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1.
Activities of ribulose bisphosphate carboxylase/oxygenase (RuBPCO), phosphoenolpyruvate carboxylase (PEPC), and carbonic anhydrase
(CA) were determined in leaves of cotton (Gossypium hirsutum L. cv. H-777) subjected to 8-d waterlogging (WL) at the vegetative stage, or to drought (D) at the reproductive stage, or
to interaction of both stresses. The soil moisture of control plants was kept at field capacity. One day prior to stress various
growth hormones (5 μM) were sprayed up to runoff. WL reduced RuBPCO and CA activities, while PEPC activity increased. Upon
D, RuBPCO and PEPC activities were reduced while CA activity was increased. Imposition of both stresses increased activities
of all three enzymes. Effect of stresses on enzyme activity was alleviated by benzylaminopurine (BAP), but indol-3-yl-acetic
acid was more promoting under interactive stress. No CA activity with BAP was observed during interactive stress.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
2.
J. Kveton 《Biologia Plantarum》2006,50(1):21-30
Three types of transgenic plants of Solanum tuberosum cvs. Kamyk and Oreb, and Nicotiana tabacum cvs. Maryland Mammoth and Trapezond were selected according to intensity of introduced ipt gene expression and resulting amount of synthesised cytokinins (CKs). In comparison with controls, original transgenic regenerants
grown in vitro showed a massive increase of CK contents, in tobacco by 379 % and in potato by 159 % (MAS). Potato grown in soil from tubers
of transgenic plants demonstrated a moderate increase (44 %) of CK contents (MOD). Transgenic tobacco grown from seeds in vitro did not show any significant change in CK contents (NOT). Initial (RuBPCi and RuBPOi) and total (RuBPCt) activities of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO), and the activity of phosphoenolpyruvate carboxylase (PEPC) were not significantly affected by the transformation in the NOT plants. In the MOD plants, the
RuBPCO activities were stimulated by up to 34 % whereas the PEPC activity was decreased by 17 %. On the other hand, all the
measured enzyme activities were 32 – 91 % lower in the MAS. Leaf area, fresh and dry masses, and chlorophyll and soluble protein
contents also went down with increasing CK amounts in the transformants. Dependence of RuBPCi/RuBPOi and RuBPCt/PEPC ratios on the relative CK amounts in transgenic plants revealed that the individual enzyme activities were not affected
uniformly. Endogenous CK contents in the MAS thus apparently exceeded an optimum needed for positive effects on many physiological
traits and became a stress factor for such plants. 相似文献
3.
In two winter wheat (Triticum aestivum L.) cultivars differing in their response to high temperature, JD8 (tolerant) and J411 (sensitive) we studied the effect of heat stress on the activities of phosphoenolpyruvate carboxylase (PEPC) and ribulose-1,5-bisphosphate carboxylase (RuBPC) in green organs during grain-filling. There were significantly higher PEPC activities and lower RuBPC activities in each of the non-leaf organs (awn, glume, lemma, peduncle, and sheath) than in the flag leaf blade. Under heat stress for 12 d, the activity of RuBPC quickly declined and the activity of PEPC first increased and later declined in all organs, resulting in a great increase of the PEPC/RuBPC ratios in the organs, particularly in non-leaf organs which had a higher PEPC/RuBPC than the flag leaf blade in all times. The PEPC activity and PEPC/RuBPC ratio in every organ of JD8 were higher than those in the same organ of J411. Thus the differences in PEPC activities and PEPC/RuBPC may be associated with the differences in photosynthetic heat tolerance among the organs of the same plant or between the two cultivars. 相似文献
4.
Photosynthetic Activity of Ripening Tomato Fruit 总被引:4,自引:0,他引:4
Gas exchanges, chlorophyll (Chl) a fluorescence and carboxylation activities of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) and phosphoenolpyruvate carboxylase (PEPC) were determined in tomato (Lycopersicon esculentum Mill.) fruits picked at different developmental stages (immature, red-turning, mature, and over-ripe). The fruits did not show signs of CO2 fixation. However, photochemical activity was detectable and an effective electron transport was observed, the values of Chl fluorescence parameters in green fruits being similar to those determined in the leaves. The RuBPCO activity, which was similar to those recorded in the leaves at the immature stage of the fruit, decreased as the fruit ripened. PEPC activity was always higher than RuBPCO activity. 相似文献
5.
