Alessandra Bonetti | Consiglio Nazionale delle Ricerche (CNR) (original) (raw)

Papers by Alessandra Bonetti

Research paper thumbnail of Composition and content of seed flavonoids in forage and grain legume crops

Journal of Separation Science, 2007

Flavonoid content and composition in 124 accessions of forage and grain legumes was assessed by m... more Flavonoid content and composition in 124 accessions of forage and grain legumes was assessed by means of HPLC-DAD and HPLC-ESI-MS analyses of seed extracts. Excluding soybean, only 7 out of 77 grain legume accessions exhibited a total flavonoid content higher than 0.1 mg/g fresh seed weight (mean content 0.33 l 0.31 mg/ g fresh seed weight); while in 38 out of 47 forage legume, the mean flavonoid content was 1.49 l 0.89 mg/g fresh seed weight. On the basis of their higher seed flavonoid content and agronomic relevance, two grain and five forage legume accessions were selected for further HPLC-ESI-MS analyses aimed to identify bioactive compounds. Chemical analysis of the selected accessions permitted the identification of several flavonoids with pharmaceutical properties such as vitexin in Vigna angularis and Trigonella foenum-graecum, quercetin in all Trifolium spp and Medicago sativa, taxifolin in Trifolium pratense and Trifolium alexandrinum, myricetin in Trifolium repens, kaempferol in Phaseolus vulgaris and T. repens and luteolin in M. sativa and T. alexandrinum. Since much of literature information is regarding flavonoid content and composition of the green part of legume species, the obtained results contributed to fill the gap in knowledge about flavonoid content at the seed level.

Research paper thumbnail of Separation and detection of herbicides in water by micellar electrokinetic capillary chromatography

Journal of Chromatography B: Biomedical Sciences and Applications, 1994

The herbicides linuron, metolachlor, atrazine and metsulfuron were analysed using micellar electr... more The herbicides linuron, metolachlor, atrazine and metsulfuron were analysed using micellar electrokinetic capillary chromatography (MECC) after a lOOO-fold concentration step by solid-phase extraction (SPE). Recoveries ranged from 80 to 92%, depending on the concentration and the number of active substances in the sample. Furthermore, the hydrolysis products of metsulfuron were analysed by MECC and by gas chromatography-mass spectrometry (GC-MS). Representative MECC and GC-MS profiles are shown and the structures of the hydrolysis products are proposed on the basis of their chromatographic and mass spectra features. A tentative pathway for the degradation of metsulfuron is proposed.

Research paper thumbnail of Composition and content of seed flavonoids in forage and grain legume crops

Journal of Separation Science, 2007

Flavonoid content and composition in 124 accessions of forage and grain legumes was assessed by m... more Flavonoid content and composition in 124 accessions of forage and grain legumes was assessed by means of HPLC-DAD and HPLC-ESI-MS analyses of seed extracts. Excluding soybean, only 7 out of 77 grain legume accessions exhibited a total flavonoid content higher than 0.1 mg/g fresh seed weight (mean content 0.33 l 0.31 mg/ g fresh seed weight); while in 38 out of 47 forage legume, the mean flavonoid content was 1.49 l 0.89 mg/g fresh seed weight. On the basis of their higher seed flavonoid content and agronomic relevance, two grain and five forage legume accessions were selected for further HPLC-ESI-MS analyses aimed to identify bioactive compounds. Chemical analysis of the selected accessions permitted the identification of several flavonoids with pharmaceutical properties such as vitexin in Vigna angularis and Trigonella foenum-graecum, quercetin in all Trifolium spp and Medicago sativa, taxifolin in Trifolium pratense and Trifolium alexandrinum, myricetin in Trifolium repens, kaempferol in Phaseolus vulgaris and T. repens and luteolin in M. sativa and T. alexandrinum. Since much of literature information is regarding flavonoid content and composition of the green part of legume species, the obtained results contributed to fill the gap in knowledge about flavonoid content at the seed level.

Research paper thumbnail of Characterization of Italian populations of Lolium spp. resistant and susceptible to diclofop by inter simple sequence repeat

Weed Science, 2004

... At the genus level, four (LOL2 900 bp; LOL 2 1,000 bp; LOL4 700 bp; LOL9 700 bp), two (LOL2 1... more ... At the genus level, four (LOL2 900 bp; LOL 2 1,000 bp; LOL4 700 bp; LOL9 700 bp), two (LOL2 1,600 bp; LOL9 1,300 bp), and one (LOL4 1,500 bp) ISSR fragments were exclusively detected in all analyzed Lolium, Festuca, and Festulolium samples, re-...

