Coordinated activation of cellulose and repression of lignin biosynthesis pathways in rice
Ontology highlight
ABSTRACT: Cellulose from plant biomass is the largest renewable energy resource of carbon fixed from the atmosphere, which can be converted into fermentable sugars for production into ethanol. However, the cellulose present as lignocellulosic biomass is embedded in a hemicellulose and lignin matrix from which it needs to be extracted for efficient processing. Here, we show that expression of an Arabidopsis transcription factor SHINE (SHN) in rice, a model for the grasses, causes a 34% increase in cellulose and a 45% reduction in lignin content. Rice genotypes expressing the Arabidopsis SHN2 gene hereafter called rice AtSHN lines were used in this study. Progenies of three independent AtSHN lines were grown in controlled growth chambers. For all analyses, six plants were used for each of the two transgenic lines and WT. For total RNA isolation, rice leaf tissue of WT and AtSHN lines was used. Samples were hybridized to the rice Affymetrix GeneChip.
Project description:Like protein coding genes, loci that produce microRNAs (miRNAs) are generally considered to be under purifying selection, consistent with miRNA polymorphisms being able to cause disease. Nevertheless, it has been hypothesized that variation in miRNA genes may contribute to phenotypic diversity. Here we demonstrate that a naturally occurring polymorphism in the MIR164A gene interacts epistatically with an unlinked locus to affect leaf shape and shoot architecture in Arabidopsis thaliana. A single-base pair substitution in the miRNA complementary sequence alters the stability of the miRNA:miRNA* duplex. It thereby interferes with processing of the precursor and greatly reduces miRNA accumulation. We demonstrate that this is not a rare exception, but that natural strains of Arabidopsis thaliana harbor dozens of similar polymorphisms that affect processing of a wide range of miRNA precursors. Our results suggest that natural variation in miRNA processability due to cis mutations is a common contributor to phenotypic variation in plants. sRNA sequencing transgenic A. thaliana
Project description:The use of syn-tasiRNAs has been proposed as an RNA interference technique alternative to those previously described: hairpin based, virus induced gene silencing or artificial miRNAs. In this study we engineered the TAS1c locus to impair Plum pox virus (PPV) infection by replacing the five native siRNAs with two 210-bp fragments from the CP and the 3´NCR regions of the PPV genome. Deep sequencing analysis of the small RNA species produced by both constructs in planta has shown that phased processing of the syn-tasiRNAs is construct-specific. While in syn-tasiR-CP construct the processing was as predicted 21-nt phased in register with miR173-guided cleavage, the processing of syn-tasiR-3NCR is far from what was expected. A 22-nt species from the miR173-guided cleavage was a guide of two series of phased small RNAs, one of them in an exact 21-nt register, and the other one in a mixed of 21-/22-nt frame. In addition, both constructs produced abundant PPV-derived small RNAs in the absence of miR173 as a consequence of a strong sense PTGS induction. The antiviral effect of both constructs was also evaluated in the presence or absence of miR173 and showed that the impairment of PPV infection was not significantly higher when miR173 was present. The results show that syn-tasiRNAs processing depends on construct-specific factors that should be further studied before the so-called MIGS (miRNA-induced gene silencing) technology can be used reliably. Two samples were analyzed. The control sample has no presence of miR173.
Project description:Transcriptional profiling of young leaves of rice (Oryza sativa) comparing control wild-type plants with transgenic plants transformed with a pBI-nptII-OsDDM1 gene. The latter makes the methylation level of the genomic DNA decreased. Goal was to determine the effects of decreased level of genomic DNA on global rice gene expression. Two-condition experiment, Control vs. Transgenic plants. Biological replicates: 2 control replicates, 2 transfected replicates.
Project description:Redox Responsive Transcription Factor1 (RRTF1) in Arabidopsis is rapidly and transiently upregulated by H202, as well as biotic and abiotic induced redox signals. Inactivation of RRTF1 restricts and overexpression promotes reactive oxygen species (ROS) accumulation in response to stress. Overexpressor (oe) lines are impaired in root and shoot development, light sensitive and susceptible to Alternaria brassicae infection. These symptoms are diminished by the beneficial root endophyte Piriformospora indica which reduces ROS accumulation locally in roots and systemically in shoots, and by antioxidants and ROS inhibitors which scavenge ROS. More than 850 stress-, redox-, ROS regulated-, ROS scavenging-, defense-, cell death- and senescence-related genes are regulated by RRTF1, ~ 30% of them have ROS related functions. Bioinformatic analyses and in vitro DNA binding assays demonstrate that RRTF1 binds to GCC-box and GCC-box like sequences in the promoter of RRTF1-responsive genes. Upregulation of RRTF1 by stress stimuli as well as H2O2 requires WRKY18/40/60. RRTF1 is co-regulated with the phylogenetically related RAP2.6, which contains GCC-box like sequene in its promoter, but RAP2.6 oe lines do not accumulate higher ROS levels. RRTF1 stimulates systemic ROS accumulation in distal non-stressed leaves. We conclude that the highly conserved RRTF1 rapidly, transiently and systemically induce ROS accumulation in response to ROS and ROS-producing abiotic and biotic stress signals. Necrotrophs stimulate RRTF1 expression, while symbiotic interactions of Arabidopsis with (hemi)-biotrophs and P. indica do not affect or repress RRTF1 expression. The seedlings were grown on MS medium with 1.37% sucrose under short day conditions and low light intensity (30 µmol m-2s-1) at 20˚C for 14 days. Transcriptome analysis was performed for the rrtf1 knock-out line and a RRTF1-overlexpressor line (called oe18) in comparison to wild-type seedlings.
