The first enzyme of the shikimate pathway, 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase (EC 4.1.2.15), is induced by wounding potato or tomato tissue. The increase in enzyme activity is associated with elevated amounts of the enzyme as determined by immunoblots. The specific wound-induced protein synthesis is preceded by an increase in the mRNA encoding this enzyme. The induced mRNA of potato tuber, leaf, and stem tissue is translated into a precursor polypeptide that is recognized by antibodies raised against the mature enzyme from tuber plastids. Wounding also induces mRNA encoding phenylalanine ammonia-lyase (EC 4.3.1.5), a key enzyme of plant secondary metabolism. The time courses for the induction of the two enzymes are similar, suggesting coordinate regulation for the biosynthesis of primary and secondary aromatic compounds.Plants respond to wounding by increased production of compounds involved in the repair of wound damage and in defense against microbial invasion. Wound and defense responses are intimately connected, since many pathogens create, or enter through, wounds in the epidermis. Repair requires lignin and suberin (1); defense against pathogens is associated with the synthesis of phytoalexins (2), low molecular weight antimicrobial compounds (3).Wounding stimulates polysome formation and induces synthesis of proteins for several metabolic pathways (4). The initiation of wound repair is characterized by the accumulation of hydroxyproline-rich proteins in plant cell walls (5). These proteins impart wall rigidity and may provide sites for lignin deposition (6). The synthesis of these proteins in response to wounding is due to gene activation (7,8). Different transcripts accumulate in response to different stresses caused by wounding, fungal infection (9), or ethylene treatment (10). Lignification appears to be ubiquitous in wounded plants. Lignin accumulation is accompanied by the activation of enzymes of lignin biosynthesis, including phenylalanine ammonia-lyase (11, 12), cinnamate 4-hydroxylase (13), p-hydroxycinnamate-CoA ligase (14), and chorismate mutase (15). Genes encoding key enzymes of lignin biosynthesis are transcriptionally activated by wounding (8,16,17).Lignin is synthesized from phenylalanine, one end-product of the shikimate pathway (18) The plastidic potato DAHP synthase was purified to electrophoretic homogeneity (23), and antibodies against this enzyme (anti-potato DAHP synthase) were raised in rabbits (21). The 374-base pair (bp) EcoRI-Kpn I cDNA fragment encoding part of the plastidic potato DAHP synthase was prepared as described (24). cDNAs encoding the Glycine max phenylalanine ammonia-lyase (EC 4.3.1.5) and the Electrophorus electricus calmodulin (26) were gifts of L. Vodkin (University of Illinois) and A. R. Means (Baylor Medical School), respectively. Potato (Solanum tuberosum cv. Superior) and tomato (Lycopersicon esculentum cv. Rutgers) plants were grown under greenhouse conditions. Plant Wounding. Potato tubers were surface sterilized in 0.05% NaClO fo...

Light and fungal elicitor induce mRNA encoding 3-deoxy-Darabino-heptulosonate 7-phosphate (DAHP) synthase in suspension cultured cells of parsley (Petroselinum crispum L.). The kinetics and dose response of mRNA accumulation were similar for DAHP synthase and phenylalanine ammonia-lyase (PAL). Six micrograms of elicitor from Phytophthora megasperma f. glycinia gave a detectable induction within 1 hour. Induction of DAHP synthase and PAL mRNAs by light was transient, reaching maximal levels at 4 hours and retuming to pretreatment levels after 24 hours. Our data suggest that either light or fungal elicitor transcriptionally activate DAHP synthase. A coordinate regulation for key enzymes in the synthesis of primary and secondary metabolites is indicated.

Tomato (Lycopersicon esculentum L. cv. UC82b) was found to contain two distinct 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthase genes that are differentially expressed. The corresponding cDNAs were isolated and characterized. Both genes code for putative plastidic DAHP synthase isoforms. The deduced amino acid sequences are 79% identical. A comparison of the known Solanaceae DAHP synthases indicates two distinct conserved isoforms. The steady-state levels of transcripts of the two tomato genes differ in all organs analysed.

In alpha 1-antitrypsin deficiency in humans, inadequately regulated activity of serine protease activity is responsible for the chronic lung tissue degeneration and irreversible loss of pulmonary function seen in those individuals with emphysema. Typically, disease symptoms in this patient population are exacerbated by cigarette smoke. Here we show that inhaled recombinant alpha 1-antitrypsin (rAAT) can provide significant protection against the development of emphysema in cigarette smoke-treated mice. As has been reported previously, cigarette smoke was seen to increase significantly the recruitment of neutrophils and macrophages into the lungs of these animals, leading to concomitant alveolar airspace enlargement and emphysema. In smoking animals treated for 6 months with inhaled rAAT, effects on lavage levels of neutrophils and macrophages were only moderate when compared with untreated animals. Furthermore, neutralizing antibodies to rAAT were generated in all rAAT-treated animals. Despite this, however, reductions in airspace enlargement of up to 73% were observed. These findings demonstrate that delivery of rAAT directly to the lungs of smoke-treated mice can inhibit lung tissue damage mediated by proteases, suggesting that rAAT inhalation therapy might represent a practical approach towards treating emphysema in humans, by modifying the course of the disease.