Genotypic properties of the entomopathogenic fungus Nomuraea rileyi

The dimorphic entomopathogenic fungus Nomuraea rileyi, an important biologi cal control agent of various noctuid defoliators, is known to regulate Anti carsia gemmatalis, the key soybean pest in South America and the southeaste rn United States. At present, very little is known about the isolates that are associated with the endemic or epizootic phases of this disease agent. The development of molecular markers capable of delineating N. rileyi patho types is essential for such an analysis. In this study, various molecular t echniques, including internal transcribed spacer (ITS) sequence analysis, r andomly amplified polymorphic DNA (RAPD), amplified fragment length polymor phism (AFLP), and telomeric fingerprinting methods, were employed to identi fy genotypes. Analysis of the ITS-5.8s and 28s regions of N. rileyi isolate s suggested that this species was more closely related to Metarhizium aniso pliae and M. flavoviride than to Nomuraea atypicola and N. anemonoides. The se findings and comparisons with other studies suggest that the systematics of the genus Nomuraea needs reexamination. Analysis of the telomeric finge rprinting, RAPD, and AFLP data produced very similar associations among dif ferent Nomuraea. In all cases, the non-rileyi isolates (N. anemonoides and N. atypicola) appeared unrelated to the N. rileyi. The N. rileyi isolates, mainly isolated from A. gemmatalis, were grouped into two clusters: one con tained the Florida isolates and the other consisted of a diffuse group of S outh American isolates. Calculated genetic distances among the different N. rileyi isolates corresponded to geographical isolation. (C) 2000 Academic Press.