Project description:The plant hormone auxin represents an important regulator of growth and development. Significant insight into the mechanisms of auxin action have been obtained from studies of auxin resistant mutants such as aux1 and axr3. The Arabidopsis axr4 mutant was identified in a screen for auxin resistant root growth. In addition to the root growth of axr4 being resistant to exogenous auxin, there is also a 50% reduction in the number of lateral roots that form. The double axr4/aux1 mutant shows an additive effect in reducing lateral root numbers to 10% of wild-type. Gaining further information about the potential interaction between AUX1 and AXR4 may provide important insight into auxin regulated plant growth. Mapping experiments have placed the AXR4 gene on the lower arm of chromosome 1 between the ch1 and le markers (Hobbie and Estelle 1995). However, the AXR4 gene remains to be cloned. Identifying the AXR4 gene will help in elucidating the function of the protein. A transcript analysis of axr4 mutant seedlings will be used in 2 ways. Firstly, the transcription level of genes in the locality of the axr4 map position will be examined to identify those which are absent or significantly reduced in axr4 compared to the Col0 control. If the lesion causing the axr4 mutation results in a highly unstable mRNA or abolishes transcription then the signal will be dramatically reduced. Potential candidate genes identified in this way will be further analysed using a combination of RT-PCR and sequencing to identify the AXR4 gene. Secondly, the transcriptomics data obtained from axr4 and Col0 will be compared to identify genes which show significant transcript level differences and therefore represent targets for either direct or indirect regulation by AXR4. Hobbie, L. and Estelle, M. (1995) The axr4 auxin-resistant mutants of Arabidopsis thaliana define a gene important for root gravitropism and lateral root initiation. Plant J. 7 211-220 Experiment Overall Design: 2 samples

Project description:Aims We aim to use transcriptome analysis to establish on a genome-wide scale the identity and regulatory clusters of genes that specify microgametogenesis from the haploid microspore to mature functional pollen in Arabidopsis. Background Pollen as the haploid male gametophyte plays a vital role in plant fertility and crop production through the ability to deliver the male gametes in fertilisation. Despite the obvious importance for plant fertility and crop production we have a very limited understanding of the regulatory mechanisms that have evolved to specify male gametophyte development and functions and less than 150 genes have been identified that are gametophytically expressed in the anther.The availability of functional genomic resources now provides the opportunity to undertake a comprehensive approach to describing cellular development in terms of the transcriptome. This approach is particularly powerful where the complete transcriptome of a single developing cell can be analysed. The male gametophyte is a uniquely accessible cell type for such studies, enabling RNA analysis from distinct purified cell populations during development.The proposed experiments are designed to support a current application (P19208, Twell) to investigate the gametophytic transcriptome and transcription factor networks. The results obtained will extend our knowledge of the contribution of haploid gene expression to anther development and will be used directly to extend BBSRC funded work (P15086, Wilson) to investigate the role and targets the MALE STERILE 1 gene (MS1). In particular the data will be used in collaboration to extract haploid gene expression from datasets of transcriptome analysis of staged flower buds of wild type (Ler) and ms1. This work will also complement BBSRC funded work on sporogenesis (G13338, Dickinson and Scott) and meiosis (G15941, Franklin and Jones) that are focussed on earlier steps in anther development. Biological material and methods. Isolated microspores and pollen at 4 different developmental stages will be analysed. We will isolate spores from developmentally staged buds of Ler grown under defined growth conditions. Buds from several batches of 100 plants will be rapidly sorted into 4 groups according to developmental age, uninucleate microspores (UM), bicellular pollen (BP) tricellular pollen (TP) and mature pollen. Spores will be released by gentle mechanical tissue disruption and purified by filtration and purification of spores. We are confident that our spore isolation procedures are rigorous since we could not detect even trace expression of highly abundant sporophytic transcripts such RbcS and Cab transcripts in microarray data from pollen RNA. Experiment Overall Design: Number of plants pooled:over 100

Project description:In Antirrhinum, the equivalent mutant to the Arabidopsis cuc1 cuc2 double is called cup. We have cloned CUP and shown that it encodes a NAC-domain transcription factor homologous to CUC1 and CUC2. Yeast two-hybrid analysis shows that CUP interacts with TIC, an Antirrhinum TCP transcription factor. Moving back to Arabidopsis, the closest homologues to TIC encode TCP factors TCP13 and TCP14 which, we have now shown, also interact in two-hybrid experiments with CUC1 and CUC2. We have identified insertions in both TCP13 and TCP14. CUP, CUC1 and CUC2 play a role in the establishment of boundaries between lateral organs. As evolutionarily conserved interactors, we expect TCP13 and TCP14 to act in the same process. Homozygous tcp13 mutant flowers show mixed cell identity (mci) with the boundaries of organ identity out of register with those of physical organ development. tcp 14 mutants show a very weak phenotype, but the double heterozygote is identical to the tcp13 homozygote. The double homozygote is underway at the moment and this application takes into account the time required to generate these plants.The aim of this microarray experiment is to identify targets of TCP13 and TCP14. We propose to compare expression levels in WT, tcp13, tcp14, tcp13/+ tcp14/+, and tcp13 tcp14 plants. Although we initially propose only duplicate experiments for each mutant, requiring a total of 10 chips, the experimental material will serve as internal replicates, since we expect to see different degrees of inactivation/activation of at least a core of conserved genes. The fact that all of the mutant combinations observed so far produce flowers with the appropriate cell types present, but in a different position, suggests that, unlike in homeotic mutants, very similar sets of floral genes will be present in each sample. This gives us hope that we might find a smaller number of genes with altered expression. Our tissue samples will be wild type and mutant inflorescences and, as such, will contain a variety of flowers at different stages of development. By taking a large number of flowers and buds we hope to overcome any sampling errors. Although we have requested 10 chips - for duplicate analyses of WT, both single mutants, the heterozygote and the double mutant - it remains a formal possibility that the double homozygote is inviable, or produces no inflorescence. In this unlikely eventuality we would only submit 8 of the 10 samples.

