Exploring root rot pathogens in wheat-pea rotations in Kansas

In 2018, over 277,000 bushels of wheat were produced on 7.7 million acres of land in Kansas alone. Based on the price of wheat by the end of 2018, this accounted for $1.44 million. This wheat is normally rotated with soybeans or fallow, but recent interest has arisen regarding the growth of peas in northern Kansas. As of 2019, there are both research and commercial growing operations underway. Many plant diseases have been especially prevalent during the summer because of the high rainfall and heat. In order to assess the severity of pea disease in Kansas, as well as explore potential interconnectivity between wheat and pea pathogens, a survey was conducted, and efforts were made to isolate and culture fungal pathogens of both wheat and pea

Characterization of the necrotrophic effector ToxA in Kansas fungal leaf spot pathogen populations

Doctor of PhilosophyDepartment of Plant PathologyJessica RuppThe Kansas fungal necrotrophic wheat leaf spot complex includes the pathogens Bipolaris sorokiniana, Pyrenophora tritici-repentis, and Parastagonospora nodorum. While all of these pathogens utilize multiple pathogenicity factors, in the last 20 years, all three pathogens were discovered to contain a highly conserved copy of the necrotrophic effector (NE) gene, ToxA. Evidence indicates that ToxA was likely transferred between the species through an interspecific gene-transfer event. This gene enables pathogenesis in susceptible hosts through an inverse gene-for-gene interaction with the wheat susceptibility gene, Tsn1. The primary research objectives of this study are to characterize the distribution and diversity of ToxA in the Kansas leaf spot pathogen population, and to determine the frequency of the genes ToxA, ToxB, and ToxC in the P. tritici-repentis population. A survey of Kansas cereals was conducted to collect isolates of leaf spot pathogens. Isolates of all three pathogens were molecularly characterized for presence of ToxA and their haplotype diversity was evaluated through comparison of ToxA sequences. Isolates of P. tritici-repentis were phenotypically screened against a wheat differential set, and molecularly characterized for presence of the genes ToxA, and ToxB. Results show that the NE gene ToxA was represented in 87% and 100% of P. tritici-repentis and P. nodorum isolates respectively, while only being represented in 44% of B. sorokiniana isolates. Additional evaluation of the P. tritici-repentis population showed that in addition to ToxA, only ToxC was common in the collected isolates. Characterization of the haplotype diversity in the three populations showed that the characterized isolates contain limited genetic diversity in all three backgrounds, but the most limited diversity is in the P. tritici-repentis population. The result that ToxA has now been found in three Kansas pathogen populations highlights the importance of ToxA and its susceptibility factor (Tsn1) in wheat. Knowledge about the rates of ToxA in these populations will help pathologists in making management recommendations and will help breeders make selection decisions. Now that a baseline for ToxA has been established in the B. sorokiniana population in Kansas, future surveillance will be required to monitor for an increase of the NE gene. As ToxA likely increases pathogen fitness, selection in the population could potentially lead to a future in which B. sorokiniana is a more economically important pathogen

2023 Soybean Disease Update

Wednesday, July 26, 2023 2023 Soybean Disease Update Hot weather and recent precipitation in many areas of the state have created ideal conditions for soybean diseases. Nebraska Extension Plant Pathologist Dylan Mangel talks about what he’s seeing in soybean fields

Selection of favorable alleles of genes controlling flowering and senescence improves malt barley quality

Malt barley (Hordeum vulgare L.) is an important cash crop with stringent grain quality standards. Timing of the switch from vegetative to reproductive growth and timing of whole-plant senescence and nutrient remobilization are critical for cereal grain yield and quality. Understanding the genetic variation in genes associated with these developmental traits can streamline genotypic selection of superior malt barley germplasm. Here, we determined the effects of allelic variation in three genes encoding a glycine-rich RNA-binding protein (HvGR-RBP1) and two NAC transcription factors (HvNAM1 and HvNAM2) on malt barley agronomics and quality using previously developed markers for HvGR-RBP1 and HvNAM1 and a novel marker for HvNAM2. Based on a single-nucleotide polymorphism (SNP) in the first intron, the utilized marker differentiates NAM2 alleles of low-grain protein variety ‘Karl’ and of higher protein variety ‘Lewis’. We demonstrate that the selection of favorable alleles for each gene impacts heading date, senescence timing, grain size, grain protein concentration, and malt quality. Specifically, combining ‘Karl’ alleles for the two NAC genes with the ‘Lewis’ HvGR-RBP1 allele extends grain fill duration, increases the percentage of plump kernels, decreases grain protein, and provides malt quality stability. Molecular markers for these genes are therefore highly useful tools in malt barley breeding.U.S. Department of Agriculture12 month embargo; published online: 22 September 2022This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Deferasirox (ExJade): A Fluorescent Pro-Chelator Active Against Antibiotic Resistant Bacteria

Deferasirox, ExJade, an FDA-approved treatment for iron overload disorders has been shown to inhibit the growth of both gram-positive and -negative bacteria through iron (Fe(III)) chelation. Modification of the ExJade framework led to the identification of a new fluorescent platform ExPh and ExBT. Functionalization of the phenol moieties on ExBT with phosphate units afforded a ratiometric fluorescent pro-chelator (ExPhos), which was effective in the inhibition of two clinically relevant antibiotic-resistant bacteria, (MRSA (ATCC 43300) and VRE (ATCC 51299)), and allowed the fluorescent imaging of MRSA. Remarkably, this pro-chelation strategy proved selective towards bacteria with no cytotoxicity observed for ExPhos treated A549 cells (72 h incubation). This work represents a new pro-chelator antibiotic strategy that can be modified with a chosen reactive chemical trigger to provide a diagnostic signal in conjunction with a therapeutic response with a potential of minimal off-target toxicities.</p