Water stress effects on photosynthesis in different mulberry cultivars 总被引:10,自引:0,他引:10
The effect of water stress on photosynthesis was determined in five mulberry cultivars (Morus alba L. cv. K-2, MR-2, BC2-59, S-13 and TR-10). Drought was imposed by withholding water and the plants were maintained at different water potentials ranging from 0.5 -MPa to 2.0 -MPa. Photosynthetic rates, activities of ribulose-1,5-bisphosphate carboxylase and sucrose phosphate synthase, photosystem II activity and chlorophyll content were used as key parameters to assess photosynthetic performance. There was a marked variation in the photosynthetic rates and ribulose-1,5-bisphosphate carboxylase activity among the five mulberry cultivars subjected to water stress. Photosystem II (PSII) and sucrose phosphate synthase activities were also severely reduced as measured by drought conditions. Of the five mulberry cultivars, S-13 and BC2-59 showed higher photosynthetic rates, ribulose-1,5-bisphosphate carboxylase activity, high sucrose phosphate synthase activity and photochemical efficiency of PSII compared to the other varieties. 相似文献
6.
mRNA expression patterns of genes for metabolic key enzymes sucrose phosphate synthase (SPS), phosphoenolpyruvate carboxylase (PEPC), pyruvate kinase, ribulose 1,5-bisphosphate carboxylase/oxygenase, glutamine synthetase 1, and
glutamine synthetase 2 were investigated in leaves of rice plants grown at two nitrogen (N) supplies (N0.5, N3.0). The relative gene expression patterns were similar in all leaves except for 9th leaf, in which mRNA levels were generally depressed. Though increased N supply prolonged the expression period of each mRNA,
it did not affect the relative expression intensity of any mRNA in a given leaf. SPS Vmax, SPS limiting and PEPC activities, and carbon flow were examined. The ratio between PEPC activity and SPS Vmax was higher in leaves developed at the vegetative growth stage (vegetative leaves: 5th and 7th leaves) than in leaves developed after the ear primordia formation stage (reproductive leaves: 9th and flag leaves). PEPC activity and SPS Vmax decreased with declining leaf N content. After using 14CO2 the 14C photosynthate distribution in the amino acid fraction was higher in vegetative than in reproductive leaves when compared
for the same leaf N status. Thus, at high PEPC/SPS activities ratio, more 14C photosynthate was distributed to the amino acid pool, whereas at higher SPS activity more 14C was channelled into the saccharide fraction. Thus, leaf ontogeny was an important factor controlling photosynthate distribution
to the N- or C-pool, respectively, regardless of the leaf N status. 相似文献
7.
Blanca Gallego-Tévar Procopio Peinado-Torrubia Rosario Álvarez Jacinto Gandullo Brenda J. Grewell Enrique Figueroa Jesús M. Castillo 《Physiologia plantarum》2020,169(1):83-98
Hybridization is a relevant evolutionary mechanism linked to the invasiveness of plant species, but little is known about its effect on enzymatic activities in response to stress. We analyzed the effects of salinity on key mechanistic traits of phosphoenolpyruvate carboxylase (PEPC) enzyme for two hybrid taxa derived from native Spartina maritima (Curtis) Fernald and invasive Spartina densiflora Brongn. in comparison with their parental species. Parental species showed contrasted strategies at the PEPC level to cope with salinity. Spartina maritima showed its physiological optimum at 10 to 40 ppt salinity, with high PEPC activity (per unit leaf soluble protein), in contrast to the lower salinity optimum of 0.5 and 10 ppt for S. densiflora, where highest levels of PEPC apparent specific activity coincided with high light-induced activation of PEPC. Both hybrids showed constant PEPC apparent specific activity from fresh water to hypersalinity and exhibited higher net photosynthesis rates in fresh water than their parents. Spartina maritima × densiflora presented three transgressive PEPC-related traits, being the only taxon able to increase its PEPC activation in darkness at high salinity. Spartina densiflora × maritima showed most PEPC-related traits intermediate between its parents. Inheritance types operating differently in reciprocal hybrids determine key functional traits conditioning their ecological performance. 相似文献
8.
