Transposition of the maize transposable element Ac in barley (Hordeum vulgare L.)

Transposition of the maize autonomous element Ac (Activator) was investigat ed in barley (Hordeum vulgare L.) with the aim of developing a transposon t agging system for the latter. The Ac element was introduced into meristemat ic tissue of barley by microprojectile bombardment. Transposon activity was then examined in the resulting transgenic plants. Multiple excision events were detected in leaf tissue of all plant lines. The mobile elements gener ated empty donor sites with small DNA sequence alterations, similar to thos e found in maize. Reintegration of Ac at independent genomic loci in somati c tissue was demonstrated by isolation of new element-flanking regions by A IMS-PCR (amplification of insertion-mutagenized sites). In addition, transm ission of transposed Ac elements to progeny plants was confirmed. The resul ts indicate that the introduced Ac element is able to transpose in barley. This is a first step towards the establishment of a transposon tagging syst em in this economically important crop.