Photosynthesis in mesophyll protoplasts and bundle sheath cells of various type of C4 plants. III. Fluorescence emission spectra, delayed light emission, and P700 content

Mayne, Berger C.; Dee, A.M.; Edwards, Gerald E.

doi:10.1016/s0044-328x(75)80158-9

Cited by 53 publications

(40 citation statements)

References 22 publications

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“…The absolute Chl/P700 ratios given in Table II indicate a 2-fold higher P700 content in bundle sheath chloroplasts. We thus confirm the original observations (3,22) that bundle sheath tissue is significantly enriched in P700.…”

Section: Methodssupporting

confidence: 92%

Comparison of Photosynthetic Activities of Spinach Chloroplasts with Those of Corn Mesophyll and Corn Bundle Sheath Tissue

Hardt¹,

Kok²

1978

Plant Physiol.

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Bundle sheath and mesophyll chloroplasts from Zea mays showed comparable rates of 02 evolution, which amounted to about half of the rate observed in spinach ( Spinacia oleracea) chloroplasts.Ratios of 4.5, 4.6, and 6.2 Mn2" atoms per 400 chlorophylls were observed in mesophyll, bundle sheath, and spinach chloroplasts, respectively. These ratios roughly correspond to the observed 02 evolution rates.Rates of electron transport from water to methylviologen (photosystem I and 11) in both types of corn chloroplasts were about one-third that in spinach. Compared to spinach, transport rates from reduced diaminodurene to methylviologen (photosystem 1) were about one-third and greater than one-half in mesophyll and bundle sheath material, respectively.In both types of corn chloroplasts, electron flow from photosystem 11 to P700 was abnormal. This observation, together with the low rates of all activities, suggests that damage occurred during isolation. Such damage may limit the quantitative significance of observations made with these materials (including the following data).Measurements of flash yields of 02 evolution or 02 uptake showed that the size of the photosynthetic unit was the same in photosystems I and 11 and in all three types of chloroplasts (about 400 chlorophylls per equivalent).

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Section: Methodssupporting

confidence: 92%

Comparison of Photosynthetic Activities of Spinach Chloroplasts with Those of Corn Mesophyll and Corn Bundle Sheath Tissue

Hardt¹,

Kok²

1978

Plant Physiol.

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“…Our work focuses on Panicum miliaceum, an NAD-malic enzyme species of C4 plant that has well-developed chloroplasts in both the mesophyll and bundle sheath cells. Previous work on this subgroup of C4 plants has led to the generalization that the PSII level in the mesophyll chloroplasts is relatively low compared to the level in the bundle sheath chloroplasts (10,21). The results of the present work on P. miliaceum demonstrate that the PSII properties of the two chloroplast types differ in several other aspects as well.…”

supporting

confidence: 47%

Fluorescence and Delayed Light Emission from Mesophyll and Bundle Sheath Cells in Leaves of Normal and Salt-Treated Panicum miliaceum

Li¹,

Nothnagel²

1989

Plant Physiol.

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A modified fluorescence microscope system was used to measure chlorophyll fluorescence and delayed light emission from mesophyll and bundle sheath cells in situ in fresh-cut sections from leaves of Panicum miliaceum L. The fluorescence rise in 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU)-treated leaves and the slow fluorescence kinetics in untreated leaves show that mesophyll chloroplasts have larger photosystem 11 unit sizes than do bundle sheath chloroplasts. The larger photosystem 11 units imply more efficient noncyclic electron transport in mesophyll chloroplasts. Quenching of slow fluorescence also differs between the cell types with mesophyll chloroplasts showing complex kinetics and bundle sheath chloroplasts showing a relatively simple decline. Properties of the photosynthetic system were also investigated in leaves from plants grown in soil containing elevated NaCI levels. As judged by changes in both fluorescence kinetics in DCMU-treated leaves and delayed light emission in leaves not exposed to of the growth of the area over this fluorescence induction curve (22, 23) have revealed two distinct components: a fast, nonexponential component (a) and a slower, exponential component (j3). These two components have sometimes been attributed to two different forms of PSII, termed PSIIa and PSIIO, which are considered to be distinct physical entities (22). Alternatively, it has been suggested that the biphasic nature ofthe fluorescence rise simply reflects different degrees of connectivity between PSII units (5). Other explanations are that the heterogeneity of the induction curve is due to the ability of DCMU to inhibit linear electron flow away from PSII (14, 15), or that it is a consequence of different degrees of connectivity between the light-harvesting complex and the PSII reaction center (26). Although no general agreement has yet been reached for the mechanism of this biphasicity, it is widely accepted that analysis of the induction curve provides a useful probe of PSII organization and function.Decay of the slow fluorescence kinetics is largely the result of two quenching mechanisms: quenching by the reoxidation of Q, which reflects the redox state of the electron transfer system, and quenching by other factors which are largely dependent upon the magnitude of the pH gradient across the thylakoid membrane (17). Slow fluorescence kinetics from leaves are intimately related to changes in the rates of lightdependent oxygen evolution and carbon metabolism (12,30).Delayed light emission is a result of the recombination of positive charges on the donor side of PSII with negative charges on the acceptor side. This charge recombination is sometimes considered to be a true reversal of the primary photoreaction of photosynthesis (18). Delayed light emission from PSI is thought to be much less than that from PSII (4, 27). Treatments such as heat, salt, electron transport inhibitors, etc., which alter the photosynthetic properties of PSII, will alter delayed light emission as well as Chl fluorescence...