The net CO2 assimilation by leaves of maize (Zea mays L. cv. Adonis) plants subjected to slow or rapid dehydration decreased without changes in the total extractable activities of phosphoenolpyruvate carboxylase (PEPC), malate dehydrogenase (MDH) and malic enzyme (ME). The phosphorylation state of PEPC extracted from leaves after 2–3 h of exposure to light was not affected by water deficit, either. Moreover, when plants which had been slowly dehydrated to a leaf relative water content of about 60% were rehydrated, the net CO2 assimilation by leaves increased very rapidly without any changes in the activities of MDH, ME and PEPC or phosphorylation state of PEPC. The net CO2-dependent O2 evolution of a non-wilted leaf measured with an oxygen electrode decreased as CO2 concentration increased and was totally inhibited when the CO2 concentration was about 10%. Nevertheless, high CO2 concentrations (5–10%) counteracted most of the inhibitory effect of water deficit that developed during a slow dehydration but only counteracted a little of the inhibitory effect that developed during a rapid dehydration. In contrast to what could be observed during a rapidly developing water deficit, inhibition of leaf photosynthesis by cis-abscisic acid could be alleviated by high CO2 concentrations. These results indicate that the inhibition of leaf net CO2 uptake brought about by water deficit is mainly due to stomatal closure when a maize plant is dehydrated slowly while it is mainly due to inhibition of non-stomatal processes when a plant is rapidly dehydrated. The photosynthetic apparatus of maize leaves appears to be as resistant to drought as that of C3 plants. The non-stomatal inhibition observed in rapidly dehydrated leaves might be the result of either a down-regulation of the photosynthetic enzymes by changes in metabolite pool sizes or restricted plasmodesmatal transport between mesophyll and bundle-sheath cells. 相似文献
9.
A series of experiments were conducted to characterize the water stress-induced changes in the activities of RuBP carboxylase (RuBPCO) and sucrose phosphate synthase (SPS), photosystem 2 activity, and contents of chlorophylls, carotenoids, starch, sucrose, amino acids, free proline, proteins and nucleic acids in mulberry (Morus alba L. cv. K-2) leaves. Water stress progressively reduced the activities of RuBPCO and SPS in the leaf extracts, the chlorophyll content, and PS2 activity in isolated chloroplasts. Plants exposed to drought showed lower content of starch and sucrose but higher total sugar content than control plants. While the soluble protein content decreased under water stress, the amino acid content increased. Proline accumulation (2.5-fold) was noticed in stressed leaves. A reduction in the contents of DNA and RNA was observed. Reduced nitrogen content was associated with the reduction in nitrate reductase activity. SDS-PAGE protein profile showed few additional proteins (78 and 92 kDa) in the water stressed plants compared to control plants. 相似文献
10.
11.
Changes of Photosynthetic Characteristics in Relation to Leaf Senescence in Two Maize Hybrids with Different Senescent Appearance 总被引:6,自引:0,他引:6
A field experiment was conducted to investigate the changes in chlorophyll (Chl) and nitrogen (N) contents, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) and phosphoenolpyruvate carboxylase (PEPC) contents and PEPC activity, and the photon-saturated net photosynthetic rate (P
Nsat), and their relationships with leaf senescence in two maize hybrids with different senescent appearance. One stay-green (cv. P3845) and one earlier senescent (cv. Hokkou 55) hybrid were used in this study, and we found that Chl and N contents and the P
Nsat in individual leaves of P3845 were greater than those in corresponding leaves of Hokkou 55 at the successive growth stages. In addition, larger contents of RuBPCO and PEPC, and a greater activity of PEPC were observed in P3845. Due to the lower rates of decrease of Chl, RuBPCO, and PEPC amounts per unit of N, and the lower net C translocation rate per unit of N in the stay-green hybrid, leaf senescence was delayed in comparison to the earlier senescent hybrid. 相似文献
12.
