Browsing by Person "Link, Tobias Immanuel"

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Mating-type analysis in Diaporthe isolates from soybean in central Europe
(2025) Hosseini, Behnoush; Käfer, Lena Sophia; Link, Tobias Immanuel; Cai, Lei
Species of the genus Diaporthe have a mating-type system with the two mating types MAT1-1 and MAT1-2, like other ascomycetes. They can either be heterothallic, which means that any isolate only possesses one of the two mating types and needs a mating partner for sexual reproduction, or homothallic, which means that they possess both mating types and are self-fertile. For several Diaporthe species, no sexual reproduction has been observed so far. Using PCR with primers specific to the defining genes MAT1-1-1 and MAT1-2-1 , we determined the mating types of 33 isolates of Diaporthe caulivora , D. eres , D. longicolla , and D. novem from central Europe. In addition, we partially sequenced the mating-type genes of 25 isolates. We found that different D. longicolla isolates either possess MAT1-1-1 or MAT1-2-1, making the species heterothallic, which is in contrast to previous studies and the general assumption that D. longicolla only reproduces asexually. D. eres and D. novem were also found to be heterothallic. Using genomic sequence information and re-sequencing of DNA and RNA, we identified the MAT1-1-1 gene in D. caulivora and present here the full sequence of the mating-type locus of this homothallic species. Finally, we used sequence information from MAT1-1-1 and MAT1-2-1 , respectively, for improved phylogenetic resolution of our isolates.
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.