Excellent wavelength-dependence of laser-induced delayed light-emission from mesophyll and bundle-sheath cells of maize.
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ABSTRACT:
SUBMITTER: Ross DA
PROVIDER: S-EPMC1158599 | biostudies-other | 1982 Aug
REPOSITORIES: biostudies-other
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Project description:Chloroplasts or cells from maize (Zea mays) bundle sheath show a very low intensity of delayed light emission compared with mesophyll protoplasts or chloroplasts. The bundle-sheath chloroplasts retain only the fast (less than 1 ms) component of the emission. They also fail to show fluorescence induction in contrast to the mesophyll, which behaved normally. The mesophyll material could be made to resemble the bundle-sheath chloroplasts in respect of both phenomena by adding to it 1-(3',4'-dichlorophenyl)-3,3-dimethyl-urea and hydroxylamine, together. It is concluded that Photosystem II, that gives rise to both effects, is not active in the bundle sheath but may be present in an inhibited form.
| S-EPMC1161043 | biostudies-other
Project description:Chloroplasts of maize leaves differentiate into specific bundle sheath (BS) and mesophyll (M) types to accommodate C(4) photosynthesis. Chloroplasts contain thylakoid and envelope membranes that contain the photosynthetic machineries and transporters but also proteins involved in e.g. protein homeostasis. These chloroplast membranes must be specialized within each cell type to accommodate C(4) photosynthesis and regulate metabolic fluxes and activities. This quantitative study determined the differentiated state of BS and M chloroplast thylakoid and envelope membrane proteomes and their oligomeric states using innovative gel-based and mass spectrometry-based protein quantifications. This included native gels, iTRAQ, and label-free quantification using an LTQ-Orbitrap. Subunits of Photosystems I and II, the cytochrome b(6)f, and ATP synthase complexes showed average BS/M accumulation ratios of 1.6, 0.45, 1.0, and 1.33, respectively, whereas ratios for the light-harvesting complex I and II families were 1.72 and 0.68, respectively. A 1000-kDa BS-specific NAD(P)H dehydrogenase complex with associated proteins of unknown function containing more than 15 proteins was observed; we speculate that this novel complex possibly functions in inorganic carbon concentration when carboxylation rates by ribulose-bisphosphate carboxylase/oxygenase are lower than decarboxylation rates by malic enzyme. Differential accumulation of thylakoid proteases (Egy and DegP), state transition kinases (STN7,8), and Photosystem I and II assembly factors was observed, suggesting that cell-specific photosynthetic electron transport depends on post-translational regulatory mechanisms. BS/M ratios for inner envelope transporters phosphoenolpyruvate/P(i) translocator, Dit1, Dit2, and Mex1 were determined and reflect metabolic fluxes in carbon metabolism. A wide variety of hundreds of other proteins showed differential BS/M accumulation. Mass spectral information and functional annotations are available through the Plant Proteome Database. These data are integrated with previous data, resulting in a model for C(4) photosynthesis, thereby providing new rationales for metabolic engineering of C(4) pathways and targeted analysis of genetic networks that coordinate C(4) differentiation.
| S-EPMC2556027 | biostudies-literature
Project description:During Zea mays (maize) C4 differentiation, mesophyll (M) and bundle sheath (BS) cells accumulate distinct sets of photosynthetic enzymes, with very low photosystem II (PSII) content in BS chloroplasts. Consequently, there is little linear electron transport in the BS and ATP is generated by cyclic electron flow. In contrast, M thylakoids are very similar to those of C3 plants and produce the ATP and NADPH that drive metabolic activities. Regulation of this differentiation process is poorly understood but involves expression and coordination of nuclear and plastid genomes. Here, we identify a recessive allele of the maize Hcf136 homologue that in Arabidopsis thaliana functions as a PSII stability or assembly factor located in the thylakoid lumen. Proteome analysis of the thylakoids and electron microscopy reveal that Zm hcf136 lacks PSII complexes and grana thylakoids in M chloroplasts, consistent with the previously defined Arabidopsis function. Interestingly, hcf136 is also defective in processing the full-length psbB-psbT-psbH-petB-petD polycistron specifically in M chloroplasts. To determine whether the loss of PSII in M cells affects C4 differentiation, we performed cell-type specific transcript analysis of hcf136 and wild-type seedlings. The results indicate that M and BS cells respond uniquely to the loss of PSII, with little overlap in gene expression changes between data sets. These results are discussed in the context of signals that may drive differential gene expression in C4 photosynthesis. Keywords: cell type comparison
