The Arabidopsis thaliana VERNALIZATION INDEPENDENCE (VIP) gene class has multiple functions in development, including repression of flowering through activation of the MADSbox gene FLC. Epigenetic silencing of FLC plays a substantial role in the promotion of flowering through cold (vernalization). To better understand how VIP genes influence development, we undertook a genetic and molecular study of the previously uncharacterized VIP5 and VIP6 genes. We found that loss of function of these genes ...[more]
Project description:Polyamines are multifaceted compounds which play a role in regulating plant growth and stress tolerance in interactions with plant hormones. The aim of the present study was to reveal how exogenous polyamines influence the synthesis of salicylic acid, with a special emphasis on the effect of salicylic acid deficiency on the polyamine metabolism and polyamine-induced changes in other plant hormone contents. Our hypothesis was that the individual polyamines induced different changes in the polyamine and salicylic acid metabolism of the wild type and salicylic acid-deficient Arabidopsis mutants, which in turn influenced other hormones. To our knowledge, such a side-by-side comparison of the influence of eds5-1 and sid2-2 mutations on polyamines has not been reported yet. To achieve our goals, wild and mutant genotypes were tested after putrescine, spermidine or spermine treatments. Polyamine and plant hormone metabolism was investigated at metabolite and gene expression levels. Individual polyamines induced different changes in the Arabidopsis plants, and the responses were also genotype-dependent. Polyamines upregulated the polyamine synthesis and catabolism, and remarkable changes in hormone synthesis were found especially after spermidine or spermine treatments. The sid2-2 mutant showed pronounced differences compared to Col-0. Interactions between plant hormones may also be responsible for the observed differences.
Project description:geLC-MS/MS analysiswas performed to identify proteins that are present in apoplastic fluid isolated from rosette leaves of 8-week-old wild type and carbonic anhydrase (ca1ca4) mutant Arabidopsis plants.
Project description:Extensins are members of the cell wall hydroxyproline-rich glycoprotein (HRGP) superfamily that form covalently cross-linked networks in primary cell walls. A knockout mutation in EXT3 (AT1G21310), the gene coding EXTENSIN 3 (EXT3) in Arabidopsis Landsberg erecta resulted in a lethal phenotype, although about 20% of the knockout plants have an apparently normal phenotype (ANP). In this study the root cell wall HRGP components of wild-type, ANP and the ext3 mutant seedlings were characterized by peptide fractionation of trypsin digested anhydrous hydrogen fluoride deglycosylated wall residues and by sequencing using LC-MS/MS. Several HRGPs, including EXT3, were identified in the wild-type root walls but not in walls of the ANP and lethal mutant. Indeed the ANP walls and walls of mutants displaying the lethal phenotype possessed HRGPs, but the profiles suggest that changes in the amount and perhaps type may account for the corresponding phenotypes.
Project description:BACKGROUND AND AIMS: The epidermis of an expanding dicot leaf is a mosaic of cells differing in identity, size and differentiation stage. Here hypotheses are tested that in such a cell mosaic growth is heterogeneous and changes with time, and that this heterogeneity is not dependent on the cell cycle regulation per se. METHODS: Shape, size and growth of individual cells were followed with the aid of sequential replicas in expanding leaves of wild-type Arabidopsis thaliana and triple cyclinD3 mutant plants, and combined with ploidy estimation using epi-fluorescence microscopy. KEY RESULTS: Relative growth rates in area of individual epidermal cells or small cell groups differ several fold from those of adjacent cells, and change in time. This spatial and temporal variation is not related to the size of either the cell or the nucleus. Shape changes and growth within an individual cell are also heterogeneous: anticlinal wall waviness appears at different times in different wall portions; portions of the cell periphery in contact with different neighbours grow with different rates. This variation is not related to cell growth anisotropy. The heterogeneity is typical for both the wild type and cycD3. CONCLUSIONS: Growth of leaf epidermis exhibits spatiotemporal variability.
Project description:The goal of this study is to establish the global gene expression profiles of Arabidopsis wild type and ago1-36 mutant plants, and identify novel potential miRNA targets. Overall design: RNA-seq was performed using Arabidopsis wild type and ago1-36 mutant seedlings.
Project description:The goal of this study is to establish the global gene expression profiles of Arabidopsis wild type and ago1-27 mutant plants, and identify novel potential miRNA targets. Overall design: RNA-seq was performed using Arabidopsis wild type and ago1-27 mutant flower buds. Three biological replicates were conducted for each genotype.
Project description:Genetic analyses of plant symbiotic mutants has led to the identification of key genes involved in Rhizobium-legume communication as well as in development and function of nitrogen fixing root nodules. However, the impact of these genes in coordinating the transcriptional programs of nodule development has only been studied in limited and isolated studies. Here, we present an integrated genome-wide analysis of transcriptome landscapes in Lotus japonicus wild-type and symbiotic mutant plants. Encompassing five different organs, five stages of the sequentially developed determinate Lotus root nodules, and eight mutants impaired at different stages of the symbiotic interaction, our data set integrates an unprecedented combination of organ- or tissue-specific profiles with mutant transcript profiles. In total, 38 different conditions sampled under the same well-defined growth regimes were included. This comprehensive analysis unravelled new and unexpected patterns of transcriptional regulation during symbiosis and organ development. Contrary to expectations, none of the previously characterized nodulins were among the 37 genes specifically expressed in nodules. Another surprise was the extensive transcriptional response in whole root compared to the susceptible root zone where the cellular response is most pronounced. A large number of transcripts predicted to encode transcriptional regulators, receptors and proteins involved in signal transduction, as well as many genes with unknown function, were found to be regulated during nodule organogenesis and rhizobial infection. Combining wild type and mutant profiles of these transcripts demonstrates the activation of a complex genetic program that delineates symbiotic nitrogen fixation. The complete data set was organized into an indexed expression directory that is accessible from a resource database, and here we present selected examples of biological questions that can be addressed with this comprehensive and powerful gene expression data set.
Project description:BACKGROUND: Small-secreted peptides are emerging as important components in cell-cell communication during basic developmental stages of plant cell growth and development. Plant peptide containing sulfated tyrosine 1 (PSY1) has been reported to promote cell expansion and differentiation in the elongation zone of roots. PSY1 action is dependent on a receptor PSY1R that triggers a signaling cascade leading to cell elongation. However little is known about cellular functions and the components involved in PSY1-based signaling cascade. RESULTS: Differentially expressed genes were identified in a wild type plant line and in a psy1r receptor mutant line of Arabidopsis thaliana after treatment with PSY1. Seventy-seven genes were found to be responsive to the PSY1 peptide in wild type plants while 154 genes were responsive in the receptor mutant plants. PSY1 activates the transcripts of genes involved in cell wall modification. Gene enrichment analysis revealed that PSY1-responsive genes are involved in responses to stimuli, metabolic processes and biosynthetic processes. The significant enrichment terms of PSY1-responsive genes were higher in psy1r mutant plants compared to in wild type plants. Two parallel responses to PSY1 were identified, differing in their dependency on the PSY1R receptor. Promoter analysis of the differentially expressed genes identified a light regulatory motif in some of these. CONCLUSION: PSY1-responsive genes are involved in cellular functions and stimuli responses suggesting a crosstalk between developmental cues and environmental stimuli. Possibly, two parallel responses to PSY1 exist. A motif involved in light regulation was identified in the promoter region of the differentially expressed genes. Reduced hypocotyl growth was observed in etiolated receptor mutant seedlings.