Plant Physiol. (1998) 118: 1089-1099

Heterogeneity of Mitochondrial Protein Biogenesis during Primary Leaf Development in Barley¹

Peter Thompson, Caroline G. Bowsher, and Alyson K. Tobin^*

Plant Science Laboratory, School of Environmental and Evolutionary Biology, Sir Harold Mitchell Building, University of St. Andrews, St. Andrews, Fife KY16 9TH, Scotland (P.T., A.K.T.); and School of Biological Sciences, Stopford 3.614, University of Manchester, Manchester M13 9PT, United Kingdom (C.G.B.)

	ABSTRACT

Top Abstract Introduction Methods Results Discussion References

The natural developmental gradient of light-grown primary leaves of barley (Hordeum vulgare L.) was used to analyze the biogenesis of mitochondrial proteins in relation to the age and physiological changes within the leaf. The data indicate that the protein composition of mitochondria changes markedly during leaf development. Three distinct patterns of protein development were noted: group A proteins, consisting of the E1 -subunit of the pyruvate dehydrogenase complex, ORF156, ORF577, alternative oxidase, RPS12, cytochrome oxidase subunits II and III, malic enzyme, and the - and -subunits of F₁-ATPase; group B proteins, consisting of the E1 -subunit of the pyruvate dehydrogenase complex, isocitrate dehydrogenase, HSP70A, cpn60C, and cpn60B; and group C proteins, consisting of the four subunits of the glycine decarboxylase complex (P, H, T, and L proteins), fumarase, and formate dehydrogenase. All of the proteins increased in concentration from the basal meristem to the end of the elongation zone (20.0 mm from the leaf base), whereupon group A proteins decreased, group B proteins increased to a maximum at 50 mm from the leaf base, and group C proteins increased to a maximum at the leaf tip. This study provides evidence of a marked heterogeneity of mitochondrial protein composition, reflecting a changing function as leaf cells develop photosynthetic and photorespiratory capacity.

	INTRODUCTION

Top Abstract Introduction Methods Results Discussion References

In eukaryotic cells mitochondria function in the production of ATP via oxidative phosphorylation, which is coupled to substrate oxidation primarily through the TCA cycle. This function is likely to be particularly important in plant cells with immature chloroplasts. In photosynthetic cells there is an additional demand for the mitochondria to oxidize Gly, which is generated as an intermediate of the photorespiratory pathway (Keys et al., 1978). The presence of chloroplasts as a second site of ATP production via photophosphorylation may lessen the demand for mitochondrial ATP synthesis in photosynthetically mature cells.

To determine whether there are functional differences between mitochondria from photosynthetic and nonphotosynthetic cells, we used the natural developmental gradient that exists within barley (Hordeum vulgare L.) primary leaves. This and other species of Gramineae, such as wheat, have been used in a number of previous studies into the development of photosynthesis and photorespiration (Viro and Kloppstech, 1980; Dean and Leech, 1982a, 1982b; Tobin et al., 1985, 1988; Barkardottir et al., 1987; Baumgartner et al., 1989; Tobin and Rogers, 1992). The linear development of cells away from a basal intercalary meristem produces a gradient of increasing cell age from the leaf base to the tip. The basal leaf cells contain small, immature chloroplasts and are nonphotosynthetic and heterotrophic, importing carbon from more mature leaf tissue or from the seed (Dale, 1972). With increasing maturity, the mesophyll cells enlarge, the plastids increase in size, protein content, and number, and there is coordinated development of key photosynthetic and photorespiratory enzymes within chloroplasts, peroxisomes, and mitochondria (Tobin and Rogers, 1992).

There is some evidence that plant mitochondria differ in structure, activity, and protein composition depending on the metabolic activity and function of the cells in which they are localized (Rios et al., 1991; Colas des Francs-Small et al., 1992; Tobin and Rogers, 1992). Mitochondria from nonphotosynthetic or etiolated tissues, for example, oxidize Gly at very low rates (Arron and Edwards, 1980; Gardestrom et al., 1980) and have much lower amounts of GDC proteins than mitochondria in photosynthetic cells (Walker and Oliver, 1986; Tobin et al., 1989). In wheat primary leaves, we previously found a coordinated increase in GDC subunits during leaf cell development, which results in a greater than 3-fold increase in the concentration of GDC protein within the mitochondria (Rogers et al., 1991). This occurs after the development of maximum activities of other mitochondrial enzymes such as Cyt oxidase and glutamate dehydrogenase (Tobin et al., 1988; Tobin and Rogers, 1992).

This study is an extension of our earlier investigations into mitochondrial development, and identifies significant heterogeneity in the biogenesis of major mitochondrial protein complexes. The physiological significance of this heterogeneity will be discussed with particular reference to the changing metabolic function of mitochondria during leaf cell development.

