Electrophoretic Karyotype of the Obligate Biotrophic Parasite Plasmodiophora brassicae Wor.

Abstract

Classical genetic analysis is not possible with the protist Plasmodiophora brassicae due to the intracellular life of this obligate biotrophic parasite. An electrophoretic karyotype has been obtained using contour‐clamped homogeneous electric field gel electrophoresis to facilitate gene mapping of P. brassicae. Using two different separation conditions 16 chromosomal bands of P. brassicae were distinguished ranging in approximate size from 2.2 Mb to 680 kb. According to this determination of chromosome number and size, the total genome size of P. brassicae was estimated to be 20.3 Mb. The chromosomal bands were further designated by their hybridization pattern with repetitive elements of P. brassicae. The repetitive element H4 (1800 bp) hybridized with 14 chromosomal bands, but the sequence of H4 showed no homology to known centromere or telomere structures and revealed no repetitive motifs.

Characterization of a Single‐Spore Isolate Population of Plasmodiophora brassicae Resulting from a Single Club

“…(2003). These repetitive fragments were selected from a partial genomic library of P. brassicae and localized on 14, 8, and 5 chromosomal bands, respectively (Klewer et al., 2001, Graf et al., 2001). DNA fragments were labelled with the DIG system using Random Primed Oligolabeling kit (Roche Diagnostics, Mannheim, Germany) following the manufacturer's instructions.…”

“…PCR analysis using primers for the repetitive fragment H4 was performed according to Graf et al. (2001).…”

“…Pulsed field electrophoresis for separation of Plasmodiophora chromosomes and visualization of the chromosomal bands by Southern analysis using the Plasmodiophora ‐specific repetitive element H4 () and the fragment Tsu_19 () were performed according to Graf et al. (2001).…”

“…Open arrows indicate differences in size or hybridization. Designation by roman numbers and the corresponding size of the chromosomes (in kb) are given for isolate ‘e 3 ’ according to Graf et al (2001)…”

“… a These plants only showed weak root swellings. In these plants the pathogen can be detected by PCR using primers for the repetitive element H4 according to Graf et al. (2001), but they were not included in further analysis due to lack of material. …”