Carbonic anhydrase in Tectona grandis: Kinetics, stability, isozyme analysis and relationship with photosynthesis

Genetics and Plant Propagation Division, Tropical Forest Research Institute, P.O.- R.F.R.C., Jabalpur 482 021 (M.P.), India.
Tree Physiology (Impact Factor: 3.66). 09/2006; 26(8):1067-73. DOI: 10.1093/treephys/26.8.1067
Source: PubMed


Carbonic anhydrase (CA, EC: activity in teak (Tectona grandis L.f.) was studied to determine its characteristics, kinetics and isozyme patterns. We also investigated effects of leaf age,
plant age and genotype on CA activity and gas exchange parameters. Carbonic anhydrase extracted from leaves in 12 mM veronal
buffer, pH 7.8, had a Km for CO2 of 15.20 mM and a Vmax of 35,448 U mg−1 chlorophyll min−1, which values declined by 50 and 70%, respectively, after 1 week of storage at 4 °C. A 15% native polyacrylamide gel revealed
the absence of CA isozymes in teak, with only a single CA band of 45 kD molecular mass observed across 10 segregating half-sib
families and groups of trees ranging in age from 10 to 25 years. Activity remained stable during the first month in storage
at 0 °C, but gradually declined to 25% of the initial value after 1 year in storage. During the period of active growth (February–May),
maximal CA activity was observed in fully expanded and illuminated leaves. Significant variation was observed in CA activity
across 10 1-year-old half-sib families and 21 5-year-old half-sib families. There was a positive correlation between CA activity
and photosynthetic rate in a population of 10-year-old trees (P < 0.005). Positive correlations between CA activity and photosynthetic rate were found in 10 of 21 5-year-old half-sib families
(P < 0.005 to P < 0.05), which showed greater diversity in CA activity than in photosynthetic characteristics. Thus, CA may serve as a biochemical
marker for photosynthetic capacity in teak genotypes.

