Characterisation of the ABA sensitivity infl uencing Arabidopsis PPR gene

T-DNA insertion mutagenesis is a recently developed tech-nique, allowing the identifi cation and easy isolation of genes from higher plants, in this case from Arabidopsis thaliana. We initiated a mutagenesis program by generating a collection of T-DNA insertion mutants (Szabados et al. 2000). Using this technique, we are trying to genetically dissect signal transduc-tion pathways mediating cellular and organ differentiation, developmental regulation and stress responses. In order to identify tagged genes, T-DNA insertions sites are character-ized by random sequencing the fl anking genomic plant DNA (Szabados et al. 2002). During this mutagenesis program, we identifi ed a transgenic line with different behaviour possess-ing for osmotic and hormonally stress response, where the T-DNA insertion is in the exon of At3g16890. The tagged gene encodes a pentatricopeptide repeat-containing protein