Genomic clones of a wild‐type allele and a transposable element‐induced mutant allele of the sucrose synthase gene of Zea mays L

In an attempt to isolate the transposable genetic element Ds from Zea mays L., we cloned DNA fragments hybridizing to a cDNA clone derived from the sucrose synthase gene in a λ vector (λ::Zm Sh). The fragments cloned from wild‐type and from the Ds‐induced mutant sh‐m5933 (λ::Zm sh‐m5933) share a segment 6 kb long while a contiguous segment of 15 kb of λ::Zm sh‐m5933 (mutant‐derived DNA) does not hybridize to the DNA segment cloned from the wild‐type. Restriction maps are given, and the junction point between the two DNA segments in the mutant clone was determined. Hybridization of DNA fragments, present in the wild‐type DNA of λ::Zm Sh, but not in the mutant clone, λ::Zm sh‐m5933, to genomic DNA of sh‐m5933 showed that no part of this DNA is deleted. It cannot be said whether the DNA found in the mutant, but not in the wild‐type clone, has been brought there by Ds insertion or by another Ds‐dependent DNA rearrangement. The mutant‐derived DNA was hybridized to genomic DNA of various maize lines digested by several restriction endonucleases. Approximately 40 bands were detected. The mutant‐derived DNA contains two pairs of inverted repeats several hundred nucleotide pairs long, one of which is located at the junction to wild‐type‐derived DNA.