Separation of plant pathogens from different hosts and tissues by capillary electromigration techniques

Colorimetric aptasensor based on self-screened aptamers and cascaded catalytic reaction for the detection of quarantine plant bacteria

Quarantine plant bacteria (QPB) are significant component of invasive alien species that result in substantial economic losses and serious environmental damage. Herein, a colorimetric aptasensor has been proposed based on the sandwich structure and the cascaded catalytic strategy for on-site detecting Xanthomonas hyacinthi, a type of QPB, in natural environments. The self-screened aptamer obtained through SELEX can bind to specific sites on the surface of viable organism with high affinity and specificity, which guarantees the selectivity of aptasensor. As an important part of the aptasensor, MIL-88-NH2(Fe) not only acts as a multifunctional carrier for both aptamers and glucose oxidase, but also catalyzes enzyme-like reaction because of specific surface area, amino and peroxidase-like activity. The present of Xanthomonas hyacinthi can trigger the formation of a sandwich structure and the occurrence of cascade catalytic reaction, enabling the detection with UV-Vis spectra and naked eyes. The proposed aptasensor presents a low detection limit of 2 cfu/mL and a wide linear range of 10 -107 cfu/mL. Compared to traditional detection methods for QPB, the reasonable design, high selectivity and convenience significantly improve the detection efficiency and contribute to environmental protection.

Comparative Analysis of Virulence and Molecular Diversity of Puccinia striiformis f. sp. tritici Isolates Collected in 2016 and 2023 in the Western Region of China

Puccinia striiformis f. sp. tritici (Pst) is adept at overcoming resistance in wheat cultivars, through variations in virulence in the western provinces of China. To apply disease management strategies, it is essential to understand the temporal and spatial dynamics of Pst populations. This study aimed to evaluate the virulence and molecular diversity of 84 old Pst isolates, in comparison to 59 newer ones. By using 19 Chinese wheat differentials, we identified 98 pathotypes, showing virulence complexity ranging from 0 to 16. Associations between 23 Yr gene pairs showed linkage disequilibrium and have the potential for gene pyramiding. The new Pst isolates had a higher number of polymorphic alleles (1.97), while the older isolates had a slightly higher number of effective alleles, Shannon's information, and diversity. The Gansu Pst population had the highest diversity (uh = 0.35), while the Guizhou population was the least diverse. Analysis of molecular variance revealed that 94% of the observed variation occurred within Pst populations across the four provinces, while 6% was attributed to differences among populations. Overall, Pst populations displayed a higher pathotypic diversity of H > 2.5 and a genotypic diversity of 96%. This underscores the need to develop gene-pyramided cultivars to enhance the durability of resistance.

Sorting and simultaneous quantitation of intact mixed-cell samples via capillary isotachophoresis

A great need currently exists for rapid, inexpensive, and accurate methods for microbial analysis in the medical, food, industrial, and water quality fields. Here, a novel capillary isotachophoresis (CITP) method is presented for the focusing, sorting, and quantitation of intact cells in mixed samples based on their electrophoretic mobility ranges. Using a series of ion spacers dissolved in the sample, this technique results in several efficient cell peaks in the electropherogram corresponding to specific cell electrophoretic mobility ranges. The concentrations of different species in mixed-cell samples are determined from the cell peak areas and the known peak response factors for the cell species using a series of linear equations. Method design and optimization are discussed, including the choice of running buffer, pH, and ion spacers. Mixed-cell samples of up to four different species were focused and quantified as a proof-of-principle of the method. When sample cell concentrations were toward the middle of the linear response range, accuracies between 1% and 11% and relative standard deviations of 1%-14% were obtained, depending on the number of cell species in the mixture. This work provides a useful basis for future studies of cell quantitation using CITP, which could be potentially applied to a variety of fields including cell growth studies, microbial contamination testing, and sterility testing.

Detection of the Chilli Leaf Curl Virus Using an Attenuated Total Reflection-Mediated Localized Surface-Plasmon-Resonance-Based Optical Platform

The development of a nanoparticle-based optical platform has been presented as a biosensor for detecting target-specific plant virus DNA. The binding dynamics of gold nanoparticles has been studied on the amine-functionalized surface by the attenuated total reflection (ATR)-based evanescent wave absorption method monitoring the localized surface plasmon resonance (LSPR). The developed surface was established as a refractive index sensor by monitoring the LSPR absorption peak of gold nanoparticles. This nanoparticle-immobilized surface was explored to establish as a biosensing platform with target-specific immunoglobulin (IgG) antibody-antigen interaction. The IgG concentration-dependent variation of absorbance was correlated with the refractive index change. After successfully establishing this ATR configuration as an LSPR-based biosensor, the single-stranded DNA of the chilli leaf curl virus was detected using its complementary DNA sequence as a receptor. The limit of detection of this sensor was determined to be 1.0 μg/mL for this target viral DNA. This ATR absorption technique has enormous potential as an LSPR based nano-biosensor for the detection of other begomoviruses.

Recent advances in the analysis of biological particles by capillary electrophoresis

This review covers research papers published in the years 2005-2007 that describe the application of capillary electrophoresis to the analysis of biological particles such as whole cells, subcellular organelles, viruses and microorganisms.