequence when up to three mismatches per 26 base pairs were allowed, and 23.3% matched without mismatch. Fifteen pair wise comparisons were performed between the nine SuperSAGE samples to identify transcripts that were differentially expressed in response to infection (six comparisons) or between three genotype pools at the infection time points T0, T1 and T2 (nine comparisons). The number of unitags per comparison ranged from 127 000 to 182 000 (average 158 000). Between 2100 and 11800 tags were differentially expressed in pair wise comparisons, depending on arbitrary cut-off p-values for a significant difference. The highest number of differences was observed for the comparison between genotype pools A1 and A2 one day after infection (A1-T1 vs A2-T1), and the lowest between genotype pools A2 and B2 two days after infection (B2-T2 vs A2-T2). The number of differences in response to infection and between genotype pools even before infection (T0) was in the same order of magnitude. Based on the annotations in the DFCI potato gene index, in the potato genome and in few cases by BLASTX searches against the protein database at NCBI, transcripts that showed reproducible differential expression over the infection time course or between genotype pools A1, A2 and B2 were grouped in 16 functional categories, with overlaps between categories. Genes with genotype dependent, constitutive differential expression provide excellent targets for developing novel diagnostic markers for breeding cultivars with improved quantitative resistance to late blight and possibly other biotic and abiotic stresses. Relevant in this respect appear, besides numerous genes of unknown or ill-defined function, genes with known function involved in stress responses, photosynthesis, protein biosynthesis, protein degradation via the 26S proteasome, transport of proteins, lipids, ions and other small molecules, cell wall structure and many others.

Project description:Background The combination of high-throughput transcript profiling and next-generation sequencing technologies is a prerequisite for genome-wide comprehensive transcriptome analysis. Our recent innovation of deepSuperSAGE is based on an advanced SuperSAGE protocol and its combination with massively parallel pyrosequencing on RocheM-bM-^@M-^Ys 454 sequencing platform. As a demonstration of the power of this combination, we have chosen the salt stress transcriptomes of roots and nodules of the third most important legume crop chickpea (Cicer arietinum L.). While our report is more technology-oriented, it nevertheless addresses a major world-wide problem for crops generally: high salinity. Together with low temperatures and water stress, high salinity is responsible for crop losses of millions of tons of various legume (and other) crops. Continuously deteriorating environmental conditions will combine with salinity stress to further compromise crop yields. As a good example for such stress-exposed crop plants, we started to characterize salt stress responses of chickpeas on the transcriptome level. Results We used deepSuperSAGE to detect early global transcriptome changes in salt-stressed chickpea. The salt stress responses of 86,919 transcripts representing 17,918 unique 26bp deepSuperSAGE tags (UniTags) from roots of the salt-tolerant variety INRAT-93 two hours after treatment with 25 mM NaCl were characterized. Additionally, the expression of 57,281 transcripts representing 13,115 UniTags was monitored in nodules of the same plants. From a total of 144,200 analyzed 26bp tags in roots and nodules together, 21,401 unique transcripts were identified. Of these, only 363 and 106 specific transcripts, respectively, were commonly up- or down-regulated (>3.0-fold) under salt stress in both organs, witnessing a differential organ-specific response to stress. Profiting from recent pioneer works on massive cDNA sequencing in chickpea, more than 9,400 UniTags were able to be linked to UniProt entries. Additionally, gene ontology (GO) categories over-representation analysis enabled to filter out enriched biological processes among the differentially expressed UniTags. Subsequently, the gathered information was further cross-checked with stress-related pathways. From several filtered pathways, here we focus exemplarily on transcripts associated with the generation and scavenging of reactive oxygen species (ROS), as well as on transcripts involved in Na+ homeostasis. Although both processes are already very well characterized in other plants, the information generated in the present work is of high value. Information on expression profiles and sequence similarity for several hundreds of transcripts of potential interest is now available. Conclusions This report demonstrates, that the combination of the high-throughput transcriptome profiling technology SuperSAGE with one of the next-generation sequencing platforms allows deep insights into the first molecular reactions of a plant exposed to salinity. Cross validation with recent reports enriched the information about the salt stress dynamics of more than 9,000 chickpea ESTs, and enlarged their pool of alternative transcripts isoforms. As an example for the high resolution of the employed technology that we coin deepSuperSAGE, we demonstrate that ROS-scavenging and -generating pathways undergo strong global transcriptome changes in chickpea roots and nodules already 2 hours after onset of moderate salt stress (25mM NaCl). Additionally, a set of more than 15 candidate transcripts are proposed to be potential components of the salt overly sensitive (SOS) pathway in chickpea. Newly identified transcript isoforms are potential targets for breeding novel cultivars with high salinity tolerance. We demonstrate that these targets can be integrated into breeding schemes by micro-arrays and RT-PCR assays downstream of the generation of 26bp tags by SuperSAGE. SuperSAGE libraries from chickpea roots and nodules were constructed starting from hydro aeroponics-generated material. Control and stressed plants were grown in parallel Sequencing Instrument: First gerenration 454-Machine Place of sequencing: 454 Life Sciences, Branford, CT, USA

