FUNCTIONAL-ANALYSIS OF THE RUBISCO LARGE SUBUNIT N-EPSILON-METHYLTRANSFERASE PROMOTER FROM TOBACCO AND ITS REGULATION BY LIGHT IN SOYBEAN HAIRY ROOTS

The ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) large su bunit (LS) N-epsilon-methyltransferase (Rubisco LSMT) catalyzes post-t ranslational methylation of the epsilon-amino group of lysine-14 in th e LS of Rubisco. The entire nucleotide sequence for the tobacco (Nicot iana tabacum) Rubisco LSMT (rbcMT-T) gene including the putative promo ter region was recently reported, and sequence analysis of the promote r region revealed seven GT-1 motifs. The ability of several truncated rbcMT-T promoter fragments to confer light responsiveness to reporter gene expression in transgenic soybean (Glycine max:) hairy roots was e xamined. Chimeric constructs consisting of the rbcMT-T promoter fused to a bacterial beta-glucuronidase (GUS) reporter gene and transferred to soybean via Agrobacterium rhizogenes were evaluated. The rbcMT-T pr o meter fragments conferred expression of the reporter gene in transge nic hairy roots, callus, and cell suspension cultures based on histoch emical and fluorometric GUS analyses. The results suggest a quantitati ve role for the number of GT-1 motifs in determining differential expr ession between light and dark conditions.