	MATERIALS AND METHODS

Top Abstract Introduction Methods Results Discussion References

Growth and Harvest of Plant Material

2

1

Determination of Cell Age

Mitotic Index

Interstomatal Distance

Mesophyll Cell Number

Measurement of Photosynthesis and Respiration in Leaf Sections

2

1

The procedure for measurement of respiration was the same as for photosynthesis except that NaHCO₃ was omitted from the medium and eight leaf sections were used. The linear rate of O₂ uptake was recorded in the dark for four separate measurements from each region of the leaf.

Protein Extraction and Quantification

1

Protein was determined using a microassay (Bio-Rad) with thyroglobulin as the standard.

Slot-Blot Analysis of Mitochondrial Proteins

Sample Application

Immunodetection of Mitochondrial Proteins

The PVDF membrane was placed directly onto film (type RX, Fuji Photo Film Co. Ltd., Tokyo, Japan) that had been preflashed using a "sensitized" preflash unit (Amersham). Test strips were exposed to establish the optimum exposure time, and the film was developed using an automatic x-ray film processor (model RGII, Fuji).

Image Analysis of Immunodetected Proteins

Primary Antisera

Before the antibodies were used in slot-blot assays their specificity was tested by western-blot analysis of total protein extracts from barley leaves and of isolated barley chloroplasts. In all cases the antibodies were highly specific for polypeptides of the predicted molecular mass, and there was no significant cross-reactivity with chloroplast proteins (data not shown).

	RESULTS

Top Abstract Introduction Methods Results Discussion References

Growth and Development of the Barley Primary Leaf

View larger version (29K): [in this window] [in a new window]   Figure 1. a, Change in the number of mesophyll cells during primary leaf development in barley. Transverse 5.0-mm sections were taken at intervals along the length of 160-h-old primary leaves. Each data point represents the mean ± SE of six determinations of mesophyll cell number in sections from four individual primary leaves. Inset, Change in the interstomatal distance during primary leaf development in barley. Interstomatal distance was measured at 1.0-mm intervals as shown and each data point represents the mean ± SE of three measurements of 10 individual primary leaves. b, Relationship between cell age and the position of a cell within the barley primary leaf. Cell age was calculated from the VD of cells within 160-h-old primary leaves, as described in ``Materials and Methods''. c, Soluble protein content in developing cells of barley primary leaves. Soluble protein was extracted from serial transverse sections of 10 individual 160-h-old primary leaves. Each data point represents the mean ± SE of three separate protein extractions. d, Change in photosynthetic activity during primary leaf development in barley. Photosynthetic activity (CO2-dependent O2 evolution) was measured in 5.0-mm sections of 160-h-old primary leaves. Each data point represents the mean ± SE of four independent measurements. e, Change in respiratory activity during primary leaf development in barley. Respiration (dark O2 uptake) was measured in 5.0-mm sections of 160-h-old primary leaves. Each data point represents the mean ± SE of five independent measurements. Rates are expressed relative to the number of mesophyll cells or to the amount of soluble protein within comparable leaf sections (using data from a and c, respectively).

Cell division was confined to the basal 5 mm of the leaf, since no mitotically active cells were detected beyond this region (data not shown).

With the displacement of cells away from the basal meristematic region, there was a gradient of increasing cell age toward the leaf tip (Fig. 1b). The final increase in age of cells between 80 and 90 mm was attributable to the time between imbibition and emergence of the shoot tissue from the seed (see ``Materials and Methods'').

The amount of soluble protein within transverse (5.0-mm) leaf sections decreased from the leaf base to the end of the elongation zone (20 mm from the leaf base) and then increased toward the leaf tip (Fig. 1c). The soluble protein content per cell increased linearly from the leaf base to the tip, where it was 4-fold more concentrated (Fig. 1c).

Photosynthetic activity, measured as CO₂-dependent O₂ evolution, increased along the length of the primary leaf (Fig. 1d). The transition between net O₂ uptake and net O₂ evolution occurred between 15.0 and 20.0 mm from the basal meristem when cells were approximately 13 h old. This coincided with the end of the zone of cell elongation (compare Fig. 1a).

In contrast to photosynthesis, the rate of "dark" respiratory O₂ uptake per cell remained constant throughout the length of the primary leaf. When expressed relative to the amount of soluble leaf protein, respiration rates decreased to a minimum at the leaf tip (Fig. 1e). Inhibitor-titration experiments indicated that the rate of salicylhydroxamic acid-sensitive O₂ uptake in the presence of KCN remained a constant proportion of the total rate of respiration, approximately 40% in all leaf sections (data not shown).

Analysis of Mitochondrial Proteins in Barley Primary Leaves

View larger version (28K): [in this window] [in a new window]   Figure 2. Mitochondrial proteins of group A, with maximum intensity of signal occurring 20.0 mm from the basal meristem. The data were calculated from the mean values of each of the mitochondrial proteins categorized as group A. The group A mean is also represented by a dashed line in each of the individual protein profiles. Note that in the case of the  and  ATPase proteins, "A" and "C" refer to different monoclonal antibodies that recognize different epitopes of the same subunit type (Luethy et al., 1993).