Project description:Background The combination of high-throughput transcript profiling and next-generation sequencing technologies is a prerequisite for genome-wide comprehensive transcriptome analysis. Our recent innovation of deepSuperSAGE is based on an advanced SuperSAGE protocol and its combination with massively parallel pyrosequencing on Roche’s 454 sequencing platform. As a demonstration of the power of this combination, we have chosen the salt stress transcriptomes of roots and nodules of the third most important legume crop chickpea (Cicer arietinum L.). While our report is more technology-oriented, it nevertheless addresses a major world-wide problem for crops generally: high salinity. Together with low temperatures and water stress, high salinity is responsible for crop losses of millions of tons of various legume (and other) crops. Continuously deteriorating environmental conditions will combine with salinity stress to further compromise crop yields. As a good example for such stress-exposed crop plants, we started to characterize salt stress responses of chickpeas on the transcriptome level. Results We used deepSuperSAGE to detect early global transcriptome changes in salt-stressed chickpea. The salt stress responses of 86,919 transcripts representing 17,918 unique 26bp deepSuperSAGE tags (UniTags) from roots of the salt-tolerant variety INRAT-93 two hours after treatment with 25 mM NaCl were characterized. Additionally, the expression of 57,281 transcripts representing 13,115 UniTags was monitored in nodules of the same plants. From a total of 144,200 analyzed 26bp tags in roots and nodules together, 21,401 unique transcripts were identified. Of these, only 363 and 106 specific transcripts, respectively, were commonly up- or down-regulated (>3.0-fold) under salt stress in both organs, witnessing a differential organ-specific response to stress. Profiting from recent pioneer works on massive cDNA sequencing in chickpea, more than 9,400 UniTags were able to be linked to UniProt entries. Additionally, gene ontology (GO) categories over-representation analysis enabled to filter out enriched biological processes among the differentially expressed UniTags. Subsequently, the gathered information was further cross-checked with stress-related pathways. From several filtered pathways, here we focus exemplarily on transcripts associated with the generation and scavenging of reactive oxygen species (ROS), as well as on transcripts involved in Na+ homeostasis. Although both processes are already very well characterized in other plants, the information generated in the present work is of high value. Information on expression profiles and sequence similarity for several hundreds of transcripts of potential interest is now available. Conclusions This report demonstrates, that the combination of the high-throughput transcriptome profiling technology SuperSAGE with one of the next-generation sequencing platforms allows deep insights into the first molecular reactions of a plant exposed to salinity. Cross validation with recent reports enriched the information about the salt stress dynamics of more than 9,000 chickpea ESTs, and enlarged their pool of alternative transcripts isoforms. As an example for the high resolution of the employed technology that we coin deepSuperSAGE, we demonstrate that ROS-scavenging and -generating pathways undergo strong global transcriptome changes in chickpea roots and nodules already 2 hours after onset of moderate salt stress (25mM NaCl). Additionally, a set of more than 15 candidate transcripts are proposed to be potential components of the salt overly sensitive (SOS) pathway in chickpea. Newly identified transcript isoforms are potential targets for breeding novel cultivars with high salinity tolerance. We demonstrate that these targets can be integrated into breeding schemes by micro-arrays and RT-PCR assays downstream of the generation of 26bp tags by SuperSAGE.

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HT-SuperSAGE of the gut tissue of a Vip3A-resistant Heliothis virescens F. (Lepidoptera: Noctuidae) strain provides insights into its evolution and toxin adaptation

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