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Available from: Shamim Akhtar Ansari, Dec 19, 2013
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    • "Present investigation was carried out to persuade the finding of Tiwari et al (2006) at gene level, where the CA isozymes of the species were found identical to those reported in the monocots. In molecular phylogeny based classification (Angiosperm Phylogeny Group 2009) the species is categorised under family 'Lamiaceae' (mint family) and earlier it was considered under family 'Verbenaceae'. "
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    DESCRIPTION: Carbonic anhydrase (CA) is a ubiquitous enzyme and is widely distributed among prokaryotes and eukaryotes. It catalyzes the reaction: CO2+H2O = HCO3– + H+. The enzyme represents 1–2% of the total soluble protein in leaves of C3 plants, second only to Rubisco in concentration and it is also reported as biochemical marker to detect isozyme variation in Indian teak (Tectona grandis L. f.). In present investigation fifteen individual of Indian teak plus trees were assessed for cross amplification by the nineteen EST (Expressed sequence tags) primers designed from DNA sequences encoding carbonic anhydrase enzyme in four model plant species viz., Arabidopsis thaliana (dicot), Nicotiana tabacum (dicot), Zea mays (monocot) and Oryza sativa (monocot). Twelve out of nineteen primers were resulted the highest polymorphic bands and those all belong to monocotyledon plants (Zea mays and Oryza sativa). It reveals that the genes encoding carbonic anhydrase in Indian teak is identical to the sequences found in monocotyledon model plants.
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    • "Generally, increased stomatal and intracellular limitations may efficiently affect a secondary limitation on photosynthetic induction by decreasing the rate of Rubisco activation as a result of a low CO 2 diffusion rate into the chloroplasts (Valladares et al. 1997, Allen and Pearcy 2000b). An alternative hypothesis is that slower Rubisco activation in mature leaves is caused by decreased activity of carbonic anhydrase, which catalyzes the conversion between HCO 3 − and CO 2 , with leaf age, as has been shown for two genotypes of Triticum (Rengel 1995) and for Tectona grandis L. f. (Tiwari et al. 2006). "
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    ABSTRACT: We tested the hypothesis that leaf age affects photosynthetic induction, because conductance to CO2 diffusion usually decreases with increasing leaf age. Photosynthetic inductions, primarily determined by the light modulation of Rubisco activity and stomatal opening, were investigated in both young and mature leaves, as defined by leaf plastochron index (LPI), from three poplar clones: Populus alba L., P. nigra L. and P. x euramericana (Dode) Guinier. In all clones, maximum assimilation rates (A max), maximum stomatal conductance (G Smax) and dark respiration rates (RD) were higher in young leaves (LPI = 3-5) than in mature leaves (LPI = 10-14), and A max decreased from P. alba via P. x euramericana to P. nigra. The clones with high photosynthetic capacity had low induction states 60 s after leaf illumination (IS60; indicating a slow initial induction phase), and required less time to reach 90% photosynthetic induction (T90). In contrast, the clone with the lowest photosynthetic capacity (P. nigra) exhibited high IS60 (high initial induction state) but a long induction time (high T90). A comparison of mature leaves with young leaves revealed significantly (P < 0.01) lower IS60 values in mature leaves of P. nigra only, and significantly higher T90 values in mature leaves of P. alba only. In all clones, young leaves exhibited a lower percentage of maximum transient stomatal limitation during photosynthetic induction (4-9%) compared with mature leaves (16-30%). Transient biochemical limitation, assessed on the basis of the time constants of Rubisco activation (tau), was significantly higher in mature leaves than in young leaves of P. alba; whereas there were no significant differences in tau between young and mature leaves of the other poplar clones. Thus, our hypothesis that leaf age affects photosynthetic induction was confirmed at the level of transient stomatal limitation, which was significantly higher in mature leaves than in young leaves in all clones. For the induction parameters IS60, T90 and tau, photosynthetic induction was more clone-specific and was dependent on leaf age only in some cases, an observation that may apply to other tree species.
    Tree Physiology 08/2008; 28(8):1189-97. DOI:10.1093/treephys/28.8.1189 · 3.66 Impact Factor
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    • " modification of carbonic anhydrase activity in transgenic plants revealed some ( about 25% ) or no change in gm and photosynthesis ( Price et al . 1994 ; Williams , Flanagan & Coleman 1996a ) , and regression analysis showed only a modest correlation between carbonic anhydrase activity and photosynthesis in different families of Tectona grandis ( Tiwari et al . 2006 ) . An explanation was provided by Gillon & Yakir ( 2000 ) , who showed that the relative contribution of carbonic anhydrase to the overall gm is species depen - dent . They suggested that carbonic anhydrase - mediated CO2 diffusion may be more important when gm is low because of structural properties of the leaves , as is the case for "
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    ABSTRACT: During photosynthesis, CO2 moves from the atmosphere (C(a)) surrounding the leaf to the sub-stomatal internal cavities (C(i)) through stomata, and from there to the site of carboxylation inside the chloroplast stroma (C(c)) through the leaf mesophyll. The latter CO2 diffusion component is called mesophyll conductance (g(m)), and can be divided in at least three components, that is, conductance through intercellular air spaces (g(ias)), through cell wall (g(w)) and through the liquid phase inside cells (g(liq)). A large body of evidence has accumulated in the past two decades indicating that g(m) is sufficiently small as to significantly decrease C(c) relative to C(i), therefore limiting photosynthesis. Moreover, g(m) is not constant, and it changes among species and in response to environmental factors. In addition, there is now evidence that g(liq) and, in some cases, g(w), are the main determinants of g(m). Mesophyll conductance is very dynamic, changing in response to environmental variables as rapid or even faster than stomatal conductance (i.e. within seconds to minutes). A revision of current knowledge on g(m) is presented. Firstly, a historical perspective is given, highlighting the founding works and methods, followed by a re-examination of the range of variation of g(m) among plant species and functional groups, and a revision of the responses of g(m) to different external (biotic and abiotic) and internal (developmental, structural and metabolic) factors. The possible physiological bases for g(m), including aquaporins and carbonic anhydrases, are discussed. Possible ecological implications for variable g(m) are indicated, and the errors induced by neglecting g(m) when interpreting photosynthesis and carbon isotope discrimination models are highlighted. Finally, a series of research priorities for the near future are proposed.
    Plant Cell and Environment 06/2008; 31(5):602-21. DOI:10.1111/j.1365-3040.2007.01757.x · 6.96 Impact Factor
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