Research paper thumbnail of Micellar electrokinetic capillary chromatography analysis of water-soluble vitamins and multi-vitamin integrators

Electrophoresis, 1994

Micellar electrokinetic capillary chromatography (MECC) was applied to the determination of water... more Micellar electrokinetic capillary chromatography (MECC) was applied to the determination of water-soluble vitamins (WSV) in pharmaceutical preparations. The analytical procedure employed in the WSV separation by MECC showed a satisfactory average column efficiency (195000 N) and resolution (more than 100 theoretical peaks separable). The mean reproducibility in the retention time of consecutive and day-to-day runs was 1.1% and 5.1%, respectively. Analyses were performed after extraction of active ingredients by solid phase extraction. Recoveries (92–103%) and relative variation coefficients (less than 5%) confirmed the potential of MECC in the field of pharmaceutical analysis.

Research paper thumbnail of Compared Use of HPLC and FZCE for Cluster Analysis of Triticum spp and for the Identification of T. durum Adulteration

Journal of Agricultural and Food Chemistry, 2004

Wheat quality criteria continually evolve in response to market pressure and consumer preference.... more Wheat quality criteria continually evolve in response to market pressure and consumer preference. Characterization of cereal cultivars for quality and agronomic properties, have widely shown the importance of the protein content to ensure good quality products. The aim of this work is a comparison of reversed-phase high performance liquid chromatography (RP-HPLC) and free zone capillary electrophoresis (FZCE) in the identification of Italian wheat cultivars and detection of durum wheat flour adulteration. Mainly alcohol soluble (gliadins) and water soluble (albumins) proteins were extracted from 14 common wheat cultivars and from 9 durum wheat cultivars. In RP-HPLC chromatograms, wheat albumins and gliadins eluted between 3 and 9 min and between 10 and 42 min, respectively. Even if the chosen chromatographic conditions (reversed phase) did not permit a complete resolution of hydrophilic proteins such as albumins, a good reproducibility was observed for both albumins and gliadins. In FZCE electropherograms, wheat albumins and gliadins migrated between 8 and 14 min and 16-25 min, respectively. A good reproducibility was found for wheat albumins, while the relatively poor reproducibility of gliadin fractions was a consequence of the selected separation conditions aimed to separate in the same run either hydrophilic (albumins) and alcohol-soluble (gliadins) proteins. The principal component analysis (PCA) of HPLC and FZCE data evidenced that both techniques allowed the univocal identification of the great proportion of investigated wheat cultivars. Three peaks were exclusively detected in RP-HPLC chromatograms of common wheat cultivars, while three unique peaks were found in FZCE electropherograms of common wheat cultivars. These peaks were investigated as a basis for detecting and estimating the adulteration of durum wheat flour with flour from common wheat. The direct relationship between the area of the peaks and adulteration level enabled standard curves to be constructed. The standard curves showed that adulteration may be quantified by either RP-HPLC or FZCE.

Research paper thumbnail of Comparison of Capillary Electrophoresis, HPLC, and Enzyme Immunoassay for Terbuthylazine Detection in Water

Journal of Agricultural and Food Chemistry, 1995

Tap water and groundwater samples spiked with terbuthylazine were analyzed by capillary electroph... more Tap water and groundwater samples spiked with terbuthylazine were analyzed by capillary electrophoresis (CE), HPLC, and a commercial enzyme immunoassay kit. Over the range of concentrations tested (0.2-2.4 pg L-l), the results obtained by the different methods were highly correlated. CE proved to be viable for the detection of terbuthylazine, with good resolution and reproducibility. The detection limit of CE is higher than that of HPLC to detect the lowest concentration of terbuthylazine (0.2 pg L-l), but retention times were shorter. Compared to enzyme immunoassay, CE and HPLC needed sample extraction and concentration before analysis but showed higher accuracy and lower variation. Ulrich, P.; Weil, L.; Niessner, R. Rapid fluorescence immunoassay (FIA) for the determination of terbuthylazine.