13.
A Zea mays callus culture containing chlorophyll was established and grown photomixotrophically. Cell chloroplast structure, and pigment and soluble protein contents were examined. Expression of some key enzymes of C4 carbon metabolism was compared with that of etiolated (heterotrophic) and green photoautotrophic leaves. Chlorophyll content of the callus was 15–20% that of green leaves. Soluble protein content of callus was half that of leaf cells. Electron microscopic observations showed that green callus cells contained only typical granal chloroplasts. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.38) activities in green callus were ca 30% those of green leaves but 2–3 times higher than in etiolated leaves. Quantitative enzyme protein determination, using antibodies specific to maize leaf Rubisco showed that the chloroplastic carboxylase represented about 7% of total soluble protein in green callus, in parallel to its low chlorophyll content. The specific activity of Rubisco in callus and leaves was unchanged. Phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) activity in green callus was about 20% that of green leaves and similar to that measured in etiolated leaves. Apparent Km (PEP) values (0.08 mM) for PEPC isolated from green callus and etiolated leaves were very different from values (0.5 mM) obtained with PEPC from green leaves. These kinetic characteristics together with the absence of inhibition by malate and activation by glucose-6-phosphate suggest that the properties of PEPC isolated from green callus and etiolated maize leaves are very similar to those of PEPPC from C3 plants. Using PEPC antibodies specific to green maize leaf enzyme, immunotitration of PEPC preparations containing identical enzyme units allowed complete precipitation of the green leaf enzyme with increasing antibody volumes. In contrast, 60–70% of the activity of PEPC from etiolated and green callus was inhibited, suggesting low affinity for the maize green leaf PEPC antiserum (typical C4 form). Ouchterlony double diffusion tests revealed only partial recognition of PEPC in green callus and etiolated leaves. NAD-malate dehydrogenase (NAD-MDH, EC 1.1.1.37) activity in callus was 2 and 3 times higher, respectively, than in etiolated and green leaves. NADP-malic enzyme (NADP-ME, EC 1.1.1.40) activity in callus cultures was much lower than in green leaves. All our data support the hypothesis that cultures of fully dedifferentiated chlorophyllous tissues of Zea mays possess a C3-like metabolism. 相似文献
14.
Measurements of net CO2 exchange, malate accumulation, properties and capacity of phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) in leaves of different ages of two short-day dependent Crassulacean acid metabolism (CAM) plants (Kalanchoe blossfeldiana v. Poelln. Tom thumb and K. velutina Welw.) show that, in both species: a) young leaves from plants grown under long days display a CO2 exchange pattern typical of C3 plants; b) leaf aging promotes CAM under long-day conditions; c) short-day treatment induces CAM in young leaves to a higher degree than aging under long days; d) at least in K. blossfeldiana, the PEPC form developed with leaf aging under long days and the enzyme form synthetized de novo in young leaves grown under short days were shown to have similar properties. Short days also promote CAM in older leaves though at a lesser extent than in young leaves: The result is that this photoperiodic treatment increases the general level of CAM performance by the whole plant. The physiological meaning of the control of PEPC capacity by photoperiodism could be to afford a precisely timed seasonal increase in CAM potentiality, enabling the plant to immediately optimize its response to the onset of drought periods.Abbreviations CAM
Crassulacean acid metabolism
- PEP
phosphoenolpyruvate
- PEPC
phosphoenolpyruvate carboxylase (EC 4.1.1.31)
- LD
long day
- SD
short day 相似文献
15.
