AN ANALYSIS OF THE RELATIVE ACTIVITIES OF A NUMBER OF PROMOTER CONSTRUCTS FROM GENES WHICH ARE EXPRESSED DURING LATE POLLEN DEVELOPMENT AS DETERMINED BY PARTICLE BOMBARDMENT

The promoters of a tobacco actin gene, a tobacco pectate lyase, a toba cco and maize polygalacturonase and a Brassica S-locus related gene ha ve been fused to the beta-glucuronidase reporter gene and their activi ties determined by biolistic transient assay in tobacco pollen. In sta bly transformed tobacco all the transgenes with the exception of Cauli flower Mosaic Virus-35S-beta-glucuronidase appear to express efficient ly in maturing pollen. Transient assay analysis showed that the tobacc o pectate lyase and the polygalacturonase constructs were 8x more acti ve than the tobacco actin construct, and that the tobacco polygalactur onase construct was some 33x more active than the maize polygalacturon ase construct. Constructional manipulations that altered the lengths o f the 5'-untranslated leaders including one which resulted in the remo val of a 490 bp leader intron had little effect on the observed level of expression. However, the alteration of the context of the ATG from A/TnnATGG to CnnATGT resulting in a 70% reduction in the observed leve ls of activity, was obtained with the pectate lyase and polygalacturon ase promoters. An identical reductional was also observed in transgeni c plant populations transformed with the polygalacturonase transgenes.