Project description:Transformation of undifferentiated stem cells into cells with special functions is central for organismal development. The phloem tissue mediates long-distance transport of energy metabolites along plant bodies and is characterized by an exceptional degree of cellular specialization. How the phloem-specific developmental program is implemented is, however, unknown. Here we reveal that the ubiquitously expressed PHD-finger protein OBERON3 (OBE3) and the phloem-specific SUPPRESSOR OF MAX2 1-LIKE 5 (SMXL5) protein form a central module for establishing phloem identity in Arabidopsis thaliana (Arabidopsis). By phloem-specific ATAC-seq analyses, we show that OBE3 and SMXL5 proteins establish a phloem-specific chromatin profile.
Project description:We report the application of laser capture microdissection (LCM) for high resolution transcriptome profiling of the second internode of the Arabidopsis thaliana inflorescence stem. In this series, we used LCM to determine and compare the transcriptome profiles of the phloem cap, the pith, and the remaining vascular bundle area.
Project description:Phloem-feeding pests cause extensive crop damage throughout the world yet little is understood about how plants perceive and defend themselves from these threats. The silverleaf whitefly (SLWF; Bemisia tabaci type B) is a good model for studying phloem-feeding insect-plant interactions as SLWF nymphs cause little wounding and have a long, continuous interaction with the plant. Using the Arabidopsis ATH1 GeneChip, the global responses to Silverleaf Whitefly 2nd instar feeding were examined. Keywords: stress response
Project description:This sudy focuses on the identification of transcripts in the shoot phloem of the model plant Arabidopsis thaliana. Transcripts expressed in the phloem tissue (parenchyma cell, companion cell, sieve element) were excised by laser microdissection pressure catapulting (LMPC). These were compared with transcripts isolated from leaf phloem exudates by EDTA-chelation technique. Optimization of sample harvest resulted in RNA of high quality from both sources. Modifications of the RNA amplification procedure obtained RNA of sufficient yield and quality for microarray experiments. Microarrays (Affymetrix, ATH1) hybridized with RNA derived from phloem tissue by LMPC or phloem sap allowed us to differentiate between phloem located and mobile transcript species. The datasets provide a search criterion for phloem-based signals and will facilitate reverse genetic studies and forward genetic screens for phloem and long distance RNA signaling mutants. Keywords: profiles of mobile and stationary Arabidopsis phloem transcripts
Project description:In this study we used vascular specific promoters and a translating ribosome affinity purification strategy to identify phloem-associated translatome responses to infection by tobacco mosaic virus (TMV) in the systemic host Arabidopsis thaliana ecotype Shahdara. Three different promoter:FLAG-RPL18 lines were used. These included two phloem specific promoters (pSUC2 and pSULTR2;2) as well as the more ubiquitously expressed cauliflower mosaic virus 35S promoter (p35S). Immunopurification of ribosome-mRNA complexes was accomplished by the method described in Reynoso et al. (Plant Functional Genomics: Methods and Protocols, 185-207; 2015). The dataset includes samples from the leaves of 5-week-old plants inoculated with TMV (1 mg/mL) or mock inoculated with sterile water.
Project description:The widespread use of plant grafting has enabled different plants to join and combine their best properties to improve stress tolerance, growth and yields. Grafting is commonly performed between closely related eudicots or gymnosperms where mechanisms permit tissue fusion yet limit success as plants become unrelated. To investigate these aspects, we developed a micrografting method using young conifer tree seedlings that enabled divergent conifer members to successfully graft. Conifer grafts showed rapid connection of phloem and xylem at the junction, while a genome-wide transcriptome analysis of the Picea abies (Norway spruce) healing junction revealed differential expression of thousands of genes including those related to auxin response and cell wall biogenesis. We compared these genes to those induced during Arabidopsis thaliana graft healing and found a common activation of cambium, cell division, phloem and xylem-related genes. A gene regulatory network analysis revealed that PHYTOCHROME A SIGNAL TRANSDUCTION 1 (PAT1) acted as a central hub during Picea grafting and was also induced during Arabidopsis grafting. Arabidopsis mutants lacking PATs failed to attach tissues or successfully graft, while complementing Arabidopsis PAT mutants with the Picea abies PAT1 homolog could rescue tissue attachment and enhance callus formation. Together, our data demonstrate a competency for young tissues to graft to distantly related species and identifies the PAT gene family as conserved regulators of graft healing and tissue regeneration in eudicots and gymnosperms.