Sonali Majumdar Sibdas Ghosh Bernard R. Glick Erwin B. Dumbroff 《Physiologia plantarum》1991,81(4):473-480
The effects of senescence and drought on the levels and activities of chlorophyllase (EC 3.1.1.14), phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) and ribulose-1,5-bisphosphate carboxylase (Rubisco, EC 4.1.1.39) in the intact primary leaves of soybean ( Glycine max L. cv. Jackson) were monitored. Plants were grown either (1) for 2 to 8 weeks and the primary leaves harvested every week or (2) for 2 weeks and the plants subjected to drought stress and compared to control plants that were watered daily. In the senescence experiment, chlorophyllase activity changed in parallel with water content, leaf chlorophyll and total protein per unit dry weight of leaf tissue, with all factors increasing in concert during expansion of the primary leaves in the first 4 to 5 weeks of seedling development. Thereafter, all factors, including chlorophyllase activity, declined reaching markedly reduced values at weeks 7 and 8 when the primary leaves were yellow and ready to abscise. PEPC and Rubisco activities peaked in the third week, i.e. well before full leaf expansion, and then declined. In contrast to its response during senescence, chlorophyllase activity per unit leaf dry weight did not change during drought stress, but the specific activity of the enzyme rose and showed an inverse relationship to total leaf chlorophyll and protein content. Rubisco activity was highly sensitive to drought, with decrements observed in the activity and in levels of the large subunit within 2 days of withholding water and before significant changes in leaf water content were detected. 相似文献
16.
Seasonal variation in ribulose bisphosphate carboxylase activity in Pinus silvestris 总被引:3,自引:0,他引:3
Ribulose bisphosphate carboxylase activity was examined in Pinus silvestris L. during successive seasons. The enzyme activities were studied both in seedlings, kept under controlled conditions in a climate chamber, and in needles from a 15-year-old tree in a natural stand. The enzyme activities were analysed in cell-free extracts prepared with Tween 80 as protective agent. The carboxylase activity fluctuated periodically both in the seedlings and in the natural stand. In the seedlings, the weight-related activity in the older needles increased 50–100% (in the cotyledons c. 200%) in the beginning of the “summer”. It decreased as the new shoot developed. The specific activity increased c. 100%. With chlorophyll as base, the activity usually decreased during “summer”. In the developing current needles the carboxylase activity increased when expressed on a weight or on a protein basis. The decrease in weight-related carboxylase activity in the older needles was preceded by, or simultaneous with, loss of total protein. It is suggested that protein, including the carboxylase, is utilized as nitrogen reserve for the new shoot. During hardening by combined photoperiod and thermoperiod, the carboxylase activity decreased when expressed relative to dry weight and protein. Calculated on a chlorophyll basis, the activity was rather constant. In the natural stand the activity in the one- and two-year-old needles increased during spring and summer and decreased during autumn and winter. Even at severe winter stress substantial carboxylase activity remained in the needles. The activity of the enzyme in vivo is discussed with respect to electron transport and net photosynthesis. 相似文献
17.
J. Kvto 《Biologia Plantarum》2001,44(3):447-450
Three clones of tobacco transformed with the T-DNA of Agrobacterium rhizogenes Ri plasmid A4b cultivated in vitro on a solid agar medium neither showed pronounced morphological diversity nor significantly differed in chlorophyll (Chl) contents from control plants. However, the transformation caused a 27 to 83 % decay in leaf oxygen evolution and in both ribulose-1,5-bisphosphate carboxylase (RuBPC) and phosphoenolpyruvate carboxylase (PEPC) activities. Therefore, the transformation brought about a reduction of active PEPC as well as activable RuBPC amounts in plant tissues. Individual clones did not mutually differ. In tobacco transformed with A. rhizogenes strain TR101 and grown in soil only the mean leaf area tended to reduce. Chl contents, Chl a/b ratio, oxygen evolution, and activities of both RuBPC and PEPC were insignificantly affected by the transformation. 相似文献
18.
