ABSTRACT
Isolates of entomopathogenic fungus Metarhizium anisopliae var. anisopliae were characterized using internal transcribed spacer-RFLP, ISSR and intron splice site primers. Thirty-seven isolates were studied, most of which were obtained from the sugar cane pest, Mahanarva fimbriolata (Hemiptera: Cercopidae) from Tangará da Serra, Southwest Mato Grosso State, Brazil. Internal transcribed spacer-RFLP did not differentiate the isolates of M. anisopliae var. anisopliae, while ISSR and intron primers identified three distinct groups. Variability among these groups was 96% for (GTG)(5) and 100% for the other primers. We found considerable genetic variability, even among isolates from the same geographical origin and host.
Subject(s)
Hypocreales/genetics , Polymorphism, Genetic , DNA Primers , DNA, Fungal/genetics , Genetic Variation , Introns , Microsatellite Repeats , Polymorphism, Restriction Fragment Length , RNA Splice SitesABSTRACT
Expression analysis of the genes involved in germination, conidiogenisis and pathogenesis of Metarhizium anisopliae during its saprophytic and pathogenic life stages can help plan strategies to increase its efficacy as a biological control agent. We quantified relative expression levels of the nitrogen response regulator gene (nrr1) and a G-protein regulator of genes involved in conidiogenesis (cag8), using an RT-qPCR assay. Comparisons were made between M. anisopliae var. anisopliae and M. anisopliae var. acridum during germination and conidiogenesis and at different stages of pathogenesis. The cag8 gene was repressed during germination and induced during conidial development and the pathogenic phase, and the nrr1 gene was induced during germination, conidiogenesis and the pathogenic phase. Both genes were more expressed in M. anisopliae var. anisopliae, demonstrating that different varieties of M. anisopliae differ in activation of genes linked to virulence for certain environments and hosts. This suggests that differences among these varieties in the ability to adapt could be attributed not only to specific genomic regions and genes, but also to differential gene expression in this fungus, modulating its ability to respond to environmental stimuli.
