l-Phenylalanine ammonia-lyase (PAL) activity is low in the external layers (flavedo) of intact mature grapefruit peel. Flavedo discs evince upon incubation increasing PAL activity and ethylene production. Light has no effect in enhancing PAL activity in discs. Exogenous ethylene stimulates PAL activity in the flavedo of intact mature grapefruits (half maximum stimulation at 15 ppm); such activi...

Poplar (Populus tremula x alba) trees (clone INRA 717-1-B4) were cultivated for 1 month in phytotronic chambers with two different levels of ozone (60 and 120 nL L(-1)). Foliar activities of shikimate dehydrogenase (EC 1.1.1.25), phenylalanine ammonia lyase (EC 4.3.1.5), and cinnamyl alcohol dehydrogenase (CAD, EC 1.1.1.195) were compared with control levels. In addition, we examined lignin con...

Two Myb-related transcription factors, Myb305 and Myb340, are expressed specifically in flowers of Antirrhinum. The proteins are structurally very similar throughout their DNA binding domains, implying that they bind to common target motifs. This binding has been demonstrated experimentally. Myb305 has been shown to activate the gene encoding the first enzyme of phenylpropanoid metabolism, phen...

In a recent study of N-acylphosphatidylethanolamine (NAPE) metabolism in elicitor-treated tobacco (Nicotiana tabacum L.) cells, we identified a rapid release and accumulation of medium-chain N-acylethanolamines (NAEs) (e.g. N-myristoylethanolamine or NAE 14:0) and a compensatory decrease in cellular NAPE (K.D. Chapman, S. Tripathy, B. Venables, A.D. Desouza [1998] Plant Physiol 116: 1163-1168)....

One of the earliest detectable events during plant-pathogen interaction is a rapid increase in ethylene biosynthesis. This gaseous plant stress hormone may be a signal for plants to activate defense mechanisms against invading pathogens such as bacteria, fungi, and viruses. The effect of ethylene on four plant genes involved in three separate plant defense response pathways was examined; these ...

Aspartate ammonia-lyase (AAL) catalyzes the reversible conversion reactions of aspartate to fumaric acid and ammonia. In this work, Lactobacillus paracasei LpAAL gene was heterologously expressed in Escherichia coli. As well as a recombinant His-tagged protein, maltose-binding protein (MBP) fused used enhance its solubility expression level. Both proteins showed broad substrate specificity, cat...