Project description:In multicellular systems changes to the patterning of gene expression drive modifications in cell function and trait evolution. One striking example is found in more than sixty plant lineages where compartmentation of photosynthesis between cell types allowed evolution of the efficient C4 pathway from the ancestral C3 state. The molecular events enabling this transition are unclear. We used single nuclei sequencing to generate a cell level expression atlas for C3 rice and C4 sorghum during photomorphogenesis. In both species a conserved cistrome was identified for each cell type and initiation of photosynthesis gene expression was conditioned by cell identity. Photosynthesis genes switching expression from mesophyll in rice to bundle sheath in sorghum acquire hallmarks of bundle sheath identity. The sorghum bundle sheath has also acquired gene networks associated with C3 guard cells. We conclude C4 photosynthesis is based on rewiring in cis that exapts cell identity networks of C3 plants.
2023-12-05 | GSE248919 | GEO
Project description:Analysis of translation in mesophyll and bundle sheath enriched fractions of maize
Project description:Maize, as a C4 plant, possesses two distinct types of photosynthetic cells, the mesophyll (M) and the bundle sheath (BS) cells. To elucidate their functional and regulatory differentiation we isolated large quantities of highly homogeneous M and BS cells from new mature leaves for transcriptome profiling by Illumina sequencing. More than 100,000,000 reads for each cell type were mapped to the maize genome, revealing 44,964 expressed genes. Among these, 37,105 genes were expressed in M cells, including 423 M-enriched genes and 20 M-enriched transcription factor (TF) genes, whereas 42,782 genes were expressed in BS cells, including 771 BS-enriched genes and 75 BS-enriched TF genes. Pathway analyses revealed cell differentiation in various cellular activities, with M cells playing more important roles in light reaction, protein synthesis, abiotic stress, tetrapyrrole synthesis and RNA-RNA binding, while BS cells specializing in transport, signaling, protein degradation, major C metabolism, and the Calvin cycle. Genes coding for enzymes and transporters involved in photosynthesis exhibit a strong cellular preference in expression. To a lesser extent, cell differentiation also occurs in genes involved in the metabolism of starch, sucrose, nitrogen, sulfur, amino acid, and secondary metabolites. This comprehensive dataset will be useful for studying the regulation and evolution of C4-specific and related genes.
Project description:C4 grasses, such as maize (Zea mays), have high photosynthetic efficiency through combined biochemical and structural adaptations.C4 photosynthesis is established along the developmental axis of the leafblade, leading from an undifferentiated leaf base just above the ligule into highly specialized mesophyll cells (MCs) and bundle sheath cells (BSCs) at the tip. To resolve the kinetics of maize leaf development and C4 differentiation and to obtain a systems-level understanding of maize leaf formation, the accumulation profiles of proteomes of the leaf and the isolated BSCs with their vascular bundle along the developmental gradient were determined using large-scale mass spectrometry. This was complemented by extensive qualitative and quantitative microscopy analysis of structural features (e.g., Kranz anatomy, plasmodesmata, cell wall, and organelles). More than 4300 proteins were identified and functionally annotated. Developmental protein accumulation profiles and hierarchical cluster analysis then determined the kinetics of organelle biogenesis, formation of cellular structures, metabolism, and coexpression patterns. Two main expression clusters were observed, each divided in subclusters, suggesting that a limited number of developmental regulatory networks organize concerted protein accumulation along the leaf gradient. The coexpression with BSC and MC markers provided strong candidates for further analysis of C4 specialization, in particular transporters and biogenesis factors. Based on the integrated information, we describe five developmental transitions that provide a conceptual and practical template for further analysis. An online protein expression viewer is provided through the PlantProteomeDatabase.
Project description:Zea mays is a C4 plant that utilizes two distinct cell types, mesophyll (M) and bundle sheath (BS), to cooperatively fix carbon. Regulation of M and BS cell differentiation is poorly understood. Here, we explore the transcriptional networks of M and BS cells by microarray analysis. The maize mutant bundle sheath defective2 lacks the accumulation of Rubisco small and large subunits (Roth et al 1996; Brutnell et al 1999) and cannot perform the Calvin Cycle (Smith et al 1998). Therefore, this mutant provides an opportunity to study M and BS cell differentiation in a perturbed BS background, potentially revealing regulons important to cell identity. M and BS cells were independently isolated from mutant and wild-type siblings. Transcriptional profiling was then performed in a cell specific manner between mutant and wild-type.
2018-04-30 | GSE13758 | GEO
Project description:Transcriptomes of rice mesophyll, bundle sheath and vein using LCM RNAseq
Project description:The biotrophic fungus Ustilago maydis causes smut disease on maize (Zea mays L.), which is characterized by immense plant tumours. To establish disease and reprogram organ primordia to tumours, U. maydis deploys effector proteins in an organ-specific manner. However, the cellular contribution to leaf tumours remains unknown. We investigated leaf tumour formation on the tissue- and cell type-specific level. Cytology and metabolite analysis were deployed to understand the cellular basis for tumourigenesis. Laser-capture microdissection was performed to gain a cell-type specific transcriptome of U. maydis during tumour formation. In-vivo visualization of plant DNA synthesis identified bundle sheath cells as the origin of hyperplasic tumour cells, while mesophyll cells become hypertrophic tumour cells. Cell type specific transcriptome profiling of U. maydis revealed tailored expression of fungal effector genes. Moreover, U. maydis See1 was identified the first cell type specific fungal effector, being required for induction of cell cycle reactivation in bundle sheath cells. Identification of distinct cellular mechanisms in two different leave cell types, and See1 as an effector for induction of proliferation of bundle-sheath cells, are major steps in understanding U. maydis-induced tumor formation. Moreover, the cell-type specific U. maydis transcriptome data is a valuable resource to the scientific community.