ANTISENSE-MEDIATED SUPPRESSION OF TRANSGENE EXPRESSION TARGETED SPECIFICALLY TO POLLEN

A potential problem in the field release of transgenic plants is the s pread of foreign gene products via pollen. Therefore, the use of the t omato pollen-specific lat52 gene promoter was investigated as a means of targeting antisense RNA to pollen without affecting transgene expre ssion elsewhere in the plant, A transgenic tobacco line, T115, which s howed GUS expression in pollen, leaves and roots was retransformed wit h a construct containing the pollen-specific lat52 promoter driving th e GUS encoding uid A gene in antisense orientation, From 24 independen t transformants obtained, 19 showed a significant reduction in pollen GUS activity. Of these lines, four showed a reproducible antisense eff ect in pollen in the next generation, while it was shown in one line t hat GUS activity in leaves and roots was also unaffected. To ascertain the effectiveness of the antisense strategy to downregulate Very high levels of pollen expression, a lat52-gus antisense construct was intr oduced into tobacco lines containing lat52-gus, which had pollen GUS a ctivity of up to 250 times greater than in line T115, Results showed t hat 30 out of 34 independent lines exhibited a significant antisense e ffect in pollen, confirming the effectiveness of pollen-targeted antis ense startegy to reduce undesirable expression in pollen independent o f expression level in pollen.