Identification and light-induced expression of a novel gene of NADPH-protochlorophyllide oxidoreductase isoform in Arabidopsis thaliana11The nucleotide sequence reported in this paper has been submitted to the GenBank/EBI Data Bank with accession number AB035746.

In Arabidopsis thaliana, we identified a novel gene of a NADPH-protochlorophyllide oxidoreductase (POR) isoform, which catalyzes the light-dependent protochlorophyllide a reduction in the chlorophyll (Chl) biosynthetic pathway. The deduced amino acid sequence of the novel POR isoform (PORC) showed significant identities (∼75%) with the previously isolated two POR isoforms of A. thaliana. Contrasting with these POR isoforms, the PORC transcript increased in etiolated seedlings by illumination, and was dominantly expressed in immature and mature tissues. The present results demonstrated that Chl biosynthesis and chloroplast biogenesis in A. thaliana are controlled by three POR isoforms, which are differentially controlled by light and development.