STRATEGIES FOR TARGETED TRANSPOSON TAGGING OF ABA BIOSYNTHETIC MUTANTS IN TOMATO

The ABA biosynthetic pathway has been studied in detail and the steps impaired in some ABA-deficient mutants are known. However, little is k nown of the molecular control mechanisms regulating ABA production in planta. A direct route for improving our understanding of these mechan isms is to transposon tag and clone the wild-type counterparts of the ABA mutant alleles. On the basis of the observation that maize transpo sons move preferentially to linked sites in both homologous and hetero logous systems and in doing so disrupt gene function, a targeted trans poson mutagenesis strategy is being developed towards cloning ABA bios ynthetic genes from tomato. The possibility of using marker genes to i dentify T-DNA insertion sites in selected parts of the genome has been examined and compared with an inverse PCR/RFLP approach to mapping T- DNAs.