Antifungal and peroxidative activities of nonheme chloroperoxidase in relation to transgenic plant protection.
J Agric Food Chem
; 48(10): 4561-4, 2000 Oct.
Article
en En
| MEDLINE
| ID: mdl-11052700
Nonheme chloroperoxidase (CPO-P) of Pseudomonas pyrrocinia catalyzes the oxidation of alkyl acids to peracids by hydrogen peroxide. Alkyl peracids possess potent antifungal activity as found with peracetate: 50% killing (LD(50)) of Aspergillus flavus occurred at 25 microM compared to 3.0 mM for the hydrogen peroxide substrate. To evaluate whether CPO-P could protect plants from fungal infection, tobacco was transformed with a gene for CPO-P from P. pyrrocinia and assayed for antifungal activity. Leaf extracts from transformed plants inhibited growth of A. flavus by up to 100%, and levels of inhibition were quantitatively correlated to the amounts of CPO-P activity expressed in leaves. To clarify if the peroxidative activity of CPO-P could be the basis for the increased resistance, the antifungal activity of the purified enzyme was investigated. The LD(50) of hydrogen peroxide combined with CPO-P occurred at 2.0 mM against A. flavus. Because this value was too small to account for the enhanced antifungal activity of transgenic plants, the kinetics of the enzyme reaction was examined and it was found that the concentration of hydrogen peroxide needed for enzyme saturation (K(m) = 5.9 mM) was already lethal. Thus, the peroxidative activity of CPO-P is not the basis for antifungal activity or enhanced resistance in transgenic plants expressing the gene.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Enfermedades de las Plantas
/
Cloruro Peroxidasa
/
Plantas Modificadas Genéticamente
/
Antifúngicos
Idioma:
En
Revista:
J Agric Food Chem
Año:
2000
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos