I got a request to post the antisense references I received, so here are both of them: J. Li et al. 1995. Arabdiopsis phosphoribosylanthranilate isomerase: molecular genetic analysis of triplicate tryptophan pathway genes. Plant Cell 7, 447-461 H. Xu et al. 1995. Bcp1, a gene required for male fertility in Arabidopsis. PNAS 92, 2106-2110.