Project description:Using a high-end mass spectrometry, we screened phosphoproteins and phosphopeptides in five types of Alzheimer's disease (AD) mouse models (5xFAD, APP-tg, PS1-tg, PS2-tg and APP-KI) and four types of frontotemporal lobar degeneration (FTLD) mouse models(CHMP2B-KI, PGRN-KI, VCP-KI and TDP43-KI) at multiple time points (1, 3 and 6 months).
Project description:Plants capture solar energy and atmospheric carbon dioxide (CO2) through photosynthesis, which is the primary component of crop yield, and needs to be increased considerably to meet the growing global demand for food. Environmental stresses, which are increasing with climate change, adversely affect photosynthetic carbon metabolism (PCM) and limit yield of cereals such as rice (Oryza sativa) that feeds half the world. To study the regulation of photosynthesis, we developed a rice gene regulatory network and identified a transcription factor HYR (HIGHER YIELD RICE) associated to PCM, which on expression in rice enhances photosynthesis under multiple environmental conditions, determining a morpho-physiological program leading to higher grain yield (GY) under normal, drought and high temperature stress conditions. We show HYR is a master regulator, directly activating photosynthesis genes, cascades of transcription factors and other downstream genes involved in PCM and yield stability under drought and high temperature environmental stress conditions. To assess the role of increased HYR expression in rice, whole-genome microarrays were used to generate gene expression profiles of rice cultivar Nipponbare transformed with an overexpression construct of the HYR gene (Loc_Os03g02650) under control of the CaMV 35S promoter, along with control wild-type (WT) lines. Two biological replicate samples each from the HYR and WT-control lines were profiled using rice whole-genome microarrays.
Project description:Laccases were proposed to catalyze the oxidative polymerization of monolignols. We identified 49 laccase gene models in Populus trichocarpa, of which 29 were predicted to be targets of ptr-miR397a. We overexpressed Ptr-MIR397a in transgenic P. trichocarpa. In each of all 9 transgenic lines tested, 17 PtrLACs were down-regulated as analyzed by RNA-seq. Transgenic lines with severe reduction in the expression of these laccase genes resulted in an approximately 40% decrease in the total laccase activity. Overexpression of Ptr-MIR397a in these transgenic lines also reduced lignin content, whereas levels of all monolignol biosynthetic gene transcripts remained unchanged. A hierarchical genetic regulatory network (GRN) built by a bottom-up Graphic Gaussian Model algorithm provides additional support for a role of ptr-miR397a as a negative regulator of laccases for lignin biosynthesis. Full transcriptome based differential gene expression in the overexpressed transgenics and protein domain analyses implicate previously unidentified transcription factors and their targets in an extended hierarchical GRN including ptr-miR397a and laccases that coregulate lignin biosynthesis in wood formation. Ptr-miR397a, laccases and other regulatory components of this network may provide additional strategies for genetic manipulation of lignin content. Total twelve trees were used. Those include nine individual transgenic trees for overexpressing Ptr-miR397a, as nine biological replicates, and three wild-type trees.
Project description:The severity of impact of drought on crops is contingent on the developmental stage of the plant, with the most sensitive stage being the reproductive stage. Hence, gene expression profiling has been used to understanding drought response and resistance mechanism in rice. Here we present drought transcriptomes of rice in three developmental stages and gain insights into the processes and regulatory mechanisms involved in common and stage specific drought responses. Total RNA was isolated from the rice seedlings, vegetative (V4) and reproductive (R4) tissues of both control and stress treated plants for hybridization on Affymetrix microarrays. Two independent replicates for seedling and reproductive stages, and three replicates for vegetative stages were generated, for both control and stress samples. For drought treatments, plants were gradually subjected to field drought conditions in order to reach 50% field capacity (FC) by regulating water supply, whereas control plants were maintained at 100% FC.
Project description:Secretome profiling of the Teredinibacter turnerae E7MBN strain grown in sucrose, major plant cell wall polysaccharides (i.e., cellulose, xylan, and pectin), and rice hull biomass.