In a Southern hybridization experiment, the 5 kb maize EcoRl fragment, LC1, seems to be unique in the Zea mays Line C genome (Shepherd et al., 1982, Mol. Gen. Genet. 188:266-271). However, in a Northern Flint maize line the homologous fragment was found to contain the repetitive DNA insert Cin 1 (see previous article). Using LC1 as a radioactive probe in Southern hybridization experiments, the genomic fragment homologous to LC1 is observed to vary in size between various Zea mays lines and also in Zea mexicana (Teosinte). For example, both the 5 kb LC1 fragment and an 8 kb fragment are seen in Teosinte Guerrero. The 8 kb fragment, TG2, was cloned into lambda-gtWES (manuscript in preparation). A heteroduplex between TG2 and the maize LC1 or NF1 fragment clearly shows that the increase in molecular weight is due to a 3 kb insert having a very unique structure (see Figure). This insert is called Teo 1. It seems to occur approximately 50 bp from the original site of the Cin 1 insert and does not contain sequences homologous to Cin1. DNA sequence analysis of Teo 1 is currently in progress.

Schematic drawing of a TG2 and NF1 heteroduplex.

N. S. Shepherd, B. Deumling, U. Wienand, J. Blumberg and H. Saedler

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