Project description:Arabidopsis plants transfer information from the leaf tip to the petiole base to induce adaptive upward leaf movement upon neighbour detection through Far-Red light enrichment in the leaf tip. To determine how a distally derived signal can specifically regulate growth in the abaxial petiole we analysed the transcriptome in the leaf tip and abaxial-adaxially split petiole sections during the first hours of far-red enrichment.
Project description:Quinoa, like a large fraction of halophytes, use so-called bladder cells to detoxify excess salt. These leaf exterior structures are formed by specialized trichomes and consist of a leaf epidermal cell, a stalk cell and the bladder cell itself. Under salt stress, Na+ and Cl- as well as K+ and metabolites are imported from leaf sources and stored in the bladder. During this process the stalk cell simultaneously operates as both a selectivity filter and a flux controller. We submerged detached leaves in buffer, then lightly brushed the abaxial surface with a fine paintbrush to remove only the EBCs. The abaxial epidermis was then removed using tweezers and sampled in buffer for RNA extraction and RNA sequencing to separate the gene expression profiles of stalk cells from bladders and leaves.
Project description:The establishment of ad/abaxial polarity is a fundamental event in plant development. It is critical for correct polar development of the leaf (the upper portion of the leaf is chloroplast rich and optimized for light capture while the lower portion is optimized for gas exchange) and for creating an environment that allows the formation of new meristems (centers of stem cell growth). Class III homeodomain-leucine zipper (HD-ZIPIII) proteins are conserved plant proteins that act as potent regulators of ad/abaxial polarity. HD-ZIPIII protein activity promotes the development of upper (adaxial) leaf fates and meristem formation; in its absence lower (abaxial) leaf fates develop and meristems fail to form. A network of regulatory factors controls the establishment of ad/abaxial leaf fates. However, this network is incomplete and how these factors control one another is poorly understood. Here we report a new family of plant genes, the LITTLE ZIPPER (ZPR) genes (consisting principally of a stretch of leucine zipper similar to the leucine zipper in HD-ZIPIII proteins) that are transcriptionally up-regulated by HD-ZIPIII activity. Furthermore, we show that the ZPR proteins interact with and repress HD-ZIPIII activity, thus forming a negative feedback loop. Our results suggest that HD-ZIPIII proteins exist in active homodimers and, together with the ZPR proteins, in inactive heterodimers. The newly discovered HD-ZIPIII/ZPR regulatory module would not only serve to dampen the effect of fluctuations in HD-ZIPIII protein levels but more importantly would provide a point of regulation - control over the ratio of inactive heterodimers to active homodimers - that could be influenced by other components of the pathway. For instance, the binding of a small hydrophobic molecule to the conserved (yet little understood) START domain present in the HD-ZIPIII proteins may influence the type of dimer formed. Published in: Wenkel, S., Emery, J., Hou, B.-H., Evans, M.M.S. and M.K. Barton, 2007, A Feedback Regulatory Module Formed by LITTLE ZIPPER and HD-ZIPIII Genes. Plant Cell 2007 Keywords: screen for downstream genes, transcription factor induction
Project description:The establishment of ad/abaxial polarity is a fundamental event in plant development. It is critical for correct polar development of the leaf (the upper portion of the leaf is chloroplast rich and optimized for light capture while the lower portion is optimized for gas exchange) and for creating an environment that allows the formation of new meristems (centers of stem cell growth). Class III homeodomain-leucine zipper (HD-ZIPIII) proteins are conserved plant proteins that act as potent regulators of ad/abaxial polarity. HD-ZIPIII protein activity promotes the development of upper (adaxial) leaf fates and meristem formation; in its absence lower (abaxial) leaf fates develop and meristems fail to form. A network of regulatory factors controls the establishment of ad/abaxial leaf fates. However, this network is incomplete and how these factors control one another is poorly understood. Here we report a new family of plant genes, the LITTLE ZIPPER (ZPR) genes (consisting principally of a stretch of leucine zipper similar to the leucine zipper in HD-ZIPIII proteins) that are transcriptionally up-regulated by HD-ZIPIII activity. Furthermore, we show that the ZPR proteins interact with and repress HD-ZIPIII activity, thus forming a negative feedback loop. Our results suggest that HD-ZIPIII proteins exist in active homodimers and, together with the ZPR proteins, in inactive heterodimers. The newly discovered HD-ZIPIII/ZPR regulatory module would not only serve to dampen the effect of fluctuations in HD-ZIPIII protein levels but more importantly would provide a point of regulation - control over the ratio of inactive heterodimers to active homodimers - that could be influenced by other components of the pathway. For instance, the binding of a small hydrophobic molecule to the conserved (yet little understood) START domain present in the HD-ZIPIII proteins may influence the type of dimer formed. Published in:; Wenkel, S., Emery, J., Hou, B.-H., Evans, M.M.S. and M.K. Barton, 2007, A Feedback Regulatory Module Formed by LITTLE ZIPPER and HD-ZIPIII Genes. Plant Cell 2007 Experiment Overall Design: One of the five Arabidopsis HD-ZIPIII proteins, REVOLUTA, was placed under glucocorticoid control by fusing the glucocorticoid receptor (GR) domain to its amino terminus. This gene fusion was placed under the control of the highly and constitutively expressed viral CaMV35S promoter. Since the HD-ZIPIII genes are controlled by microRNAs, it was also necessary to introduce mutations that disrupted the microRNA complementary sequence. Transgenic Arabidopsis seedlings carrying this construct (GR-REV) as well as wild-type seedlings were grown in liquid culture for ten days. At this point, one flask each of wt and transgenic seedlings was treated with carrier alone (ethanol) and one flask each of wt and transgenic seedlings was treated with dexamethasone. RNA was harvested from these samples after one hour, labeled and hybridized to Affymetrix microarrays.
