EXPRESSION PATTERNS OF THE CINNAMIC ACID 4-HYDROXYLASE GENE DURING LIGNIFICATION IN ZINNIA-ELEGANS

Cinnamic acid 4-hydroxylase (CA4H) is one of the core enzymes in pheny lpropanoid biosynthetic pathway. A cDNA clone encoding CA4H was isolat ed from differentiating tracheary elements (TEs) induced from isolated mesophyll cells of Zinnia elegans. RNA gel blot analysis showed that while CA4H mRNA was induced when the isolated mesophyll cells were cul tured, its marked accumulation was specifically associated with TE dif ferentiation. Quantitative analysis showed that CA4H mRNA accumulated about nine times more in TEs than in non-TE cells. Consistently, CA4H activity was about five rimes higher in TEs than in non-TE cells. The accumulation of CA4H mRNA in Zinnia stems was closely associated with lignification in phloem fibers and xylem cells. Given its expression p atterns in both cultured cells and organs, the CA4H gene can be used a s a marker for identification of genes for their possible involvement in lignification in the Zinnia system. Copyright (C) 1996 Elsevier Sci ence Ireland Ltd