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1.
We studied the influence of UV-B radiation on chlorophyll and rubisco activation by rubisco activase in the leaves of jackbean
(Canavalia ensiformis). Chlorophyll content was decreased, indicating that the synthesis of those molecules may have been degraded or repressed
after exposure. Rubisco content was significantly lower in radiated tissue compared with the untreated control; rubisco activity
showed a similar pattern of change. Based on these data, we suggest that rubisco activity is associated with the level of
rubisco protein, and that UV-B inhibits its activation and induction, as well as that of rubisco activase. Therefore, we propose
that the inhibitory effect of rubisco by UV-B may be caused by rubisco activase. 相似文献
2.
We studied the effect of cadmium on chlorophylls and rubisco activation inCanavalia ensiformis L. leaves. Chlorophyll levels were reduced by 5.0 μM Cd. Rubisco activity at 5.0 μM Cd was significantly smaller than that
at no treatment. Rubisco content showed patterns of change similar to rubisco activity. These data suggest that rubisco activity
was associated with an amount of rubisco protein, and that the activation and induction of rubisco is inhibited by Cd. The
degree of intensity of 50 and 14.5 kD polypeptides identified as the large and small subunit of rubisco by SDS-PAGE analysis
at 5.0 μM Cd was significantly lower than that at control, indicating Cd had a effect on both subunits. Under the assumption
that effects of Cd on rubisco may be related to rubisco activase, in addition to, its activity and content were determined.
The rubisco activase activity at 5.0 μM Cd was more decreased than, the control. A similar change pattern was also observed
in content of rubisco activase. Remarkable differences in the intensitiy of both the 45 kD and 41 kD band were found between
at control and Cd-treatment. These results suggest that the change in the levels of rubisco activase leads to a subsequent
alteration of rubisco levels. 相似文献
3.
Kwang Soo Roh Mi Jung Oh Seung Dal Song Hwa Sook Chung Jong Suk Song 《Biotechnology and Bioprocess Engineering》2001,6(2):100-106
This investigation was performed to study the influence of benomyl on photosynthetic pigments and enzymes in soybean leaves.
Chlorophyll and pheophytin levels were reduced by benomyl 45 days after greening. These results indicate that chlorophylla andb, and pheophytin must be controlled by benomyl. SDS-PAGE analysis showed that 50 and 14.5 kD polypeptides represented as the
large and small subunits of rubisco. In the both of these subunits, the band intensity of the control was significantly higher
than that after benomyl treatment, indicating that these two subunits are affected by benomyl. Benomyl strongly inhibited
both the activity and content of rubisco as its concentration was gradually increased. However, it remains unclear whether
this reduction of rubisco level was due to a reduced level of rubisco activase. Two major polypeptides of 46 and 42 kD were
identified as rubisco activase subunits by SDS-PAGE. The intensity of these two bands was shown to be higher in the control
than after benomyl treatment. These results indicate that the rubisco decrease resulting from increased benomyl concentrations
was caused by rubisco activase. A significant decrease in both the activity and content of rubisco activase by benomyl was
also observed. These results suggest that the decrease in rubisco level caused by benomyl is accompanied by a decrease in
both the activity and content of rubisco activase. 相似文献
4.
At bicarbonate concentrations equivalent to air levels of CO2, activation of ribulosebisphosphate carboxylase/oxygenase (rubisco) was inhibited by micromolar concentrations of glyoxylate in intact, lysed, and reconstituted chloroplasts and in stromal extracts. The concentration of glyoxylate required for 50% inhibition of light activation in intact chloroplasts was estimated to be 35 micromolar. No direct inhibition by glyoxylate was observed with purified rubisco or rubisco activase at micromolar concentrations. Levels of ribulose 1,5-bisphosphate and ATP increased in intact chloroplasts following glyoxylate treatment. Results from experiments with well-buffered lysed and reconstituted chloroplast systems ruled out lowering of pH as the cause of inhibition. With intact chloroplasts, micromolar glyoxylate did not prevent activation of rubisco at high (10 mM) concentrations of bicarbonate, indicating that rubisco could be spontaneously activated in the presence of glyoxylate. These results suggest the existence of a component of the in vivo rubisco activation system that is not yet identified and which is inhibited by glyoxylate.Abbreviations PEP
phosphoenolpyruvate
- PGA
3-phosphoglycerate
- rubisco
ribulosebisphosphate carboxylase/oxygenase
- RuBP
ribulose 1,5-bisphosphate 相似文献
5.
The influence of sucrose onin vitro growth, chlorophyll content, and rubisco/rubisco activase were studied in tobacco leaves. The most pronounced effect onin vitro growth and the chlorophyll content was found at 4% sucrose. The rubisco content increased with increasing concentrations
of sucrose, but a point was reached beyond which the increasing concentrations of sucrose caused an inhibition of this enzyme.
The rubisco activity showed patterns of change similar to the rubisco content. These data suggest that sucrose may have an
affect on the activation and induction of rubisco and that sucrose can be both a positive effector and negative effector depend
on its concentration. The degree of intensity of 55 and 15 kD polypeptides, which were identified as the large and small subunit
of rubisco, respectively, by SDS-PAGE analysis at 4% sucrose was significantly higher than that of other treatments, indicating
that sucrose had an effect on both subunits. We subsequently examined whether the rubisco content and activity of being induced
by sucrose is associated with rubisco activase. The rubisco activase content at 4% sucrose was higher than that of the other
treatments. A similar change pattern was also observed in the activity of rubisco activase. The intensity of two 52 and 51
kD polypeptide bands at 4% sucrose was higher than that of corresponding bands of other treatments. The stimulatory and inhibitory
effects of rubisco by sucrose seemed to be caused by rubisco activase. 相似文献
6.
7.
Yi-Chin Candace Tsai Lynette Liew Zhijun Guo Di Liu Oliver Mueller-Cajar 《The Journal of biological chemistry》2022,298(1)
The CO2-fixing enzyme rubisco is responsible for almost all carbon fixation. This process frequently requires rubisco activase (Rca) machinery, which couples ATP hydrolysis to the removal of inhibitory sugar phosphates, including the rubisco substrate ribulose 1,5-bisphosphate (RuBP). Rubisco is sometimes compartmentalized in carboxysomes, bacterial microcompartments that enable a carbon dioxide concentrating mechanism (CCM). Characterized carboxysomal rubiscos, however, are not prone to inhibition, and often no activase machinery is associated with these enzymes. Here, we characterize two carboxysomal rubiscos of the form IAC clade that are associated with CbbQO-type Rcas. These enzymes release RuBP at a much lower rate than the canonical carboxysomal rubisco from Synechococcus PCC6301. We found that CbbQO-type Rcas encoded in carboxysome gene clusters can remove RuBP and the tight-binding transition state analog carboxy-arabinitol 1,5-bisphosphate from cognate rubiscos. The Acidithiobacillus ferrooxidans genome encodes two form IA rubiscos associated with two sets of cbbQ and cbbO genes. We show that the two CbbQO activase systems display specificity for the rubisco enzyme encoded in the same gene cluster, and this property can be switched by substituting the C-terminal three residues of the large subunit. Our findings indicate that the kinetic and inhibitory properties of proteobacterial form IA rubiscos are diverse and predict that Rcas may be necessary for some α-carboxysomal CCMs. These findings will have implications for efforts aiming to introduce biophysical CCMs into plants and other hosts for improvement of carbon fixation of crops. 相似文献
8.
The identification and metabolism of GA9 and its metabolites in seed coats and shoots of pea,line G2 总被引:1,自引:0,他引:1
[3H]gibberellin A9 was applied to shoots or seed parts of G2 pea to produce radiolabeled metabolites. These were used as markers during purification for the recovery of endogenous GA9 and its naturally occurring metabolites. GA9 and its metabolites were purified by HPLC, derivatized and examined by GC-MS. Endogenous GA9, GA20, GA29 and GA51 were identified in pea shoots and seed coats. GA51-catabolite and GA29-catabolite were also detected in seed coats. GA70 was detected in seed coats following the application of 1 g of GA9. Applied [3H]GA9 was metabolized through both the 13-hydroxylation and 2-hydroxylation pathways. Labeled metabolites were tentatively identified on the basis of co-chromatography on HPLC with endogenous compounds identified by GC-MS. In shoots [3H]GA51 and [3H]GA51-catabolite were the predominant metabolites after 6 hrs, but by 24 hrs there was little of these metabolites remaining, while [3H]GA29-catabolite and an unidentified metabolite predominated. In seed coats [3H]GA51 was the initial product, later followed by [3H]GA51-catabolite and an unidentified metabolite (different from that in shoots), with lesser amounts of [3H]GA20, [3H]GA29 and [3H]GA29-catabolite. [3H]GA70 was a very minor product in both cases. [3H]GA9 was not metabolized by pea cotyledons.Edited by T.J. Gianfagna.Author for correspondence 相似文献
9.
Michael E. Salvucci Archie R. Portis Jr. William L. Ogren 《Photosynthesis research》1985,7(2):193-201
Ribulosebisphosphate carboxylase/oxygenase (EC 4.1.1.39) (rubisco) must be fully activated in order to catalyze the maximum rates of photosynthesis observed in plants. Activation of the isolated enzyme occurs spontaneously, but conditions required to observe full activation are inconsistent with those known to occur in illuminated chloroplasts. Genetic studies with a nutant of Arabidopsis
thaliana incapable of activating rubisco linked two chloroplast polypeptides to the activation process in vivo. Using a reconstituted light activation system, it was possible to demonstrate the participation of a chloroplast protein in rubisco activation. These results indicate that a specific chloroplast enzyme, rubisco activase, catalyzes the activation of rubisco in vivo. 相似文献
10.
Hemant Pandey Shyamal K. Nandi Bhuwan Chandra Mohammad Nadeem Lok Man S. Palni 《Acta Physiologiae Plantarum》2001,23(4):467-474
Podophyllum hexandrum Royle, an important alpine herb, is the source of highly valued podophyllotoxin. The effect of some plant growth substances
(GA3, BAP & ABA), uniconazole (an inhibitor of GA biosynthesis), and a combination of GA3 and uniconazole were examined in respect to influence on sprouting in rhizomes of P. hexandrum and on induction of flowering at a lower altitude. Amongst the various chemicals tested, GA3 had a marked effect resulting in uniform sprouting and also induced flowering in about half of the treated rhizomes. While
BAP also promoted early sprouting, delayed sprouting was seen in rhizomes treated with ABA. Uniconazole treatment, either
alone or with GA3 was found to inhibit flowering and also resulted in reduced plant height. GA3 treatment of rhizomes from plants that was maintained for up to 30 months at a lower altitude also induced flowering thus
replacing the normal chilling requirement of plants. These results suggest that treatment of GA3 could be effectively used for inducing uniform sprouting and flowering in rhizomes of P. hexandrum grown at lower altitudes. 相似文献
11.
