Journal of Heredity Advance Access published online on April 13, 2006
Journal of Heredity, doi:10.1093/jhered/esj031
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 From the Department of Biology, 1205 Noyce Science Center, Grinnell College, 1116 8th Avenue, Grinnell, IA 50112
* To whom correspondence should be addressed. Aspergillus niger is an asexual, haploid fungus which infects the seeds of Namibia's national plant, Welwitschia mirabilis, severely affecting plant viability. We used 31 randomly amplified polymorphic DNA markers to assess genetic variation among 89 A. niger isolates collected from three W. mirabilis populations in the Namib Desert. While all isolates belonged to the same vegetative compatibility group, 84% were unique genotypes, and estimates of genotypic evenness and Simpson's index of diversity approached 1.0 in the three populations. Analysis of molecular variance revealed that 78% of the total variation sampled was among isolates from individual W. mirabilis plants. Lower, but significant, amounts of variation detected among isolates from different plants (12%) and different sites (10%) also indicated some site- and plant-level genetic differentiation. Total gene diversity (HT = 0.264) was mostly attributable to diversity within populations (HS = 0.217); the relatively low level of genetic differentiation among the sites (GST = 0.141) suggests that gene flow is occurring among the three distant sites. Although sexual reproduction has never been observed in this fungus, parasexuality is a well-known phenomenon in laboratory strains. We thus attribute the high levels of genetic variation to parasexuality and/or wind-facilitated gene flow from an as of yet undocumented broader host range of the fungus on other desert vegetation. Given the apparent ease of transmission, high levels of genetic diversity, and potentially broad host range, A. niger infections of W. mirabilis may be extremely difficult to control or prevent.
Received July 18, 2005
Accepted February 7, 2006
Article
High Levels of Genetic Variation Exist in Aspergillus niger Populations Infecting Welwitschia mirabilis Hook
Elizabeth Pekarek 1,
Kathryn Jacobson 1 *,
and
Anna Donovan 1
Kathryn Jacobson, E-mail: jacobsok{at}grinnell.edu
Abstract 
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  B. C. Lamb, S. Mandaokar, B. Bahsoun, I. Grishkan, and E. Nevo Differences in spontaneous mutation frequencies as a function of environmental stress in soil fungi at "Evolution Canyon," Israel PNAS, April 15, 2008; 105(15): 5792 - 5796. [Abstract] [Full Text] [PDF]
|
|