Differential Wound Activation of Members of the Phenylalanine Ammonia-Lyase and 4-Coumarate: CoA Ligase Gene Families in Various Organs of Parsley Plants

Abstract

We analyzed the developmental regulation and the activation by wounding of several stressrelated genes in various parsley organs. The genes encode phenylalanine ammonia-lyase (PAL) and 4-coumarate: CoA ligase (4 CL), two enzymes of general phenylpropanoid metabolism; a flavonoid specific enzyme, chalcone synthase (CHS); a furanocoumarin specific enzyme, bergaptol O-methyltransferase (BMT); and a pathogenesis-related protein (PR 1). All genes or gene families exhibited high levels of expression in roots and during certain stages of leaf development. PAL, 4 CL and CHS were preferentially expressed in young leaves, BMT and PR 1 in old leaves. An appreciable increase in CHS mRNA levels was observed in wounded leaves. By contrast, root wounding led to a decrease in the existing CHS m RNA levels. A biphasic response (a decrease followed by an increase) to wounding was seen for BMT and PR 1 m RNA s in roots and for BMT mRNA in attached leaves. Using gene-specific oligonucleotide probes to measure the expression rates of three of the four PAL genes and of the two 4 CL genes separately we observed a differential behavior of the individual family members under many of the conditions tested. While PAL-3 was preferentially activated in wounded leaves and 4CL-1 in wounded roots, PAL-2 and 4C L-2 were primarily responsible for the high constitutive expression levels in roots and flowering stems respectively. Despite the differential expression of their individual members, the PAL and 4 CL gene families displayed very similar changes in the overall patterns of expression, reflecting their closely related functions in phenylpropanoid metabolism.

Aluminum-Induced Genes (Induction by Toxic Metals, Low Calcium, and Wounding and Pattern of Expression in Root Tips)

“…Homologs to wali4 (encoding PAL) have been shown to be wound inducible in other plant species (Lois and Hahlbrock, 1992). The wali4 transcript was induced in wounded leaves but not in roots, whereas walil, -3, and -5 were a11 induced in both wounded roots and leaves (Fig.…”

Oligopeptide elicitor-mediated defense gene activation in cultured parsley cells.

“…In contrast, recent studies using gene-specific probes for the four PAL genes (ref. 48 Fig. 9 C-K. Total PAL mRNA was present in oil ducts in both etiolated and illuminated leaf buds ( Fig.…”

“…Although certain methodological difficulties precluded a definite answer for 4CL (48), all available evidence suggests that the two 4CL genes respond similarly to light and elicitor. In contrast, recent studies using gene-specific probes for the four PAL genes (ref.…”

Structure, Inheritance, and Expression of Hybrid Poplar (Populus trichocarpa x Populus deltoides) Phenylalanine Ammonia-Lyase Genes

“…differentiation of certain cells, tissues, and organs, and in response to stresses such as wounding, pathogen infection, and elicitor treatment (Lawton and Lamb, 1987;Bevan et al, 1989;Liang et al, 1989b;Lois et al, 1989;Ohl et al, 1989;Schmelzer et al, 1989;Lois and Hahlbrock, 1992). PAL is encoded by small gene families in several plants (Cramer et al, 1989;Lois et al, 1989;Ohl et al, 1989;Gowri et al, 1991), but recent reports suggest that potato contains 40 to 50 PAL genes (Joos and Hahlbrock, 1992), whereas loblolly pine may contain a single PAL gene (Whetten and Sederoff, 1992).…”