Functional Properties of a Phenylalanine Ammonia-Lyase Promoter from Arabidopsis

Abstract

Phenylalanine ammonia-lyase (PAL) is encoded by a small family of genes in Arabidopsis. We cloned and partially characterized one of these genes, PAL1. The deduced amino acid sequence is highly similar to PAL from bean, parsley, and rice. The promoter contains sequence elements homologous to two putative regulatory elements conserved among severa1 phenylpropanoid genes. The regulation of the PAL1 gene was examined by analysis of P-glucuronidase (GUS) activity in transgenic Arabidopsis containing PAL1-GUS gene fusions. The PAL1 promoter was activated early in seedling development and in adult plants was strongly expressed in the vascular tissues of roots and leaves, but was not active in the root tip or the shoot apical meristem. In flowers, expression was observed in sepals, anthers, and carpels, but not in petals. Transcripts encoded by the endogenous PAL genes and GUS transcripts from the PAL1-GUS gene fusion were induced by wounding, HgCI,-stress, and light. Analysis of the regulatory properties of 5' deleted promoters showed that the proximal region of the promoter to -290 was sufficient to establish the full tissue-specific pattern of expression and that the proximal region to -540 was responsive to environmental stimuli. Negative and positive elements were located between -1816 and -823 and between -823 and -290, respectively.

Differential induction of 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase genes in Arabidopsis thaliana by wounding and pathogenic attack.

“…The level of transcripts encoding phenylalanine am- monia lyase (PAL), the first enzyme in the phenylpropanoid pathway, also increased about 2-to 3-fold after wounding. The difference between our results and those ofOhl et al (26), who observed induction of PAL RNA 1 hr after wounding Arabidopsis plants, may be due to differences in the manner and severity of the wounding procedure. Not all amino acid biosynthetic pathways respond to wounding, because transcripts from ALS, the single-copy Arabidopsis gene encoding acetolactate synthase (25), an enzyme in the isoleucine-valine pathway, showed the same pattern of expression as DHS2 (Fig.…”

In situ Localization of Phenylpropanoid-Related Gene Expression in Different Tissues of Light- and Dark-Grown Parsley Seedlings

“…In contrast to these find ings in tobacco is a recent report by Ohl et al [28] on transgenic Arabidopsis plants. These authors isolated one endogenous PAL prom oter, fused it to the ß-glucuronidase reporter gene, and found no expression in the root and shoot apices.…”

Modes of expression and common structural features of the complete phenylalanine ammonia-lyase gene family in parsley.

“…PAL was described in 1961 by Koukol and Conn (1) and has since been one of the most extensively studied enzymes in plants. Various structural and regulatory properties of PAL genes from bean (2-4), rice (5), parsley (6,7),Arabidopsis (8,9), potato (10), loblolly pine (11), pea (12,13), tomato (14), and poplar (15) have been reported. As far as analyzed, the number of PAL genes per haploid plant genome varies from 1 (11) to 5 (14), except for potato, which contains an unusually large family of "40-50 PAL genes (10).…”