Research paper thumbnail of Physiological and molecular bases of glyphosate resistance in Conyza bonariensis biotypes from Spain

Weed Research, 2008

The physiological and molecular bases of glyphosate resistance in one susceptible (S) and four re... more The physiological and molecular bases of glyphosate resistance in one susceptible (S) and four resistant (R) Conyza bonariensis biotypes (sampled in orchards from Andalusia, Spain) were investigated. Resistance index (RI) values of the four R biotypes ranged between 2.9 and 5.6. The main physiological difference between S and R biotypes was the dissimilar mobility of glyphosate in the whole plant. In R biotypes, the herbicide was translocated less from leaves to culm and root, and more from culm to leaves compared with the S biotype. The upward mobility of glyphosate via xylem suggests that the herbicide may be sequestered to the apoplast or the vacuole. The hypothesis of an insensitive 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) was provisionally discarded on the basis of shikimate accumulation in R plant tissues after glyphosate treatment. At the molecular level, the relative abundance of EPSPS mRNA prior to glyphosate treatment was approximately double in two R biotypes compared with the S standard and the other R biotypes. Moreover, the two R biotypes having both no translocation and doubled EPSPS mRNA levels had also the highest RI. These results suggest that two factors may be related to glyphosate resistance in the R biotypes: (i) impaired translocation and (ii) high basal EPSPS transcript levels. The comparison between these findings and earlier results on glyphosate resistance mechanism in Conyza canadensis biotypes from the USA, suggests that similar agronomic factors (repeated application of glyphosate, no crop and herbicide rotation, no tillage) have selected similar traits on different genetic pools of the resistance-prone Conyza genus.

Research paper thumbnail of Content of flavonols in Italian bean ( Phaseolus vulgaris L.) ecotypes

Food Chemistry, 2006

Methanol extracts of seeds from 23 accessions of 3 Phaseolus vulgaris ecotypes (''Sarconi'', ''La... more Methanol extracts of seeds from 23 accessions of 3 Phaseolus vulgaris ecotypes (''Sarconi'', ''Lamon'', ''Zolfino del Pratomagno''), grown in different Italian regions (Basilicata, Veneto, Tuscany) were analyzed for their flavonoid content. Flavonoid glycosides were found in the seed coat from ten accessions of the ''Zolfino'' ecotype and in one accession of the ''Sarconi'' ecotype. From highest to lowest concentration these compounds were kaempferol 3-O-glucoside (compound 2), kaempferol 3-O-xylosylglucoside (compound 1) and a not completely identified kaempferol monoglucoside (compound 3). Total flavonol content varied from 0.19 to 0.84 g/kg of seed fresh weight. A great variability in the total flavonol content, being between 18% and 50%, and in the relative abundance of different kaempferol derivatives was observed for the same genotypes sampled in the original locations in the 2001-2003 period. Fluctuation in flavonol content suggests that further researches are necessary for an exhaustive comprehension of physiological mechanisms influencing the expression of these phenolic compounds. Obtained results evidenced that some Italian bean ecotypes may be an important source of functional compounds as kaempferol glycosides.

Research paper thumbnail of Separation of sulfonylurea metabolites in water by capillary electrophoresis

Journal of Chromatography A, 1995

The potential of capillary electrophoresis (CE) for the separation and detection of the metabolit... more The potential of capillary electrophoresis (CE) for the separation and detection of the metabolites of nine sulfonylurea herbicides in aqueous solution was evaluated. A relationship between the structure of the sulfonylureas tested and the metabolites formed was found: the non-o-benzene-substituted sulfonylurea rimsulfuron gave only one metabolite, whereas the other eight, o-benzene-substituted, sulfonylureas gave 4-6 metabolites. CE was confirmed to be a very efficient separation technique, suitable for the determination of sulfonylurea herbicides and their metabolites formed during hydrolysis.

Research paper thumbnail of Physiological and molecular insight on the mechanisms of resistance to glyphosate in Conyza canadensis (L.) Cronq. biotypes

Pesticide Biochemistry and Physiology, 2006

The physiological and molecular basis of glyphosate resistance in susceptible (S) and resistant (... more The physiological and molecular basis of glyphosate resistance in susceptible (S) and resistant (R) horseweed (Conyza canadensis (L.) Cronq.) populations collected from regions across the USA (Arkansas, Delaware, Ohio, Virginia, Washington) was investigated. At twoleaf stage approximately the same ED 50 values were observed for the S and R populations, while at the rosette stage the R biotypes were approximately three times more resistant than the S biotypes. After treatment with severe glyphosate doses (more than 1· the recommended field rate), different morphological responses in R and S biotypes were observed. In S biotypes, the first phytotoxic effects were found in the meristematic tissues, while in the R biotypes the first phytotoxic effects were observed in leaves. At 2 to 4 weeks after the treatment, R plants recovered by emitting new leaves and/or new branches from the center of the rosette. A significant increase of the mean number of branches per surviving R plants as a function of glyphosate-applied dose was observed. As regards the physiological mechanism of resistance, the main difference between R and S biotypes was the dissimilar mobility of glyphosate in the whole plant. In the R biotypes the herbicide was less translocated in the downward direction (from leaves to roots) and more translocated in the upward direction (from culm to leaves) with respect to the S biotypes. Finally, in R biotypes the relative level of EPSPS mRNA was from 1.8 to 3.1 times higher than that found in S biotypes. On the basis of obtained results three factors may concur to glyphosate resistance in the investigated R biotypes: impaired translocation of the herbicide, increase in EPSP synthase transcript levels, and enhanced ramification.

Research paper thumbnail of Evaluation of Bt-toxin uptake by the non-target herbivore, Myzus persicae (Hemiptera: Aphididae), feeding on transgenic oilseed rape

Bulletin of Entomological Research, 2007

As consequence of the concern about the biosafety of genetically modified plants, biological and ... more As consequence of the concern about the biosafety of genetically modified plants, biological and ecological studies are considered crucial for environmental risk assessment. Laboratory experiments were carried out in order to evaluate the transfer of the Cry1Ac Bt-toxin from a transgenic Bt-oilseed rape to a non-target pest, Myzus persicae Sulzer. Cry1Ac protein levels in plants and aphids were determined using a double sandwich enzyme-linked immunosorbent assay. Phloem sap from (Bt+) and (Btx) oilseed rape plants was collected from leaves using a standard method of extraction in an EDTA buffer. Bt-toxin was present in phloem sap, with a mean concentration of 2.7+1.46 ppb, corresponding to a 24-fold lower level than in oilseed rape leaves. Toxin was also detected in aphid samples, with a mean concentration in the positive samples of 2.0+0.8 ppb. The evidence that Bt-toxin remains in herbivores, in this case an aphid, could be useful to clarify functional aspects linked to possible consequences of Bt-crops on food chains involving herbivore-natural enemy trophic systems. Further studies are needed in order to improve the knowledge on the functional aspects linked to the transfer of the Cry1Ac Bt-toxin from GM-oilseed rape to aphids and their possible consequence.

Research paper thumbnail of High-performance liquid chromatographic determination of sulfonylureas in soil and water

Journal of Chromatography A, 1995

Isocratic and gradient conditions for the separation of four sulfonylurea herbicides, namely chlo... more Isocratic and gradient conditions for the separation of four sulfonylurea herbicides, namely chlorsulfuron, metsulfuron, chlorimuron and thifensulfuron, by reversed-phase high-performance liquid chromatography (HPLC) on C 6 and C~8 columns were established. Liquid-liquid (LL) and solid-phase extraction (SPE) procedures for the extraction and concentration of the herbicides from water and soil samples were tested. LL and SPE recoveries, HPLC detection limits and repeatability and dependence of the capacity factor on mobile phase composition are discussed. Typical chromatograms are shown.

Research paper thumbnail of Germination ecology, emergence and host detection in Cuscuta campestris

Weed Research, 2005

Trials were carried out to study the germination and dormancy of Cuscuta campestris Y. (dodder) s... more Trials were carried out to study the germination and dormancy of Cuscuta campestris Y. (dodder) seeds and factors influencing the success of early parasitisation of sugarbeet. Primary dormancy can be removed by seed scarification. Germination was negligible at 10°C and optimal at 30°C, while it was not influenced by light. Seed burial induced a cycle of induction and breaking of secondary dormancy. Seedling emergence was inversely proportional to the depth of seed burial and only seed buried within 5 cm of the soil surface emerged. Storage of C. campestris seeds in a laboratory for 12 years resulted in the loss of primary dormancy, enabling the germination of all viable seeds. Host infection (i.e. protrusion of parasite haustoria from host tissue) was heavily influenced by host growth stage. Tropism towards a host was due to the perception of light transmitted by green parts of sugarbeet plants. Insertion of a transparent glass sheet between host leaves and parasite seedlings did not modify this response. This phototropism permitted Cuscuta to identify host plants with high chlorophyll content as a function of the lower red/far red ratio of transmitted light.

