Catalase overexpression reduces the germination time and increases the pathogenicity of the fungus Metarhizium anisopliae |
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Authors: | Claudia Erika Morales Hernandez Israel Enrique Padilla Guerrero Gloria Angelica Gonzalez Hernandez Eduardo Salazar Solis Juan Carlos Torres Guzman |
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Institution: | (1) Department of Biology, University of Guanajuato, Noria Alta s/n, Col. Noria Alta, Guanajuato, Guanajuato, CP. 36050, Mexico;(2) Department of Agronomy, University of Guanajuato, Guanajuato, Mexico; |
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Abstract: | Catalases and peroxidases are the most important enzymes that degrade hydrogen peroxide into water and oxygen. These enzymes
and superoxide dismutase are the first lines of cell defense against reactive oxygen species. Metarhizium anisopliae displays an increase in catalase–peroxidase activity during germination and growth. To determine the importance of catalase
during the invasion process of M. anisopliae, we isolated the cat1 gene. cat1 cDNA expression in Escherichia coli and the subsequent purification of the protein confirmed that the cat1 gene codes for a monofunctional catalase. Expression analysis of this gene by RT-PCR from RNA isolated from fungus grown
in liquid cultures showed a decrease in the expression level of the cat1 gene during germination and an increase during mycelium growth. The expression of this gene in the fungus during the infection
process of the larvae of Plutella xylostella also showed a significant increase during invasive growth. Transgenic strains overexpressing the cat1 gene had twice the catalase activity of the wild-type strain. This increase in catalase activity was accompanied by a higher
level of resistance to exogenous hydrogen peroxide and a reduction in the germination time. This improvement was also observed
during the infection of P. xylostella larvae. M. anisopliae transgenic strains overexpressing the cat1 gene grew and spread faster in the soft tissue of the insect, reducing the time to death of the insect by 25% and the dose
required to kill 50% of the population 14-fold. |
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