Project description:Plant growth and development are strongly affected by light signals perceived by phytochromes (phy) and cryptochromes (cry). The physical interaction between photoreceptors and the cross-talk among downstream signalling steps creates a network of interactions in which the action of one photoreceptor depends on the status of the others. The processes modulated by phy and or cry include seed germination, seedling de-etiolation, plant body formation and flowering. Compared to the wild type the leaves of the phyB mutant are characterised by their extended petioles and pale colour. These features resemble the phenotype of normal plants grown under the low red to far-red ratios typical of dense plant canopies thus providing support to the idea that phyB plays a key role in the perception of high red to far-red ratios. The triple mutant lacking phyA cry1 and cry2 shows little differences in leaf size and shape with the wild typebut the quadruple phyA phyB cry1 cry2 mutant shows severely impaired leaf expansion. In addition to the specific effects on leaf sizeshape and pigmentation the phyB mutation accelerates flowering in the wild type background. This effect can be observed as a reduced number of days between sowing and visible flower buds (time scale) and as a reduced final number of leaves (developmental scale). However in the phyA cry1 cry2 triple mutant background the phyB mutation accelerates flowering on a developmental scale but severely delays flowering on a time scale. The long photoperiods inducing flowering are perceived by the leaves. Flowering signals that could include hormones and sugars migrate from the leaves to the apex in response to the light stimulus. We propose to compare the following mRNA samples of expanding leaves: 1) wild type 2) phyB mutant 3) phyA cry1 cry2 triple mutant 4) phyA phyB cry1 cry2 quadruple mutant. The comparison between the wild type and the phyB mutant will help to uncover the changes in leaf mRNA patterns underlying enhanced petiole growthreduced pigmentation and early flowering in response to the absence of phyB activity. The comparison between the phyA cry1 cry2 triple mutant and the phyA phyB cry1 cry2 quadruple mutant should reveal the mRNA differences between photosynthetic leaves with dramatically different abilities to expand. The added value of the simultaneous analysis of the two comparisons is that effect of phyB is different in both genetic backgrounds and this should provide information on the mechanisms and significance of photoreceptor interactions.

Project description:In Antirrhinum, the equivalent mutant to the Arabidopsis cuc1 cuc2 double is called cup. We have cloned CUP and shown that it encodes a NAC-domain transcription factor homologous to CUC1 and CUC2. Yeast two-hybrid analysis shows that CUP interacts with TIC, an Antirrhinum TCP transcription factor. Moving back to Arabidopsis, the closest homologues to TIC encode TCP factors TCP13 and TCP14 which, we have now shown, also interact in two-hybrid experiments with CUC1 and CUC2. We have identified insertions in both TCP13 and TCP14. CUP, CUC1 and CUC2 play a role in the establishment of boundaries between lateral organs. As evolutionarily conserved interactors, we expect TCP13 and TCP14 to act in the same process. Homozygous tcp13 mutant flowers show mixed cell identity (mci) with the boundaries of organ identity out of register with those of physical organ development. tcp 14 mutants show a very weak phenotype, but the double heterozygote is identical to the tcp13 homozygote. The double homozygote is underway at the moment and this application takes into account the time required to generate these plants.The aim of this microarray experiment is to identify targets of TCP13 and TCP14. We propose to compare expression levels in WT, tcp13, tcp14, tcp13/+ tcp14/+, and tcp13 tcp14 plants. Although we initially propose only duplicate experiments for each mutant, requiring a total of 10 chips, the experimental material will serve as internal replicates, since we expect to see different degrees of inactivation/activation of at least a core of conserved genes. The fact that all of the mutant combinations observed so far produce flowers with the appropriate cell types present, but in a different position, suggests that, unlike in homeotic mutants, very similar sets of floral genes will be present in each sample. This gives us hope that we might find a smaller number of genes with altered expression. Our tissue samples will be wild type and mutant inflorescences and, as such, will contain a variety of flowers at different stages of development. By taking a large number of flowers and buds we hope to overcome any sampling errors. Although we have requested 10 chips - for duplicate analyses of WT, both single mutants, the heterozygote and the double mutant - it remains a formal possibility that the double homozygote is inviable, or produces no inflorescence. In this unlikely eventuality we would only submit 8 of the 10 samples. Experiment Overall Design: Number of plants pooled:10

Dataset Information

Identification of genes differentially expressed in dormant versus active axillary shoot apical mersitems.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets