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Dramatic difference in the responses of phosphoenolpyruvate carboxylase to temperature in leaves of C3 and C4 plants

Author: Chinthapalli Bhaskarrao
Murmu Jhadeswar
Raghavendra Agepati S.
Publication venue: 'Oxford University Press (OUP)'
Publication date: 01/01/2003
Field of study

Temperature caused phenomenal modulation of phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) in leaf discs of Amaranthus hypochondriacus (NAD-ME type C4 species), compared to the pattern in Pisum sativum (a C3 plant). The optimal incubation temperature for PEPC in A. hypochondriacus (C4) was 45°C compared to 30°C in P. sativum (C3). A. hypochondriacus (C4) lost nearly 70% of PEPC activity on exposure to a low temperature of 15°C, compared to only about a 35% loss in the case of P. sativum (C3). Thus, the C4 enzyme was less sensitive to supra- optimal temperature and more sensitive to sub- optimal temperature than that of the C3 species. As the temperature was raised from 15°C to 50°C, there was a sharp decrease in malate sensitivity of PEPC. The extent of such a decrease in C4 plants (45%) was more than that in C3 species (30%). The maintenance of high enzyme activity at warm temperatures, together with a sharp decrease in the malate sensitivity of PEPC was also noticed in other C4 plants. The temperature-induced changes in PEPC of both A. hypochondriacus (C4) and P. sativum (C3) were reversible to a large extent. There was no difference in the extent of phosphorylation of PEPC in leaves of A. hypochondriacus on exposure to varying temperatures, unlike the marked increase in the phosphorylation of enzyme on illumination of the leaves. These results demonstrate that (i) there are marked differences in the temperature sensitivity of PEPC in C3 and C4 plants, (ii) the temperature induced changes are reversible, and (iii) these changes are not related to the phosphorylation state of the enzyme. The inclusion of PEG-6000, during the assay, dampened the modulation by temperature of malate sensitivity of PEPC in A. hypochondriacus. It is suggested that the variation in temperature may cause significant conformational changes in C4-PEPC

Protein difference among the leaf explants determined for shoot regeneration and callus growth in Mulberry (Morus indica L.)

Author: Chinthapalli Bhaskarrao
Chitra D.S. Vijaya
Padmaja G.
Publication venue: 'Scienceflora Publishers Pvt. Ltd.'
Publication date: 31/03/2017
Field of study

A comparison of protein profiles of leaves during different stages of shoot and callus induction showed similarities as well as differences in the expression of proteins.Â A protein of 39 kDa was expressed in low levels in leaf explants and increased in intensity during induction of shoot organogenesis in both the cultivars. Analysis of protein patterns during organogenesis and callus proliferation from leaves by two dimensional gel analysis revealed the separation of 39 kDa protein into four spots during organogenesis with pI values ranging from 4.2-5.8.Â However, the isoforms of 39 kDa protein with pI values of 4.2 and 5.8 were highly expressed in callus of M-5 cultivar in contrast to S-36 cultivar where only one isoform with pI value of 4.2 was detectable. The analysis of protein synthesis in different stages of development in the cultures may acts as markers to differentiate the group of specific isoforms

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Marked modulation by phosphate of phosphoenolpyruvate carboxylase in leaves of Amaranthus hypochondriacus, a NAD-ME type C4 plant: decrease in malate sensitivity but no change in the phosphorylation status

Author: Chinthapalli Bhaskarrao
Murmu Jhadeswar
Raghavendra Agepati S.
Publication venue: 'Oxford University Press (OUP)'
Publication date: 01/01/2003
Field of study

The effect of Pi on the properties of phosphoenolpyruvate carboxylase (PEPC) from Amaranthus hypochondriacus, a NAD-ME type C4 plant, was studied in leaf extracts as well as with purified protein. Efforts were also made to modulate the Pi status of the leaf by feeding leaves with either Pi or mannose. Inclusion of 30 mM Pi during the assay enhanced the enzyme activity in leaf extracts or of purified protein by >2-fold. The effect of Pi on the enzyme purified from dark-adapted leaves was more pronounced than that from light-adapted ones. The Ki for malate increased >2.3-fold and >1.9-fold by Pi in the enzyme purified from dark-adapted leaves and light-adapted leaves, respectively. Pi also induced an almost 50-60% increase in Km for PEP or Ka for glucose-6-phosphate. Feeding the leaves with Pi also increased the activity of PEPC in leaf extracts, while decreasing the malate sensitivity of the enzyme. On the other hand, Pi sequestering by mannose marginally decreased the activity, while markedly suppressing the light activation, of PEPC. There was no change in phosphorylation of PEPC in leaves of A. hypochondriacus due to the feeding of 30 mM Pi. However, feeding with mannose decreased the light-enhanced phosphorylation of PEPC. The marked decrease in malate sensitivity of PEPC with no change in phosphorylation state indicates that the changes induced by Pi are independent of the phosphorylation of PEPC. It is suggested here that Pi is an important factor in regulating PEPC in vivo and could also be used as a tool to analyse the properties of PEPC

A comparative study on field performance of micropropagated plants and stem cutting derived plants of S-36 cultivar of Mulberry (Morus indica L.)

Author: Chinthapalli Bhaskarrao
Chitra D S Vijaya
Padmaja G
Publication venue: 'Scienceflora Publishers Pvt. Ltd.'
Publication date: 10/02/2016
Field of study

Micropropagated and stem cutting derived plants of Mulberry (Morus indicaÂ L. cv. S-36) were transferred to the similar field conditions. A comparative study was conducted based on morphological parameters and growth characteristics for three consecutive years.Â The results demonstrated that micropropagation gave rise to superior clonal populations with respect to number of branches/plant and leaf yield/plant that will be suitable for the mass production of plants.Â Thus in vitro grown plants did not exhibit any significant quantitative variation as compared to the conventionally grown plants, indicating the varietal multiplication to be of true-to-type

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Cultivation of micro-algae for Production of Biodiesel: An optimized Process

Author: Chinthapalli Bhaskarrao
Chitra D. S. Vijaya
Demissie Abebe Girma
Tenaw Shumet
Publication venue: 'Scienceflora Publishers Pvt. Ltd.'
Publication date: 28/08/2016
Field of study

Microalgae are considered as one of the potential source of biodiesel for the future. The search to obtain the potential strains from the algal diversity capable of producing oil is critical for sustainable production of biodiesel. In the present study, microalgae biomass with oil/lipid accumulation capability and their morphological features was isolated from Lake Abaya and Chamo. The algal biomass was cultivated in vitro and media optimization for maximum biomass was done using different basal media, BG-11 medium, and Chu -10. In addition the various carbon sources, nitrogen sources, pH and temperature were considered in this study for optimization. Green algae Oedogonium, Chlorella and Cladophora species were observed to be dominant species and the maximum oil per dry algal biomass was found to be from Oedogonium sp. Thus from the present study for the cultivation of the selected algae, BG-11 medium supplemented with tryptone (0.2%) sucrose (2%) and pH- 6 with incubation temperature of 300C was found to be suitable.Â These results suggest that Oedogonium sp. has several desirable features that make it a potential candidate for biodiesel production

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Immunological characteristics of PEP carboxylase from leaves of C3, C4- and C3C4 intermediate species of Alternanthera - Comparison with selected C3 and C4- plants

Author: Chinthapalli Bhaskarrao
Gayathri J
Parvathi K
Raghavendra A S
Westhoff Peter
Publication venue: NISCAIR-CSIR, India
Publication date: 01/07/2001
Field of study

643-649Immunological cross-reactivity of phosphoenolpyruvate carboxylase (PEPC) in leaf ex tracts of C3-, C4- and C3-C4 intermediate species of Alternanthera (along with a few other C3- and C4- plants) was studied using anti-PEPC antibodies raised against PEPC of Amaranthus hypochondriacus (belonging to the same family as that of Altemanthera, namely Amaranthaceae) . Antibodies were also raised in rabbits against the purified PEPC from Zea mays (C4 - monocot - Poaceae) as well as Alternanthera pungens (C4 - dicot - Amaranthaceae). Monospecificity of PEPC-antiserum was confirmed by immunoprecipitation. Amount of PEPC protein in leaf extracts of A. hypochondriacus could be quantified by single radial immunodiffusion. Cros- reactivit y of PEPC in leaf extracts from selected C3-, C4-, and C3C4 intermediate species (including those of Alternanthera) was examined using Ouchterlony double diffusion and Western blots. Anti-PEPC anti serum raised against A. hypochondriacus enzyme showed high cross-reactivity with PEPC in leaf extracts of A. hvpochondriacus or Amaranthus viridis or Alternanthera pungens (all C4 dicots), but limited cross-reactivity with that of Zea mays, Sorghum or Pennisetum (all C4 monocots). Interestingly, PEPC in leaf extracts of AIternathera tenella. A. ficoides,. Parthenium hysterophorus (C3-C4 intermediates) exhibited stronger cross-reactivity (with anti-serum raised against PEPC from Amaranthus hypochondriacus) than that of Pisum sativum, Commelina benghalensis, Alternanthera sessilis (C3 plants). Further studies on cross-reactivities of PEPC in leaf ex tracts of these plants with anti-PEPC antisera raised against PEPC from leaves of Zea mays or Altemanthera pungens confirmed two points - (i) PEPC of C3-C4 intermediate is distinct from C3 species and intermediate between those of C3- and C4-species; and (ii) PEPC of C4-dicots was closer to that of C3species or C3C4 intermediates (dicots) than to that of C4-monocots. </span

NOPR

Phospho enol pyruvate carboxylase purified from leaves of C3, C4, and C3-C4 intermediate species of Alternanthera: properties at limiting and saturating bicarbonate

Author: Bläsing O.
Chinthapalli Bhaskarrao
Raghavan Chitra
Raghavendra A. S.
Westhoff P.
Publication venue: Springer
Publication date
Field of study

Phosphoenolpyruvate carboxylase (PEPC) was purified from leaves of four species of Alternanthera differing in their photosynthetic carbon metabolism: Alternanthera sessilis (C3), A. pungens (C4), A. ficoides and A. tenella (C3-C4 intermediates or C3-C4). The activity and properties of PEPC were examined at limiting (0.05 mM) or saturating (10 mM) bicarbonate concentrations. The Vmax as well as Km values (for Mg2+ or PEP) of PEPC from A. ficoides and A. tenella (C3-C4 intermediates) were in between those of C3 (A. sessilis) and C4 species (A. pungens). Similarly, the sensitivity of PEPC to malate (an inhibitor) or G-6-P (an activator) of A. ficoides and A. tenella (C3-C4) was also of intermediate status between those of C3 and C4 species of A. sessilis and A. pungens, respectively. In all the four species, the maximal activity (Vmax), affinity for PEP (Km), and the sensitivity to malate (KI) or G-6-P (KA) of PEPC were higher at 10 mM bicarbonate than at 0.05 mM bicarbonate. Again, the sensitivity to bicarbonate of PEPC from C3-C4 intermediates was in between those of C3- and C4-species. Thus the characteristics of PEPC of C3-C4 intermediate species of Alternanthera are intermediate between C3- and C4-type, in both their kinetic and regulatory properties. Bicarbonate could be an important modulator of PEPC, particularly in C4 plants

Dramatic difference in the responses of phosphoenolpyruvate carboxylase to temperature in leaves of C<SUB>3</SUB> and C<SUB>4</SUB> plants

Protein difference among the leaf explants determined for shoot regeneration and callus growth in Mulberry (Morus indica L.)

Marked modulation by phosphate of phosphoenolpyruvate carboxylase in leaves of Amaranthus hypochondriacus, a NAD-ME type C<SUB>4</SUB> plant: decrease in malate sensitivity but no change in the phosphorylation status

A comparative study on field performance of micropropagated plants and stem cutting derived plants of S-36 cultivar of Mulberry (Morus indica L.)

Cultivation of micro-algae for Production of Biodiesel: An optimized Process

Phospho enol pyruvate carboxylase purified from leaves of C<SUB>3</SUB>, C<SUB>4</SUB>, and C<SUB>3</SUB>-C<SUB>4</SUB> intermediate species of Alternanthera: properties at limiting and saturating bicarbonate