Translation initiation by non-AUG codons in Arabidopsis thaliana transgenic plants.

The efficiency of translation initiation at codons differing at one or two nucleotides from AUG was tested as initiation codons for the phosphinotricin-acetyltransferase gene in T-DNA plant transformation in Arabidopsis thaliana. With the exception of UUA codon that differs from AUG at two nucleotides and does not permit any detectable activity, all the other codons (AUC, GUG, ACG, and CUG) present a phosphinotrycin acetyltransferase activity that varies between 5 and 10% of the AUG activity. This low activity is sufficient to confer glufosinate resistance to some of the plants. These results indicate that, in plants as is the case in animals, non-AUG initiating codons may be used for translation initiation, namely when a low expression rate is needed.