Accurate and effective positive marker excision is indispensable for the 
introduction of desired mutations into the plant genome via gene targeting (GT) 
using a positive/negative counter selection system. In mammals, the moth-derived 
piggyBac transposon system has been exploited successfully to eliminate a 
selectable marker from a GT locus without leaving a footprint. Here, we present 
evidence that the piggyBac transposon also functions in plant cells. To 
demonstrate the use of the piggyBac transposon for effective marker excision in 
plants, we designed a transposition assay system that allows the piggyBac 
transposition to be visualized as emerald luciferase (Eluc) luminescence in rice 
cells. The Eluc signal derived from piggyBac excision was observed in 
hyperactive piggyBac transposase-expressing rice calli. Polymerase chain 
reaction, Southern blot analyses and sequencing revealed the efficient and 
precise transposition of piggyBac in these calli. Furthermore, we have 
demonstrated the excision of a selection marker from a reporter locus in T0 
plants without concomitant re-integration of the transposon and at a high 
frequency (44.0% of excision events), even in the absence of negative selection.