Enhanced frequency of transposition of the maize transposable element Activator following excision from T-DNA in Petunia hybrida

Ac as a tool for the functional genomics of rice

To examine whether the maize autonomous transposable element Ac can be used for the functional analysis of the rice genome, we used Southern blot analysis to analyze the behaviour of Ac in 559 rice plants of four transgenic families through three successive generations. All families showed highly active transposition of Ac, and 103 plants (18.4%) contained newly transposed Ac insertions. In nine of the 12 independent transpositions analyzed, their germinal transmission was detected. Partial sequencing of 99 Ac-flanking sequences revealed that 21 clones exhibited significant similarities with protein-coding genes in databases and four of them matched rice cDNA sequences. These results indicate preferential Ac transposition into protein-coding rice genes. To examine the feasibility of PCR-based screening of gene knockouts in rice Ac plants, we prepared bulked genomic DNA from the leaves of approximately 6000 rice Ac plants and pooled the DNA according to a three-dimensional matrix. Of 14 randomly selected genes, two gene knockouts were identified, and one encoding a rice cytochrome P450 (CYP86) gene was shown to be stably inherited to the progeny. Together, these results suggest that Ac can be efficiently used for the functional analysis of the rice genome.

Movers and shakers: maize transposons as tools for analyzing other plant genomes

Transposons have been successfully exploited as insertional mutagens for the efficient identification and isolation of genes (transposon tagging) in many organisms. Plants are no exception. The maize Activator and Suppressor-mutator transposons function when transferred into heterologous plant species, and many different gene tagging systems have been developed. These systems have recently been used to clone novel and important genes, including disease resistance loci from Nicotiana tabacum, tomato and flax.