- The mutation bronze-mutable 4 derivative 6856 in maize is caused by the insertion of a novel 6.7-kilobase pair transposon in the untranslated leader region of the bronze-1 gene. Klein, A.S., Clancy, M., Paje-Manalo, L., Furtek, D.B., Hannah, L.C., Nelson, O.E. Genetics (1988)