Characterization of lysine acetylation of a phosphoenolpyruvate carboxylase involved in glutamate overproduction in Corynebacterium glutamicum
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Megumi Nagano‐Shoji Yuma Hamamoto Yuta Mizuno Ayuka Yamada Masaki Kikuchi Mikako Shirouzu Takashi Umehara Minoru Yoshida Makoto Nishiyama Saori Kosono 《Molecular microbiology》2017,104(4):677-689
Protein Nε‐acylation is emerging as a ubiquitous post‐translational modification. In Corynebacterium glutamicum, which is utilized for industrial production of l ‐glutamate, the levels of protein acetylation and succinylation change drastically under the conditions that induce glutamate overproduction. Here, the acylation of phosphoenolpyruvate carboxylase (PEPC), an anaplerotic enzyme that supplies oxaloacetate for glutamate overproduction was characterized. It was shown that acetylation of PEPC at lysine 653 decreased enzymatic activity, leading to reduced glutamate production. An acetylation‐mimic (KQ) mutant of K653 showed severely reduced glutamate production, while the corresponding KR mutant showed normal production levels. Using an acetyllysine‐incorporated PEPC protein, we verified that K653‐acetylation negatively regulates PEPC activity. In addition, NCgl0616, a sirtuin‐type deacetylase, deacetylated K653‐acetylated PEPC in vitro. Interestingly, the specific activity of PEPC was increased during glutamate overproduction, which was blocked by the K653R mutation or deletion of sirtuin‐type deacetylase homologues. These findings suggested that deacetylation of K653 by NCgl0616 likely plays a role in the activation of PEPC, which maintains carbon flux under glutamate‐producing conditions. PEPC deletion increased protein acetylation levels in cells under glutamate‐producing conditions, supporting the hypothesis that PEPC is responsible for a large carbon flux change under glutamate‐producing conditions. 相似文献
19.
Regulation of enzymes involved in C4 photosynthesis and the antioxidant metabolism by UV-B radiation in Egeria densa,a submersed aquatic species 总被引:2,自引:0,他引:2
Egeria densa, a submersed aquatic species, was exposed to different treatments under UV-B radiation, and the response of phosphoenolpyruvate
carboxylase (PEPC) and NADP-malic enzyme (NADP-ME) was determined. Exposure to UV-B radiation for 4 h per day over 7–16 days
caused an increase in both enzymes, together with an increase in the activity of some isoforms of several enzymes involved
in the antioxidant metabolism, such as superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and peroxidase
(POD). The content of chlorophylls and carotenoids was considerably decreased, suggesting that degradation or repression of
the synthesis of these molecules may be occurring after UV-B exposure. Reactive oxygen species (ROS) were also required for
UV-B induction of PEPC and NADP-ME, as the addition of ascorbic acid before UV-B treatment prevented the induction of these
enzymes, while salicylic acid was not effective in inducing NADP-ME but increased the expression of the lower molecular mass
isoform of PEPC. On the other hand, damage to the photosynthetic machinery may be occurring after exposure to UV-B radiation
for 8 per day over 1–2 days, as indicated by a decrease in the levels of Rubisco, PEPC and NADP-ME. Some of the enzymes involved
in the antioxidant metabolism, such as CAT and APX, were also sensitive to continuous exposure, evidenced by a decrease in
their activity. In this way, in E. densa, several enzymes involved in different metabolic pathways showed a distinct response, depending on the UV-B treatment.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
20.
Leaf water potential was decreased by withholding irrigation to provide three levels of stress described as mild ({ie69-1}) moderate ({ie69-2}) and severe ({ie69-3}). The specific activity of NADP linked glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, aldolase, phosphogluco-isomerase and RuBP carboxylase decreased under mild stress, but the activity of phosphoglucomutase showed an increase whilst ribulose-5-phosphate kinase was least affected. With further decrease in water potential, the activity of NADP linked glyceraldehyde-3-phosphate dehydrogenase and aldolase showed a decrease, whereas, the activities of fructose-1,6-bisphosphatase, phosphoglycerate kinase, phosphogulcomutase and RuBP carboxylase increased. Net CO2 fixation decreased sharply with stress, whereas, respiration and photorespiration increased in moderate stress, but decreased under severe stress. Stomatal resistance also increased with decrease in water potential. It seems that in vitro enzyme activities of PCR cycle are not responsible for decreased photosynthesis in pigeonpea under short term water stress. 相似文献