John L. Caruso

Low-temperature induction of starch degradation in roots of a biennial weed

Abstract Decreasing temperatures were observed to induce starch degradation in roots of mullein, a biennial weedy species. Virtually no starch remains in the roots when the acclimation period of decreasing temperatures is followed by an extended period of exposure to 4 °C. The breakdown of starch which is presumed to occur in late autumn under field conditions may provide cryoprotective chemicals for the overwintering rosette. Such chemicals might also serve as an energy source for the bolting process which occurs during the following spring or early summer.

Immunoassay Methods of Plant Hormone Analysis

The use of immunoassays in the analysis of plant hormones has increased significantly since the founding work of Weiler and associates (58). Immunoassays are based on the ability of animals to produce proteins (antibodies) which recognize and bind to specific compounds (antigens) foreign to the animal. The specificity and sensitivity of antibodies make immunoassays attractive for the quantitation of plant hormones, which usually occur at low concentrations. Small amounts of plant tissue can thus be used in the assay, and, in addition, large numbers of samples can be processed in a brief period of time. Although some purification of extracts is generally required for the immunoassays, it is generally less than the more extensive clean-up needed in physico-chemical methods.

Elisa determination of IAA using antibodies against ring-linked IAA

Abstract An enzyme-linked immunosorbent assay (ELISA) for indole-3-acetic acid (IAA) is described which uses antibodies raised against IAA conjugated to carrier protein on the indolic ring of IAA. As little as 0.5 pmol of IAA is detectable with the ELISA. There is no significant cross-reactivity with amide conjugates of IAA and samples do not need methylation, in contrast to an ELISA using antibodies raised against carboxyl-linked IAA. Affinity chromatography on IAA-agarose was used to purify antibody preparations. Measurements of IAA levels in crown gall tumour tissue lines were made using the assay.

The influence of low temperatures on activities of starch degradative enzymes in a cold-requiring plant.

Summary An increase in the activities of α-amylase, β-amylase and glucan phosphorylase was observed in roots of Verbascum thapsus when plants were subjected to low temperatures. Both amylases showed their greatest activities at 15°C, whereas the phosphorylase enzyme had its greatest activity at 10°C. α-Amylase and phosphorylase showed another increase in activities when plants commenced growing at higher temperatures after a long exposure to 4°C. β-Amylase in the root does not appear to be directly related to the growth of the shoot system following vernalization.

Indole-3-acetic acid in Douglas fir seedlings: A reappraisal

Abstract The use of ring-labelled, pentadeutero IAA as an internal standard in selected ion monitoring analysis of Douglas fir seedlings revealed an estimate of IAA which was nearly an order of magnitude smaller than that reported earlier.

Early seedling survival of Melilotus in bluegrass sod.

Seeds of Melilotus alba and M. officinalis were sown in four different—sized openings in Canada bluegrass, a dominant of an old field. A relationship between seed germination and size of opening in the sod was not apparent but early seedling survival was correlated (P < .01) with size of opening, the larger openings yielding a greater number of viable seedlings. The areal extent of the dominant plant in the old field thus appears to regulate the number of sweetclover plants at an early stage of their life cycle. See full-text article at JSTOR

Influence of the carcinogenic pollutant benzo[a]pyrene on plant development: Fern gametophytes

