Project description:The common bean (Phaseolus vulgaris L.) is one of the most important food legumes, far ahead of other legumes. The average grain yield of the common bean worldwide is much lower than its potential yields, primarily due to drought in the field. However, the gene network that mediates plant responses to drought stress remains largely unknown in this species. The major goals of our study are to identify a large scale of genes involved in drought stress using RNA-seq. First, we assembled 270 million high-quality trimmed reads into a non-redundant set of 62,828 unigenes, representing approximately 49 Mb of unique transcriptome sequences. Of these unigenes, 26,501 (42.2%) common bean unigenes had significant similarity with unigenes/predicted proteins from other legumes or sequenced plants. All unigenes were functionally annotated within the GO, COG and KEGG pathways. The strategy for de novo assembly of transcriptome data generated here will be useful in other legume plant transcriptome studies. Second, we identified 10,482 SSRs and 4,099 SNPs in transcripts. The large number of genetic markers provides a resource for gene discovery and development of functional molecular markers. Finally, we found differential expression genes (DEGs) between terminal drought and optimal irrigation treatments and between the two different genotypes Long 22-0579 (drought tolerant) and Naihua (drought sensitive). DEGs were confirmed by quantitative real-time PCR assays, which indicated that these genes are functionally associated with the drought-stress response. These resources will be helpful for basic and applied research for genome analysis and crop drought resistance improvement in the common bean.
Project description:Chickpea ranks third among the food legume crops production in the world. However, the genomic resources available for chickpea are still very limited. In the present study, the transcriptome of chickpea was sequenced with short reads on Illumina Genome Analyzer platform. We have assessed the effect of sequence quality, various assembly parameters and assembly programs on the final assembly output. We assembled ~107million high-quality trimmed reads using Velvet followed by Oases with optimal parameters into a non-redundant set of 53 409 transcripts (?100 bp), representing about 28 Mb of unique transcriptome sequence. The average length of transcripts was 523 bp and N50 length of 900 bp with coverage of 25.7 rpkm (reads per kilobase per million). At the protein level, a total of 45 636 (85.5%) chickpea transcripts showed significant similarity with unigenes/predicted proteins from other legumes or sequenced plant genomes. Functional categorization revealed the conservation of genes involved in various biological processes in chickpea. In addition, we identified simple sequence repeat motifs in transcripts. The chickpea transcripts set generated here provides a resource for gene discovery and development of functional molecular markers. In addition, the strategy for de novo assembly of transcriptome data presented here will be helpful in other similar transcriptome studies.
Project description:BackgroundSalinity, alkalinity, and drought stress are the main abiotic stress factors affecting plant growth and development. Sophora alopecuroides L., a perennial leguminous herb in the genus Sophora, is a highly salt-tolerant sand-fixing pioneer species distributed mostly in Western Asia and northwestern China. Few studies have assessed responses to abiotic stress in S. alopecuroides. The transcriptome of the genes that confer stress-tolerance in this species has not previously been sequenced. Our objective was to sequence and analyze this transcriptome.ResultsTwelve cDNA libraries were constructed in triplicate from mRNA obtained from Sophora alopecuroides for the control and salt, alkali, and drought treatments. Using de novo assembly, 902,812 assembled unigenes were generated, with an average length of 294 bp. Based on similarity searches, 545,615 (60.43%) had at least one significant match in the Nr, Nt, Pfam, KOG/COG, Swiss-Prot, and GO databases. In addition, 1673 differentially expressed genes (DEGs) were obtained from the salt treatment, 8142 from the alkali treatment, and 17,479 from the drought treatment. A total of 11,936 transcription factor genes from 82 transcription factor families were functionally annotated under salt, alkali, and drought stress, these include MYB, bZIP, NAC and WRKY family members. DEGs were involved in the hormone signal transduction pathway, biosynthesis of secondary metabolites and antioxidant enzymes; this suggests that these pathways or processes may be involved in tolerance towards salt, alkali, and drought stress in S. alopecuroides.ConclusionOur study first reported transcriptome reference sequence data in Sophora alopecuroides, a non-model plant without a reference genome. We determined digital expression profile and discovered a broad survey of unigenes associated with salt, alkali, and drought stress which provide genomic resources available for Sophora alopecuroides.