Research paper thumbnail of Hydrolytic Dissipation of Four Sulfonylurea Herbicides

Journal of Agricultural and Food Chemistry, 1997

ABSTRACT

Research paper thumbnail of Composition and content of seed flavonoids in forage and grain legume crops

Journal of Separation Science, 2007

Flavonoid content and composition in 124 accessions of forage and grain legumes was assessed by m... more Flavonoid content and composition in 124 accessions of forage and grain legumes was assessed by means of HPLC-DAD and HPLC-ESI-MS analyses of seed extracts. Excluding soybean, only 7 out of 77 grain legume accessions exhibited a total flavonoid content higher than 0.1 mg/g fresh seed weight (mean content 0.33 l 0.31 mg/ g fresh seed weight); while in 38 out of 47 forage legume, the mean flavonoid content was 1.49 l 0.89 mg/g fresh seed weight. On the basis of their higher seed flavonoid content and agronomic relevance, two grain and five forage legume accessions were selected for further HPLC-ESI-MS analyses aimed to identify bioactive compounds. Chemical analysis of the selected accessions permitted the identification of several flavonoids with pharmaceutical properties such as vitexin in Vigna angularis and Trigonella foenum-graecum, quercetin in all Trifolium spp and Medicago sativa, taxifolin in Trifolium pratense and Trifolium alexandrinum, myricetin in Trifolium repens, kaempferol in Phaseolus vulgaris and T. repens and luteolin in M. sativa and T. alexandrinum. Since much of literature information is regarding flavonoid content and composition of the green part of legume species, the obtained results contributed to fill the gap in knowledge about flavonoid content at the seed level.

Research paper thumbnail of Separation and detection of herbicides in water by micellar electrokinetic capillary chromatography

Journal of Chromatography B: Biomedical Sciences and Applications, 1994

The herbicides linuron, metolachlor, atrazine and metsulfuron were analysed using micellar electr... more The herbicides linuron, metolachlor, atrazine and metsulfuron were analysed using micellar electrokinetic capillary chromatography (MECC) after a lOOO-fold concentration step by solid-phase extraction (SPE). Recoveries ranged from 80 to 92%, depending on the concentration and the number of active substances in the sample. Furthermore, the hydrolysis products of metsulfuron were analysed by MECC and by gas chromatography-mass spectrometry (GC-MS). Representative MECC and GC-MS profiles are shown and the structures of the hydrolysis products are proposed on the basis of their chromatographic and mass spectra features. A tentative pathway for the degradation of metsulfuron is proposed.

Research paper thumbnail of Composition and content of seed flavonoids in forage and grain legume crops

Journal of Separation Science, 2007

Flavonoid content and composition in 124 accessions of forage and grain legumes was assessed by m... more Flavonoid content and composition in 124 accessions of forage and grain legumes was assessed by means of HPLC-DAD and HPLC-ESI-MS analyses of seed extracts. Excluding soybean, only 7 out of 77 grain legume accessions exhibited a total flavonoid content higher than 0.1 mg/g fresh seed weight (mean content 0.33 l 0.31 mg/ g fresh seed weight); while in 38 out of 47 forage legume, the mean flavonoid content was 1.49 l 0.89 mg/g fresh seed weight. On the basis of their higher seed flavonoid content and agronomic relevance, two grain and five forage legume accessions were selected for further HPLC-ESI-MS analyses aimed to identify bioactive compounds. Chemical analysis of the selected accessions permitted the identification of several flavonoids with pharmaceutical properties such as vitexin in Vigna angularis and Trigonella foenum-graecum, quercetin in all Trifolium spp and Medicago sativa, taxifolin in Trifolium pratense and Trifolium alexandrinum, myricetin in Trifolium repens, kaempferol in Phaseolus vulgaris and T. repens and luteolin in M. sativa and T. alexandrinum. Since much of literature information is regarding flavonoid content and composition of the green part of legume species, the obtained results contributed to fill the gap in knowledge about flavonoid content at the seed level.

Research paper thumbnail of Characterization of Italian populations of Lolium spp. resistant and susceptible to diclofop by inter simple sequence repeat

Weed Science, 2004

... At the genus level, four (LOL2 900 bp; LOL 2 1,000 bp; LOL4 700 bp; LOL9 700 bp), two (LOL2 1... more ... At the genus level, four (LOL2 900 bp; LOL 2 1,000 bp; LOL4 700 bp; LOL9 700 bp), two (LOL2 1,600 bp; LOL9 1,300 bp), and one (LOL4 1,500 bp) ISSR fragments were exclusively detected in all analyzed Lolium, Festuca, and Festulolium samples, re-...

