Complete genetic linkage maps from an interspecific cross between Fusarium circinatum and Fusarium subglutinans
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Figure 2. Linkage group 12. Markers are indicated to the right and distances between markers to the left of the linkage group. The markers in each linkage group have been ordered and arranged to determine their most probable position along the linkage group. |
Fusarium circinatum and Fusarium subglutinans belong to a group of fungi that includes a large number of plant pathogens of agricultural crops and trees. These two species belong to the Gibberella fujikuroi complex which is the sexual stage associated with strains of Fusarium. Fusarium circinatum is one of the most important pathogens of pines (Figure 1), that has caused serious damage to trees in plantations as well as in natural ecosystems. Fusarium subglutinans is a pathogenof maize. An intriguing characteristic of these two fungi is that it has been possible to make a sexual cross between these two species. Such an interspecific cross between two fungi with different hosts and other ecological features has presented an opportunity to generate a linkage map for this interspecific cross (De Vos et al., 2007).
In this study, genetic linkage maps were compiled to study the order and arrangement of markers or genes along the chromosomes (Figure 2). If two markers/genes are co-inherited, we can assume that these are on the same chromosome (the markers/genes are said to be linked). If these are linked we can also determine the genetic distance separating the linked genes. This is the first map to have ever been produced for a fungus in South Africa.
The study resulted in 12 linkage groups being identified, which corresponds to the number of chromosomes found in F. subglutinans. In Fusarium, progeny (Figure 3) are expected to receive genes/markers from the male (F. subglutinans) and female (F. circinatum) parent with equal likelihood. We observed a clear bias to F. subglutinans genes/markers being preferentially inherited in the progeny. This map has already aided in understanding Fusarium genetics and it will allow for subsequent studies on the virulence in the two parental genomes.
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References
De Vos, L., Myburg, A.A., Wingfield. M.J., Desjardins, A.E., Gordon, T.R. & Wingfield, B.D. 2007. Complete genetic linkage maps from an interspecific between Fusarium circinatum and Fusarium subglutinans. Fungal Genetics and Biology, doi: 10.1016/j.fgb.2007.02.007.
