Biology subjects

Wildermuth, M. C.

Publications and source records attributed to Wildermuth, M. C..

6 recordsLinked to original sources

bioRxiv2026

Arabidopsis Acyl-CoA Binding Protein 4, ACBP4, functions in developmentally programmed endoreduplication

Powdery mildew fungi induce localized endoreduplication, a variant of the cell cycle in which DNA is replicated but cells do not divide, in leaf mesophyll cells underlying the fungal feeding structure. Induced endoreduplication occurs concurrent with powdery mildew (PM) spore production and is associated with enhanced metabolic capacity and flux to lipids. The final ploidy of these cells is highly correlated with fungal spores produced and is the consequence of both basal (developmental) ploidy and PM-induced endoreduplication programs. Herein, we find the Arabidopsis lipid trafficking and regulatory protein ACYL-COA BINDING PROTEIN 4 (ACBP4) enhances PM spore production on Arabidopsis leaves. ACBP4 does not limit plant defense but instead supports basal mesophyll cell ploidy, with decreased final ploidy in cells underlying the fungal feeding structure in acbp4 mutants compared to wild-type (WT). Leaf epidermal cell size is decreased and stomatal density is increased in acbp4, consistent with a role for ACBP4 in developmentally programmed endoreduplication. Moreover, hypocotyl elongation in the dark, which is driven by programmed developmental endoreduplication, shows reduced hypocotyl length, cell length and ploidy in acbp4 versus WT. Together, our findings establish a novel means by which a plant ACBP promotes cell metabolism and development, with potential applications to agricultural productivity and quality.

plant biology↗

bioRxiv2025

Powdery mildew exploits host plastoglobuli functions via DGAT3 and FBN2 for proliferation

Plastoglobuli (PG) are specialized lipid-containing compartments attached to thylakoid membranes within chloroplasts. PGs participate in various metabolic pathways in response to environmental stresses such as high light, nitrogen deficiency, and heat stress. However, their roles in biotic stress remain largely unexplored. In this study, two distinct lines of investigation converge on the importance of PGs to the powdery mildew-Arabidopsis interaction. First, powdery mildew infection results in the accumulation of PGs and PG-localized Arabidopsis Diacylglycerol Acyltransferase 3 (DGAT3), a triacylglycerol biosynthetic enzyme that supports powdery mildew proliferation. Second, a bioinformatic analysis led to the identification of a powdery mildew effector that is PG-localized and interacts specifically with FIBRILLIN 2 (FBN2), one of the most abundant PG core proteins. While silencing the effector limits powdery mildew proliferation, an FBN2 knockout results in increased spore production, providing a direct link between PG function and pathogen manipulation of the host. These findings underscore the significance of PGs in host-pathogen interactions and offer new insights into the intricate mechanisms underlying the interaction of an obligate biotroph with its host. SIGNIFICANCEPlastoglobuli (PG) functions are largely unexplored in the context of host-pathogen interactions. Using the Arabidopsis-powdery mildew system, we uncover new roles for PGs in host-pathogen dynamics through integrated genetic, biochemical, and microscopic analyses. Mutants in PG-localized proteins impact powdery mildew proliferation. Moreover, a powdery mildew effector that interacts with the core PG protein FBN2 is identified and found to contribute to virulence. These findings suggest this obligate biotrophic pathogen exploits PGs for its own gain.

plant biology↗

bioRxiv2024

Altered host pyruvate metabolism fuels and regulates fungal asexual reproduction

Powdery mildew (PM) fungi are widespread pathogens impacting agricultural productivity. As obligate biotrophs, PMs get all nutrients from their host plant. Concurrent with asexual reproduction, the PM Golovinomyces orontii induces host lipid body accumulation in plant mesophyll cells underlying the epidermal cell that houses the fungal feeding structure. Herein, we show a PM-induced shift in plant primary metabolism, to bypass the pyruvate dehydrogenase complex (PDHc), acts in a dose-dependent manner to support host storage lipid production for PM acquisition. Not only are plant PDHc bypass-derived lipids incorporated into spore storage lipids, but they also act in a regulatory capacity to control the number of fungal reproductive structures per colony, ensuring the fitness of spores that are formed. Evolutionarily distant plant and animal obligate biotrophs manipulate host lipid metabolism for their own acquisition and we propose altered host pyruvate metabolism, bypassing the host PDHc bottleneck, as a common strategy to increase host source flux to acetate/acetyl-CoA for obligate microbial lipid acquisition.

plant biology↗

bioRxiv2024

TEtrimmer: a novel tool to automate the manual curation of transposable elements

Transposable elements (TEs) are repetitive DNA sequences capable of moving within genomes. Accurate annotation and classification of TEs is crucial but challenging due to their sequence diversity and often fragmented occurrence. We present TEtrimmer, a novel tool to automate manual TE curation. TEtrimmer integrates multiple sequence alignment (MSA) clustering, MSA sequence extension, MSA cleaning, TE boundary definition, and TE classification, and provides report plots and a graphical user interface (GUI) application to inspect and improve results. Benchmarked on the genomes of six organisms from various kingdoms of life, TEtrimmer consistently improved the identification of intact TEs compared to established tools.

bioinformatics↗

bioRxiv2023

Powdery mildew infection induces a non-canonical route to storage lipid formation at the expense of host thylakoid lipids to fuel its spore production

Powdery mildews are obligate biotrophic fungi that manipulate plant metabolism to supply lipids, particularly during fungal asexual reproduction when fungal lipid demand is extensive. The mechanism for host response to fungal lipid demand has not been resolved. We found storage lipids, triacylglycerols (TAGs), increase by 3.5-fold in powdery mildew-infected tissue. In addition, lipid bodies, not observable in uninfected mature leaves, are present in both cytosol and chloroplasts at the infection site. This is concurrent with decreased thylakoid membrane lipids and thylakoid disassembly. Together, these findings indicate that the powdery mildew induces localized thylakoid membrane degradation to promote storage lipid formation. Genetic analyses show the canonical ER pathway for TAG synthesis does not support powdery mildew spore production. Instead, Arabidopsis DIACYLGLYCEROL ACYLTRANSFERASE 3 (DGAT3), shown to be chloroplast-localized and to be largely responsible for powdery mildew-induced chloroplast TAGs, promotes fungal asexual reproduction. Powdery mildew-induced leaf TAGs are enriched in thylakoid associated fatty acids, which are also present in the produced spores. This research provides new insights on obligate biotrophy and plant lipid metabolism plasticity and function. Furthermore, by understanding how photosynthetically active leaves can be converted into TAG producers, more sustainable and environmentally benign plant oil production could be facilitated.

plant biology↗

bioRxiv2022

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

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.

microbiology↗