1.Metalaxyl Resistance in Phytophthora infestans: Assessing Role of RPA190 Gene and Diversity Within Clonal Lineages.
Matson ME1, Small IM1, Fry WE1, Judelson HS1. Phytopathology. 2015 Dec;105(12):1594-600. doi: 10.1094/PHYTO-05-15-0129-R. Epub 2015 Nov 9.
Prior work has shown that the inheritance of resistance to metalaxyl, an oomycete-specific fungicide, is complex and may involve multiple genes. Recent research indicated that a single nucleotide polymorphism (SNP) in the gene encoding RPA190, the largest subunit of RNA polymerase I, confers resistance to metalaxyl (or mefenoxam) in some isolates of the potato late blight pathogen Phytophthora infestans. Using both DNA sequencing and high resolution melt assays for distinguishing RPA190 alleles, we show here that the SNP is absent from certain resistant isolates of P. infestans from North America, Europe, and Mexico. The SNP is present in some members of the US-23 and US-24 clonal lineages, but these tend to be fairly sensitive to the fungicide based on artificial media and field test data. Diversity in the level of sensitivity, RPA190 genotype, and RPA190 copy number was observed in these lineages but were uncorrelated. Controlled laboratory crosses demonstrated that RPA190 did not cosegregate with metalaxyl resistance from a Mexican and British isolate.
2.Comparison of extraction solvents and sorbents in the quick, easy, cheap, effective, rugged, and safe method for the determination of pesticide multiresidue in fruits by ultra high performance liquid chromatography with tandem mass spectrometry.
Liu S1, He H1, Huang X1, Jin Q1, Zhu G2. J Sep Sci. 2015 Oct;38(20):3525-32. doi: 10.1002/jssc.201500625. Epub 2015 Sep 9.
An improved analytical method was developed for the simultaneous quantification of several plant growth regulators and fungicides (carbendazim, pyrimethanil, metalaxyl, triadimefon, paclobutrazol, thiophanate, prochloraz, dimethomorph, difenoconazole, (4-chlorophenoxy)-acetic acid, (2,4-dichlorophenoxy)-acetic acid, thiadiazuron, forchlorfenuron and gibberellins) in fruits followed by ultra high performance liquid chromatography with tandem mass spectrometry. Samples were extracted and purified using a modified QuEChERS method. Different extraction solvents and sorbents in the QuEChERS method were compared. Optimum results were followed by the addition of 1% acetic acid in acetonitrile; C18 sorbent was added due to the acidic nature of several pesticides. The recoveries of the pesticides were in the range 73.7-118.4%, with relative standard deviations lower than 16.63%. Limits of detection ranged from 0.1-1.0 μg/kg. The method presented here is simple, rapid, sensitive and can be applied to large-scale monitoring programs to screen the presences of pesticides in fruits.
3.Comparison of two extraction methods for the determination of 135 pesticides in Corydalis Rhizoma, Chuanxiong Rhizoma and Angelicae Sinensis Radix by liquid chromatography-triple quadrupole-mass spectrometry. Application to the roots and rhizomes of Chinese herbal medicines.
Liu J1, Tong L2, Li D2, Meng W2, Sun W1, Zhao Y3, Yu Z4. J Chromatogr B Analyt Technol Biomed Life Sci. 2016 Apr 1;1017-1018:233-40. doi: 10.1016/j.jchromb.2016.03.003. Epub 2016 Mar 7.
In this study, two simple pretreatment methods were comprehensively evaluated for the determination of 135 pesticide residues in roots and rhizomes of Chinese herbal medicines (CHMs). The studied methodologies are (a) solid-phase extraction (SPE) and (b) Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS). For SPE, extraction solvents, SPE cartridges and types and volume of eluent were accessed and optimized. For QuEChERS, different versions, acetic acid concentration and dispersive solid-phase extraction (dSPE) sorbent materials were tested. SPE and QuEChERS were estimated in recovery range, the number of pesticides that were recovered ranging from 90% to 110% and expenses in Corydalis Rhizoma, Chuanxiong Rhizoma and Angelicae Sinensis Radix. QuEChERS method showed better performance than SPE. The method showed good linearity over the range assayed 0.9986-0.9999 (1-80ng/mL for 124 pesticides, 1-50ng/mL for 10 pesticides, 1-20ng/mL for satisfar).
4.Contribution to the food products' analysis: A research and evaluation on the hemolytic effect of some pesticides used in Lebanon.
Al-Alam J1,2, Millet M2, Chbani A1,3, Fajloun Z1,4. J Environ Sci Health B. 2015;50(11):788-96. doi: 10.1080/03601234.2015.1058095.
Pesticides are a real concern for the society as their use has become critical, leading sometimes to their accumulation as residues in fruits and vegetables. After examining the pesticides sold in Northern Lebanon, this study is focused on the analysis and identification of pesticides residues in fruits and vegetables that are harvested in this region and treated with the locally sold pesticides. Results show: first, (i) a use of Zineb by the name of another pesticide Micronized Sulfur to avoid prosecution; (ii) a significant presence of Metalaxyl in lemons and oranges; (iii) a significant presence of Trifluralin in strawberries; and (iv) a significant presence of Zineb in lemons and tomatoes. Second, with the use of hemolytic tests on human blood results show: (i) a critical concentration and a significant hemolytic effect of some pesticides used in Lebanon; and (ii) an absence of hemolytic effect in the collected fractions of the different analyzed fruit extracts containing pesticides.