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

Abstract

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 lambda vector (lambda::Zm Sh). The fragments cloned from wild-type and from the Ds-induced mutant sh-m5933 (lambda::Zm sh-m5933) share a segment 6 kb long while a contiguous segment of 15 kb of lambda::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 lambda::Zm Sh, but not in the mutant clone, lambda::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.