Although abscisic acid (ABA) and gibberellins (GAs) play pivotal roles in many physiological processes in plants, their interaction in the control of leaf growth remains elusive. In this study, genetic analyses of ABA and GA interplay in leaf growth were performed in Arabidopsis thaliana. The results indicate that for ABA and GA interaction, leaf growth of both the aba2/ga20ox1 and aba2/GA20OX1-OE plants exhibits partially additive effects but is similar to the aba2 mutant. Consistent with this result, transcriptome analysis suggests that a substantial proportion (45-65%) of the gene expression profile of aba2/ga20ox1 and aba2/GA20OX1-OE plants overlaps and shares a similar pattern to the aba2 mutant. Thus, these data support that ABA deficiency dominates leaf growth regardless of GA levels. Moreover, gene ontology (GO) analysis indicates gene enrichment in the categories of hormone response, developmental and metabolic processes, and cell wall organization in these three genotypes. Leaf developmental genes are also involved in ABA-GA interaction. Collectively, these data support that the genetic relationship of ABA and GA interaction involves multiple coordinated pathways rather than a simple linear pathway in the regulation of leaf growth.
Genetic analyses of the interaction between abscisic acid and gibberellins in the control of leaf development in Arabidopsis thaliana.
Specimen part
View SamplesAlthough the nucleolus is known to be involved in the plant stress response, the underlying mechanisms remain unclear. In the present study, we genetically isolated and characterized the Arabidopsis thaliana salt hypersensitive mutant 1 (sahy1), which exhibits slow growth, short roots, and sterility. SAHY1 encodes an unknown protein that is predominantly expressed in root tips and mature pollens. Subcellular localization further demonstrated that SAHY1 is a nucleolar protein. Ploidy analysis and detection of S-phase cell cycle progression indicated that mitosis is reduced in the root tips of sahy1 plants. Furthermore, levels of reactive oxygen species (ROS) are reduced in the mutant. In addition to exhibiting changes in venation pattern, palisade mesophyll cells, the auxin response, and fertility, the sahy1 mutant is resistant to the protein translation inhibitors, streptomycin and cycloheximide, and has altered expression profiles of ribosome-related genes, reflecting the involvement of SAHY1 in ribosome assembly. Using a combination of transcriptome and gene coexpression clustering analyses, we identified a striking functional module in which SPIRAL 1-LIKE 4 (SPL4), which encodes a microtubule-localized protein, mediates the salt response that acts by modulating dynamic microtubule instability. Supporting evidence indicates that sahy1 is resistant to a microtubule-destabilizing drug (oryzalin), that the cortical microtubule array in sahy1 exhibits changes in dynamic instability, and that the spr1/spl2/spl3/spl4 quadruple mutant is oversensitive to salt. Collectively, these data demonstrate that a novel nucleolar protein, SAHY1, plays critical roles in salt sensitivity, plant growth, and development by integrating the diverse functions of its downstream genes.
No associated publication
Specimen part
View SamplesDue to limited bio-availability of Fe, plants evolved adaptive alterations in development regulated at the transcriptional level. We investigated the early transcriptional response to Fe deficiency.
Early iron-deficiency-induced transcriptional changes in Arabidopsis roots as revealed by microarray analyses.
Specimen part
View SamplesThe environmental light plays a vital role in regulating the plant growth and development. Transcriptomic profilings were widely used to examine how light regulates the changes of mRNA populations at a genome-wide scale. However, it remains unclear if translational regulation represents a new dimension of gene expression regulation in response to the light signal. Through a transcriptomic comparison of steady-state and polysome-bound mRNAs, we revealed an increased translational efficiency in de-etiolating Arabidopsis seedlings. Over 3,500 genes are subjected to translational regulation whereas only about 770 genes have increased mRNA abundances in response to the light signal. This result suggests a stronger impact of translational control over transcriptomic changes during photomorphogenesis. Genes encoding ribosomal protein are preferentially regulated at the translational level, possibly contributing to the enhancement of translation efficiency as observed. We also uncovered mRNAs regulated at the translational level share characteristics of longer half-lives and shorter cDNA length. The presence of a cis-element, TAGGGTTT, in the 5untranslated region of a transcript renders its translational regulation by light signals. Taken together, our study revealed a previously neglected aspect of gene expression regulation during Arabidopsis photomorphogenesis. The identities and molecular signatures associated with mRNAs regulated at the translational level also offer new directions to perform mechanistic studies of light-trigged translational enhancement in Arabidopsis.
