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Kinetic properties of cell wall bound superoxide dismutase in leaves of wheat (<i>Triticum aestivum</i> L.) following stripe rust (<i>Puccinia striiformis</i>) infection

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Title Kinetic properties of cell wall bound superoxide dismutase in leaves of wheat (Triticum aestivum L.) following stripe rust (Puccinia striiformis) infection
 
Creator Asthir, Bavita
Koundal, A
Bains, N S
 
Subject Puccinia striiformis
Superoxide dismutase
Thermodynamic properties
Triticum aestivum
 
Description 341-345
Stripe
rust (Puccinia striiformis f.sp. tritici) is the most devastating
disease of wheat (Triticum aestivum L.) accounting huge economical
losses to the industry worldwide. HD 2329 was a widely grown wheat cultivar
which had become highly susceptible to stripe rust and was used to understand
the biochemical aspects of the host pathogen interaction through
characterization of superoxide dismutase (SOD). In the present study, two types
of SOD, ionically or covalently bound to the particulate fraction were found in
the stripe rust infected and uninfected wheat leaves of susceptible
cultivar HD 2329. Cell walls of leaves contained a high level of SOD, of which
41-44% was extractable by 2 M NaCl and 10-13% by 0.5% EDTA in infected and
uninfected leaves. The NaCl-released SOD constituted the predominant fraction.
It exhibited maximum activity at pH 9.0, had a Km value of
1.82-2.51 for uninfected and 1.77-2.37 mM for infected, respectively with
pyrogallol as the substrate, and a Vmax of 9.55-21.4 and
12.4-24.1 A min-1g-1FW. A temperature optimum of 20oC
was observed for SOD of both uninfected and infected leaves. SOD showed
differential response to metal ions, suggesting their distinctive nature.
Inhibition of wall bound SOD by iodine and its partial regeneration of activity
by mercaptoethanol suggested the involvement of cysteine in active site
of the enzyme. These two forms showed greater differences with respect to
thermodynamic properties like energy of activation (Ea) and enthalpy
change (H), while entropy change (S) and free energy change (G) were
similar. The results further showed that pathogen infection of the leaves of
susceptible wheat cultivar induced a decrease in the SOD activity and kinetics
which might be critical during the response of plant cells to the infection.
 
Date 2011-10-21T11:04:05Z
2011-10-21T11:04:05Z
2011-10
 
Type Article
 
Identifier 0975-0959 (Online); 0301-1208 (Print)
http://hdl.handle.net/123456789/12943
 
Language en_US
 
Rights CC Attribution-Noncommercial-No Derivative Works 2.5 India
 
Publisher NISCAIR-CSIR, India
 
Source IJBB Vol.48(5) [October 2011]