Chromosome Size Polymorphism in<i>Leptosphaeria maculans</i>

Abstract

Chromosome size polymorphism among nine isolates of Leptosphaeria maculans was studied by hybridization of homologous and heterologous DNA fragments to chromosomes separated by contour-clamped homogeneous electric field (CHEF) electrophoresis. Four of the fungal isolates were highly virulent and three were weakly virulent in Brassica plants; the remaining two originated from the cruciferous weed Thlaspi arvense. There was a high degree of chromosome size polymorphism, and no two isolates had the same karyotype. However, three general patterns could be distinguished by differences in size range, distribution of bands within the size ranges, and hybridization to probes. These three banding patterns corresponded to the three pathogenicity groups []