Polycyclic aromatic hydrocarbons (PAHs), ubiquitous environmental pollutants, are known to be biologically active in mammalian systems and are accumulated by plants. A few reports suggest that PAHs stimulate growth in plants and induce morphogenesis in plant tissue in culture. To investigate the growth altering abilities of PAHs in plants, polypodiaceous fern gametophytes were grown under sterile conditions on media containing a biologically active PAH, benzo[a]pyrene (BaP), at doses ranging from 0.1 to 10.0 micrograms/ml. The growth pattern of polypodiaceous fern gametophytes enables alterations in growth and morphogenesis to be observed at the cellular level in an intact plant. Doses of BaP in the range 0.1--3.2 micrograms/ml enhanced the onset of the morphological transitions from 1-dimensional (1D) to 2-dimensional (2D) growth. This transition for BaP treated plants occurred after fewer cell divisions than the corresponding solvent and untreated controls. The low (0.1 and 0.32 micrograms) and high (1.0 and 3.2 micrograms) doses of BaP were found to accelerate and inhibit cell proliferation, respectively. The 10.0 microgram dose was toxic and resulted in decreased germination of spores and reduced survival of plants. A slight but significant decrease in survival was also observed in ferns treated with 3.2 micrograms. This is the first example of PAH influencing cell differentiation in a whole plant system.

Effects of IAA and four IAA conjugates on morphogenesis and callus growth from tomato leaf discs

The effects of indole-3-acetic acid (IAA) and four IAA conjugates, indoleacetylalanine (IAAla), indoleacetylaspartic acid (IAAsp), indoleacetylglycine (IAGly), and indoleacetylphenylalanine (IAPhe), on growth and morphogenesis in tomato leaf discs in vitro were examined. Free IAA stimulated root initiation in the absence of cytokinin and stimulated callus growth in the presence of 0.89 μM benzylaminopurine (BAP). Free IAA also inhibited shoot initiation obtained with 8.9 μM BAP. The activities of the IAA conjugates depended on the conjugating amino acid, the concentration of the conjugate, and the response being measured. IAAsp had little or no activity in promoting root initiation or callus growth or in inhibiting shoots, while IAPhe was similarly inactive except at the highest concentration tested (100 μM). IAAla and IAGly were both very active in inhibiting shoots and promoting callus growth, but were much less active in stimulating rooting, except at 100 μM, at which concentration they were as effective as free IAA. Thin-layer chromatography of the IAA conjugates revealed that IAAla, IAGly and IAPhe were largely stable to autoclaving, but that IAAsp underwent some hydrolysis to products identical with free IAA and aspartic acid. Pretreatment of seedlings with IAA, IAAla or IAGly altered the subsequent shoot initiation response from leaf discs on media with and without IAA.

Auxin and cytokinin levels in selected and temperature-induced morphologically distinct tissue lines of tobacco crown gall tumors

Two morphologically distinct tissue culture lines were selected from a tobacco (Nicotiana tabacum L. ‘Wisconsin 38’) crown gall tumor: (1) a green teratomous line producing numerous abnormal shoots, designated leafy; and (2) a white, hard, spherical tissue, designated white. These were originally isolated at 27°C, but temperature changes were also found to control these morphologies, with 33°C favoring the development of the leafy form and 21°C favoring the white form. The higher temperature was also correlated with a decrease in the endogenous levels of both auxin and cytokinin, whereas the lower temperature was correlated with an increase in the levels of these growth regulators. There was no significant difference, however, in the auxin and cytokinin levels in the two forms maintained at 27°C, suggesting that the basis for morphological changes at this temperature resides either in very subtle differences in auxin and cytokinin or in factors other than these two growth regulators.

Influence of low temperature on phosphatase in roots of Verbascum thapsus, a biennial weed

Abstract The temperature peak (15 °C) of acid and alkaline phosphatase in this study coincides with a peak in alpha-amylase as seen in an earlier study of roots of Verbascum thapsus . It is speculated that one of the results of higher phosphatase activities may be increased amount of orthophosphate which can be utilized in phosphorylation of soluble carbohydrates which in turn are in greater supply due to the higher activities of the starch-degrading enzymes. A second peak in activities of acid and alkaline phosphatase was seen in plants which were returned to the greenhouse following cold treatment. This increase in enzymatic activities is also similar to increases in activities of three starch degrading enzymes studied earlier. Alkaline phosphatase showed greater activities than did acid phosphatase at lower temperatures (10 and 4 °C) and under greenhouse conditions following cold treatment.