Browsing by Person "Voegele, Ralf Thomas"

Now showing 1 - 2 of 2

Assessment of induced resistance in Agrostis stolonifera after application of UV-C irradiation and antagonistic microorganisms
(2025) Pawar, Seema; Voegele, Ralf Thomas
Agrostis stolonifera is a cool season grass widely used on golf courses and sports turf, where disease management requires intensive maintenance. Increasing restrictions on pesticide use have intensified the search for alternative, sustainable plant protection strategies. One potential approach is the application of low-dose UV-C irradiation (280 nm) to induce protection against pathogens through the stimulation of plant defences in turfgrass. This study investigated the effects of UV-C irradiation on A. stolonifera, with a particular focus on the expression of the defence-related genes PR3 and NPR1 (Non-expresser of PR genes). Turfgrass was exposed to single or repeated UV-C treatments under greenhouse conditions using doses ranging from 30 to 180 mJ/cm², corresponding to irradiation times of 1–6 s. Leaf samples were collected at defined intervals following treatment, and gene expression was quantified using RT-qPCR with TEF1-α as the reference gene. Defence-related gene expression was transiently upregulated, with peak expression generally observed 30 min post-irradiation, while no comparable changes were detected in untreated controls. Relative expression was calculated using the ΔΔCt method. In parallel, outdoor field trials were conducted on a golf course using a battery powered mobile and controllable support frame with a roller fitted with UV-C lamps during the active growth phase of turfgrass. UV-C treatments were applied twice weekly over a four-week period, and additional trials assessed the combined application of UV-C irradiation and selected antagonistic microorganisms. Here too, UV-C applications resulted in transient upregulation of the two defence-related genes. Repeated applications gave slightly stronger responses than single treatments. The combined use of UV-C and biological control agents was associated with reduced dollar spot incidence. Here, clear differences could be observed depending on the number of UV-C applications. The transient induction of defence-related gene expression following UV-C treatment together with observable long-term effects on dollar spot incidence indicates defence priming rather than sustained constitutive activation. Together, the greenhouse and field observations indicate that UV-C irradiation can activate defence responses in A. stolonifera and may contribute to disease suppression in turf management.
Successful silencing of the mycotoxin synthesis gene TRI5 in fusarium culmorum and observation of reduced virulence in VIGS and SIGS experiments
(2022) Tretiakova, Polina; Voegele, Ralf Thomas; Soloviev, Alexander; Link, Tobias Immanuel
Crops constantly experience various biotic stresses during their life cycle, and Fusarium spp. remain one of the most serious groups of pathogens affecting plants. The ability to manipulate the expression of certain microorganism genes via RNAi creates the opportunity for new-generation dsRNA-based preparations to control a large number of diseases. In this study, we applied virus-induced gene silencing (VIGS), and spray-induced gene silencing (SIGS) to silence the trichothecene-producing gene TRI5 in F. culmorum as a means to reduce its aggressiveness on spring wheat. Treatment of the fungus with dsTRI5RNA in vitro reduced deoxynivalenol (DON) and 3-acetyldeoxynivalenol (3-A-DON) accumulations by 53–85% and 61–87%, respectively, and reduced TRI5 expression by 84–97%. VIGS decreased the proportion of infected wheat spikelets by 73%, but upregulation was observed for TRI5. SIGS on wheat leaves and ears using certain dsTRI5RNA amounts negatively impacted F. culmorum growth. However, when performing in vivo analyses of TRI5 mRNA levels, the upregulation of the gene was determined in the variants where fungal colonization was restricted, suggesting a compensatory reaction of the pathogen to RNAi.