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: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 light of the changes in precipitation and soil water availability expected with climate change, understanding the mechanisms underlying plant responses to water deficit is essential. Toward that end we have conducted an integrative analysis of responses to drought stress in the perennial C4 grass and biofuel crop, Panicum virgatum (switchgrass). Responses to soil drying and re-watering were measured at transcriptional, physiological, and metabolomic levels. To assess the interaction of soil moisture with diel light:dark cycles, we profiled gene expression in drought and control treatments under pre-dawn and mid-day conditions. Soil drying resulted in reduced leaf water potential, gas exchange, and chlorophyll fluorescence along with differential expression of a large fraction of the transcriptome (37%). Many transcripts responded differently depending on time of day (e.g. up-regulation pre-dawn and down-regulation mid-day). Genes associated with C4 photosynthesis were down-regulated during drought, while C4 metabolic intermediates accumulated. Rapid changes in gene expression were observed during recovery from drought, along with increased water use efficiency and chlorophyll fluorescence. Our findings demonstrate that drought responsive gene expression depends strongly on time of day and that gene expression is extensively modified during the first few hours of drought recovery. Analysis of covariation in gene expression, metabolite abundance, and physiology among plants revealed non-linear relationships that suggest critical thresholds in drought stress responses. Future studies may benefit from evaluating these thresholds among diverse accessions of switchgrass and other C4 grasses.
Project description:In light of the changes in precipitation and soil water availability expected with climate change, understanding the mechanisms underlying plant responses to water deficit is essential. Toward that end we have conducted an integrative analysis of responses to drought stress in the perennial C4 grass and biofuel crop, Panicum virgatum (switchgrass). Responses to soil drying and re-watering were measured at transcriptional, physiological, and metabolomic levels. To assess the interaction of soil moisture with diel light:dark cycles, we profiled gene expression in drought and control treatments under pre-dawn and mid-day conditions. Soil drying resulted in reduced leaf water potential, gas exchange, and chlorophyll fluorescence along with differential expression of a large fraction of the transcriptome (37%). Many transcripts responded differently depending on time of day (e.g. up-regulation pre-dawn and down-regulation mid-day). Genes associated with C4 photosynthesis were down-regulated during drought, while C4 metabolic intermediates accumulated. Rapid changes in gene expression were observed during recovery from drought, along with increased water use efficiency and chlorophyll fluorescence. Our findings demonstrate that drought responsive gene expression depends strongly on time of day and that gene expression is extensively modified during the first few hours of drought recovery. Analysis of covariation in gene expression, metabolite abundance, and physiology among plants revealed non-linear relationships that suggest critical thresholds in drought stress responses. Future studies may benefit from evaluating these thresholds among diverse accessions of switchgrass and other C4 grasses. mRNA profiles of leaf tissue from clonal replicates at various time points during drydown and recovery were generated by deep sequencing 3' mRNA tags using SOLiD.
Project description:Switchgrass (Panicum virgatum) is a perennial crop producing deep roots thus highly tolerant to soil water deficit conditions. However, seedling establishment in field is very susceptible to prolonged and periodic drought stress. In this study, a “sandwich” system simulating a gradual water deletion process was developed. Switchgrass seedlings were subjected to a 20-day gradual drought treatment process when soil water tension was increased to 0.05 MPa (moderate drought stress) and leaf physiological properties had expressed significant alteration. Drought-induced changes in leaf proteomes were identified using the relative and absolute quantitation (iTRAQ) labeling method followed by nano-scale liquid chromatography mass spectrometry (nano-LC-MS/MS) analysis. Additionally, total leaf proteins were processed using a combinatorial library of peptide ligands to enrich for lower abundance proteins. Both total proteins and those enriched samples were analyzed to increase the coverage of the quantitative proteomics analysis. A total of 7,006 leaf proteins were identified, and 257 (4% of the leaf proteome) expressed a significant difference (P < 0.05, fold change < 0.6 or > 1.7) from the non-treated control to drought-treated conditions. Results from this study, in addition to revealing molecular responses to drought stress, provide a large number of proteins (candidate genes) that can be employed to improve switchgrass seedling growth and establishment under soil drought condition.
Project description:In this study, we used transcriptomic and hormonomic approaches to examine drought-induced changes in barley roots and leaves and its rhizosphere. By studying hormonal responses, alternative splicing events in barley, and changes in the rhizosphere microbiome, we aimed to provide a comprehensive view of barley drought-adaptive mechanisms and potential plant-microbe interactions under drought stress. This approach improved our understanding of barley adaptive strategies and highlighted the importance of considering plant-microbe interactions in the context of climate change.
Project description:A heat and drought tolerant rice cultivar (N22) was grown in the field under control and drought conditions during the dry season in 2013. Drought was applied during early grain filling and resulted in simultaneous heat stress, leading to reduced grain yield and quality. Total RNA was extracted from developing seeds under stress and control (fully flooded) conditions and RNA-seq analysis was performed. These samples are a part of a bigger experiment analysing the responses of three contrasting rice cultivars (N22, Dular, Anjali) to combined heat and drought stress including different organs (developing seeds, flag leaves, flowering spikelets) and developmental stages (early grain filling, flowering) at the transcriptomic level.
Project description:Co-immunoprecipitation with endogenous Hfq3xFlag in exponential, stationary, non-induced and virulence induced conditions, followed by RNA-sequencing, revealed 1697 mRNAs and 208 ncRNAs associated with Hfq. We identified 56 new ncRNAs and validated 3 Hfq-dependent trans sRNAs on by Northern blot analysis. Interestingly, 55% of the ncRNAs were encoded antisense to a protein coding sequence. Abundance of 4 asRNAs and their corresponding target mRNAs was altered upon hfq, indicating a substantial influence of Hfq on asRNA-target interactions.
Project description:Switchgrass plants were grown in a Sandwich tube system to induce gradual drought stress by withholding watering. After 29 days, leaf photosynthetic rate decreased significantly, compared to the control plants which were watered regularly. The drought-treated plants recovered to the same leaf water content after three days of re-watering. Root tip (1cm basal fragment, designated as RT1 hereafter) and the elongation/maturation zone (the next upper 1 cm tissue, designated as RT2 hereafter) tissues were collected at the 29th day of drought stress treatment, (named SDT for severe drought treated), one (D1W) and three days (D3W) of re-watering. The tandem mass tags mass spectrometry-based quantitative proteomics analysis was performed to identify the proteomes, and drought-induced differentially expressed proteins (DEPs). From RT1 tissues, 6,156, 7,687 and 7,699 proteins were quantified, and 296, 535 and 384 DEPs were identified in the SDT, D1W and D3W samples, respectively. From RT2 tissues, 7,382, 7,255 and 6,883 proteins were quantified, and 393, 587 and 321 proteins DEPs were identified in the SDT, D1W and D3W samples. Between RT1 and RT2 tissues, very few DEPs overlapped at SDT, but the number of such proteins increased during the recovery phase. A large number of hydrophilic proteins and stress-responsive proteins were induced during SDT and remained at a higher level during the recovery stages. A large number of DEPs in RT1 tissues maintained the same expression pattern throughout drought treatment and the recovery phases. The DEPs in RT1 tissues were classified in cell proliferation, mitotic cell division, and chromatin modification, and those in RT2 were placed in cell wall remodeling and cell expansion processes. This study provided information pertaining to root zone-specific proteome changes during drought and recover phases, which will allow us to choose the proteins (genes) as better defined targets for developing drought tolerant plants.