Widespread translational control contributes to the regulation of Arabidopsis photomorphogenesis.
Specimen part, Treatment, Time
View SamplesCsUBC13 was identified via proteomics from iron starvation treated Cucumber root. ubc13A is an ABRC seed stock (CS51269). CS851269 was purchased from ABRC and confirmed as homozygous Atubc13A knock-out T-DNA mutant. We generated transgenic arabidopsis with ectopic expression of CsUBC13 gene under control of the cauliflower 35S promotor. Both genotypes and Col-0 were used to investigate the transcriptional response to Iron (Fe) deficiency.
A lysine-63-linked ubiquitin chain-forming conjugase, UBC13, promotes the developmental responses to iron deficiency in Arabidopsis roots.
Specimen part
View SamplesWe have reported that JMJ17 act as a repressor to a set of genes involved in photosynthesis, tetrapyrrole biosynthesis and light response related development in the dark, while during dark to light irradiation it acts as an activator of same set of genes.
No associated publication
Specimen part, Treatment
View SamplesPlants can be primed by a stress cue to mount a faster and stronger activation of defense mechanisms upon a subsequent stress. A crucial component of such stress priming is the modified reactivation of genes upon recurring stress, a phenomenon known as transcriptional memory. The transcriptional memory in response to heat stress is not clear at the genome scale.
Distinct heat shock factors and chromatin modifications mediate the organ-autonomous transcriptional memory of heat stress.
Age, Specimen part
View SamplesPluripotent stem cells, including human embryonic stem (hES) and induced pluripotent stem (hiPS) cells, have been regarded as useful sources for cell?based transplantation therapy. However immunogenicity of the cells remains the major determinant for successful clinical application. We report the examination of several hES cell lines (NTU1 and H9), hiPS cell lines, and their derivatives (including stem cell?derived hepatocytes) for the expression of major histocompatibility complex (MHC), natural killer (NK) cell receptor (NKp30, NKp44, NKp46) ligand, immune?related genes, human leukocyte antigen (HLA) haplotyping, and the effects in functional mixed lymphocyte reaction (MLR). Flow cytometry showed lower levels (percentages and fluorescence intensities) of MHC class I (MHC?I) molecules, 2?microglobulin and HLA?E in undifferentiated stem cells, but the levels were increased after co?treatment with interferon gamma and/or in vitro differentiation. Antigen presenting cell markers (CD11c, CD80 and CD86) and MHC?II (HLA?DP, DQ and DR) remained low throughout the treatments. Recognitions of stem cells/derivatives by NK lysis receptors were lower or absent. Activation of responder lymphocytes was significantly lower by undifferentiated stem cells than by allogeneic lymphocytes in MLR, but differentiated NTU1 hES cells induced a cell number?dependent lymphocyte proliferation comparable with that by allogeneic lymphocytes. Interestingly activation of lymphocytes by differentiated hiPS cells or H9 cells became blunted at higher cell numbers. Real?time RT?PCR showed significant differential expression of immune privilege genes (TGF?2, Arginase 2, Indole 1, GATA3, POMC, VIP, CALCA, CALCB, IL?1RN, CD95L, CR1L, Serpine 1, HMOX1, IL6, LGALS3, HEBP1, THBS1, CD59 and LGALS1) in pluripotent stem cells/derivatives when compared to somatic cells. It is concluded that pluripotent stem cells/derivatives are predicted to be immunogenic, though evidences suggest some levels of potential immune privilege. In addition, differential immunogenicity may exist between different pluripotent stem cell lines and their derivatives
Characteristic expression of major histocompatibility complex and immune privilege genes in human pluripotent stem cells and their derivatives.
Sex, Specimen part
View SamplesHSFA1s are a gene family of HSFA1 with four members, HSFA1a, HSFA1b, HSFA1d, and HSFA1e. HSFA1s are the master regulators of heat shock response. As a part of the heat shock response, HSFA2 can prolong the heat shock response and amplify the heat shock response in response to repeat heat shock. To identify the heat-shock-responsive genes differentially regulated by HSFA1s and HSFA2, we compared the transcriptomic differences of plants containing only constitutively expressed HSFA1s or HSFA2 after heat stress.
Common and distinct functions of Arabidopsis class A1 and A2 heat shock factors in diverse abiotic stress responses and development.
Age, Specimen part
View Samplesa novel orphan peptide, IRON-REGULATED PROTEIN1 (IRP1) that is rapidly induced by Fe deficiency and improves growth on Fe-deplete media.
No associated publication
Specimen part
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