José Fenoll

Berry Flesh and Skin Ripening Features in Vitis vinifera as Assessed by Transcriptional Profiling

Background Ripening of fleshy fruit is a complex developmental process involving the differentiation of tissues with separate functions. During grapevine berry ripening important processes contributing to table and wine grape quality take place, some of them flesh- or skin-specific. In this study, transcriptional profiles throughout flesh and skin ripening were followed during two different seasons in a table grape cultivar ‘Muscat Hamburg’ to determine tissue-specific as well as common developmental programs. Methodology/Principal Findings Using an updated GrapeGen Affymetrix GeneChip® annotation based on grapevine 12×v1 gene predictions, 2188 differentially accumulated transcripts between flesh and skin and 2839 transcripts differentially accumulated throughout ripening in the same manner in both tissues were identified. Transcriptional profiles were dominated by changes at the beginning of veraison which affect both pericarp tissues, although frequently delayed or with lower intensity in the skin than in the flesh. Functional enrichment analysis identified the decay on biosynthetic processes, photosynthesis and transport as a major part of the program delayed in the skin. In addition, a higher number of functional categories, including several related to macromolecule transport and phenylpropanoid and lipid biosynthesis, were over-represented in transcripts accumulated to higher levels in the skin. Functional enrichment also indicated auxin, gibberellins and bHLH transcription factors to take part in the regulation of pre-veraison processes in the pericarp, whereas WRKY and C2H2 family transcription factors seems to more specifically participate in the regulation of skin and flesh ripening, respectively. Conclusions/Significance A transcriptomic analysis indicates that a large part of the ripening program is shared by both pericarp tissues despite some components are delayed in the skin. In addition, important tissue differences are present from early stages prior to the ripening onset including tissue-specific regulators. Altogether, these findings provide key elements to understand berry ripening and its differential regulation in flesh and skin.

Leaching potential of several insecticides and fungicides through disturbed clay-loam soil columns

A laboratory study was conducted in order to determine the leaching potential of five insecticides and six fungicides commonly used during pepper cultivation by use of disturbed soil columns. The tested compounds were pyridaben, pyriproxyfen, tebufenpyrad, buprofezin and pirimicarb (insecticides/acaricides) and azoxyxtrobin, kresoxim-methyl, hexaconazole, tebuconazole, triadimenol, and pyrimethanil (fungicides). For this purpose, 100 µg of each pesticide were added to columns (n = 5) filled with 150 g of a clay loam soil and leached with 600 mL of 0.01 M CaCl2 during 10 days. Finally, leachates and soil fractions were analysed for pesticide residues. For insecticides only pirimicarb was found in leachates (48% of the initial amount) while 55% was recovered from the soil layers. For the other studied insecticides, the percentage remaining in the top soil fraction was nearly the total amount added and therefore showing ‘non-leaching’ behaviour. In the case of fungicides 41% of triadimenol and 6% of pyrimethanil were found in leachates. The amount recovered in leachates for the other fungicides was lower than 2%, hexaconazole and tebuconazole exhibiting the higher retention on the upper layer of soil. Therefore, is extremely important to propose methods and conduct to avoid the potential adverse effect of pesticides behaving as ‘leacher’ compounds.

