Resistance developments in Estonia’s population of pollen beetles (Brassicogethes aeneus)

A total of 111 local pollen beetle populations were collected from both winter and spring oilseed rape fields, in the main oilseed growing regions of Estonia between 2015−2019. The objective was to analyse the insecticide-susceptibility of the pollen beetle population (in the form of Brassicogethes aeneus). The pollen beetle samples were tested for sensitivity to lambda-cyhalothrin, thiacloprid, and chlorpyrifos. The efficacy of the tested insecticides varied considerably by region. We observed a clear decrease in susceptibility to lambda-cyhalothrin and thiacloprid, but sensitivity to chlorpyrifos remained stable throughout the period between 2015 and 2019. Amongst the tested samples in that period, a total of 3% were classified as susceptible to lambda-cyhalothrin, 18% as moderately resistant, 70% as resistant, and 7% as highly resistant. In the case of thiacloprid, 21% of the samples were highly susceptible to the insecticide, 39% were susceptible, and 41% had reduced levels of susceptibility to the insecticide. The information which was presented tended to confirm the ongoing evolution of insecticide resistance in the B. aeneus population in Estonia, while also highlighting the importance of data-based decisions when optimising insecticide resistance management in the field

Genome-Wide Association Analysis and Genomic Prediction for Adult-Plant Resistance to Septoria Tritici Blotch and Powdery Mildew in Winter Wheat

Septoria tritici blotch (STB) caused by the fungal pathogen Zymoseptoria tritici and powdery mildew (PM) caused by Blumeria graminis f.sp tritici (Bgt) are among the forefront foliar diseases of wheat that lead to a significant loss of grain yield and quality. Resistance breeding aimed at developing varieties with inherent resistance to STB and PM diseases has been the most sustainable and environment-friendly approach. In this study, 175 winter wheat landraces and historical cultivars originated from the Nordic region were evaluated for adult-plant resistance (APR) to STB and PM in Denmark, Estonia, Lithuania, and Sweden. Genome-wide association study (GWAS) and genomic prediction (GP) were performed based on the adult-plant response to STB and PM in field conditions using 7,401 single-nucleotide polymorphism (SNP) markers generated by 20K SNP chip. Genotype-by-environment interaction was significant for both disease scores. GWAS detected stable and environment-specific quantitative trait locis (QTLs) on chromosomes 1A, 1B, 1D, 2B, 3B, 4A, 5A, 6A, and 6B for STB and 2A, 2D, 3A, 4B, 5A, 6B, 7A, and 7B for PM adult-plant disease resistance. GP accuracy was improved when assisted with QTL from GWAS as a fixed effect. The GWAS-assisted GP accuracy ranged within 0.53-0.75 and 0.36-0.83 for STB and PM, respectively, across the tested environments. This study highlights that landraces and historical cultivars are a valuable source of APR to STB and PM. Such germplasm could be used to identify and introgress novel resistance genes to modern breeding lines

PEPPSI-Type Pd(II)—NHC Complexes on the Base of <i>p-tert</i>-Butylthiacalix[4]arene: Synthesis and Catalytic Activities

The creation of effective catalytic systems for cross-coupling reactions, reduction, etc., capable of working in water-organic or pure aqueous media is in great demand. The article presents the synthesis of NHC-palladium complexes of the PEPPSI type based on monoimidazolium derivatives of thiacalix[4]arene. The structure of the imidazolium precursors, obtained in 81–88% yields and the complexes themselves, obtained in 40–50% yields, is established using modern methods, including X-ray structural analysis and high-resolution mass spectrometry. It is shown that the obtained complex with bulk substituents near the palladium atom is not inferior to the well-known PEPPSI-type Organ’s catalyst in the catalysis of Suzuki-Miyaura coupling and is four times superior to the latter in the p-nitrophenol reduction reaction. Given the presence of free phenolic hydroxyl groups in the macrocycle, the obtained complexes are of interest for further post-modification or for immobilization on a carrier

Dimerization of long hibernation promoting factor from Staphylococcus aureus: Structural analysis and biochemical characterization

International audienceStaphylococcus aureus hibernation promoting factor (SaHPF) is responsible for the formation of 100S ribosome dimers, which in turn help this pathogen to reduce energy spent under unfavorable conditions. Ribosome dimer formation strongly depends on the dimerization of the C-terminal domain of SaHPF (CTDSaHPF). In this study, we solved the crystal structure of CTDSaHPF at 1.6 Å resolution and obtained a precise arrangement of the dimer interface. Residues Phe160, Val162, Thr171, Ile173, Tyr175, Ile185 andThr187 in the dimer interface of SaHPF protein were mutated and the effects were analyzed for the formation of 100S disomes of ribosomes isolated from S. aureus. It was shown that substitution of any of single residues Phe160, Val162, Ile173, Tyr175 and Ile185 in the SaHPF homodimer interface abolished the ribosome dimerization in vitro