ANALYSIS OF T-DNA-MEDIATED TRANSLATIONAL BETA-GLUCURONIDASE GENE FUSIONS

Three random translational P-glucuronidase (gus) gene fusions were pre viously obtained in Arabidopsis thaliana, using Agrobacterium-mediated transfer of a gus coding sequence without promoter and ATG initiation site. These were analysed by IPCR amplification of the sequence upstr eam of gus and nucleotide sequence analysis. In one instance, the gus sequence was fused, in inverse orientation, to the nos promoter sequen ce of a truncated tandem T-DNA copy and translated from a spurious ATG in this sequence. In the second transgenic line, the gus gene was fus ed to A. thaliana DNA, 27 bp downstream an ATG. In this Line, a large deletion occurred at the target site of the T-DNA. In the third line, gus is fused in frame to a plant DNA sequence after the eighth codon o f an open reading frame encoding a protein of 619 amino acids. This pr otein has significant homology with animal and plant (receptor) serine /threonine protein kinases. The twelve subdomains essential for kinase activity are conserved. The presence of a potential signal peptide an d a membrane-spanning domain suggests that it may be a receptor kinase . These data confirm that plant genes can be tagged as functional tran slational gene fusions.