Wound responses in a variety of injured plant tissues were assessed using conventional lignin tests and fluorescence techniques for suberin detection in tissues present at the time of wounding. The tissue assessed included twigs of four conifer species, barley and cherry foliage, fern rachis, potato tuber, carrot root, musksmelon cotyledons, and cucumber hypocotyl. Apple leaves infected by a leaf spotting fungus (Botryosphaeria obtusa) were also examined. All tissues, except barley and apple foliage and fern rachis, formed a morphologically distinct lignosuberized boundary layer from cells present at the time of wounding. The boundary layer consisted initially of cells with lignified walls which with time developed suberin lamellae. In the fern rachis, the boundary layer was suberized in the absence of lignin. In the wounded barley and infected apple foliage, neither lignin nor suberin was detected histochemically.

Seeds of canola, lettuce, tomato, barley, wheat, and oats were inoculated with either the wild-type plant growth promoting rhizobacterium (PGPR), Pseudomonas putida GR12–2, or the mutant P. putida GR 12–2lacd68 (deficient in the activity of the enzyme 1-aminocyclopropane-1-carboxylate deaminase) alone and in conjunction with either an inhibitor of ethylene biosynthesis, L-α-(aminoethoxyvinyl)-glycine (AVG), or the chemical ethylene generator, (2-chloroethyl) phosphonic acid (ethophon). For the different treatments, variations in root length under gnotobiotic conditions were compared. Canola, lettuce, tomato, and wheat responded to all of the treatments in a similar manner: The root lengths increased when seeds were treated with P. putida GR 12–2 and/or AVG but not with the mutant strain, in comparison with a MgSO4 control treatment, while the ethophon treatment inhibited root elongation. With barley and oat, none of the treatments had any effect on root lengths; however, when the ethophon concentration was increased, root elongation of these two plants was also inhibited. These observations are consistent with a model in which promotion of root growth by P. putida GR 12–2 is a consequence of inhibition of ethylene production within the developing seedling.

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A new combination of embedding material and high contrast stain has provided the means for demonstrating, photographically, tangential sections of endodermal cells showing complete Casparian strips.

Fourteen-day-old Phaseolus vulgaris L. cv. Top Crop (bush bean) plants were sprayed with the plant growth stimulant, potassium naphthenate (20 mM). Seven days after treatment the contents of glutamic acid dehydrogenase, glutamic-oxaloacetic transaminase, nitrate reductase, glutamine synthetase, and cytochrome oxidase in the trifoliate leaf blades of treated plants were significantly larger, and the specific activity of the last four was significantly greater. Potassium nephthenate (1 AM) in the assay solutions did not significantly alter the activity of these enzymes in the cell-free extracts of untreated plants. Leaf Naphthenic acid is the name applied to the complex mixture of acids extracted from petroleum. The diesel oil fraction (180-400 C) may contain 0.03% naphthenic acid. The structure of the individual higher molecular-weight acids in the mixture has yet to be determined, but it is known that others are carboxylic derivatives of cyclopentane, cyclohexane, and cyclo- heptane. The carboxyl group of most of the acids is separated from the saturated ring by an aliphatic side chain containing one or more methylene groups. In our laboratory, gas-liquid chromatography of naphthenates derived from the diesel fraction of a Venezuelan crude oil yielded a tracing in which most of the components appeared to be in the C. to C17 range.Within this range there were 25 major peaks.The acid mixture and some of its individual members have been shown to stimulate the vegetative and reproductive growth of a large variety of plants. Severson (16) has tabulated their effects on growth, yield, and composition of over 50 species.The stimulated growth of the green bush bean, Phaseolus vulgaris L. cv. Top Crop, following naphthenate application, has been shown to be accompanied by increased rates of photosynthesis and respiration, and greater specific activity of phosphorylase, phosphoglycerate kinase, nitrate reductase, and glutamic-pyruvic transaminase (5). The activity of catalase in grape (9) and of peroxidase and ascorbic acid oxidase in cotton (1) has also been found to be stimulated as a result of naphthenate application.It has been suggested (5) that the stimulation of plant growth by naphthenates rests to a large extent on an increased flow of metabolic intermediates and a greater supply of energy as ATP, coupled with an enhanced activity of anabolic enzymes.The investigation described below uses Phaseolus vulgaris cv. Top Crop in a study of the effect of KNap' on the amount and activity of four enzymes of nitrogen metabolism and of cytochrome oxidase; the contents of DNA and RNA, amino acids, and protein; and the incorporation of '4C-leucine into protein.MATERIALS AND METHODS Growth of Plants. Five seeds of the bush bean Phaseolus vulgaris L. cv. Top Crop were sown in 15-cm pots of composted soil. Seven days later the seedlings were thinned to two per pot, and 5 days after this one plant was allowed to remain. As a result, the population was very uniform.The plants were grown in a growth room fitted with coo...