Research paper thumbnail of Micellar electrokinetic capillary chromatography analysis of water-soluble vitamins and multi-vitamin integrators

Electrophoresis, 1994

Micellar electrokinetic capillary chromatography (MECC) was applied to the determination of water... more Micellar electrokinetic capillary chromatography (MECC) was applied to the determination of water-soluble vitamins (WSV) in pharmaceutical preparations. The analytical procedure employed in the WSV separation by MECC showed a satisfactory average column efficiency (195000 N) and resolution (more than 100 theoretical peaks separable). The mean reproducibility in the retention time of consecutive and day-to-day runs was 1.1% and 5.1%, respectively. Analyses were performed after extraction of active ingredients by solid phase extraction. Recoveries (92–103%) and relative variation coefficients (less than 5%) confirmed the potential of MECC in the field of pharmaceutical analysis.

Research paper thumbnail of Compared Use of HPLC and FZCE for Cluster Analysis of Triticum spp and for the Identification of T. durum Adulteration

Journal of Agricultural and Food Chemistry, 2004

Wheat quality criteria continually evolve in response to market pressure and consumer preference.... more Wheat quality criteria continually evolve in response to market pressure and consumer preference. Characterization of cereal cultivars for quality and agronomic properties, have widely shown the importance of the protein content to ensure good quality products. The aim of this work is a comparison of reversed-phase high performance liquid chromatography (RP-HPLC) and free zone capillary electrophoresis (FZCE) in the identification of Italian wheat cultivars and detection of durum wheat flour adulteration. Mainly alcohol soluble (gliadins) and water soluble (albumins) proteins were extracted from 14 common wheat cultivars and from 9 durum wheat cultivars. In RP-HPLC chromatograms, wheat albumins and gliadins eluted between 3 and 9 min and between 10 and 42 min, respectively. Even if the chosen chromatographic conditions (reversed phase) did not permit a complete resolution of hydrophilic proteins such as albumins, a good reproducibility was observed for both albumins and gliadins. In FZCE electropherograms, wheat albumins and gliadins migrated between 8 and 14 min and 16-25 min, respectively. A good reproducibility was found for wheat albumins, while the relatively poor reproducibility of gliadin fractions was a consequence of the selected separation conditions aimed to separate in the same run either hydrophilic (albumins) and alcohol-soluble (gliadins) proteins. The principal component analysis (PCA) of HPLC and FZCE data evidenced that both techniques allowed the univocal identification of the great proportion of investigated wheat cultivars. Three peaks were exclusively detected in RP-HPLC chromatograms of common wheat cultivars, while three unique peaks were found in FZCE electropherograms of common wheat cultivars. These peaks were investigated as a basis for detecting and estimating the adulteration of durum wheat flour with flour from common wheat. The direct relationship between the area of the peaks and adulteration level enabled standard curves to be constructed. The standard curves showed that adulteration may be quantified by either RP-HPLC or FZCE.

Research paper thumbnail of Comparison of Capillary Electrophoresis, HPLC, and Enzyme Immunoassay for Terbuthylazine Detection in Water

Journal of Agricultural and Food Chemistry, 1995

Tap water and groundwater samples spiked with terbuthylazine were analyzed by capillary electroph... more Tap water and groundwater samples spiked with terbuthylazine were analyzed by capillary electrophoresis (CE), HPLC, and a commercial enzyme immunoassay kit. Over the range of concentrations tested (0.2-2.4 pg L-l), the results obtained by the different methods were highly correlated. CE proved to be viable for the detection of terbuthylazine, with good resolution and reproducibility. The detection limit of CE is higher than that of HPLC to detect the lowest concentration of terbuthylazine (0.2 pg L-l), but retention times were shorter. Compared to enzyme immunoassay, CE and HPLC needed sample extraction and concentration before analysis but showed higher accuracy and lower variation. Ulrich, P.; Weil, L.; Niessner, R. Rapid fluorescence immunoassay (FIA) for the determination of terbuthylazine.