Project description:Single-molecule sequencing instruments can generate multikilobase sequences with the potential to greatly improve genome and transcriptome assembly. However, the error rates of single-molecule reads are high, which has limited their use thus far to resequencing bacteria. To address this limitation, we introduce a correction algorithm and assembly strategy that uses short, high-fidelity sequences to correct the error in single-molecule sequences. We demonstrate the utility of this approach on reads generated by a PacBio RS instrument from phage, prokaryotic and eukaryotic whole genomes, including the previously unsequenced genome of the parrot Melopsittacus undulatus, as well as for RNA-Seq reads of the corn (Zea mays) transcriptome. Our long-read correction achieves >99.9% base-call accuracy, leading to substantially better assemblies than current sequencing strategies: in the best example, the median contig size was quintupled relative to high-coverage, second-generation assemblies. Greater gains are predicted if read lengths continue to increase, including the prospect of single-contig bacterial chromosome assembly.
Project description:The common vetch (Vicia sativa) is often used as feed for livestock because of its high nutritional value. However, drought stress reduces forage production through plant damage. Here, we studied the transcriptional profiles of common vetch exposed to drought in order to understand the molecular mechanisms of drought tolerance in this species. The genome of the common vetch has not been sequenced, therefore we used Illumina sequencing to generate de novo transcriptomes. Nearly 500 million clean reads were used to generate 174,636 transcripts, including 122,299 unigenes. In addition, 5313 transcription factors were identified and these transcription factors were classified into 79 different gene families. We also identified 11,181 SSR loci from di- to hexa-nucleotides whose repeat number was greater than five. On the basis of differentially expressed genes, Gene Ontology analysis identified many drought-relevant categories, including "oxidation-reduction process", "lipid metabolic process" and "oxidoreductase activity". In addition to these, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis identified pathways, such as "Plant hormone signal transduction", "Glycolysis/Gluconeogenesis" and "Phenylpropanoid biosynthesis", as differentially expressed in the plants exposed to drought. The expression results in this study will be useful for further extending our knowledge on the drought tolerance of common vetch.
Project description:Cluster bean (Cyamopsis tetragonoloba L.) is one of the multipurpose underexplored crops grown as green vegetable and for gum production in dryland areas. Cluster bean is known as relatively tolerant to drought and salinity stress. To elucidate the molecular mechanisms involved in the drought tolerance of cluster bean cultivar RGC-1025, RNA sequencing (RNA-seq) of the drought-stressed and control samples was performed. De novo assembly of the reads resulted in 66,838 transcripts involving 203 pathways. Among these transcripts, differentially expressed gene (DEG) analysis resulted in some of the drought-responsive genes expressing alpha dioxygenase 2, low temperature-induced 65 kDa protein (LDI65), putative vacuolar amino acid transporter, and late embryogenesis abundant protein (LEA 3). The analysis also reported drought-responsive transcription factors (TFs), such as NAC, WRKY, GRAS, and MYB families. The relative expression of genes by qRT-PCR revealed consistency with the DEG analysis. Key genes involved in the wax biosynthesis pathway were mapped using the DEG data analysis. These results were positively correlated with epicuticular wax content and the wax depositions on the leaf surfaces, as evidenced by scanning electron microscope (SEM) image analysis. Further, these findings support the fact that enhanced wax deposits on the leaf surface had played a crucial role in combating the drought stress in cluster beans under drought stress conditions. In addition, this study provided a set of unknown genes and TFs that could be a source of engineering tolerance against drought stress in cluster beans.
Project description:Molecular changes elicited by common bean (Phaseolus vulgaris L.) in response to Fusarium oxysproum f. sp. Phaseoli (FOP) remain elusive. We studied the changes in root metabolism during common bean-FOP interactions using a combined de novo transcriptome and metabolome approach. Our results demonstrated alterations of transcript levels and metabolite concentrations in common bean roots 24 h post infection as compared to control. The transcriptome and metabolome responses in common bean roots revealed significant changes in structural defense i.e., cell-wall loosening and weakening characterized by hyper accumulation of cell-wall loosening and degradation related transcripts. The levels of pathogenesis related genes were significantly higher upon FOP inoculation. Interestingly, we found the involvement of glycosylphosphatidylinositol- anchored proteins (GPI-APs) in signal transduction in response to FOP infection. Our results confirmed that hormones have strong role in signaling pathways i.e., salicylic acid, jasmonate, and ethylene pathways. FOP induced energy metabolism and nitrogen mobilization in infected common bean roots as compared to control. Importantly, the flavonoid biosynthesis pathway was the most significantly enriched pathway in response to FOP infection as revealed by the combined transcriptome and metabolome analysis. Overall, the observed modulations in the transcriptome and metabolome flux as outcome of several orchestrated molecular events are determinant of host's role in common bean-FOP interactions.
