Transposons

Transposons, or mobile DNA elements, make up to 80% of the plant genome and are major players in contributing to rapid genome evolution. We have studied their transposition mechanism, regulation and evolution. Recently, we showed that transposon activation can interfere with the normal activities of neighboring genes on a genome wide scale, effectively disabling some genes, and turning on other genes when they should be switched off. We found that transcriptional readout from the termini of transposons can generate antisense RNA for adjacent genes that are in opposite orientation to the readout transcripts. Conversely, readout activity can activate adjacent genes that are oriented in the same direction as the transcriptional readout.

We are currently studying the mechanism of activation of transposons, trying to determine how they sense genomic and environmental stresses. In addition, we have developed a new high-throughput system for gene discovery and functional genomics in tomato, based on transposon mutagenesis in the background of Micro-Tom, a miniature tomato that can be grown at a density of up to 1000 plants per m2 and has a rapid life cycle of 70-90 days. We are building, in collaboration with Dr. Asaph Aharoni, a new transposon system that can be used for both knockout and activation tagging in Micro-Tom and that is well suited for the isolation of metabolic mutants.