Research paper thumbnail of Physiological and molecular bases of glyphosate resistance in Conyza bonariensis biotypes from Spain

Weed Research, 2008

The physiological and molecular bases of glyphosate resistance in one susceptible (S) and four re... more The physiological and molecular bases of glyphosate resistance in one susceptible (S) and four resistant (R) Conyza bonariensis biotypes (sampled in orchards from Andalusia, Spain) were investigated. Resistance index (RI) values of the four R biotypes ranged between 2.9 and 5.6. The main physiological difference between S and R biotypes was the dissimilar mobility of glyphosate in the whole plant. In R biotypes, the herbicide was translocated less from leaves to culm and root, and more from culm to leaves compared with the S biotype. The upward mobility of glyphosate via xylem suggests that the herbicide may be sequestered to the apoplast or the vacuole. The hypothesis of an insensitive 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) was provisionally discarded on the basis of shikimate accumulation in R plant tissues after glyphosate treatment. At the molecular level, the relative abundance of EPSPS mRNA prior to glyphosate treatment was approximately double in two R biotypes compared with the S standard and the other R biotypes. Moreover, the two R biotypes having both no translocation and doubled EPSPS mRNA levels had also the highest RI. These results suggest that two factors may be related to glyphosate resistance in the R biotypes: (i) impaired translocation and (ii) high basal EPSPS transcript levels. The comparison between these findings and earlier results on glyphosate resistance mechanism in Conyza canadensis biotypes from the USA, suggests that similar agronomic factors (repeated application of glyphosate, no crop and herbicide rotation, no tillage) have selected similar traits on different genetic pools of the resistance-prone Conyza genus.

Research paper thumbnail of Content of flavonols in Italian bean ( Phaseolus vulgaris L.) ecotypes

Food Chemistry, 2006

Methanol extracts of seeds from 23 accessions of 3 Phaseolus vulgaris ecotypes (''Sarconi'', ''La... more Methanol extracts of seeds from 23 accessions of 3 Phaseolus vulgaris ecotypes (''Sarconi'', ''Lamon'', ''Zolfino del Pratomagno''), grown in different Italian regions (Basilicata, Veneto, Tuscany) were analyzed for their flavonoid content. Flavonoid glycosides were found in the seed coat from ten accessions of the ''Zolfino'' ecotype and in one accession of the ''Sarconi'' ecotype. From highest to lowest concentration these compounds were kaempferol 3-O-glucoside (compound 2), kaempferol 3-O-xylosylglucoside (compound 1) and a not completely identified kaempferol monoglucoside (compound 3). Total flavonol content varied from 0.19 to 0.84 g/kg of seed fresh weight. A great variability in the total flavonol content, being between 18% and 50%, and in the relative abundance of different kaempferol derivatives was observed for the same genotypes sampled in the original locations in the 2001-2003 period. Fluctuation in flavonol content suggests that further researches are necessary for an exhaustive comprehension of physiological mechanisms influencing the expression of these phenolic compounds. Obtained results evidenced that some Italian bean ecotypes may be an important source of functional compounds as kaempferol glycosides.

Research paper thumbnail of Separation of sulfonylurea metabolites in water by capillary electrophoresis

Journal of Chromatography A, 1995

The potential of capillary electrophoresis (CE) for the separation and detection of the metabolit... more The potential of capillary electrophoresis (CE) for the separation and detection of the metabolites of nine sulfonylurea herbicides in aqueous solution was evaluated. A relationship between the structure of the sulfonylureas tested and the metabolites formed was found: the non-o-benzene-substituted sulfonylurea rimsulfuron gave only one metabolite, whereas the other eight, o-benzene-substituted, sulfonylureas gave 4-6 metabolites. CE was confirmed to be a very efficient separation technique, suitable for the determination of sulfonylurea herbicides and their metabolites formed during hydrolysis.

Research paper thumbnail of Physiological and molecular insight on the mechanisms of resistance to glyphosate in Conyza canadensis (L.) Cronq. biotypes

