© 2006 Heron Publishing—Victoria, Canada
Carbonic anhydrase in Tectona grandis: kinetics, stability, isozyme analysis and relationship with photosynthesis
Anita Tiwari (1), Pramod Kumar (1), Pravin H. Chawhaan (1), Sanjay Singh (1) and S. A. Ansari (1, 2)
1. Genetics and Plant Propagation Division, Tropical Forest Research Institute, P.O.- R.F.R.C., Jabalpur 482 021 (M.P.), India / 2. Corresponding author (shamimansari_1@yahoo.co.uk) / Received June 20, 2005; accepted November 11, 2005; published online May 1, 2006
Summary
Carbonic anhydrase (CA, EC: 4.2.1.1) 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.
Keywords:
biochemical marker, carbon sequestration, extraction buffer, half-sib families, Km, population, storage, tree age, Vmax.
