Fusarium species and the mycotoxins produced by them represent a significant problem for agriculture and human health. Thus, the development of novel management strategies and tools is of high importance. Spray-induced gene silencing (SIGS), based on the natural mechanism of RNA interference (RNAi), has been considered as a highly specific and ecologically safe alternative to chemical fungicides, the use of which is restricted by the emergence of resistant strains and environmental concerns. At the same time, massive application of SIGS is challenged by the degradability of RNA molecules in the environment. Nanoparticles have been widely applied to protect RNA from degradation and improve its action. The aims of this study were to evaluate whether RNAi-mediated silencing of the regulatory FgVe1 gene leads to inhibition of growth, mycotoxin production, and pathogenicity of Fusarium graminearum and whether the use of CaP nanoparticles (CaPs) as double-stranded RNA (dsRNA) carriers enhances and prolongs the silencing effect. It was shown that dsRNA treatment of fungal liquid cultures resulted in 19.78-fold silencing of FgVe1 expression as well as inhibition of expression of genes related to secondary metabolism, including those involved in trichothecene and aurofusarin biosynthesis, thus leading to a reduction in DON accumulation and changes in culture color. The results also demonstrated that naked dsRNA and CaPs:dsRNA nanocomplexes differed in their abilities to induce a high silencing effect at different time points. Naked dsRNA proved more effective in inducing silencing in the early stages of fungal growth, whereas application of nanocomplexes provided a prolonged effect up to 10 days in liquid cultures and up to 14 days on detached leaves. The obtained data can be considered as a basis for the further development of new efficient SIGS-based plant protection strategies.

ADP-ribosylation (ADPRylation) is a mechanism which post-translationally modifies proteins in eukaryotes in order to regulate a broad range of biological processes including programmed cell death, cell signaling, DNA repair, and responses to biotic and abiotic stresses. Poly(ADP-ribosyl) polymerases (PARPs) play a key role in the process of ADPRylation, which modifies target proteins by attaching ADP-ribose molecules. Here, we investigated whether and how PARP1 and PARylation modulate responses of Nicotiana benthamiana plants to methyl viologen (MV)-induced oxidative stress. It was found that the burst of reactive oxygen species (ROS), cell death, and loss of tissue viability invoked by MV in N. benthamiana leaves was significantly delayed by both the RNA silencing of the PARP1 gene and by applying the pharmacological inhibitor 3-aminobenzamide (3AB) to inhibit PARylation activity. This in turn reduced the accumulation of PARylated proteins and significantly increased the gene expression of major ROS scavenging enzymes including SOD (NbMnSOD; mitochondrial manganese SOD), CAT (NbCAT2), GR (NbGR), and APX (NbAPX5), and inhibited cell death. This mechanism may be part of a broader network that regulates plant sensitivity to oxidative stress through various genetically programmed pathways.

Potato virus Y (PVY; genus Potyvirus, family Potyviridae) is one of the most devastating and economically important potato pathogens. Members of the Potyviridae family demonstrate high recombination rates. In nature, five major parental variants of PVY were identified with at least 35 recombinants. In this study, we report two novel PVY recombinants discovered in the sprouts of potato tubers produced in field conditions in the Astrakhan region of Russia in 2021 using high-throughput sequencing and de novo genome assembly. These recombinants, which were named Ast-A-I and Ast-A-II, have previously unknown arrangements of genome sections derived from PVY^O and PVY^N, with a novel recombination junction at position 7,850 nt of the PVY genome in the middle part of the RNA-dependent RNA polymerase (NIb) gene, with PVY^O type sequence at the 5′ end relative to this junction and PVY^N type at the 3′ end. Other recombinant junctions in the novel PVY variants were previously found in PVY^NTNa and PVY^NTNb. This includes those at positions 2,390 and 9,200 (PVY^N at the 5′ end and PVYIS° at the 3′ end), which were present in both novel recombinants, and at position 500 (PVY^O at the 5′ end and PVY^N at the 3′ end), which present in Ast-A-II. The presence of PVY variants with a novel recombinant point is verified by Sanger sequencing. Phylogenetic analysis of genomic RNA showed that the sequences of these recombinants form a separate branch that do not cluster with previously described PVY strains.