Cress inhibition

The dlterpene lactone 17-acetoxyacanthoaustralide (25) has minor effects, showing promotion of clover (112%), cucumber (109%) and Palmer amaranth (111%) and inhibition of carrot germination (91%). The flavonoid artemetin (26) at 0.05 mM concentrations slightly affects onion (93%), oat (91%) and promotes seed germinations In carrot (116%) and Palmer amaranth (113%). In closing, it is noteworthy to point out that lettuce and cress are not significantly affected by all ten sesquiterpene lactones as well as the dlterpene (25) and artemetin (26). 

Figure 2. Bioassay of several actinomycetous isolates on solid medium. Note striking inhibition of cress (top of plates), barnyard grass (middle), and cucumber (bottom) caused by isolates E5 and E8, compared to non-inoculated control (C). Cucumber was stimulated by D22 and F6.

Figure 3. Histograms showing growth response of cress, barnyard grass, and cucumber to 347 microbial isolates bioassayed on solid medium. Growth response 1) seedling growth minimal or germination nil, 2) pronounced inhibition, 3) slight inhibition, 4) growth comparable to controls, 5) stimulation over controls.

Table III. Effect of culture broth (2 ml/petri dish) and dichloromethane extract of culture broth (0.2 mg/petri dish) on cress radicle growth, as related to presence of cyclohex-imide. Data are for all isolates tested in liquid culture whose broth inhibited cress radicle growth to 50% of controls...

Balsevich et al. reported the activity and utility of ABA with a 3 -thioether linker arm [29], Sepharose-linked ABA (8) showed specifically bound anti-ABA immunoglobulins, although the form with only a linker (9) was 10 times weaker than ABA in the inhibition of cress seed germination. A fluorescent ABA derivative (10) also showed 1/10 the inhibitory activity of ABA. 

Compound Lettuce/Cress Seedling Assays Promotion 8Root Growth at 10-6M Inhibition... 

The response of seedling roots to exogenous BR also figures in the early communication of Yopp et al. (24). In dark-grown cress (Lepidium sativum cv. Curley) seedlings, root growth was inhibited by IAA at 0.1 pM or greater, but little affected either way by up to 10 pM BR. 

Phytotropins are synthetic molecules which affect the tropic responses, inhibit auxin transport and bind to the receptor for 1-N-naphthylphthalamic acid (NPA) (10-1) [91-93]. For a recent review see [94]. A simple assay to detect and compare activities is measurement of antigravitropic activity on cress seedlings [95]. There are two phytotropin recognition sites on the NPA receptor, or two receptors, which recognize phytotropins... 

Crude extracts, fractions, or pure compounds are dissolve in an appropriate solvent, then serially diluted to obtain the desired concentration. Solutions are filter sterilized prior to bioassay. In a glass petri dish, a known quantity of test solutions are applied onto a filter paper (Whatman No. 1) and allowed to evaporate to dryness. To each petri dish, 10-15 seeds of the test species are added followed by deionized Water (1.5 ml). For example, curley cress (Lepidium sativum L.)is used as an example for a broad leaf species. Negative controls consist of an equal amounts of evaporated solvent and deionized H2O. All treatments are replicated thrice. Petri dishes are then covered, randomized, and placed in a humid chamber for 72 h at 26°C. Thereafter, root lengths are measured and an I50 (50% germination or growth inhibition) level is determined for each of the treatments. Data are subjected to ANOVA and means are compared by an LSD test [92]. 

C22H28O6, Mr 388.46, square prisms, mp. 196-197 °C. G., a very bitter-tasting diterpene of the 4a,5/S- cler-odane type from the liverwort Gymnocolea inflata, shows a number of biological activities Thus anti-feedant effects on larvae of Japanese Pieris species, inhibition of root growth (10 -10 Mol) in the cress (Lepidium sativum), and promotion of germination (10 -10" Mol) of wheat seeds have been reported. Ut. J. Hattori Bot. Lab. 39,215 (1975). Zinsmeister Mues (eds.), Bryophytes, their Chemistry and Chemotaxonomy (Proc. Phytochem. Soc. Eur. 29), p. 399,404, Oxford Clarendon Press 1990. 

F. Kremer, A. Poglitch, L. Santo, D. Sperher, and L. Genzel, Low Intensity Millimeter Waves Inhibit the Growth of Cress Roots, Z. S. Naturf. C. (in print). 

The mode of action of file phenylthiazolines has been investigated by looking for file accumulation of metabolic intermediates in chlorotic cress leaves. Treated plants showed an increase in levels of a compound that can not be observed in controls, identified by UV spectroscopy and HPLC cochromatography with an authentic phytoene. The latter has been produced by the application of file known carotenoid synthesis inhibitors such as flurtamon and identified independently by UV and mass spectroscopy. From these results, it can be assumed that chlorosis is caused by inhibition of carotenoid synthesis at the phytoene desaturase step. 

The ecotoxicological impact of lactic acid-based polymers was evaluated by biotests, i.e. by the Flash test, measuring the inhibition of light production of Vibrio fisheri, and by plant growth tests with cress, radish, and barley [16]. Poly(lactic acid)s, poly(esterurethane)s... 

Research results have shown that inhibition results obtained from soil samples after the degradation of polymers, using the three most commonly used species, i.e., cress, millet and rape, may differ greatly. In our group, we found that the typical physical and chemical parameters of such soil samples did not correlate strictly with the measured inhibition values. Some of the substances responsible for the effects may not be detected by conventional soil analysis and remain unknown. Following Chen and Inbar [66], and interpreting results obtained by our group [67] the most probable causes may be ... 

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