bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2022.09.13.507682

SPRAY-INDUCED GENE SILENCING IDENTIFIES PATHOGEN PROCESSES CONTRIBUTING TO POWDERY MILDEW PROLIFERATION

McRae, A. G.·Taneja, J.·Yee, K.·Shi, X.·Haridas, S.·LaButti, K.·Singan, V.·Grigoriev, I. V.·Wildermuth, M. C.
View original source ↗Export metadata ↓

Abstract

Spray-induced gene silencing (SIGS) is an emerging tool for crop pest protection. It utilizes exogenously applied double stranded RNA to specifically reduce pest target gene expression using endogenous RNA interference machinery. Powdery mildews, widespread obligate biotrophic fungi infect agricultural crops including wheat, barley, cucurbits, grapevine, and ornamentals such as roses. In this study, SIGS methods were developed and optimized for powdery mildews using the known azole-fungicide target CYP51 and the Golovinomyces orontii-Arabidopsis thaliana pathosystem. Additional screening resulted in the identification of conserved gene targets and processes important to powdery mildew proliferation: apoptosis-antagonizing transcription factor in essential cellular metabolism and stress response; lipase a, lipase 1, and acetyl-CoA oxidase in lipid catabolism; 9-cis-epoxycarotenoid dioxygenase, xanthoxin dehydrogenase, and a putative abscisic acid G-protein coupled receptor predicted to function in manipulation of the plant hormone abscisic acid; and the secreted effector EC2. Powdery mildew is the dominant disease impacting grapes and extensive powdery mildew resistance to applied fungicides has been reported. Therefore, we developed SIGS for the Erysiphe necator-Vitis vinifera system and tested six successful targets identified using the G. orontii-A. thaliana system. For all targets tested, a similar reduction in powdery mildew disease was observed between systems. This indicates screening of broadly conserved targets in the G. orontii-A. thaliana pathosystem identifies targets and processes for the successful control of other powdery mildews. The flexibility, specificity, reduced environmental and health risks, and rapid transition from the bench to the field make SIGS an exciting prospect for commercial powdery mildew control.

Source connections

Explore related subjects

microbiologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

McRae, A. G., Taneja, J., Yee, K., Shi, X., Haridas, S., LaButti, K., Singan, V., Grigoriev, I. V., Wildermuth, M. C.. 2022-09-13. SPRAY-INDUCED GENE SILENCING IDENTIFIES PATHOGEN PROCESSES CONTRIBUTING TO POWDERY MILDEW PROLIFERATION. https://doi.org/10.1101/2022.09.13.507682

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Microbially conjugated bile acids differentially affect the lifecycle and pathogenesis of Clostridioides difficile

Clostridioides difficile is a Gram-positive bacterium that causes C. difficile infection (CDI). In healthy adults, it has been proposed that the gut microbiota provides colonization resistance against C. difficile by competition through nutrient limitation and antagonism through secondary bile acid metabolism, the latter of which is mediated by the deconjugation of host-derived bile acids with bacterial bile salt hydrolases (BSH). Recently, BSHs have also shown an ability to reconjugate non-canonical (i.e., not glycine or taurine) amino acids to sterol cores, resulting in novel microbially conjugated bile acids (MCBAs). MCBAs have been associated with the resolution of recurrent CDI, though the mechanism underlying these effects are not well understood. To address this gap, we synthesized 36 MCBAs with nine amino acids (cysteine, isoleucine, leucine, phenylalanine, proline, serine, tryptophan, tyrosine, and valine) conjugated to the primary and secondary bile acids found in the human gut (CA, DCA, CDCA, and LCA) and tested their impact on various stages of C. difficiles lifecycle including bacterial outgrowth, membrane integrity, sporulation, and toxin activity. We show that BSH-mediated amidation of bile acid sterol cores can either increase or decrease inhibitory effects on C. difficile in an amino acid-dependent manner. For example, serine MCBAs enhanced C. difficiles ability to grow in otherwise inhibitory bile acid concentrations, increased spore production, and elevated toxin activity. Tryptophan MCBAs increased inhibition. By demonstrating these variable effects, our work clarifies the molecular determinants of MCBA activity and highlights specific MCBAs as promising targets for the development of C. difficile microbial-based therapeutics.

microbiology↗
bioRxiv2026

Magnetic organelle gene clusters enable bacterial growth and ATP homeostasis under oxidizing conditions

Biological organisms can produce magnetic nanoparticles made of magnetite to detect the Earth's magnetic field for orientation. The evolutionary mechanisms that led to the acquisition of this capacity remain unknown. The most ancient organisms known to perform magnetic orientation are magnetotactic bacteria. Under tight genetic control, they produce chains of magnetite nanoparticles in dedicated organelles to allow efficient navigation in aquatic environments containing molecular oxygen. Yet, these bacteria have been proposed to emerge before molecular oxygen became abundant on Earth, at a time when this navigation system could not have served its current function. Here, we show that gene clusters responsible of magnetite formation and organization enable resistance against hydrogen peroxide, a toxic oxygen-derived compound that was produced during the early stages of Earth's oxygenation when iron oxidation consumed molecular oxygen. Characterization of the nanoparticle's oxidation state supported the involvement of magnetite in resistance to hydrogen peroxide-induced oxidative stress. These findings are compatible with an early emergence of magnetotactic bacteria, before natural waters became oxygenated. We propose a conceptual framework to explain the origin of magnetic orientation in bacteria, and offer tools to identify the initiation of Earth's oxygenation in a time-resolved manner.

microbiology↗
bioRxiv2026

Identification and characterization of new P. aeruginosa phages using a surface receptor platform

Bacteriophages are of increasing interest for their potential use as alternatives to antibiotics for treating drug-resistant infections. Phage steering, specifically receptor-based steering, involves use of phages that bias the development of resistance in bacteria towards phenotypes such as reduced fitness. Phage therapy typically involves administering cocktails of phages with different targets to reduce the likelihood of resistance emerging. To ensure effective steering and cocktail design, there is a need to identify the receptors used by phages of interest, and to isolate phages that use diverse receptors. Here we describe a SURFAce Receptor (SURFAR) platform consisting of a set of defined Pseudomonas aeruginosa strains and mutants for rapid characterization of phage receptors. This platform can also be used to enrich for and isolate diverse phages from environmental samples, yielding novel phage genomes from wastewater. Using the SURFAR platform, two new phages were isolated and characterized: Dalewood, which targets both flagella and the conserved LPS outer core, and Bowman, a biofilm targeting phage capable of supressing growth of a subset of carbapenem-resistant clinical isolates. This tool helps to standardize the laborious but important task of phage receptor characterization, with the goal of expanding the known repertoire of P. aeruginosa phage receptors and phages.

microbiology↗