Rubisco production in maize mesophyll cells through ectopic expression of subunits and chaperones

2021 ◽  
Author(s):  
Amber M Hotto ◽  
Coralie Salesse-Smith ◽  
Myat Lin ◽  
Florian A Busch ◽  
Isabelle Simpson ◽  
...  
Keyword(s):  
Large Subunit ◽  
Ectopic Expression ◽  
Carbon Assimilation ◽  
Rubisco Activase ◽  
Small Subunit ◽  
Bundle Sheath ◽  
Subunit Gene ◽  
In Planta ◽  
Mesophyll Cells ◽  
Assembly Factors

Abstract C4 plants, such as maize, strictly compartmentalize Rubisco to bundle sheath chloroplasts. The molecular basis for the restriction of Rubisco from the more abundant mesophyll chloroplasts is not fully understood. Mesophyll chloroplasts transcribe the Rubisco large subunit gene, and when normally quiescent transcription of the nuclear Rubisco small subunit gene family is overcome by ectopic expression, mesophyll chloroplasts still do not accumulate measurable Rubisco. Here we show that a combination of five ubiquitin promoter-driven nuclear transgenes expressed in maize leads to mesophyll accumulation of assembled Rubisco. These encode the Rubisco large and small subunits, Rubisco Assembly Factors 1 and 2, and the assembly factor Bundle Sheath Defective 2. In these plants Rubisco large subunit accumulates in mesophyll cells, and appears to be assembled into holoenzyme capable of binding the substrate analog CABP. Isotope discrimination assays suggest, however, that mesophyll Rubisco is not participating in carbon assimilation in these plants, most likely due to a lack of the substrate ribulose 1,5-bisphosphate and/or Rubisco activase. Overall, this work defines a minimal set of Rubisco assembly factors in planta and may help lead to methods of regulating the C4 pathway.

scholarly journals Detection of phosphoenolpyruvate and ribulose 1,5-bisphosphate carboxylase transcripts in maize leaves by in situ hybridization with sulfonated cDNA probes.

1989 ◽  
Vol 37 (4) ◽  
pp. 423-428 ◽  
Author(s):  
C Perrot-Rechenmann ◽  
M Joannes ◽  
D Squalli ◽  
P Lebacq
Keyword(s):  
In Situ Hybridization ◽  
Cell Types ◽  
Small Subunit ◽  
Bundle Sheath ◽  
Differential Distribution ◽  
Mesophyll Cells ◽  
Bisphosphate Carboxylase ◽  
Maize Leaves ◽  
Specific Mrnas

This report outlines an efficient in situ hybridization method for locating specific mRNAs in tissue cryosections using sulfonated cDNA probes. The method involves chemical modification of DNA probes by insertion of a sulfone radical on cytosine residues, which generates a specific epitope. Sulfonated DNA is then detected by using indirect immunochemical procedure. Alternatively, antibodies conjugated to fluorescein or to alkaline phosphatase were used for mRNA detection. In situ hybridization was developed to study aspects of mesophyll and bundle sheath cell differentiation in maize leaves. Our results indicate that phosphoenolpyruvate carboxylase (PEP C) mRNA is restricted to mesophyll cells, and the nucleus-encoded mRNA of the small subunit (SSU) ribulose 1,5-bisphosphate carboxylase (RuBP C) is limited to the cytosol of bundle sheath cells. Thus, using in situ hybridization, we have demonstrated that the differential distribution of PEP C and RuBP C proteins in the two cell types also reflects the location of their mRNAs. These data imply either a tissue-specific transcriptional regulation or a selective mRNA degradation.

Photosynthesis capacity diversified by leaf structural and physiological regulation between upland and lowland switchgrass in different growth stages

2020 ◽  
Vol 47 (1) ◽  
pp. 38
Author(s):  
Xin Cui ◽  
Huifang Cen ◽  
Cong Guan ◽  
Danyang Tian ◽  
Huayue Liu ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Panicum Virgatum ◽  
Photosynthetic Capacity ◽  
Photosynthetic Pigment ◽  
Carbon Assimilation ◽  
Industrial Applications ◽  
Bundle Sheath ◽  
Biofuel Production ◽  
Growth Stages ◽  
Mesophyll Cells

Understanding and enhancing switchgrass (Panicum virgatum L.) photosynthesis will help to improve yield and quality for bio-industrial applications on cellulosic biofuel production. In the present study, leaf anatomical traits and physiological characteristics related to photosynthetic capacity of both lowland and upland switchgrass were recorded from four varieties across the vegetative, elongation and reproductive growth stages. Compared with the upland varieties, the lowland switchgrass showed 37–59, 22–64 and 27–73% higher performance on height, stem and leaf over all three growth stages. Leaf anatomical traits indicated that the leaves of lowland varieties provided more space for carbon assimilation and transportation caused by enhanced cell proliferation with more bundles sheath cells and larger contact areas between the bundle sheath and mesophyll cells (CAMB), which lead to the 32–72% higher photosynthetic capacity found in the lowland varieties during vegetative and elongation growth. However, photosynthetic capacity became 22–51% higher in the upland varieties during the reproductive stage, which is attributed to more photosynthetic pigment. In conclusion, lowland varieties gain a photosynthetic advantage with enhanced bundle sheath cell proliferation, while the upland varieties preserved more photosynthetic pigments. Our study provides new insights for improving the yield in crops by enhancing photosynthesis with anatomical and physiological strategies.

