A new 9-lipoxygenase cDNA from developing rice seeds.

We isolated a novel C9 position specific lipoxygenase (r9-LOX1) cDNA from developing rice seeds. The enzymatic features of r9-LOX1 resembled those of rice LOX-L3 known to be contained in rice germ and to have C9-specific LOX activity. However, the expression level of the r9-LOX1 gene was higher in imbibed seeds rather than developing seeds. A homology search against the rice nucleotide database revealed the r9-LOX1 gene to be on rice chromosome 3 (accession number AC093017). The restriction enzyme map of the reported genomic sequence agreed with the result of the Southern blot analysis for the r9-LOX1. The enzyme could be useful for in vitro synthesis of 9,10-ketol-octadecadienoic acid.