View larger version (27K): [in this window] [in a new window]   Figure 3. Mitochondrial proteins of group B, with maximum intensity of signal occurring 50.0 mm from the basal meristem. The data were calculated from the mean values of each of the mitochondrial proteins categorized as group B. The group B mean is also represented by a dashed line in each of the individual protein profiles.

View larger version (28K): [in this window] [in a new window]   Figure 4. Mitochondrial proteins of group C, with maximum intensity of signal occurring at the leaf tip. The data were calculated from the mean values of each of the mitochondrial proteins categorized as group C. The group C mean is also represented by a dashed line in each of the individual protein profiles.

Eleven of the mitochondrial proteins/polypeptides fell into group A, in which the intensity of the protein band increased to a maximum at 20 mm from the basal meristem and then declined progressively toward the leaf tip (Fig. 2). These proteins were: the E1 -subunit of PDC, ORF156, ORF577, alternative oxidase, RPS12, Cyt oxidase subunits II and III, malic enzyme, and the - and -subunits of ATPase.

The proteins/polypeptides with a group B developmental profile were: the E1 -subunit of PDC, IDH, HSP70A, cpn60C, and cpn60B (Fig. 3). These increased in labeling intensity to a broad maximum between 50 and 60 mm from the leaf base, where cells were between 35 and 45 h old.

The third category of proteins, group C, showed an initial increase in labeling intensity to reach a "plateau" between 20 and 50 mm from the leaf base, as was the case for proteins of group A. However, in contrast to group A, there was a further increase in the region from 50 mm, where cells were 35 h old, up to the leaf tip (Fig. 4). Proteins in this group were the four subunits of GDC (P, H, T, and L proteins), fumarase, and FDH. This pattern of development was also found when the four GDC subunits were analyzed by western blots (data not shown).

	DISCUSSION

Top Abstract Introduction Methods Results Discussion References

Developmental Changes in Leaf Physiology

The gradient of cell age closely resembled that previously reported for barley primary leaves (Barkardottir et al., 1987). The large increment in cell age within the distal 5 mm of the leaf was attributable to the time taken for this tissue to emerge from the seed after imbibition (Barkardottir et al., 1987).

The change in soluble protein content that we found resembled that found in previous studies (Viro and Kloppstech, 1980; Barkardottir et al., 1987). The initial decrease in protein content coincided with the decrease in cell number per section as the cells were elongating. When protein content was expressed on a per-cell basis, there was an almost linear increase along the leaf. One reason for this is the increased synthesis of Rubisco (Viro and Kloppstech, 1980), with a 20-fold increase in Rubisco protein content per mesophyll cell (Dean and Leech, 1982b). Increases in other photosynthetic proteins, such as the chlorophyll a/b-binding protein (CAB; Mayfield and Taylor, 1984), chloroplast NADP-dependent glyceraldehyde 3-phosphate dehydrogenase (Sibley and Anderson, 1989; Lernmark and Gardestrom, 1994), phosphoglycerate kinase (Shah and Bradbeer, 1991), and Fru-1,6-bisphosphatase (Sibley and Anderson, 1989), have also been reported in developing barley leaves. This increase in photosynthetic protein, together with increases in chloroplast size and number (Baumgartner et al., 1989) and chlorophyll content (Barkardottir et al., 1987; Lernmark and Gardestrom, 1994), contribute to an increase in photosynthetic capacity. We detected photosynthetic activity only in cells located beyond the elongation zone, 20 mm or more from the basal meristem, where the cells were greater than 13 h old. By the time these cells had reached the leaf tip (160 h), their photosynthetic activity had increased approximately 20-fold.

In contrast to the increase in photosynthetic activity, the rate of dark respiratory O₂ uptake per cell remained constant along the leaf. Previous studies have reported a decline in respiratory activity in relation to increasing photosynthetic development (Kidd et al., 1921; Azcon-Bieto et al., 1983), and this was also the case when our data were expressed relative to soluble protein content, with a 4-fold decrease in respiration rate between the leaf base and tip. The large increase in photosynthetic protein masks any underlying response of nonphotosynthetic proteins and we therefore recommend the use of cell number as a constant parameter in developmental studies.

Development of Mitochondrial Proteins and Polypeptides

The most significant outcome of the present study was our observation that the composition of mitochondrial proteins changes during leaf cell development. All of the proteins that were analyzed increased in the early stages of development to the end of the cell elongation zone (20 mm, 13 h). From this point on there appeared to be three distinct patterns of development: group A proteins decreased and group B and C proteins remained constant up to 50 mm (35 h) from the leaf base, where group B proteins decreased and group C proteins increased up to the leaf tip (160 h).