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“…Therefore, a greater investment in the chloroplasts, which function to fix CO 2 in the C 3 cycle, appears to be a common feature of SCC 4 species. Also, in Kranz-type NAD-ME C 4 species, analyses show a higher investment in chlorophyll in the Rubisco-containing BSC chloroplasts than in the MC chloroplasts; the average for four C 4 grasses was 37% in MC and 63% in BSC (Mayne et al, 1974).…”

Section: Distribution Of Chloroplasts Between the Two Domainsmentioning

confidence: 95%

Resolving the Compartmentation and Function of C4 Photosynthesis in the Single-Cell C4 Species Bienertia sinuspersici

2011

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Bienertia sinuspersici is a land plant known to perform C 4 photosynthesis through the location of dimorphic chloroplasts in separate cytoplasmic domains within a single photosynthetic cell. A protocol was developed with isolated protoplasts to obtain peripheral chloroplasts (P-CP), a central compartment (CC), and chloroplasts from the CC (C-CP) to study the subcellular localization of photosynthetic functions. Analyses of these preparations established intracellular compartmentation of processes to support a NAD-malic enzyme (ME)-type C 4 cycle. Western-blot analyses indicated that the CC has Rubisco from the C 3 cycle, the C 4 decarboxylase NAD-ME, a mitochondrial isoform of aspartate aminotransferase, and photorespiratory markers, while the C-CP and P-CP have high levels of Rubisco and pyruvate, Pidikinase, respectively. Other enzymes for supporting a NAD-ME cycle via an aspartate-alanine shuttle, carbonic anhydrase, phosophoenolpyruvate carboxylase, alanine, and an isoform of aspartate aminotransferase are localized in the cytosol. Functional characterization by photosynthetic oxygen evolution revealed that only the C-CP have a fully operational C 3 cycle, while both chloroplast types have the capacity to photoreduce 3-phosphoglycerate. The P-CP were enriched in a putative pyruvate transporter and showed light-dependent conversion of pyruvate to phosphoenolpyruvate. There is a larger investment in chloroplasts in the central domain than in the peripheral domain (6-fold more chloroplasts and 4-fold more chlorophyll). The implications of this uneven distribution for the energetics of the C 4 and C 3 cycles are discussed. The results indicate that peripheral and central compartment chloroplasts in the single-cell C 4 species B. sinuspersici function analogous to mesophyll and bundle sheath chloroplasts of Kranz-type C 4 species.Rubisco is the central CO 2 fixation enzyme in plants. It is a bifunctional enzyme, catalyzing the carboxylation as well as the oxygenation of ribulose-bisphosphate (RuBP) to 3-phosphoglycerate (3-PGA) and phosphoglycolate, respectively. While 3-PGA is subsequently utilized in the C 3 cycle to produce triose-phosphates, phosphoglycolate has no known metabolic use (Ogren, 1984) and needs to be detoxified by the plant. This process is known as photorespiration, which is not only energy consuming but also results in a net loss of previously fixed carbon and nitrogen. The rate of carboxylation versus oxygenation through Rubisco is directly related to the availability of CO 2 and the concentration of oxygen competing for the catalytic site of the enzyme. Since Rubisco is thought to have evolved under much higher levels of CO 2 than current atmospheric concentrations, it is believed that photorespiration was insignificant earlier in photosynthetic organisms. Under current atmospheric CO 2 levels, however, significant amounts (e.g. up to 25%) of previously fixed carbon may be lost through RuBP oxygenase activity under conditions that favor photorespiration, like high temperatures or water stres...

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Photosynthesis in mesophyll protoplasts and bundle sheath cells of various type of C4 plants. III. Fluorescence emission spectra, delayed light emission, and P700 content

Cited by 53 publications

References 22 publications

Comparison of Photosynthetic Activities of Spinach Chloroplasts with Those of Corn Mesophyll and Corn Bundle Sheath Tissue

Comparison of Photosynthetic Activities of Spinach Chloroplasts with Those of Corn Mesophyll and Corn Bundle Sheath Tissue

Fluorescence and Delayed Light Emission from Mesophyll and Bundle Sheath Cells in Leaves of Normal and Salt-Treated Panicum miliaceum

Resolving the Compartmentation and Function of C4 Photosynthesis in the Single-Cell C4 Species Bienertia sinuspersici

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