BackgroundBrassica juncea var. Varuna is an economically important oilseed crop of family Brassicaceae which is vulnerable to abiotic stresses at specific stages in its life cycle. Till date no attempts have been made to elucidate genome-wide changes in its transcriptome against high temperature or drought stress. To gain global insights into genes, transcription factors and kinases regulated by these stresses and to explore 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 stresses.ResultsWe constructed and sequenced three transcriptome libraries namely Brassica control (BC), Brassica high temperature stress (BHS) and Brassica drought stress (BDS). More than 180 million purity filtered reads were generated which were processed through quality parameters and high quality reads were assembled de-novo using SOAPdenovo 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. Many of these were responsive to high temperature, drought or both stresses. 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.ConclusionsOur study provides first comprehensive discovery of B. juncea transcriptome under high temperature and drought stress conditions. Transcriptome resource 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.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-014-0405-1) contains supplementary material, which is available to authorized users.
The cereal cyst nematode (CCN, Heterodera avenae) is a major pest of wheat (Triticum spp) that reduces crop yields in many countries. Cyst nematodes are obligate sedentary endoparasites that reproduce by amphimixis. Here, we report the first transcriptome analysis of two stages of H. avenae. After sequencing extracted RNA from pre parasitic infective juvenile and adult stages of the life cycle, 131 million Illumina high quality paired end reads were obtained which generated 27,765 contigs with N50 of 1,028 base pairs, of which 10,452 were annotated. Comparative analyses were undertaken to evaluate H. avenae sequences with those of other plant, animal and free living nematodes to identify differences in expressed genes. There were 4,431 transcripts common to H. avenae and the free living nematode Caenorhabditis elegans, and 9,462 in common with more closely related potato cyst nematode, Globodera pallida. Annotation of H. avenae carbohydrate active enzymes (CAZy) revealed fewer glycoside hydrolases (GHs) but more glycosyl transferases (GTs) and carbohydrate esterases (CEs) when compared to M. incognita. 1,280 transcripts were found to have secretory signature, presence of signal peptide and absence of transmembrane. In a comparison of genes expressed in the pre-parasitic juvenile and feeding female stages, expression levels of 30 genes with high RPKM (reads per base per kilo million) value, were analysed by qRT-PCR which confirmed the observed differences in their levels of expression levels. In addition, we have also developed a user-friendly resource, Heterodera transcriptome database (HATdb) for public access of the data generated in this study. The new data provided on the transcriptome of H. avenae adds to the genetic resources available to study plant parasitic nematodes and provides an opportunity to seek new effectors that are specifically involved in the H. avenae-cereal host interaction.
The rice root-knot nematode Meloidogyne graminicola has emerged as a devastating pest of rice in SouthEast Asian countries. Here we present a draft genome sequence for M. graminicola, assembled using data from short and long insert libraries sequenced on Illumina GAIIx sequencing platform.
Advent of Next Generation Sequencing has led to possibilities of de novo transcriptome assembly of organisms without availability of complete genome sequence. Among various sequencing platforms available, Illumina is the most widely used platform based on data quality, quantity and cost. Various de novo transcriptome assemblers are also available today for construction of de novo transcriptome.In this study, we aimed at obtaining an ameliorated de novo transcriptome assembly with sequence reads obtained from Illumina platform and assembled using Trinity Assembler. We found that, primary transcriptome assembly obtained as a result of Trinity can be ameliorated on the basis of transcript length, coverage, and depth and protein homology. Our approach to ameliorate is reproducible and could enhance the sensitivity and specificity of the assembled transcriptome which could be critical for validation of the assembled transcripts and for planning various downstream biological assays.
Spodoptera is an important polyphagous agricultural insect pest in the tropical world. The genomic details are limited to understand the pest biology at molecular level. In the present study, we sequenced and assembled the transcriptome from Sf21 cells into a non redundant set of 24,038 contigs of ~ 47.38 Mb in size. A total of 26,390 unigenes were identified from the assembled transcripts and their annotation revealed the prevalent protein domains in Sf21 cells. The present study would provide a resource for gene discovery and development of functional molecular markers to understand the biology of S. frugiperda.ReviewersThis article was reviewed by Dr. Thiago Motta Venancio and Prof. Michael Gray.Electronic supplementary materialThe online version of this article (doi:10.1186/s13062-015-0072-7) contains supplementary material, which is available to authorized users.
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