The initial increase in all mitochondrial proteins occurred within a region of the leaf (0-20 mm) covered by the coleoptile, where the number of mitochondria per mesophyll cell has been found to increase in wheat primary leaves (Tobin and Rogers, 1992). This suggests that there is a general increase in the cellular concentration of mitochondrial proteins throughout the elongation zone. Despite this, there was no marked change in respiratory rate per cell (Fig. 1e), indicating that other factors such as adenylate control or substrate availability exert a stronger control over respiratory flux in vivo (Moore et al., 1992).

The proteins and polypeptides of group A include a number that are mitochondrially encoded in cereals, such as RPS12 (subunit 12 of the small ribosomal subunit), Cyt oxidase subunits II and III, the - and -subunits of ATPase (Gualberto et al., 1988; Schuster and Brennicke, 1994), and polypeptides coded by orf156 (Gualberto et al., 1991) and orf577 (Gonzalez et al., 1993; Handa et al., 1996). orf156 is part of the nad3-rps12 transcription unit of wheat mtDNA and encodes an 18-kD mitochondrial membrane protein of unknown function (Gualberto et al., 1991). orf577 is homologous to the ccl1 gene of bacteria and its gene product is thought to be involved in the assembly of c-type Cyts (Gonzalez et al., 1993; Handa et al., 1996). The relative decrease in content of these proteins in cells beyond the elongation zone coincides with the onset of photosynthesis and exposure to light as these cells emerge from beneath the coleoptile.

The remaining three proteins of group A were nuclear encoded: alternative oxidase, malic enzyme, and the E1 -subunit of PDC. All of these proteins are highly regulated. The alternative oxidase can exist in either a reduced or an oxidized form, with activity associated only with the former (Umbach and Siedow, 1997). A single cross-reacting band at 35 kD, corresponding to the reduced form of the alternative oxidase (Umbach and Siedow, 1993), was detected on western blots of crude leaf extracts from barley; however, we could not detect the 67-kD oxidized homodimer even in the presence of up to 40 mM diamide, a strong oxidizing agent (data not shown). This suggests that either there was no homodimeric form of the alternative oxidase in barley, or that the monoclonal antibody failed to cross-react with this form. The intensity of the 35-kD band increased in the presence of 10% (v/v) mercaptoethanol (data not shown), indicating that a significant proportion of the alternative oxidase was in the oxidized, homodimeric form before mercaptoethanol addition. We conclude from this that the monoclonal antibody does not recognize the oxidized form of alternative oxidase in barley.

Our preliminary analyses of western blots of crude extracts from serial, transverse leaf sections indicated that the 35-kD (reduced) form of alternative oxidase increased to a maximum at the leaf tip (data not shown). Our failure to detect a 67-kD form permits only the tentative conclusion that there is an increase in alternative oxidase protein during barley leaf development. The discrepancy between western-blot and slot-blot analysis may be attributable to the difference in conditions of the two assays. We cannot exclude the possibility that the slot-blot assay, which was carried out in the absence of mercaptoethanol, underestimated the level of alternative oxidase protein. Further work is needed to clarify this point.

Lennon et al. (1995) reported an increase in the reduced form of alternative oxidase protein during leaf development in pea, which coincided with the onset of alternative oxidase activity and with an increase in Gly oxidation capacity of the mitochondria. Although we found that the rate of salicylhydroxamic acid-sensitive respiration in the presence of KCN remained constant per cell at all stages of leaf development (data not shown), this is not a good indication of alternative pathway activity because electrons may be diverted from the Cyt pathway under these conditions (Day et al., 1996). Further analysis, ideally on purified mitochondrial preparations, is required to clearly elucidate the pattern of alternative oxidase development in barley.

The antiserum raised against NAD-dependent malic enzyme from potato recognizes both the 59- and 62-kD subunits (data not shown) and, although these have been found to be coordinately expressed in vivo (Bourguignon and Leaver, 1994), we have yet to determine if this is also the case in barley. The activity of the enzyme is regulated allosterically by a number of metabolites (Grissom et al., 1983; Day et al., 1984), and is modified by changes in the oligomeric state (Grover and Wedding, 1984). Further analysis is required, therefore, to determine if the increase in total malic enzyme protein is caused by the presence of both subunits and whether this relates directly to the activity of the enzyme.

The E1 -subunit of mammalian PDC binds to the E1 -subunit to form a heterotetramer (22) E1 subunit, or pyruvate dehydrogenase (Koike and Koike, 1976). It is not clear why the development of the E1 -subunit in barley leaves differs from that of the E1 -subunit, although the stoichiometry of PDC has yet to be determined in plants. Furthermore, the E1 -subunit is regulated by phosphorylation (Camp and Randall, 1985), so its activity cannot be directly related to the amount of protein. It will be necessary to analyze the development of the whole complex, including both the E2 and E3 proteins, to fully understand the control of PDC synthesis. A previous study of barley (Lernmark and Gardestrom, 1994) found that mitochondrial PDC activity remains constant during leaf development, although the degree of in vivo phosphorylation has yet to be established.

