THE PLANT CELL, Vol 2, Issue 5 379-392, Copyright © 1990 by American Society of Plant Biologists
Chalcone Synthase Promoters in Petunia Are Active in Pigmented and Unpigmented Cell Types
R. E. Koes, R. van Blokland, F. Quattrocchio, A. J. van Tunen and JNM. Mol
Department of Genetics, Vrije Universiteit, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands
Chalcone synthase (CHS) catalyzes the first step in the biosynthesis of
flavonoids that function in flower pigmentation, protection against stress,
and induction of nodulation. The petunia genome contains eight complete chs
genes, of which four are differentially expressed in floral tissues and
UV-light-induced seedlings. The 5[prime]-flanking regions of these four chs
genes were fused to the [beta]-glucuronidase (GUS) reporter gene and
introduced into petunia plants by Agrobacterium-mediated transformation. We
show that expression of each construct is identical to the expression of
the authentic chs gene, implying that the differences in expression pattern
between these chs genes are caused at least in part by their promoters.
Histochemical analyses of GUS expression show that chs promoters are not
only active in pigmented cell types (epidermal cells of the flower corolla
and tube and [sub] epidermal cells of the flower stem) but also in a number
of unpigmented cell types (mesophylic cells of the corolla, several cell
types in the ovary and the seed coat). Comparison of chs-GUS expression and
flavonoid accumulation patterns in anthers suggests that intercellular
transport of flavonoids and enzymes occurs in this organ. Analysis of the
flavonoids accumulated in tissues from mutant lines shows that only a
subset of the genes that control flavonoid biosynthesis in the flower
operates in the ovary and seed. This implies that (genetic) control of
flavonoid biosynthesis is highly tissue specific.