Project description:BackgroundThe perennial O. rufipogon (common wild rice), which is considered to be the ancestor of Asian cultivated rice species, contains many useful genetic resources, including drought resistance genes. However, few studies have identified the drought resistance and tissue-specific genes in common wild rice.ResultsIn this study, transcriptome sequencing libraries were constructed, including drought-treated roots (DR) and control leaves (CL) and roots (CR). Using Illumina sequencing technology, we generated 16.75 million bases of high-quality sequence data for common wild rice and conducted de novo assembly and annotation of genes without prior genome information. These reads were assembled into 119,332 unigenes with an average length of 715 bp. A total of 88,813 distinct sequences (74.42% of unigenes) significantly matched known genes in the NCBI NT database. Differentially expressed gene (DEG) analysis showed that 3617 genes were up-regulated and 4171 genes were down-regulated in the CR library compared with the CL library. Among the DEGs, 535 genes were expressed in roots but not in shoots. A similar comparison between the DR and CR libraries showed that 1393 genes were up-regulated and 315 genes were down-regulated in the DR library compared with the CR library. Finally, 37 genes that were specifically expressed in roots were screened after comparing the DEGs identified in the above-described analyses.ConclusionThis study provides a transcriptome sequence resource for common wild rice plants and establishes a digital gene expression profile of wild rice plants under drought conditions using the assembled transcriptome data as a reference. Several tissue-specific and drought-stress-related candidate genes were identified, representing a fully characterized transcriptome and providing a valuable resource for genetic and genomic studies in plants.
Project description:Cynanchum komarovii Al Iljinski is a xerophytic plant species widely distributing in the severely adverse environment of the deserts in northwest China. At present, the detailed transcriptomic and genomic data for C. komarovii are still insufficient in public databases.To investigate changes of drought-responsive genes and explore the mechanisms of drought tolerance in C. komarovii, approximately 27.5 GB sequencing data were obtained using Illumina sequencing technology. After de novo assembly 148,715 unigenes were generated with an average length of 604 bp. Among these unigenes, 85,106 were annotated with gene descriptions, conserved domains, gene ontology terms, and metabolic pathways. The results showed that a great number of unigenes were significantly affected by drought stress. We identified 3134 unigenes as reliable differentially expressed genes (DEGs). During drought stress, the regulatory genes were involved in signaling transduction pathways and in controlling the expression of functional genes. Moreover, C. komarovii activated many functional genes that directly protected against stress and improved tolerance to adapt drought condition. Importantly, the DEGs were involved in biosynthesis, export, and regulation of plant cuticle, suggesting that plant cuticle may play a vital role in response to drought stress and the accumulation of cuticle may allow C. komarovii to improve the tolerance to drought stress.This is the first large-scale reference sequence data of C. komarovii, which enlarge the genomic resources of this species. Our comprehensive transcriptome analysis will provide a valuable resource for further investigation into the molecular adaptation of desert plants under drought condition and facilitate the exploration of drought-tolerant candidate genes.
Project description:BackgroundComprehensive annotation and quantification of transcriptomes are outstanding problems in functional genomics. While high throughput mRNA sequencing (RNA-Seq) has emerged as a powerful tool for addressing these problems, its success is dependent upon the availability and quality of reference genome sequences, thus limiting the organisms to which it can be applied.ResultsHere, we describe Rnnotator, an automated software pipeline that generates transcript models by de novo assembly of RNA-Seq data without the need for a reference genome. We have applied the Rnnotator assembly pipeline to two yeast transcriptomes and compared the results to the reference gene catalogs of these organisms. The contigs produced by Rnnotator are highly accurate (95%) and reconstruct full-length genes for the majority of the existing gene models (54.3%). Furthermore, our analyses revealed many novel transcribed regions that are absent from well annotated genomes, suggesting Rnnotator serves as a complementary approach to analysis based on a reference genome for comprehensive transcriptomics.ConclusionsThese results demonstrate that the Rnnotator pipeline is able to reconstruct full-length transcripts in the absence of a complete reference genome.