Project description:The WOX1 transcription factor is a multifunctional regulator of lateral-organ development that acts as a transcriptional repressor. WOX1 promotes lamina growth, controls marginal tissue differentiation and is involved in establishment and maintenance of the adaxial-abaxial pattern from the middle domain of leaf primordia. To identify the WOX1 downstream genes, we performed a microarray analysis of shoot apices of transgenic Arabidopsis thaliana lines harboring 35S::WOX1:glucocorticoid receptor (GR) in which the WOX1 function was temporarily enhanced by dexamethasone (DEX).
Project description:Certain phytophagous insects can induce leaf curling in their host plants that may provide protected and nutrient-rich habitats. However, the mechanisms of this induction remain poorly understood. The cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae), is a serious pest of the cassava and causes leaf curling. To reveal the mechanisms of leaf-curl induction, we first inoculated varying numbers of mealybugs in different locations, namely, the apical meristem and the stem, on cassava seedlings. Second, we performed transcriptome analysis using the total RNA extracted from leaves. The results showed that a single insect was able to induce leaf curling, but the intensity and frequency of the leaf curling were positively correlated with the number of insects. Furthermore, the leaf curling occurred when the mealybugs fed on or close to the apical meristem but not when they fed on the stem. Transcriptome analysis identified a total of 3,931 differentially expressed genes (DEGs) from intact plants and the plants inoculated with mealybugs at different time points. GO analysis of the biological processes revealed that the DEGs contained a series of factors for leaf development of the adaxial–abaxial axis, and auxin biosynthesis and polarity. This suggests that alterations in these functions may cause leaf curling.
Project description:Leaf size and flatness directly affect photosynthesis and are closely related to agricultural yield. The final leaf size and shape are coordinately determined by cell proliferation, differentiation, and expansion during leaf development. Lettuce (Lactuca sativa L.) is one of the most important leafy vegetables worldwide, and lettuce leaves vary in shape and size. However, the molecular mechanisms of leaf development in lettuce are largely unknown. In this study, we showed that the lettuce APETALA2 (LsAP2) gene regulates leaf morphology. LsAP2 encodes a transcriptional repressor that contains the conserved EAR motif, which mediates interactions with the TOPLESS/TOPLESS-RELATED (TPL/TPR) corepressors. Overexpression of LsAP2 led to small and crinkly leaves, and many bulges were seen on the surface of the leaf blade. LsAP2 physically interacted with the CINCINNATA (CIN)-like TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR (TCP) transcription factors and inhibited their transcriptional activation activity. RNA sequencing analysis showed that LsAP2 affected the expression of auxin- and polarity-related genes. In addition, LsAP2 directly repressed the abaxial identity gene KANADI2 (LsKAN2). Together, these results indicate that LsAP2 regulates leaf morphology by inhibiting CIN-like TCP transcription factors and repressing LsKAN2, and our work provides insights into the regulatory mechanisms of leaf development in lettuce.
Project description:What methylation changes are occurring in different compartments of early maturation stage seed largely remains unknown. To uncover the possible role of DNA methylation in different compartments of early maturation stage seed, we characterized the methylome of two major compartments in embryonic cotyledon: cotyledon abaxial parenchyma (EM-COT-ABPY) and cotyledon adaxial parenchyma (EM-COT-ADPY) using Illumina sequencing. Illumina sequencing of bisulfite-converted genomic DNA from cotyledon abaxial parenchyma (EM-COT-ABPY) and cotyledon adaxial parenchyma (EM-COT-ADPY) compartments.
Project description:Leaves are flat determinate organs derived from indeterminate shoot apical meristems. The presence of a specific leaf meristem is debated, as anatomical features typical of meristems are not present in leaves. Here we demonstrate that multiple NGATHA (NGA) and CINCINNATA-class-TCP (CIN-TCP) transcription factors act redundantly to suppress activity of a leaf margin meristem in Arabidopsis thaliana, and that their absence confers persistent marginal growth of leaves, cotyledons and floral organs. The marginal meristem is activated by the juxtaposition of adaxial and abaxial domains and maintained by WOX homeobox transcription factors, but other margin elaboration genes are dispensable for its maintenance. This genetic framework parallels the morphogenetic program of shoot apical meristems and may represent a relic from an ancestral shoot system from which seed plant leaves evolved.
Project description:ENF1 gene (AT1G79440) encodes succinic semialdehyde dehydrogenase. Loss-of-function mutant of ENF1 shows pleiotropic phenotypes, including abnormal gene expression along the adaxial-abaxial axis in leaf development. enf1-1 allele has a point mutation in the splicing accepter site of 11th intron of ENF1. enf1-6 allele has T-DNA insertion in 5th exon of ENF1. Differential gene expression between in enf1 and in wild type was measured at shoot apex of six-day-after-sowing seedlings. Independent experiments for wild type, enf1-1, and enf1-6 were performed four, three, and three times, respectively.