Molecular analysis and mapping of two genes encoding maize glutathione S-transferases (GST I and GST II).

Maize glutathione S-transferase (GST) isozymes are encoded by a gene family comprising at least five genes, three of which (Gst I, II and III) have recently been isolated and sequenced. The enzymes are active as homo or heterodimers and exhibit intraspecific polymorphism including a "null" variant for the two major isoforms expressed in roots. Northern blot analyses performed on total root RNA from "null" and "plus" genotypes, using Gst I- and Gst II-specific probes, indicated that the Gst I gene controls the expression of the two major GST isoforms expressed in roots. Gst I and Gst II were mapped by RFLP analysis using an F2 population of 149 individuals previously characterized. Gst I was localized on the long arm of chromosome 8, while two putative Gst II loci were mapped to chromosome 8 (70 cM from Gst I) and 10, respectively.