The group B proteins, which begin to decline from 50 mm onward, are two components of the TCA cycle, the E1 -subunit of PDC and NAD-dependent IDH, and proteins involved in the transport of polypeptides into the mitochondrial matrix, mtHSP70 (Lund and Elthon, 1993; Moore et al., 1993), and cpn60 (Tsugeki et al., 1992). These data indicate that there is differential development not only of the PDC but also of mitochondrial dehydrogenases, with malic enzyme protein content declining before that of NAD-IDH. The later development of fumarase protein provides further evidence of a change in the relative content of TCA cycle proteins. In all cases, these profiles have yet to be compared with measurements of enzyme activity. However, it is interesting to note that the TCA cycle proteins involved in the decarboxylative portion of the cycle, malic enzyme, PDC, and IDH, reach a peak before that of the nondecarboxylative portion, which is represented by fumarase. This change in composition of TCA cycle proteins in barley leaves may mark a transition in the role of the mitochondria from bioenergetic to biosynthetic (Tobin and Rogers, 1992).

The peak in cellular content of the mitochondrial HSP70 (Lund and Elthon, 1993) and cpn60 proteins coincides with the stage of leaf development at which there is a major increase in the amount of GDC protein (Figs. 3 and 4). The antibodies used to detect these proteins were specific for mitochondrial HSP70 and cpn60 and did not cross-react with barley chloroplast proteins (see ``Materials and Methods''). The synthesis of GDC would be expected to impose significant demands on the protein import machinery given the major accumulation of this protein in the matrix of leaf mitochondria (Oliver, 1994).

The pattern of development of group C proteins closely resembles the development of photosynthesis, with a rapid increase occurring from 50 mm onward. This coincides with the point at which a number of photosynthetic and photorespiratory proteins also increase, and at which chloroplast division is reaching completion (Tobin et al., 1988). The proteins within this group include all four subunits of GDC, the P, H, T, and L proteins. These increase in parallel throughout the development of the barley primary leaf. This is in contrast to the findings of a previous study from our group, in which the L protein was present in high concentrations in basal cells of wheat primary leaves, whereas the remaining GDC proteins developed only after emergence of the leaf cells from beneath the coleoptile (Rogers et al., 1991). It is well established that the synthesis of the GDC proteins is light regulated (Oliver, 1994). One reason for this difference between species, therefore, might be a difference in the amount of light penetration into the immature cells beneath the coleoptile, because, in contrast to wheat, barley coleoptiles lack chlorophyll (data not shown).

The developmental pattern of GDC proteins is consistent with the function of this complex in oxidizing Gly generated during photorespiration. The reason for the parallel development of FDH is intriguing. FDH has been detected only in small amounts in leaf tissue (Oliver, 1981) and is particularly abundant in mitochondria from potato tubers (Colas des Francs-Small et al., 1993). FDH was once considered to be involved in the oxidation of formate generated by the nonenzymatic oxidation of glyoxylate by H₂O₂ to yield formate and CO₂ during photorespiration (Grodzinski and Butt, 1976; Zelitch, 1992). The presence of high concentrations of catalase in leaf peroxisomes indicates that H₂O₂ is unlikely to accumulate in sufficient quantity for glyoxylate decarboxylation to occur (Walton, 1982), and there is no evidence of increased rates of CO₂ production in catalase-deficient mutants of barley (Kendall et al., 1983). Furthermore, Colas des Francs-Small et al. (1993) found FDH to decrease during greening of etiolated leaves. Nevertheless, recent evidence from transgenic tobacco with altered catalase activity, in which CO₂ compensation points were inversely related to catalase content, once again raises the possibility that glycolate peroxidation and formate metabolism may take part in photorespiratory carbon cycling (Brisson et al., 1998).

The outcome of the present study is evidence of mitochondrial heterogeneity, with marked changes in protein composition at different stages of leaf development. Without measurements of enzyme activity or analysis of isolated mitochondria, it is not possible to conclude whether these changes affect mitochondrial activity. It is also necessary to consider the spatial heterogeneity of the leaf, for which there is already evidence of differential expression of mitochondrial proteins such as GDC (Tobin et al., 1989) between different cell types. Further analysis is required to determine the full extent of the spatial and temporal control of mitochondrial form and function in higher plants.

	FOOTNOTES

   Received April 9, 1998; accepted July 21, 1998.

	ABBREVIATIONS

Abbreviations: ECL, enhanced chemiluminescence. FDH, formate dehydrogenase. GDC, Gly decarboxylase complex. IDH, isocitrate dehydrogenase. PDC, pyruvate dehydrogenase complex. V_D, displacement velocity.

