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Appl. Environ. Microbiol., 07 1995, 2659-2664, Vol 61, No. 7
ZL Liu, LL Domier and JB Sinclair
DNA polymorphism in the 18S nuclear rRNA gene region was investigated by
using 11 restriction endonucleases for 161 isolates of 25 intraspecific
groups (ISGs) representing 11 reported anastomosis groups (AGs) of
Rhizoctonia solani. A PCR-based restriction mapping method in which
enzymatically amplified DNA fragments and subfragments were digested with
one or two restriction enzymes was employed. Four types of DNA restriction
maps of this region were constructed for these 25 ISGs. Map type I of the
18S rDNA region was represented by isolates of a majority of R. solani
ISGs. Map types II and III, represented by ISG 2E and 9 isolates and 5C
isolates, respectively, differed from map I by the absence of one (map type
II) or two (map type III) restriction sites. Map type IV, represented by
ISG 10A and B (or AG 10) isolates, showed significant restriction site
variations, with five enzymes in this region compared with those of the
remaining ISGs or AGs. Ten of the 25 restriction sites in the 18S rRNA gene
region were informative and selected for analysis. Previously reported
restriction maps of the 5.8S rRNA gene region, including the internal
transcribed spacers, were aligned with each other, and 12 informative
restriction sites were identified. These data were used alone and in
combination to evaluate group relationships. Analyses derived from these
data sets by maximum parsimony and likelihood methods showed that AG 10
isolates were distinct and distantly related to the majority isolates of
the other AGs of this species complex.
Copyright © 1995, American Society for Microbiology
Polymorphism of genes coding for nuclear 18S rRNA indicates genetic distinctiveness of anastomosis group 10 from other groups in the Rhizoctonia solani species complex
Department of Food Science, University of Illinois at Urbana-Champaign 61801, USA.
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