Shanying He Zhenli He Qiuling Wu Lei Wang Xi Zhang 《International journal of phytoremediation》2015,17(12):1153-1159
The effects of growth-promoting hormone gibberellic acid 3 (GA3) on physiology, Pb phytoextraction, and metal detoxification mechanisms in Lolium perenne were studied. Results showed that addition of GA3 alone at lower doses (1 or 10 μM) facilitated antioxidant defense of L. perenne under Pb stress, decreased the toxicity of Pb in plant shoot by increasing the proportion of Pb in cell wall, hence significantly enhanced photosynthesis and plant growth, as well as Pb uptake and accumulation in L. perenne (P < 0.05). However, these indicators showed the opposite changes when treated with GA3 at a higher dose (100 μM). Of the total Pb in plant shoot, 36–51% was associated with cell wall, and 31–40% was soluble fraction, while 41.4–49.7% was NaCl extractable, 24.6–35.4% HAc extractable followed by other fractions. These findings suggest that Pb fixation by pectates and proteins in cell wall and sequestration in vacuole are responsible for Pb detoxification in plant, and the GA3 at 1 μM appears to be optimal for enhancing Pb phytoextraction by L. perenne from Pb polluted soils. 相似文献
12.
Kwang Soo Ron Mo Sun Kwon Young Hwan Do Seung Dal Song Hwa Sook Chung Jong Suk Song 《Journal of Plant Biology》1998,41(3):233-239
Rubisco activity during photosynthesis is regulated by the rubisco activase, which facilitates the dissociation of RuBP and
other inhibitory sugar phosphates from the active site of rubisco in an ATP-dependent reaction. In this paper, barleyRca genes (RcaA1,RcaA2 andRcaB) were expressed inE. coli and the activity of rubisco activase expressed was assayed biochemically by chromatography. Then the protein was identified
electrophoretically by SDS-PAGE and detected immunologically by Western blot analysis using polyclonal antibodies raised against
the kidney bean rubisco activase as probe. The band pattern of purified proteins on the polyacrylamide gel showed two polypeptides
of 46 kD and 42 kD. Anti-rubisco activase antibodies reacted specifically with both polypeptides of 46 kD and 42 kD present
in the crude extracts ofE. coli transformants. Therefore, it was found that the genes of barley rubisco activase was successfully expressed inE. coli as active forms of 46 kD and 42 kD. 相似文献
13.
14.
The ability of Cucumis melo embryos of different ages to form plants in vitro was studied in order to rescue hybrid embryos between C. melo and Cucumis metuliferus. Plants were grown in a glasshouse at temperatures ranging from 15°CN-28°CD. Best results were obtained with ovule embryos excised 17 days after pollination. At this age, kinetin of 0.5 mg l–1 was found optimal for culturing embryo development. Similar results were obtained with ovule embryos excised 14 days after pollination which cultured on 0.5 mg l–1 kinetin with 0.5 mg l–1 GA3. 相似文献
15.
The effects of root applications of gibberellic acid (GA3) on growth and photosynthesis of 12 species of plants including C3 monocots (Triticum aestivum L., wheat, Hordeum vulgare L., barley and Avena sativa L., oat), C3 dicots (Vigna radiata L., mung bean, Cucurbita moschata L., squash and Capsicum annuum L., pepper), C4 monocots (Zea mays L., corn, Sorghum vulgare L., sorghum and Panicum ramosum L., millet) and C4 dicots (Amaranthus retroflexus L., pigweed, Kochia scoparis L., kochia and Gomphrena celosoides L., gomphrena) were evaluated. Relative growth rates (RGR) of barley, oat, squash, pepper, corn, sorghum, millet, pigweed and kochia were increased above the control by 12.7%, 9.9%, 11.3%, 10.7%, 19.2% 10.1%, 11.5%, 16.4% and 32.7% respectively, four days following optimum GA3 treatments. There was no effect of GA3 on RGR in wheat, mung bean, and gomphrena. Gibberellic acid decreased the chlorophyll content expressed on an area basis by 20.0%, 13.9%, 20.9%, 17.1%, 11.9% and 28.0% in barley, squash, pepper, sorghum, pigweed and kochia, respectively, while that of oat, wheat, mung bean, corn, millet and gomphrena remained unchanged. When photosynthetic rates were expressed per mg of chlorophyll, it showed that GA3 could stimulate photosynthesis in barley, squash, pepper, sorghum, millet, pigweed and kochia by 20.4%, 20.6%, 16.5%, 17.4%, 10.4%, 24.2%, and 29.4%; while there was no effect in oat, wheat, mung bean, corn and gomphrena. An increase in leaf blade area and/or length of sheath were observed in GA3 treated plants of oat, barley, mung bean, squash, pepper, corn, sorghum, millet and kochia. The transpiration rate remained unchanged following GA3 treatment in all 12 species.This work was supported in part by the Fair Funds administered by the Pennsylvania Department of Agriculture. Contribution No. 39, Department of Horticulture, The Pennsylvania State University. Authorized for publications as paper no. 6886 in the journal series of the Pennsylvania Agricultual Experiment Station.Research assistant and assistant professor respectively. 相似文献
16.