2008-02-01 | GSE9698 | GEO
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:During Zea mays (maize) C4 differentiation, mesophyll (M) and bundle sheath (BS) cells accumulate distinct sets of photosynthetic enzymes, with very low photosystem II (PSII) content in BS chloroplasts. Consequently, there is little linear electron transport in the BS and ATP is generated by cyclic electron flow. In contrast, M thylakoids are very similar to those of C3 plants and produce the ATP and NADPH that drive metabolic activities. Regulation of this differentiation process is poorly understood but involves expression and coordination of nuclear and plastid genomes. Here, we identify a recessive allele of the maize Hcf136 homologue that in Arabidopsis thaliana functions as a PSII stability or assembly factor located in the thylakoid lumen. Proteome analysis of the thylakoids and electron microscopy reveal that Zm hcf136 lacks PSII complexes and grana thylakoids in M chloroplasts, consistent with the previously defined Arabidopsis function. Interestingly, hcf136 is also defective in processing the full-length psbB-psbT-psbH-petB-petD polycistron specifically in M chloroplasts. To determine whether the loss of PSII in M cells affects C4 differentiation, we performed cell-type specific transcript analysis of hcf136 and wild-type seedlings. The results indicate that M and BS cells respond uniquely to the loss of PSII, with little overlap in gene expression changes between data sets. These results are discussed in the context of signals that may drive differential gene expression in C4 photosynthesis. To explore the disruption of PSII activity on gene expression, transcript profiles from separated M and BS cells were examined using two-label microarray analysis. Total RNA was isolated from the second leaves of mutant and wild-type silbings. Six biological replicates were used to compare wild-type and mutant transcript profiles in separate M and BS experiments. To maximize biological replication, different seedling pools were used for each of the 12 hybridizations. Microarray experiments and analyses were performed using the Genisphere MPX900 kit and the Maize Array Consortium oligonucleotide platform (GPL5439; GPL5440). Feature intensity values were log-transformed and corrected for local background signal, and a LOWESS procedure (Dudoit et al., 2002) was used to normalize between channels. Features with either low or saturating signal intensity were discarded from further analysis. High expression filtering was less stringent to avoid elimination of previously characterized, high abundance, C4 cell-specific transcripts. After filtering, features that were not assigned an MZ number by the Maize Array Consortium were discarded from further analysis. The moderated t-test (Smyth, 2004) using the R package limma was applied to identify differentially expressed genes. The p-values for each test (gene) were converted to q-values for false discovery rate analysis as described by Storey et al. (2004). To avoid confounding treatment effects associated with direct comparisons of M and BS transcriptomes (Sawers et al., 2007), comparisons were only made using the same cell type across the hcf136 and wild-type sibling genotypes. Bundle sheath (BS) Samples: GSM245063-GSM245164 Mesophyll (M) Samples: GSM245165 - GSM245206
2008-01-31 | E-GEOD-9698 | biostudies-arrayexpress
Project description:The high efficiency of C4 photosynthesis relies on spatial division of labor, classically with initial carbon fixation in the mesophyll and carbon reduction in the bundle sheath. By employing grinding and serial filtration over liquid nitrogen, we enriched C4 tissues along a developing leaf gradient. This method treats both C4 tissues in an integrity-preserving and consistent manner, while allowing complementary measurements of metabolite abundance and enzyme activity, thus providing a comprehensive data set. Meta-analysis of this and the previous studies highlights the strengths and weaknesses of different C4 tissue separation techniques. While the method reported here achieves the least enrichment, it is the only one that shows neither strong 3' (degradation) bias, nor different severity of 3' bias between samples. The meta-analysis highlighted previously unappreciated observations, such as an accumulation of evidence that aspartate aminotransferase is more mesophyll specific than expected from the current NADP-ME C4 cycle model, and a shift in enrichment of protein synthesis genes from bundle sheath to mesophyll during development. The full comparative dataset is available for download, and a web visualization tool (available at http://www.plant-biochemistry.hhu.de/resources.html) facilitates comparison of the the Z. mays bundle sheath and mesophyll studies, their consistencies and their conflicts.
| S-EPMC5853576 | biostudies-literature
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.