	LITERATURE  CITED

Top Abstract Introduction Methods Results Discussion References

Arron GP, Edwards GE (1980) Light-induced development of glycine oxidation by mitochondria from sunflower cotyledons. Plant Sci Lett 18: 229-235

Azcon-Bieto J, Lambers H, Day DA (1983) Respiratory properties of developing bean and pea leaves. Aust J Plant Physiol 10: 237-245

Barkardottir RB, Jensen BF, Kreiberg JD, Nielsen PS, Gausing K (1987) Expression of selected nuclear genes during leaf development in barley. Dev Genet 8: 495-511

Baumgartner BJ, Rapp JC, Mullet JE (1989) Plastid transcription activity and DNA copy number increase early in barley chloroplast development. Plant Physiol 89: 1011-1018 [Abstract/Free Full Text]

Behal RH, Oliver DJ (1997) Biochemical and molecular characterisation of fumarase from plants. Purification and characterisation of the enzyme: cloning, sequencing, and expression of the gene. Arch Biochem Biophys 348: 65-74 [CrossRef][ISI][Medline]

Bourguignon J, Leaver CJ (1994) Plant mitochondrial NAD-dependent malic enzyme: cDNA cloning, deduced primary structure of the 59-kDa and 62-kDa subunits, import, gene complexity and expression analysis. J Biol Chem 269: 4780-4786 [Abstract/Free Full Text]

Brisson LF, Zelitch I, Havir EA (1998) Manipulation of catalase levels produces altered photosynthesis in transgenic tobacco plants. Plant Physiol 116: 259-269 [Abstract/Free Full Text]

Camp PJ, Randall DD (1985) Purification and characterisation of the pea chloroplast pyruvate dehydrogenase complex. Plant Physiol 77: 571-577 [Abstract/Free Full Text]

Colas des Francs-Small C, Ambard-Bretteville F, Small ID, Remy R (1992) Variation of the polypeptide composition of mitochondria isolated from different potato tissues. Plant Physiol 98: 273-278

Colas des Francs-Small C, Ambard-Bretteville F, Small ID, Remy R (1993) Identification of a major soluble protein in mitochondria from non-photosynthetic tissues as NAD-dependent formate dehydrogenase. Plant Physiol 102: 1171-1177

Dale JE (1972) Growth and photosynthesis in the first leaf of barley: the effect of time and application of nitrogen. Ann Bot 36: 967-979 [Abstract/Free Full Text]

Day DA, Krab K, Lambers H, Moore AL, Siedow JN, Wagner AM, Wiskich JT (1996) The cyanide-resistant oxidase. To inhibit or not to inhibit, that is the question. Plant Physiol 110: 1-2 [ISI][Medline]

Day DA, Neuburger M, Douce R (1984) Activation of NAD-linked malic enzyme in intact plant mitochondria by exogenous coenzyme-A. Arch Biochem Biophys 231: 233-242 [CrossRef][ISI][Medline]

Dean C, Leech RM (1982a) Genome expression during normal leaf development. 1. Cellular and chloroplast numbers and DNA, RNA and protein levels in tissues at different ages within a 7-day-old wheat leaf. Plant Physiol 69: 904-910 [Abstract/Free Full Text]

Dean C, Leech RM (1982b) The co-ordinated synthesis of the large and small subunits of ribulose bisphosphate carboxylase during early cellular development within a 7-day-old wheat leaf. FEBS Lett 140: 113-116 [CrossRef]

Elthon TE, Nickels RL, McIntosh L (1989) Monoclonal antibodies to the alternative oxidase of higher plant mitochondria. Plant Physiol 89: 1311-1317 [Abstract/Free Full Text]

Gardestrom P, Bergman A, Ericson I (1980) Oxidation of glycine via the respiratory chain of mitochondria prepared from different parts of spinach. Plant Physiol 65: 389-391 [Abstract/Free Full Text]

Gonzalez DH, Bonnard G, Grienenberger JM (1993) A gene involved in the biogenesis of cytochromes is co-transcribed with a ribosomal protein gene in wheat mitochondria. Curr Genet 24: 248-255 [CrossRef][ISI][Medline]

Grissom CB, Canellas PF, Wedding RT (1983) Allosteric regulation of the NAD malic enzyme from cauliflower: activation by fumarate and coenzyme A. Arch Biochem Biophys 220: 133-144 [Medline]

Grodzinski B, Butt VS (1976) Hydrogen peroxide production and the release of carbon dioxide during glycolate oxidation in leaf peroxisomes. Planta 133: 261-266

Grover SD, Wedding RT (1984) Modulation of the activity of NAD malic enzyme from Solanum tuberosum by changes in oligomeric state. Arch Biochem Biophys 234: 418-425 [Medline]

