IAGLU, A GENE FROM ZEA-MAYS INVOLVED IN CONJUGATION OF GROWTH-HORMONEINDOLE-3-ACETIC

Plants contain most of the growth hormone indole-3-acetic acid (IAA) i n conjugated forms believed to be inactive in promoting growth. The ia glu gene, which controls the first step in the biosynthesis of the IAA conjugates of Zea mays, encodes (uridine hosphate-glucose:indol-3-yla cetyl)-beta-D-glucosyl transferase. Protein synthesized by Escherichia coli that contained cloned 1-O-beta-D-indol-3-ylacetyt-glucose comple mentary DNA (cDNA) was catalytically active. The predicted amino acid sequence of the cDNA was confirmed by amino-terminal sequencing of the purified enzyme. Homologous nucleotide sequences were found in all pl ants tested. The blockage or enhancement of iaglu expression may permi t regulation of plant growth.