2012-09-18 | E-MTAB-4320 | biostudies-arrayexpress
Project description:A number of taxa utilize C4 photosynthesis, to limit the impact of photorespiration upon photosynthetic performance. In order to achieve a local elevation of CO2 concentration, maize plants possess two photosynthetic cell types. Rubisco accumulation is restricted to bundle sheath (BS) cells that surround the leaf veins. Carbon fixation occurs initially in adjacent mesophyll (ME) cells. C4 compounds are transported into the BS cells where they are subsequently decarboxylated, releasing CO2. Although the major components of the C4 pathway have been well characterized, less is known about further metabolic partitioning in the maize leaf. Microarray hybridizations have been performed in order to further investigate metabolic differences between BS and ME cell types. BS strands and ME protoplasts were isolated from the leaves of 10 day old maize seedlings by mechanical disruption and enzymatic digestion respectively. To control for differences arising from these different protocols, total leaf (TO) and total leaf stress (ST) samples were also isolated. The ST sample was subjected to the same treatments as the ME sample, with the omission of cell-wall degrading enzymes. Leaves for the TO sample were harvested as for the BS strand sample. An interwoven loop design was used to compare the four treatment groups. A biological group consisted of a growth of plants from which pooled individuals were taken for the four treatments. Six biological replicates (groups) were used. Labeling was performed using the Genisphere Array 900-MPX kit according to the manufacturer's protocol. Post hybridization washes were performed according to the recommendations of the Maize Oligo Array Project. Scan settings were used for detection of moderate to high expression signals (gain ~ 60%. power 90%). Following hybridization with TO cDNA, ~1/3 of features provided signal above twice background and below saturation. A number of taxa utilize C4 photosynthesis, to limit the impact of photorespiration upon photosynthetic performance. In order to achieve a local elevation of CO2 concentration, maize plants possess two photosynthetic cell types. Rubisco accumulation is restricted to bundle sheath (BS) cells that surround the leaf veins. Carbon fixation occurs initially in adjacent mesophyll (ME) cells. C4 compounds are transported into the BS cells where they are subsequently decarboxylated, releasing CO2. Although the major components of the C4 pathway have been well characterized, less is known about further metabolic partitioning in the maize leaf. Microarray hybridizations have been performed in order to further investigate metabolic differences between BS and ME cell types. BS strands and ME protoplasts were isolated from the leaves of 10 day old maize seedlings by mechanical disruption and enzymatic digestion respectively. To control for differences arising from these different protocols, total leaf (TO) and total leaf stress (ST) samples were also isolated. The ST sample was subjected to the same treatments as the ME sample, with the omission of cell-wall degrading enzymes. Leaves for the TO sample were harvested as for the BS strand sample. An interwoven loop design was used to compare the four treatment groups. A biological group consisted of a growth of plants from which pooled individuals were taken for the four treatments. Six biological replicates (groups) were used. Labeling was performed using the Genisphere Array 900-MPX kit according to the manufacturer's protocol. Post hybridization washes were performed according to the recommendations of the Maize Oligo Array Project. Scan settings were used for detection of moderate to high expression signals (gain ~ 60%. power 90%). Following hybridization with TO cDNA, ~1/3 of features provided signal above twice background and below saturation. Keywords: Gene expression profiling of bundle sheath and mesophyll cell types
2005-12-24 | GSE3890 | GEO
Project description:Bundle sheath cells play a crucial role in photosynthesis in C4 plants, but the structure and function of photosystem II (PSII) in these cells is still controversial. Photoprotective roles of bundle sheath chloroplasts at the occurrence of environmental stresses have not been investigated so far. Non-photochemical quenching (NPQ) of chlorophyll a fluorescence is the photoprotective mechanism that responds to a changing energy balance in chloroplasts. In the present study, we found a much higher NPQ in bundle sheath chloroplasts than in mesophyll chloroplasts under a drought stress. This change was accompanied by a more rapid dephosphorylation of light-harvesting complex II (LHCII) subunits and a greater increase in PSII subunit S (PsbS) protein abundance than in mesophyll cell chloroplasts. Histochemical staining of reactive oxygen species (ROS) suggested that the high NPQ may be one of the main reasons for the lower accumulation of ROS in bundle sheath chloroplasts. This may maintain the stable functioning of bundle sheath cells under drought condition. These results indicate that the superior capacity for dissipation of excitation energy in bundle sheath chloroplasts may be an environmental adaptation unique to C4 plants.
| S-EPMC9330506 | biostudies-literature
Project description:Different sets of genes for photosynthesis are expressed in mesophyll cells (MCs) and bundle sheath cells (BSCs)--the two adjacent but morphologically and functionally distinct types of photosynthetic cells in leaves of maize and other C4 plants. For example, light-harvesting chlorophyll a/b-binding proteins of photosystem II, which are encoded by a family of cab genes, are 3- to 4-fold more abundant in maize MCs than in BSCs. Each maize cab gene is different from the others in its relative expression in MCs vs. BSCs and in its degree of photoresponsiveness. The gene cab-m1 is positively photoregulated and is highly preferentially expressed in MCs. A 159-bp sequence in the 5' flanking region of this gene (-1026 to -868 relative to the translation start site) is required for MC-preferred expression of a reporter gene in greening maize leaves. Deletion as well as gain-of-function experiments have now shown that all of the sequence information required for MC-preferred expression resides within this mesophyll-specifying region and that cab-m1 is preferentially expressed in MCs because of the presence of two types of sequence elements: one is required for suppressing expression in BSCs and the other for promoting expression in MCs. One of the four cis-acting regions mapped within the mesophyll-specifying region resembles the AT-1 box of some plant gene negative regulatory elements. Various combinations of such MC-specific enhancing and BSC-specific repressing regions could make maize cab gene family members different from one another in their relative expression in MCs vs. BSCs.
| S-EPMC46445 | biostudies-other