Figure 2.

Location of polymorphisms in rDNA of alder Phytophthora isolates. (a) Arrangement within a single repeat of an rRNA gene (rDNA) of the rRNA subunits and spacer regions (ETS, external transcribed spacer; ITS1 and ITS2, internal transcribed spacers; IGS, intergenic spacer; 18S, 5.8S, 28S, and 5S subunits). (b) Arrangement of polymorphic sites within the 831-bp region covering the ITS1 spacer, the 5.8S subunit, and ITS2 spacer: the 5′ end of ITS1 spacer sequence has been designated as 1, and all other sites are numbered accordingly. At dimorphic sites (shaded regions) both bases are shown and boxed. Numbers alongside the boxes refer to the numbers of cloned PCR products containing these bases at these sites; totals for all three standard alder isolates are also shown. Along the bottom are the restriction enzymes used to examine each of the dimorphic sites.