Gualberto JM, Bonnard JM, Lamattina L, Grienenberger JM (1991) Expression of the wheat mitochondrial nad3-rps12 transcription unit: correlation between editing and messenger RNA maturation. Plant Cell 3: 1109-1120 [Abstract/Free Full Text]

Gualberto JM, Wintz H, Weil J-H, Grienenberger JM (1988) The genes coding for subunit 3 of NADH dehydrogenase and for ribosomal protein S12 are present in the wheat and maize mitochondrial genomes and are co-transcribed. Mol Gen Genet 215: 118-127 [CrossRef][Medline]

Handa H, Bonnard G, Grienenberger JM (1996) The rapeseed mitochondrial gene encoding a homologue of the bacterial protein ccl1 is divided into two independently transcribed reading frames. Mol Gen Genet 252: 292-302 [ISI][Medline]

Kendall AC, Keys AJ, Turner JC, Lea PJ, Miflin BJ (1983) ) Planta 159: 505-511 [CrossRef][ISI]

Keys AJ, Bird IF, Cornelius MJ, Lea PJ, Wallsgrove RM, Miflin BJ (1978) Photorespiratory nitrogen cycle. Nature 275: 741-743 [CrossRef]

Kidd F, Briggs GE, West C (1921) A quantitative analysis of the growth of Helianthus annuus. I. The respiration of the plant and its parts throughout the life cycle. Proc R Soc Ser B 92: 368-384

Koike M, Koike K (1976) Structure, assembly and function of mammalian -keto acid dehydrogenase complexes. Adv Biophys 9: 187-227

Lennon AM, Pratt J, Leach G, Moore AL (1995) Developmental regulation of respiratory activity in pea leaves. Plant Physiol 107: 925-932 [Abstract]

Lernmark U, Gardestrom P (1994) Distribution of pyruvate dehydrogenase complex activities between chloroplasts and mitochondria from leaves of different species. Plant Physiol 106: 1633-1638 [Abstract]

Lightowlers R, Chrzanowska-Lightowlers Z, Marusich M, Capaldi A (1991) Subunit function in eukaryote cytochrome c oxidase: a mutation in the nuclear-coded subunit IV allows assembly but alters the function and stability of yeast cytochrome c oxidase. J Biol Chem 266: 7688-7693 [Abstract/Free Full Text]

Luethy MH, David NR, Elthon TE, Miernyk JA, Randall DD (1995a) Characterisation of a monoclonal antibody recognising the E1-alpha subunit of plant mitochondrial pyruvate dehydrogenase. J Plant Physiol 145: 443-449

Luethy MH, Horak A, Elthon TE (1993) Monoclonal antibodies to the - and - subunits of the plant mitochondrial F₁-ATPase. Plant Physiol 101: 931-937 [Abstract]

Luethy MH, Miernyk JA, Randall DD (1995b) Expression of the plant mitochondrial pyruvate dehydrogenase in Escherichia coli (abstract no. 664). Plant Physiol 108: S-129

Lund AA, Elthon TE (1993) Maize mitochondrial heat-shock and chaperone protein systems (abstract no. 724). Plant Physiol 102: S-128

Mayfield SP, Taylor WC (1984) The appearance of photosynthetic proteins in developing maize leaves. Planta 161: 481-486 [CrossRef]

McIntosh CA, Oliver DJ (1992) NAD-linked isocitrate dehydrogenase. Isolation, purification and characterisation of the protein from pea mitochondria. Plant Physiol 100: 69-75 [Abstract/Free Full Text]

Moore AL, Siedow JN, Fricaud AC, Vojnikov V, Walters AJ, Whitehouse DG (1992) Regulation of mitochondrial respiratory activity in photosynthetic systems. In AK Tobin, eds, Plant Organelles: Compartmentation of Metabolism in Photosynthetic Tissue. Cambridge University Press, Cambridge, UK, pp 188-210

Moore AL, Walters AJ, Lennon AM, Watts FZ (1993) Developmental regulation of the protein import apparatus of plant mitochondria. In A Brennicke, U Kuck, eds, Plant Mitochondria: With Emphasis on RNA Editing and Cytoplasmic Male Sterility. Weinheim, Germany, pp 291-298

Morgan CL, Turner SM, Rawsthorne S (1993) Coordination of the cell specific distribution of the 4 subunits of glycine decarboxylase and of serine hydroxymethyltransferase in leaves of C3-C4 intermediate species from different genera. Planta 190: 468-473 [CrossRef]

Oliver DJ (1981) Formate oxidation and oxygen reduction by leaf mitochondria. Plant Physiol 68: 703-705 [Abstract/Free Full Text]

Oliver DJ (1994) The glycine decarboxylase complex from plant mitochondria. Annu Rev Plant Physiol Plant Mol Biol 45: 323-337 [CrossRef][ISI]

