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Published on: July 30, 2017
Correlation between Pr1 and Pr2 gene content and virulence in Metarhizium anisopliae strains
Ninfa M Rosas-García1, Osvaldo Avalos-de-León, Jesús M Villegas-Mendoza
1Laboratorio de Biotecnología Ambiental, Centro de Biotecnología Genómica-Instituto Politécnico Nacional, Reynosa 88710, México.
Abstract:
Metarhizium anisopliae is a widely studied model to understand the virulence factors that participate in pathogenicity. Proteases such as subtilisin-like enzymes (Pr1) and trypsin-like enzymes (Pr2) are considered important factors for insect cuticle degradation. In four M. anisopliae strains (798, 6342, 6345, and 6347), the presence of pr1 and pr2 genes, as well as the enzymatic activity of these genes, was correlated with their virulence against two different insect pests. The 11 pr1 genes (A, B, C, D, E, F, G, H, I, J, and K) and pr2 gene were found in all strains. The activity of individual Pr1 and Pr2 proteases exhibited variation in time (24, 48, 72, and 96 h) and in the presence or absence of chitin as the inductor. The highest Pr1 enzymatic activity was shown by strain 798 at 48 h with chitin. The highest Pr2 enzymatic activity was exhibited by the 6342 and 6347 strains, both grown with chitin at 24 and 48 h, respectively. Highest mortality on S. exigua was caused by strain 6342 at 48 h, and strains 6342, 6345, and 6347 caused the highest mortality 7 days later. Mortality on Prosapia reached 30% without variation. The presence of subtilisin and trypsin genes and the activity of these proteases in M. anisopliae strains cannot be associated with the virulence against the two insect pests. Probably, subtilisin and trypsin enzyme production is not a vital factor for pathogenicity, but its contribution is important to the pathogenicity process.
Insights
Metarhizium anisopliae proteases (Pr1 and Pr2) were studied for insect pathogenicity. Their presence and activity did not directly correlate with virulence against pests, suggesting other factors are more critical.
Area of Science:
- Mycology
- Insect Pathology
- Biochemistry
Background:
- Metarhizium anisopliae is a model organism for studying fungal pathogenicity.
- Proteases, specifically subtilisin-like (Pr1) and trypsin-like (Pr2) enzymes, are implicated in degrading insect cuticles.
Purpose of the Study:
- To investigate the correlation between the presence and enzymatic activity of pr1 and pr2 genes in Metarhizium anisopliae strains and their virulence against insect pests.
- To determine the role of subtilisin and trypsin proteases in the pathogenicity of M. anisopliae.
Main Methods:
- Analysis of pr1 and pr2 gene presence in four M. anisopliae strains (798, 6342, 6345, 6347).
- Measurement of Pr1 and Pr2 enzymatic activity over time (24-96h) with and without chitin induction.
- Assessment of M. anisopliae virulence by measuring insect mortality (Spodoptera exigua and Prosapia spp.).
Main Results:
- All four M. anisopliae strains possessed all 11 pr1 genes and the pr2 gene.
- Enzymatic activity of Pr1 and Pr2 varied significantly based on time and chitin presence.
- Strain 6342 showed highest mortality against S. exigua, while strains 6342, 6345, and 6347 were most effective after 7 days. Mortality on Prosapia was consistently around 30%.
Conclusions:
- The presence of subtilisin and trypsin genes and their enzymatic activity in M. anisopliae strains are not directly associated with virulence against the tested insect pests.
- Subtilisin and trypsin production may not be a vital factor for M. anisopliae pathogenicity but likely contributes to the overall process.
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