Presence Of Plant Extracts Research Articles

Regulation of the expression of a pelA::uidA fusion in Erwinia chrysanthemi and demonstration of the synergistic action of plant extract with polygalacturonate on pectate lyase synthesis.

The phytopathogenicity of Erwinia chrysanthemi is chiefly supported by the production of pectate lyase isoenzymes, encoded by the pel genes. One of these enzymes, PelA, encoded by the pelA gene, seems to represent only a small part of the total pectate lyase activity, but is required for full bacterial pathogenicity. To study the regulation of pelA gene expression, a pelA::uidA gene fusion was constructed. Expression of this fusion was analysed under various growth conditions and in various genetic backgrounds. Whatever the culture conditions, the pelA gene was weakly expressed. Moreover, pelA expression seems not to be regulated by the pecS gene product, but essentially by the kdgR gene product. In many plant-associated bacteria, genes involved in pathogenicity are induced by certain plant compounds. In this work, we demonstrate that E. chrysanthemi pel genes are induced in the presence of plant extracts, but only in synergy with known pectate lyase inducers (KDG: 2-keto-3-deoxygluconate; DKII: 2,5-diketo-3-deoxygluconate). However, different pel genes did not exhibit the same sensitivity to plant signal molecules. Partial purification of inducing plant compounds suggested that plant extracts contain at least one molecule involved in pectate lyase induction. This compound is thermoresistant, and has a low molecular mass and a very hydrophilic behaviour.

A comparison of 3 reagents in converting thiamine to thiochrome in the presence of plant extracts and polyphenols

Assays of thiamine added to plant extracts, known polyphenols and reducing agents, using K3Fe(CN)6, HgCl2 and CNBr showed that the CNBr method was the least susceptible to redox interference and gave the highest thiochrome yield.

Consistency of Rst values of six organophosphorus pesticides resolved by thin-layer chromatography in the presence of plant extracts without elaborate clean-up.

This paper reports statistical analyses of the ratio of the distance travelled by each of five organophosphorus pesticides to that travelled by parathion in the presence of plant extracts, without elaborate clean-up. Mixtures of azinphos-methyl, carbophenothion, diazinon, ethion, malathion and mevinphos in the presence of apple, beet, carrot, lettuce or pea extracts were evaluated with reference to the parathion internal standard.

Comparison of Various Carbon Adsorbents and Quantitative Elution and Separation of Forty-two Pesticides from a Carbon-Solka Floe Cleanup Column

Abstract Ten different carbons were investigated as adsorbents in a column cleanup procedure for extracts of lettuce and carrots. Organochlorine pesticides were eluted with 175 nil of 1.5% acetonitrile in hexane. The quantitative elution of 13 pesticides as a mixture with and without the presence of carrot or lettuce extract was determined by gas-liquid chromatography (GLC) with electron capture detection (ECD). The mean recovery values for each pesticide from all carbons, excluding Norit A neutral, ranged from 87 to 106% with a coefficient of variation (C) of 3 to 11. In the presence of plant extracts the individual pesticide recoveries for 6 carbons ranged from 75 lo 99% with a C of 6 to 16. All pesticides from 9 individual carbons had mean recovery values ranging from 93 to 108% with a C of 5 to 10. In the presence of plant extracts these values were 81 to 100% with a C of 8 to 12. Four carbons (Darco G60, Darco S51, Nuchar C-190N, Norit FQP) were considered satisfactory in the cleanup procedure. The procedure was applied to quantitative elution of 42 pesticides representing insecticides, fungicides, and herbicides from a Darco G60-Solka Floe cleanup column. The mean per cent recoveries (3 determinations) ranged from 82 to 112 with C from 2 to 10 for 38 compounds. The mean per cent recovery of EPN was 108 with a C of 13. The per cent recoveries of three compounds were considered low: Thimet 72, Daconil 73, and Guthion 77. Twenty of the pesticides as three mixtures containing 2, 4, and 14 compounds were added to plant extracts of carrots, potatoes, wheat, and pineapples. The mean per cent recovery values ranged from 81 to 108 with a C range of 2 to 10 for 17 compounds

Insecticide Residues, Chromatographic Identification of Some Organophosphate Insecticides in the Presence of Plant Extracts

Insecticide Residues, Chromatographic Identification of Some Organophosphate Insecticides in the Presence of Plant Extracts