Lettuce root

The phenomenon of translocation within the plant has been widely studied and W. A. L. David, using 32P O.M.P.A. on broad beans, cabbage, hops, peas and strawberries has shown that the insecticide passes preferentially into the young parts of the plants, and upwards rather than downwards, although translocation in the downward direction does exist. Thus translocation of systemic insecticides has been attempted for the control of root aphis (e.g. lettuce root aphis). 

Small, yellow-white, wingless, waxy pests with dark spots on the abdomen, found among lettuce roots during summer. Overwinters mainly on Lombardy poplar, moving in June to lettuce and sow-thistle. Root colonies can persist into winter, and may survive in the soil until the next season. See a/so Aphids. 

A portion of the dried ether extract was fractionated on a Sephadex LH-20 chromatographic column. Lettuce root growth blo-assay showed significant activity (68% and 77% reduction of root elongation) In two fractions. Each of these fractions was seml-preparatlvely chromatographed on a silica HPLC column. Three phenolic compounds, hydroqulnone [V, 0.002%(w/w) of dry plant wt.], caffelc acid [VI, 0.012%(w/w)] and arbutln [VII, 0.034%(w/w)] were... 

Table I. The Effect of Small Everlasting Extracts on the Growth of Lettuce Roots and the Elongation of Leafy Spurge Roots...

Table II. The Effect of Chemical Constituents Occurring In Small Everlasting on the Growth of Lettuce Roots, Root Elongation and Cell Culture Growth of Leafy Spurge...

Phillips, S.W., Bale, J.S. and Tatchell, G.M. 1999. Escaping an ecological dead-end asexual overwintering and morph determination in the lettuce root aphid Pemphigus bursarius L. Ecological Entomology 24 336-344. 

Cyl-1 Cylindrocladium scoparium Inhibits lettuce root growth 181... 

Asparaguslc acid 5—S V COOH Etiolated asparagus shoots Inhibits lettuce root and.hypocotyl growth at 10 4M 186,187 188,189... 

Stiles et al.43 found artemisinin to inhibit respiration in Lemna minor, but the compound strongly stimulates oxygen uptake by lettuce root tips.6 All mitotic phases of onion root tips are inhibited by the compound, and it induces a low level of abnormal mitotic figures.6 Dayan et al.6 conducted a battery of simple physiological tests with several artemisinin analogues. All phytotoxic compounds had similar effects, indicating a common mode of action. In summary, the mode of action results with artemisinin as a phytotoxin are not definitive. 

Investigations carried out by our group34 to determine the effect of BOA on membrane permeability of lettuce roots showed an increase in the release of the ions studied (Fig. 12.2). This disruption was time dependent both for anions and for cations, showing a continuous time release and not a bolus effect. Significant increases in N03, P043, S042, Ca2+ or NH4+ release suggested an alteration in membrane permeability of lettuce root cells. 

Once clear inhibitory effects were detected on germination and radicle growth of lettuce plants exposed to BOA,12,35 our group developed methodology to show whether there is a detectable BOA effect on the cell cycle progression in lettuce root meristems.13 This allows a more detailed characterization of the putative direct or indirect effect on the meristems of BOA-treated seedlings. 

Mitotic indices were counted in the root tip cells from lettuce root meristems treated with 1 mM BOA (treated-meristems) or with distilled water (control-meristems) after 6 h HU synchronization (Fig. 12.3).36... 

Leafy (e.g., cabbages, lettuce) Root (e.g., carrots, parsnips, potatoes, onions, leeks)... 

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