Solarization and biosolarization enhance fungicide dissipation in the soil

Although there is some evidence regarding the effect of solarization and biosolarization on pesticide degradation, information is still scarce. The aim of this study was to determine the effect of these disinfection techniques on the degradation of eight fungicides (azoxystrobin, kresoxin methyl, tebuconazole, hexaconazole, triadimenol, cyprodinil, pyrimethanil and fludioxonil) commonly used in pepper crops under greenhouse cultivation. Seventy-five 17-L pots filled with clay-loam soil were placed in a greenhouse during the summer season and then contaminated with the studied fungicides. Treatments consisted of different disinfection treatments, including a control without disinfection, solarization and biosolarization. For the solarization and biosolarization treatments, low-density polyethylene film was used as cover. Five pots per treatment were sampled periodically up to 90d after the beginning of each treatment and fungicide residues were analyzed by GC/MS. The results showed that both solarization and biosolarization enhanced fungicide dissipation rates with regard to the control treatment, an effect which was attributed to the increased soil temperature. Most of the fungicides studied showed similar behavior under solarization and biosolarization conditions. However, triadimenol was degraded to a greater extent in the biosolarization than in the solarization treatment, while fludioxonil behaved in the opposite way. The results confirm that both solarization and biosolarization contribute to pesticide dissipation and can therefore be considered alongside other soil disinfection techniques, as a bioremediation tool for pesticide-polluted soils.

Impact of biofumigation with solarization on degradation of pesticides and heavy metal accumulation.

A greenhouse study was conducted to evaluate the effect of biofumigation (with sheep and chicken manure) combined with solarization on the dissipation of pesticides (pyrifenox, DDT and dieldrin), and on soil metals accumulation. The treatments consisted of a control, and soil disinfestations by biofumigation combined with solarization (B+S) for two, four, five, six consecutive years. B+S enhanced the dissipation of pyrifenox with regard to control treatment. Significant differences were not detected among plots disinfected with B+S for consecutive years. On the other hand, B+S had no effect on the dissipation of DDT and dieldrin, probably due to the resistance of these pesticides to microbial degradation and/or high temperatures. Biofumigation is considered to be an environmentally safe practice, since no accumulation of heavy metals such as Cd, Co, Cu, Cr, Pb, Ni, or Zn was observed after the subsequent application of organic matter through the treatments.

Response of Pepper Plants to Different Rates of Mineral Fertilizers After Soil Biofumigation and Solarization

ABSTRACT A greenhouse experiment was conducted to examine the effect of using three different rates (zero, low-input, and high-input) of a mineral fertilizer (nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg)) on growth and yield of pepper cultivated in a soil after biofumigation (with horse manure at the rate of 4 kg· m− 2) and solarization. Several physiological traits related with pepper plant development (leaf mineral concentration, net photosynthesis rate, transpiration, leaf sugar, and chlorophyll concentration) and fruit yield were determined. In T-1, chlorophyll was significantly lower and sugar concentration was significantly higher than in those where mineral fertilizers had been added (T-2 and T-3). There were no significant differences in photosynthetic rate among treatments. Increasing mineral fertilizer rates increased vegetative growth at the expense of fruit yield. Leaf nutrient concentrations most affected by the treatments were the N-fractions, and changes in the other parameters measured are discussed on the basis of these differences.

Determination of oxadiazon and oxyfluorfen in thyme by gas chromatography with electron-capture detection and gas chromatography/mass spectrometry

The present paper reports on an analytical method for the routine analysis of oxadiazon (5-tert-butyl-3-(2,4-dichloro-5-isopropoxyphenyl)-1,3,4-oxadiazol-2(3H)-one) and oxyfluorfen (2-chloro-α,α,α-trifluoro-p-tolyl 3-ethoxy-4-nitrophenyl ether) residues in thyme (Thymus vulgaris L. and Thymus zygis subsp. gracilis). Samples were extracted by sonication with a water-acetonitrile mixture and the herbicides were partitioned into dichloromethane. Residue levels in thyme were determined by gas chromatography with electron-capture detection (ECD). Confirmation analysis of herbicides was carried out by GC/MS in the selected ion monitoring (SIM) mode. The identification of compounds was based on retention time and on comparison of the primary and secondary ions. The average recovery by the GC-ECD method obtained for these compounds varied from 89.0 to 108.5% with a relative standard deviation between 1.9 and 6.1%. The detection limit by the GC-ECD for the pesticides studied varied from 4.9 to 13.9 µg kg−1. The proposed method was applied to thyme samples grown in the Region of Murcia (Spain). The results showed that this method provided a simple, rapid and sensitive way to analyse oxadiazon and oxyfluorfen residues in thyme.