Pesticide Biochemistry and Physiology, 2006

The physiological and molecular basis of glyphosate resistance in susceptible (S) and resistant (... more The physiological and molecular basis of glyphosate resistance in susceptible (S) and resistant (R) horseweed (Conyza canadensis (L.) Cronq.) populations collected from regions across the USA (Arkansas, Delaware, Ohio, Virginia, Washington) was investigated. At twoleaf stage approximately the same ED 50 values were observed for the S and R populations, while at the rosette stage the R biotypes were approximately three times more resistant than the S biotypes. After treatment with severe glyphosate doses (more than 1· the recommended field rate), different morphological responses in R and S biotypes were observed. In S biotypes, the first phytotoxic effects were found in the meristematic tissues, while in the R biotypes the first phytotoxic effects were observed in leaves. At 2 to 4 weeks after the treatment, R plants recovered by emitting new leaves and/or new branches from the center of the rosette. A significant increase of the mean number of branches per surviving R plants as a function of glyphosate-applied dose was observed. As regards the physiological mechanism of resistance, the main difference between R and S biotypes was the dissimilar mobility of glyphosate in the whole plant. In the R biotypes the herbicide was less translocated in the downward direction (from leaves to roots) and more translocated in the upward direction (from culm to leaves) with respect to the S biotypes. Finally, in R biotypes the relative level of EPSPS mRNA was from 1.8 to 3.1 times higher than that found in S biotypes. On the basis of obtained results three factors may concur to glyphosate resistance in the investigated R biotypes: impaired translocation of the herbicide, increase in EPSP synthase transcript levels, and enhanced ramification.

Research paper thumbnail of Evaluation of Bt-toxin uptake by the non-target herbivore, Myzus persicae (Hemiptera: Aphididae), feeding on transgenic oilseed rape

Bulletin of Entomological Research, 2007

As consequence of the concern about the biosafety of genetically modified plants, biological and ... more As consequence of the concern about the biosafety of genetically modified plants, biological and ecological studies are considered crucial for environmental risk assessment. Laboratory experiments were carried out in order to evaluate the transfer of the Cry1Ac Bt-toxin from a transgenic Bt-oilseed rape to a non-target pest, Myzus persicae Sulzer. Cry1Ac protein levels in plants and aphids were determined using a double sandwich enzyme-linked immunosorbent assay. Phloem sap from (Bt+) and (Btx) oilseed rape plants was collected from leaves using a standard method of extraction in an EDTA buffer. Bt-toxin was present in phloem sap, with a mean concentration of 2.7+1.46 ppb, corresponding to a 24-fold lower level than in oilseed rape leaves. Toxin was also detected in aphid samples, with a mean concentration in the positive samples of 2.0+0.8 ppb. The evidence that Bt-toxin remains in herbivores, in this case an aphid, could be useful to clarify functional aspects linked to possible consequences of Bt-crops on food chains involving herbivore-natural enemy trophic systems. Further studies are needed in order to improve the knowledge on the functional aspects linked to the transfer of the Cry1Ac Bt-toxin from GM-oilseed rape to aphids and their possible consequence.

Research paper thumbnail of High-performance liquid chromatographic determination of sulfonylureas in soil and water

Journal of Chromatography A, 1995

Isocratic and gradient conditions for the separation of four sulfonylurea herbicides, namely chlo... more Isocratic and gradient conditions for the separation of four sulfonylurea herbicides, namely chlorsulfuron, metsulfuron, chlorimuron and thifensulfuron, by reversed-phase high-performance liquid chromatography (HPLC) on C 6 and C~8 columns were established. Liquid-liquid (LL) and solid-phase extraction (SPE) procedures for the extraction and concentration of the herbicides from water and soil samples were tested. LL and SPE recoveries, HPLC detection limits and repeatability and dependence of the capacity factor on mobile phase composition are discussed. Typical chromatograms are shown.

Research paper thumbnail of Germination ecology, emergence and host detection in Cuscuta campestris

Weed Research, 2005

Trials were carried out to study the germination and dormancy of Cuscuta campestris Y. (dodder) s... more Trials were carried out to study the germination and dormancy of Cuscuta campestris Y. (dodder) seeds and factors influencing the success of early parasitisation of sugarbeet. Primary dormancy can be removed by seed scarification. Germination was negligible at 10°C and optimal at 30°C, while it was not influenced by light. Seed burial induced a cycle of induction and breaking of secondary dormancy. Seedling emergence was inversely proportional to the depth of seed burial and only seed buried within 5 cm of the soil surface emerged. Storage of C. campestris seeds in a laboratory for 12 years resulted in the loss of primary dormancy, enabling the germination of all viable seeds. Host infection (i.e. protrusion of parasite haustoria from host tissue) was heavily influenced by host growth stage. Tropism towards a host was due to the perception of light transmitted by green parts of sugarbeet plants. Insertion of a transparent glass sheet between host leaves and parasite seedlings did not modify this response. This phototropism permitted Cuscuta to identify host plants with high chlorophyll content as a function of the lower red/far red ratio of transmitted light.

Research paper thumbnail of Hydrolytic Dissipation of Four Sulfonylurea Herbicides

Journal of Agricultural and Food Chemistry, 1997

ABSTRACT