A 2-ELEMENT ENHANCER-INHIBITOR TRANSPOSON SYSTEM IN ARABIDOPSIS-THALIANA

The Enhancer-Inhibitor (En-I), also known as Suppressor-mutator (Spm-d Spm), transposable element system of maize was modified and introduced into Arabidoysis by Agrobacterium tumefaciens transformation. A stabl e En/Spm transposase source under control of the CaMV 35S promoter med iated frequent transposition of I/dSpm elements. Transposition occurre d continuously throughout plant development over at least seven consec utive plant generations after transformation. New insertions were foun d at both linked and unlinked positions relative to a transposon donor site. The independent transposition frequency was defined as a transp osition parameter, which quantified the rate of unique insertion event s and ranged from 7.8% to 29.2% in different populations. An increase as well as a decrease in I/dSpm element copy number was seen at the in dividual plant level, but not at the population level after several pl ant generations. The continuous, frequent transposition observed for t his transposon system makes it an attractive tool for use in gene tagg ing in Arabidopsis.