CO2 exchange were measured on pea seedlings (Pisum sativum L. var. Bördi) cultivated from seeds imbibed either in water (C-plants) or in gibberellic acid (GA3) at the concentration of 25 g/1 (GA-plants), and then grown under 17 W/m2 blue light (B-plants) or 11 W/m2 red light (R-plants).When measured under the same light conditions as during growth the net photosynthesis (APS) rate in B-plants was about twice higher than that in R-plants. Dark respiration (DR) rate was 70% higher in B- than in R-plants. Red light retarded the development of photosynthetic activity, but GA3 suppressed this effect. The hormone enhanced net photosynthesis and dark respiration to the same extent.When measured under saturating white light net photosynthesis rate of C-plants was also two times higher in B-plants than in R-plants. Growth conditions had only a slight effect on the APS of GA-plants under white light. APS rates of GA-plants grown under red light were higher under white light than those of C-plants, but lower than those of plants grown under blue light.We assume that blue light induced formation of plants that were adapted to higher light intensity: red light had an opposite effect, whereas gibberellic acid induced formation of plants that were adapted to medium light intensity. 相似文献
17.
以紫斑牡丹种子为试验材料,研究不同浓度的赤霉素(GA_3)处理对种子生根以及生根过程中营养物质、酶活性和内源激素水平变化的影响,为探讨紫斑牡丹种子萌发机制提供依据。结果表明:(1)GA_3处理能够促进种子生根,并以300 mg/L GA_3处理对种子生根效果最好,与对照相比可提前14.67 d生根,生根率可达71.00%。(2)与对照相比,GA_3处理可以在0~15 d时促进种子淀粉水解和可溶性糖的积累,并加速可溶性蛋白的消耗,在0~30 d促进过氧化物酶(POD)活性的提高,从而促进种子萌发生根。(3)在种子沙藏生根过程中,种子脱落酸(ABA)含量呈下降趋势,赤霉素(GA)、玉米素核苷(ZR)和吲哚乙酸(IAA)含量均表现出先上升后下降的趋势,与对照相比,GA_3处理可使种子GA、ZR和IAA的含量在沙藏前期明显上升,以解除种子休眠。研究发现,外源GA_3处理可以调控紫斑牡丹种子内源激素含量和POD活性的变化,促进营养物质转化,从而提前解除种子休眠使其萌发。 相似文献
18.