Ougham HJ, Jones TWA, Evans MLL (1987) Leaf development in Lolium temulentum L.: progressive changes in soluble polypeptide complement and isoenzymes. J Exp Bot 38: 1689-1696 [Abstract/Free Full Text]

Rios R, Debuyser J, Henry Y, Ambard-Bretteville F, Remy R (1991) 2-dimensional electrophoretic comparison of mitochondrial polypeptides from different wheat (Triticum aestivum L.) tissues. Plant Sci 76: 159-166 [CrossRef]

Rogers WJ, Jordan BR, Rawsthorne S, Tobin AK (1991) Changes to the stoichiometry of glycine decarboxylase subunits during wheat (Triticum aestivum L.) and pea (Pisum sativum L.) leaf development. Plant Physiol 96: 952-956 [Abstract/Free Full Text]

Schnyder H, Nelson CJ (1988) Diurnal growth of tall fescue leaf blades. I. Spatial distribution of growth, deposition of water, and assimilate import in the elongation zone. Plant Physiol 86: 1070-1076 [Abstract/Free Full Text]

Schuster W, Brennicke A (1994) The plant mitochondrial genome: physical structure, information content, RNA editing, and gene migration to the nucleus. Annu Rev Plant Physiol Plant Mol Biol 45: 61-78 [CrossRef][ISI]

Shah N, Bradbeer JW (1991) The development of the chloroplastic and cytosolic isoenzymes of phosphoglycerate kinase during barley leaf ontogenesis. Planta 185: 401-406

Sibley MH, Anderson LE (1989) Light/dark modulation of enzyme activity in developing barley leaves. Plant Physiol 91: 1620-1624 [Abstract/Free Full Text]

Taanman J, Capaldi RA (1993) Subunit VIa of yeast cytochrome c oxidase is not necessary for assembly of the enzyme complex but modulates the enzyme activity: isolation and characterisation of the nuclear-encoded gene. J Biol Chem 268: 18754-18761 [Abstract/Free Full Text]

Tobin AK, Ridley SM, Stewart GR (1985) Changes in the activities of chloroplast and cytosolic isoenzymes of glutamine synthetase during normal leaf growth and plastid development in wheat. Planta 163: 544-548 [CrossRef]

Tobin AK, Rogers WJ (1992) Metabolic interactions of organelles during leaf development. In AK Tobin, eds, Plant Organelles: Compartmentation of Metabolism in Photosynthetic Tissue. Cambridge University Press, Cambridge, UK, pp 293-323

Tobin AK, Sumar N, Patel M, Moore AL, Stewart GR (1988) Development of photorespiration during chloroplast biogenesis in wheat leaves. J Exp Bot 39: 833-843 [Abstract/Free Full Text]

Tobin AK, Thorpe JR, Hylton CM, Rawsthorne S (1989) Spatial and temporal influences on the cell-specific distribution of glycine decarboxylase in leaves of wheat (Triticum aestivum L.) and pea (Pisum sativum L.). Plant Physiol 91: 1219-1225 [Abstract/Free Full Text]

Tsugeki R, Mori H, Nishimura M (1992) Purification, cDNA cloning and northern blot analysis of mitochondrial chaperonin 60 from pumpkin cotyledons. Eur J Biochem 209: 453-458 [Medline]

Umbach AL, Siedow JN (1993) Covalent and non-covalent dimers of the cyanide-resistant alternative oxidase protein in higher plant mitochondria and their relationship to enzyme activity. Plant Physiol 103: 845-854 [Abstract]

Umbach AL, Siedow JN (1997) Changes in the redox state of the alternative oxidase regulatory sulfhydryl/disulfide system during mitochondrial isolation: implications for inferences of activity in vivo. Plant Sci 123: 19-28 [CrossRef]

Viro M, Kloppstech K (1980) Differential expression of the genes for ribulose-1,5-bisphosphate carboxylase and light harvesting chlorophyll a/b protein in developing barley leaves. Planta 150: 41-45 [CrossRef][ISI]

Walker JL, Oliver DJ (1986) Light-induced increases in the glycine decarboxylase multienzyme complex from pea leaf mitochondria. Arch Biochem Biophys 248: 626-638 [CrossRef][ISI][Medline]

Walton NJ (1982) Glyoxylate decarboxylation during glycolate oxidation by pea leaf extracts: significance of glyoxylate and extract concentrations. Planta 155: 218-224 [CrossRef]

Winning BM, Bourguignon J, Leaver CJ (1994) Plant mitochondrial NAD dependent malic enzyme: cDNA cloning, deduced primary structure of the 59-kDa and 62-kDa subunits, import, gene complexity and expression analysis. J Biol Chem 269: 4780-4786

Zelitch I (1992) Control of plant productivity by regulation of photorespiration. BioScience 42: 510-516

Copyright Clearance Center:   0032-0889/98/118//11
 
© 1998 American Society of Plant Physiologists