Dissipation rates of procymidone and azoxystrobin in greenhouse grown lettuce and under cold storage conditions

The dissipation of two fungicides (procymidone and azoxystrobin) was evaluated in greenhouse grown lettuce and under cold storage conditions. Lettuce samples were collected from an experimental greenhouse during a five week period, in which two consecutive applications of these pesticides were performed. Gas chromatography (GC) with electron-capture detection (ECD) was used to study the disappearance of these compounds in lettuce. Confirmation analysis of pesticides was carried out by capillary gas chromatography coupled with mass spectrometry in the selected ion monitoring (SIM) mode. The disappearance rates of these compounds on lettuces in field after two applications were described as pseudo-first-order kinetics with strong correlation between residue concentration and time (r was in all cases higher than 0.983). The half-lives for first and second applications were of 5.31 and 4.65 days for procymidone and 6.23 and 4.87 days for azoxystrobin, respectively. When procymidone and azoxystrobin were applied two times during cultivation, at maximum recommended dose, the residues of both pesticides were below maximum residue limits (MRLs) after the established preharvest intervals. After 21 days under cold and darkness storage conditions, dissipation of procymidone and azoxystrobin was not observed.

Trial of solar heating methods (solarization and biosolarization) to reduce persistence of neonicotinoid and diamide insecticides in a semiarid Mediterranean soil

This paper reports the use of solar heating techniques, solarization (S) and biosolarization (BS) as a strategy for the environmental restoration of soils containing neonicotinoid, acetamiprid (AC), imidacloprid (IM) and thiamethoxam (TH), and diamide, chlorantraniliprole (CL) and flubendiamide (FB) insecticide residues. For this, a semiarid Mediterranean soil (Haplic calcisol) was covered with low-density polyethylene (LDPE) during the hot season, to raise the maximal soil temperatures. Compost from sheep manure (CSM), meat-processing waste (MPW) and sugar beet vinasse (SBV) were used as organic wastes. The results showed that both S and BS increase insecticide disappearance rates compared with the non-disinfected soil, the increase in soil temperature and added organic matter playing a key role. The dissipation rates of TH and AC in soil were satisfactorily described by first-order (monophasic) kinetics, while IM, CL and FB showed a deviation from exponential behaviour. For them, the best results were obtained applying biphasic kinetics with a rapid initial degradation followed by a slower decline of their residues. The findings suggest that S and BS (especially using MPW) can be considered as a valuable tool for enhancing the detoxification of soils polluted with these insecticides.

Metabolite profile of the tomato dwarf cultivar Micro‐Tom and comparative response to saline and nutritional stresses with regard to a commercial cultivar

BACKGROUND The dwarf tomato variety Micro-Tom has been used as a plant model for studies of plant development. However, its response to environmental and agricultural factors has not been well studied. This work studies the phytochemical content of Micro-Tom tomato and its comparative response to saline and nutritional (N, K and Ca) stresses with regard to a commercial variety. RESULTS The chromatographic profiles of Micro-Tom were similar to those of the commercial variety and the only differences appear to be the concentration of the components. In Micro-Tom, the concentrations of sugars and organic acids increased by salinity in a lesser extent than in Optima. Moreover, contrary to that observed in the commercial variety, phenolic compounds and vitamin C did not increase by salinity in the dwarf variety. However, both varieties increased similarly the concentrations of carotenoids under saline conditions. Finally, fruit yield and most primary and secondary metabolite concentrations in Micro-Tom were not affected by N, K or Ca limitation. CONCLUSIONS The mutations leading to the dwarf phenotype did not greatly alter the metabolite profiles but studies using Micro-Tom as a plant model should consider the lower capacity for sugars and organic acids under saline conditions and the greater tolerance to nutrient limitation of the dwarf variety.