Cell-Specific Expression of Rubisco Small Subunit and Rubisco Activase Genes in C3 and C4 Species of Atriplex

1992 ◽  
Vol 19 (1) ◽  
pp. 89 ◽  
Author(s):  
GS Hudson ◽  
RE Dengler ◽  
PW Hattersley ◽  
G Dengler
Keyword(s):  
In Situ Hybridisation ◽  
Rubisco Activase ◽  
Small Subunit ◽  
Bundle Sheath ◽  
Specific Expression ◽  
Bisphosphate Carboxylase ◽  
C4 Species ◽  
Rubisco Small Subunit ◽  
Rbcs Gene

In situ hybridisation techniques have been used to determine the distribution of mRNAs for ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco: EC 4.1.1.39) and Rubisco activase in leaves of Atriplex patula L. (C3) and A. rosea L. (C4). In A. patula, mRNA for Rubisco small subunit (encoded by the rbcS gene family) was found to accumulate in the mesophyll and bundle sheath, while in A. rosea it accumulated in the bundle sheath only, as shown previously for the C4 monocot Zea mays L. The spatial distribution of rca transcripts for Rubisco activase paralleled that for the rbcS transcripts in both C3 and C4 Atriplex species, providing evidence that Rubisco activase is required in cells only where Rubisco is present.

scholarly journals Identification of quantitative trait loci for dynamic and steady-state photosynthetic traits in a barley mapping population

AoB Plants ◽  
2020 ◽  
Vol 12 (6) ◽  
Author(s):  
William T Salter ◽  
Si Li ◽  
Peter M Dracatos ◽  
Margaret M Barbour
Keyword(s):  
Steady State ◽  
Stomatal Conductance ◽  
Quantitative Trait ◽  
Mapping Population ◽  
Carbon Assimilation ◽  
Rubisco Activase ◽  
Yield Potential ◽  
In Planta ◽  
Activation Rate ◽  
Rubisco Activation

Abstract Enhancing the photosynthetic induction response to fluctuating light has been suggested as a key target for improvement in crop breeding programmes, with the potential to substantially increase whole-canopy carbon assimilation and contribute to crop yield potential. Rubisco activation may be the main physiological process that will allow us to achieve such a goal. In this study, we assessed the phenotype of Rubisco activation rate in a doubled haploid (DH) barley mapping population [131 lines from a Yerong/Franklin (Y/F) cross] after a switch from moderate to saturating light. Rates of Rubisco activation were found to be highly variable across the mapping population, with a median activation rate of 0.1 min−1 in the slowest genotype and 0.74 min−1 in the fastest genotype. A unique quantitative trait locus (QTL) for Rubisco activation rate was identified on chromosome 7H. This is the first report on the identification of a QTL for Rubisco activation rate in planta and the discovery opens the door to marker-assisted breeding to improve whole-canopy photosynthesis of barley. This also suggests that genetic factors other than the previously characterized Rubisco activase (RCA) isoforms on chromosome 4H control Rubisco activity. Further strength is given to this finding as this QTL co-localized with QTLs identified for steady-state photosynthesis and stomatal conductance. Several other distinct QTLs were identified for these steady-state traits, with a common overlapping QTL on chromosome 2H, and distinct QTLs for photosynthesis and stomatal conductance identified on chromosomes 4H and 5H, respectively. Future work should aim to validate these QTLs under field conditions so that they can be used to aid plant breeding efforts.

Depletion and Reconstitution of Active E. Coli Ribosomes

1975 ◽  
Vol 33 ◽  
pp. 640-641
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Protein Biosynthesis ◽  
Large Subunit ◽  
High Resolution Electron Microscopy ◽  
Small Subunit ◽  
Structure And Function ◽  
Biologically Active ◽  
Biological Macromolecules ◽  
E Coli ◽  
Resolution Electron ◽  
And Function

Correlations between structure and function of biological macromolecules have been studied intensively for many years, mostly by indirect methods. High resolution electron microscopy is a unique tool which can provide such information directly by comparing the conformation of biopolymers in their biologically active and inactive state. We have correlated the structure and function of ribosomes, ribonucleoprotein particles which are the site of protein biosynthesis. 70S E. coli ribosomes, used in this experiment, are composed of two subunits - large (50S) and small (30S). The large subunit consists of 34 proteins and two different ribonucleic acid molecules. The small subunit contains 21 proteins and one RNA molecule. All proteins (with the exception of L7 and L12) are present in one copy per ribosome.This study deals with the changes in the fine structure of E. coli ribosomes depleted of proteins L7 and L12. These proteins are unique in many aspects.

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