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: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 Keywords: strain_or_line_design

Project description:Inflorescence architecture contributes to essential plant traits. It determines plant shape, contributing to morphological diversity, also determines position and number of the flowers and fruits produced by the plant, influencing seed yield. Most legumes have compound inflorescences, where flowers are produced in secondary inflorescences (I2), formed at the flanks of the main primary inflorescence (I1), in contrast to simple inflorescences of plants like Arabidopsis, in which flowers are directly formed on the I1. The pea VEGETATIVE1/ FULc (VEG1) gene, and its homologues in other legumes, specify the formation of the I2 meristem, a function apparently restricted to legumes. To understand the control of I2 development it is important to identify the genes working downstream of VEG1. In this study, we adopted a novel strategy to identify genes expressed in the I2 meristem, as potential regulatory targets of VEG1. To identify pea I2-meristem genes we compared the transcriptomes of inflorescence apices from wild type and mutants affected in I2 development, proliferating inflorescence meristems (pim - with more I2 meristems), veg1 and vegetative2 (both without I2 meristems). Analysis of the differentially expressed genes using Arabidopsis genome databases combined with RT-qPCR expression analysis in pea, allowed the selection of genes expressed in the pea inflorescence apex. In situ hybridization of four of these genes showed that all four genes are expressed in the I2 meristem, proving our approach to identify I2-meristem genes successful. Finally, analysis by VIGS in pea identified one gene, PsDAO1, whose silencing lead to small plants and another gene, PsHUP54, whose silencing leads to plants with very large stubs, meaning that this gene controls activity of the I2 meristem. PsHUP54-VIGS plants also are large and, more importantly, produce large pods with almost double of seeds than the control. Our study shows a new useful strategy to isolate I2-meristem genes and identifies a novel gene, PsHUP54, which seems a promising tool to improve yield in pea and another legumes.

Dataset Information

Pleiotropic and Non-redundant Effects of an Auxin Importer in Setaria and Maize

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