Project description:Small RNA libraries were constructed, sequenced, and analyzed with our Sequence Homology Pipeline for miRNA discovery (Jeong et al. 2013) to identify 59 unique conserved miRNA sequences from 199 precursors in switchgrass.
Project description:The combined heat and drought stress influence the plant growth and development. Switchgrass is an economically important crop due to the availability of high biomass with little water and nutrient requirements. Earlier reports suggested that switchgrass growth and yield highly influenced by heat and drought. The mechanism behind heat and drought stress is not fully understood in switchgrass. This study has undertaken to analyze the epigenetic modification using ChIP-Seq analysis with the activation histone mark H3K4me3. Conclusion: Our study provides the first epigenomic analysis of heat and drought response in switchgrass. This comprehensive resource will provide other epigenomic regulated information in non-model plant species.
Project description:Sustainable production of switchgrass (Panicum virgatum) as a bioenergy crop hinges in part on efficient use of soil macronutrients, especially nitrogen (N). This study investigated the physiological, metabolic and transcriptomic responses of switchgrass to N limitation. Moderate N limitation marked a tipping point for large changes in plant growth, root-to-shoot ratio, root system architecture and total nitrogen content. Integration of transcriptomic and metabolic data revealed that N limitation reduced switchgrass photosynthetic capacity and carbon(C)-fixation activities. Switchgrass balanced C-fixation with N-assimilation, transport and recycling of N compounds by rerouting C-flux from glycolysis, the oxidative branch of the pentose phosphate pathway (OPPP) and from the tricarboxylic acid (TCA) cycle in an organ specific manner. The energy and reduction power so generated, and C-skeletons appear to be directed towards N uptake, biosynthesis of energy storage compounds with high C/N ratio such as sucrose, non-N-containing lipids, and various branches of secondary metabolism.
Project description:Purpose: Increasing biomass yield and quality of feedstock have been a recent interest in switchgrass research. Despite the economic importance of switchgrass, increasing temperature and water deficit are limiting factors to the cultivation of bioenergy crops in the semi-arid areas. The effect of individual drought or heat stress has been studied separately in switchgrass. However, there is relatively limited or no report on the molecular basis of combined abiotic stress tolerance in switchgrass particularly the combination of drought and heat stress. We used RNA-Seq approaches to elucidate the transcriptome changes of switchgrass in response to drought and high temperatures simultaneously. Method: We conducted solely drought treatment in switchgrass plant Alamo AP13 by withholding water after 45 days of growing. For the combination of drought and heat effect, heat treatment (35 °C/25 °C day/night) was imposed after 72 h of the initiation of drought. Samples were collected at 0 h, 72 h, 96 h, 120 h, 144 h, and 168 h after treatment imposition, total RNA was extracted, and RNA-Seq conducted. Results:Out of total 32,190 genes, we identified 3,912, as DT responsive genes, 2,339 and 4,635 as , heat (HT) and drought and heat (DTHT) responsive genes, respectively. There were 209, 106, and 220 transcription factors (TFs) differentially expressed under DT, HT and DTHT respectively Conclusion: Through RNA-Seq analysis, we have identified unique and overlapping genes in response to DT and combined DTHT stress in switchgrass. The combination of DT and HT stress may affect the photosynthetic machinery and phenylpropanoid pathway of switchgrass which negatively impacts lignin synthesis and biomass production of switchgrass. The biological function of genes identified particularly in response to DTHT stress could further be confirmed by techniques such as single point mutation or RNAi.
Project description:In this study we were interested in identifying the gene networks that are responsive to chronic heat treatment in a switchgrass cultivar that is widely grown in the south-western USA and where 38C day temperatures have been reported for more than 100 days in the recent years. Switchgrass Alamo plants were subjected to chronic heat stress for 50 days (38 C/30C; day/night) or maintained under optimal conditions (28C/20C). Leaves were collected at the end of the heat regime for transcriptome analysis.
Project description:Switchgrass is currently one of the plant species being investigated as a potential biofuels crop. Genetic manipulation can be used to optimize and improve switchgrass to have more properties better suited for biofuels production. We have conducted a proteome with a focus on the endomembrane system of switchgrass so candidate proteins will be available that can be used for genetic manipulation. This proteomic resource will supplement the developing switchgrass genome sequencing project.
Project description:MicroRNAs (miRNAs) play a critical role in post-transcriptional gene regulation. miRNAs have been shown to control many genes involved in various biological and metabolic processes. Deep sequencing technologies have facilitated identification of species-specific or lowly expressed as well as conserved or highly expressed miRNAs in plants. In this research, we used Solexa sequencing to discover new microRNAs in trifoliate orange (Citrus trifoliata) an important rootstock of citrus. A total of 13,106,753 reads representing 4,876,395 distinct sequences were obtained from a short RNA library generated from small RNA extracted from C. trifoliata flower and fruit tissues, Based on sequence similarity and hairpin structure prediction, we found that 178,102 reads representing 89 sequences from 42 highly conserved miRNA families, have perfect matches to known miRNAs. We also identified 10 novel miRNA candidates, whose precursors were all potentially generated from citrus ESTs. And of them five miRNA* sequences were also sequenced. These sequences had not been described in other plant species and accumulation of these 10 novel miRNAs were confirmed by qRT-PCR analysis. Potential target genes were predicted for most conserved and novel miRNAs. Moreover, four target genes included one encoding IRX12 copper ion binding/ oxidoreductase and three genes encoding NB-LRR disease resistance protein have been experimentally verified by detection of the miRNA-mediated mRNA cleavage in C. trifoliata.
Project description:Background: Since the proposal of Brachypodium distachyon as a model for the grasses over 500 Bdi-miRNAs have been annotated in miRBase making Brachypodium second in number only to rice. Other monocots, such as switchgrass, are completely absent from the miRBase database. While a significant number of miRNAs have been identified which are highly conserved across plants, little research has been done with respect to the conservation of miRNA targets. Plant responses to abiotic stresses are regulated by diverse pathways many of which involve miRNAs; however, it can be difficult to identify miRNA guided gene regulation when the miRNA is not the primary regulator of the target mRNA. Results: To investigate miRNA target conservation and stress response involvement, a set of PARE (Parallel Analysis of RNA Ends) libraries totaling over 2 billion reads was constructed and sequenced from Brachypodium, switchgrass, and sorghum representing the first public release of degradome data from the latter two species. Analysis of this data provided not only PARE evidence for miRNA guided cleavage of over 7,000 predicted target mRNAs in Brachypodium, but also evidence for miRNA guided cleavage of over 1,000 homologous transcripts in sorghum and switchgrass. A pipeline was constructed to compare RNA-seq and PARE data made from Brachypodium plants exposed to various abiotic stress conditions. This resulted in the identification of 44 miRNA targets which exhibit stress regulated cleavage. Time course experiments were performed to reveal the relationship between miR393ab, miR169a, miR394ab, and their respective targets throughout the first 36 hours of the cold stress response in Brachypodium. Conclusions: Knowledge gained from this study provides considerable insight into the degradomes and the breadth of miRNA target conservation among these three species. Additionally associations of a number of miRNAs and target mRNAs with the stress responses have been revealed which will aid researchers in developing stress tolerant transgenic crops.
Project description:Clostridium thermocellum is a Gram-positive, anaerobic, thermophilic bacterium that ferments cellulose into ethanol. It is a candidate industrial consolidated bioprocess (CBP) biocatalyst for lignocellulosic bioethanol production to produce bioethanol directly from cellulosic biomass. However, few transcriptomic studies have been reported so far for C. thermocellum using biomass as carbon source. In this study, samples were taken from exponential and stationary phases of C. thermocellum cells growing in MTC media with pretreated switchgrass as carbon source, and transcriptomic profiling change of C. thermocellum during different growth phase was investigated using both expression array and tiling array. This study will help the understanding of gene expression of C. thermocellum using cellulosic biomass as carbon source and the knowledge will facilitate future metabolic engineering effort for strain improvement. [HX12 expression array]: A eleven array study using total RNA recovered from wild-type cultures of Clostridium thermocellum at different growth phase of T2 and T3 with switchgrass as carbon source. Two biological replicates used for each phase. [3Plex tiling array]: A six array study using total RNA recovered from wild-type cultures of Clostridium thermocellum at different growth phase of T2 and T3 with switchgrass as carbon source. Two biological replicates used for each phase.