Lettuce seeds

The cytolytic agent termed aponin has been characterized in terms of biological activity, and the results to date indicate a material that does not adversely affect the organisms tested. Material isolated from cultures of Nannochloris sp. also has some phytotoxic activity as evidenced by the assays with lettuce seeds, and some antifungal activity. The materials elaborated by Nannochloris sp. thus have environmental significance, but it must be admitted that the full significance of these materials, like others, remains to be fully appreciated. 

Assessment 3 days following treatment to dry lettuce seed. Four repetitions with 25 seeds per petri dish. Growth chamber at 25 C, 12 h light and 12 h dark periods. 

Air-dried aerial plant material was solvent extracted with hexane to remove nonpolar constituents and then extracted with water according to Scheme I. The water extract was llquld/liquid extracted with ethyl acetate. A lettuce seed bloassay of the crude ethyl acetate extract (EA) (dried vacuo) showed a 22% reduction of root elongation at 200 ppm. The organic extract was extracted with aqueous sodium bicarbonate to produce acidic and basic fractions which were neutralized and extracted with ethyl acetate to achieve neutralized acidic (NA) and neutralized basic (NB) fractions. 

Fraction NA (dried vacuo) maintained the previous level of phytotoxicity observed for fraction EA in a lettuce seed bioassay. 

Preparative chromatographic fractionation of NA yielded kaemferol 3-glucuronide (K-3-G), previously described in esula (16), and acid (11) as major constituents. Lettuce seed... 

Leafy Spurge Root Extractives. Prior chemical examinations of leafy spurge have considered only aerial portions of the plant. Our recent chemical examination of root material relative to mammalian toxicity and/or allelopathy (29) resulted in the isolation and characterization of two new jatrophane diterpenes (esulone A (IX) and esulone B (X)) from the ether extract of the roots. Biological assay of esulone A showed it to be moderately phytotoxic (29% root length reduction (lettuce seeds) at 250 ppm), moderately toxic (LD50 78 23 mg/kg) and mildly Inflammatory (10 5 to 10 M, dermal) to mammals with no hyperplasia. 

Experiments using a matrix of four levels of ferulic acid and four levels of moisture stress demonstrated that the combined action was additive under more stressful levels of the individual factors than in the previous tests. Duke et al. (23) tested the germination of lettuce seeds treated with phenolic acids (1 mM) at water potentials (D-mannitol) of 0, -0.2, -0.4, and -0.6 MPa. The combined action of low water potential and exposure to phenolic acids resulted in an additive detriment to germination, and the authors concluded from probit analysis that the mechanism of action from these sources was similar. Whatever their mechanisms, moisture stress and phenolic acids appear to work together in limiting growth of plants. 

Lactuca raddeana Maxim. L. indica L. L. sativa L. Shan Wo Ju (Lettuce) (seed) Pectic compound, oxalic acid, malic acid, citric acid, ceryl alcohol, ergosterol, vitamin E.50 Anodyne, lactogogue, for genital swelling, hemorrhoids, lumbago. 

Figure 3. The effect of wavelength on the germination of lettuce seeds which were initially irradiated to establish 50% germination. Additional red light (600-700 nm) further promotes germination most efficiently, whereas far-red light (700-750 nm) inhibits germination. (Action spectrum after Flint and Alister [15].)...

Sakamoto, A., Takeba, G., Shibata, D. Tanaka, K. (1990). Phytochrome-mediated activation of the gene for cytosolic glutamine synthetase (GSi) during inhibition of photosensitive lettuce seeds. Plant Molecular Biology 15, 317-23. 

Cytokinin activity can be assayed conveniently with several plant tissues, including soybean (54) and tobacco (55,56) callus, radish leaf discs (11,12) and lettuce seed (57). The first two of these are probably the most useful since they are not excessively sensitive to light or temperature (58,59) and reflect both cell enlargement and division (60). 

The accumulated assay results obtained with the 4-alkyl-2-methylpyrrolo[2,3-d]pyrimidines are of special interest. Can-pounds 25 and 26 exhibited significant cytokinin activity in all assays utilized. On the other hand, compound 27 was a potent antagonist in the tobacco bioassay but had little activity in the other two assay systems, while 29 acted as an anticytokinin in the tobacco bioassay and a cytokinin in the lettuce seed germination assay, but was without activity in the Amaranthus test system. 

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