以1年生紫斑牡丹幼苗为试验材料,采用不同浓度(0、100、300、500 mg/L)赤霉素(GA_3)喷施叶片处理,通过透射电镜、扫描电镜、光学显微镜观察幼苗叶片解剖结构,光合仪测定幼苗光合参数并以酶联免疫吸附法测叶片内源激素含量,探究外源GA_3对紫斑牡丹幼苗叶片解剖结构、光合特性和内源激素水平的影响。结果表明:(1)低浓度GA_3处理的紫斑牡丹叶肉细胞增大,栅栏组织外层细胞中叶绿体数量增加,高浓度GA_3处理则与之相反;GA_3处理叶片的栅栏组织/海绵组织比值(P/S)、组织结构紧密度(CTR)均下降,而其组织结构疏松度(SR)增加;GA_3处理的幼苗叶片的叶肉细胞内各叶绿体大小显著大于对照,随着GA_3处理浓度增加,紫斑牡丹叶肉细胞内叶绿体的体积趋于增大,类囊体垛叠凝聚逐渐松散,叶绿体上淀粉颗粒在300 mg/L GA_3处理中较明显;叶片气孔长度、宽度、气孔器大小、气孔开度和气孔密度随着GA_3浓度升高先升高后下降,同时叶片上表皮角质层厚度随GA_3浓度的升高而增加。(2)紫斑牡丹叶片净光合速率(P_n)、气孔导度(Cond)、蒸腾速率(T_r)、水分利用率(WUE)在100和300 mg/L GA_3处理下大都显著高于对照,且300 mg/L GA_3处理显著高于其余处理,而其在500 mg/L GA_3处理下显著低于对照。(3)紫斑牡丹叶片脱落酸(ABA)和吲哚乙酸(IAA)含量均在500 mg/L GA_3下显著高于对照,而在其余浓度处理下不同程度低于对照,叶片内源玉米素核苷(ZR)和GA_3含量均在300 mg/L GA_3处理下显著高于其余处理和对照,而其余处理相比对照均无显著变化;叶片的ZR/ABA、ZR/IAA、ZR/GA_3和(IAA+GA_3+ZR)/ABA比值都在300 mg/L GA_3处理下显著高于其他处理,叶片的IAA/ABA和ABA/GA_3比值均在500 mg/L GA_3处理下显著高于其他处理。研究发现,适宜浓度外源GA_3处理,能显著提高紫斑牡丹幼苗叶片光合速率、水分利用效率及蒸腾速率,调节植物体内源激素的含量及平衡,从而使叶片能合成较多有机物,促进幼苗生长。 相似文献
19.
The development of a sensitive and specific enzyme immunoassay for GA3 is reported. This method was based on the use of peroxidase labelled GA3 and immobilized antibodies. In order to obtain a rapid immunoassay, several steps of purification were analyzed to show their necessity. Barley seed extracts were assayed at different steps of purification to exhibit the effect of extract components on the assay. It was demonstrated that HPLC had to be performed when a selective quantitation of GA3 was required. This assay allowed GA3 to be measured with reproducibility as its unmethylated form and the quantitation of GA3 in barley seeds with this enzyme immunoassay was correlated to a GC-MS method.Abbreviations GA3
gibberellin A3
- EIA
enzyme immunoassay
- DMF
dimethylformamide
- TEA
tri(n)ethylamine
- BSA
bovine serum albumin
- OVA
ovalbumine
- ECF
ethylchloroformate
- PB
phosphate buffer 相似文献
20.
Endogenous free IAA was examined with an immunohistochemical method for its involvement in the reduction of bud deterioration
after GA3 was injected into the bulbs. We found that tulip bulbs stored at 20°C constantly developed severe bud deterioration, whereas
the symptoms of deterioration was lighter in the bulbs with GA3 injection and not observed in the bulbs with 4°C treatment. 73% success in overcoming bud deterioration was achieved in 20°C
with GA3 treatment after 8 weeks of bulb storage, and the success rate was 7% after 12 weeks of storage. IAA was detected in the parenchyma
cells in the internodes of the shoot after the bulbs were stored at 4°C or at 20°C with GA3 injection for 4 weeks, but little was detected in the bulbs stored at 20°C constantly. Moreover, a weak IAA signal was present
in between the cells of the internodes irrespective of bulb treatment. After planting, the bulbs that had been treated differently
exhibited different flowering ability. The bulbs stored at 4°C for 4, 8 and 12 weeks attained high flowering percentage, which
was lower in the 20°C with GA3 treatment and lowest in the 20°C treatment. It may be concluded that GA3 injection decreases bud deterioration of tulip bulbs during dry storage at 20°C by promoting the endogenous IAA in the internodes. 相似文献