The territory of the new mass outbreak of Dendrolimus sibiriciusis northernmost Siberia. The present increase in the pest numbers started in 2011–2012, 14 years after the previous mass outbreak. As...

Fusarium crown rot (FCR), caused by Fusarium pseudograminearum, significantly impacts wheat yield and quality in China’s Huanghuai region. The rapid F. pseudograminearum epidemic and FCR outbreak within a decade remain unexplained. In this study, two high-quality, chromosome-level genomes of F. pseudograminearum strains producing 3-acetyl-deoxynivalenol (3AcDON) and 15-acetyl-deoxynivalenol (15AcDON) toxins were assembled. Additionally, 38 related strains were resequenced. Genomic differences such as single nucleotide polymorphisms (SNPs), insertions/deletions (indels), and structural variations (SVs) among F. pseudograminearum strains were analyzed. The whole-genome SNP locus-based population classification mirrored the toxin chemotype (3AcDON and 15AcDON)-based classification, indicating the presence of genes associated with the trichothecene toxin gene cluster. Further analysis of differential SNP, indel, and SV loci between the 3AcDON and 15AcDON populations revealed a predominant connection to secondary metabolite synthesis genes. Notably, the majority of the secondary metabolite biosynthesis gene cluster loci were located in SNP-dense genomic regions, suggesting high mutability and a possible contribution to F. pseudograminearum population structure and environmental adaptability. This study provides insightful perspectives on the distribution and evolution of F. pseudograminearum and for forecasting the spread of wheat FCR, thereby aiding in the development of preventive measures and control strategies.

In 2019, the bark beetle Ips amitinus (native to central Europe) was identified in south-western Siberia at a distance exceeding 2500 km east of its previously known easternmost location in the European part of Russia. In Siberia, its invasive populations are characterised by high abundance and harmfulness. Here, I. amitinus accomplishes primary attacks on standing vital trees of Pinus sibirica with a lethal outcome. This invasion has already resulted in massive dieback in stands of pine over a large geographic territory. By, 2021, the invaded area was estimated to cover at least 31,200 km². The objectives of this study were to investigate fungi associated with/vectored by I. amitinus in its invasive area in south-western Siberia and wood decay fungi that cause root and butt rots to P. sibirica. This led to the following conclusions: (i) DNA analysis of sixty adult beetles of Ips amitinus collected from P. sibirica in south-west Siberia revealed the presence of 143 fungal taxa; (ii) species richness was significantly higher in beetles collected from dead branches than from (more recently infested) dying branches; (iii) fungal communities were >90% dominated by yeasts, among which the most common were Nakazawaea holstii, Kuraishia molischiana, and N. ambrosiae; (iv) entomopathogenic Beauveria bassiana s.l. was the most common fungus isolated from dead/mycosed beetles of I. amitinus, followed by Lophium arboricola and four Ophiostoma spp.; and (v) Heterobasidion parviporum was the most common decay fungus detected, which was causing heart rot in stems of P. sibirica.

To date, the taxonomy of fusarioid fungi has undergone significant changes due to a clarification of their taxonomic status by molecular genetic methods. As a result, new species/genera have appeared, whereas some old ones have been abolished. Information on the diversity and distribution of Fusarium species do not always correspond to the modern taxonomy and requires a thorough revision. In this study we have systematized some long-term data on the species composition and specialization of fungi associated with woody plants in Russia (Far East, Siberia, the Northwestern region, and Crimea). The molecular genetic identification of 53 isolates earlier identified as Fusarium spp. has been carried out. According to morphological characteristics, phylogenetic analysis, and ecological preferences, five species complexes of Fusarium fungi have been identified. Eleven Fusarium species (F. acuminatum, F. avenaceum, F. equiseti, F. oxysporum, F. redolens, F. reticulatum, F. sambucinum, F. sporotrichioides, F. torulosum, F. tricinctum, and F. venenatum) and 1 closely related species from the genus Neocosmospora (N. solani) have been identified. In the case of woody plants, the Fusarium tricinctum species complex has been represented by the largest number of species (F. acuminatum, F. avenaceum, F. reticulatum, F. torulosum, and F. tricinctum). The maximum number of the studied isolates (17) belongs to F. avenaceum associated with various plants growing in the whole studied areas. Seven Fusarium species and N. solani have been identified on juvenile plants characterized by the signs of tracheomycotic wilt and growing in the forest nurseries of Central and Southern Siberia; species such as F. oxysporum, F. equiseti, and N. solani have been revealed only on first-year conifer seedlings. In forest and park stands, where fusarioid fungi belong mainly to saprotrophs and endophytes, nine Fusarium species have been revealed, among which F. tricinctum, F. torulosum, F. venenatum, and F. reticulatum have not been found in pathological or seed material from the forest nurseries.

The genus Armillaria is an essential component of forest ecosystems playing very important ecological role in dead wood decomposition, but it often becomes a serious pathogen causing white root rot in trees. It is also known that Armillaria species significantly differ in the level of pathogenicity. Thus, accurate identification of Armillaria is critical for assessing the risk of tree disease. In this study we analyzed 28 Armillaria isolates from Siberia and the Far East using nucleotide sequences of ITS, IGS-1-1 and TEF-1α gene regions and generated phylogenetic trees based on maximum likelihood method. In total, four Armillaria species were identified: A borealis, A. cepistipes, A. ostoyae and A. gallica. A. borealis was the most frequent among collected isolates (18 out of 28 isolates). A. gallica, A. cepistipes and A. ostoyae were much less frequent with two, five and three isolates out of 28, respectively. Thedistribution of Armillaria species in Siberia and the Far East was described for the first time. It is concluded that further studies are necessary to determine the role of Armillaria in trees pathological dieback, and A. borealis should be a key focus.