The aim of the project is to study the diversity of xylobiont fungi and bacteria in natural conditions of multi-species mesic Quercus broad-leaved forest at the sites of mass windthrow, which occurred in 2006 in the Kaluzhskie Zaseki State Nature Reserve. In 2022 the following work on the project was done.
For metagenomic analysis, 150 wood samples of eight tree species at five decomposition stages were collected. Samples were taken from the deadwood (coarse woody debris) of seven angiosperms: maple (Acer platanoides), birch (Betula pendula), common ash (Fraxinus excelsior), European aspen (Populus tremula), English oak (Quercus robur), linden (Tilia cordata) and elm (Ulmus glabra), and one gymnosperm European spruce (Picea abies). A protocol for the isolation of total DNA and amplification of ITS variant sites of fungi was optimized. Total DNA of bacteria and fungi was isolated from the wood samples. More than half of the samples were prepared for subsequent sequencing.
An analysis of the nucleotide sequences in the available international database NCBI Nucleotide was performed. It was found that 12 of the 175 species (6.9%) of aphyllophoroid fungi previously identified in the study area lacked any information on the nucleotide sequences of the ITS1-5.8S-ITS2 region of rDNA. A list of 11 taxa represented in the NCBI Nucleotide database for 1 and 2 target nucleotide sequences was compiled. DNA barcoding of fruit body samples of xylobiont aphyllophoroid fungi collected from deadwood of eight tree species at the sampling sites for metagenomic analysis was performed. Fifty nucleotide sequences of the ITS1-5.8S-ITS2 region of rDNA were obtained. Preservation of isolated genomic DNA samples in freezer conditions was ensured, determining the possibility of amplification of additional genomic regions. There was created a library of 50 reference macromycete DNA sequences prepared for deposit into the international NCBI GenBank database. For each nucleotide sequence, information is given on the DNA extraction method, the primers used, and details about the voucher herbarium sample.
Based on the sequencing of pilot samples, we identified bacterial and fungal communities containing representatives with known wood decomposition ability. In the process of wood decomposition, a pronounced increase in the diversity of the bacterial community was observed, with an increase in both the number of bacterial groups observed and the Shannon index (no individual dominant groups emerged). The relative number of representatives of the Acidobacteriaceae family and Bacili class decreased and the number of representatives of the Actinobacteria and Thermoleophilia classes increased. In the fungal community, there was a change in the dominance of representatives of Ascomycota at the first stage of decomposition by representatives of Basidiomycota at the third stage. The fungal community looked less diverse than the bacterial community: during wood decomposition, the diversity of the fungal community significantly decreased, both in terms of number of observed groups and the Shannon index (dominant groups in the community appeared).
Physical and chemical properties of deadwood of 8 tree species at 5 stages of decomposition were analyzed. Analysis of variance showed that tree species differed most clearly in the content and mass concentration of Mn, Zn, Mg, Ca and K. The leaders in the content of these elements were: Mn – Acer, Betula, Picea, and Tilia; Zn – Betula and Populus; Mg – Acer and Ulmus; Ca - Ulmus; K – Tilia and Ulmus. Wood decomposition stages proved to be a significant factor of variation for the content of Mn, P, Cu, Zn, and Ca. In the course of deadwood degradation, there was a significant increase in the content of these elements. It is concluded that the maintenance of cycles of biophilic elements is more successfully implemented in the presence of dead wood of different species at different stages of decomposition.
The results of the study were reported in oral presentations at 6 scientific conferences. There were four articles in scientific issues. One of the articles was accepted for publication in the journal Lesovedeine indexed by the SCOPUS database (to be published in 2023). Web pages on the project have been developed; they are located at:
https://www.impb.ru/index.php?id=div/lce/22-24-01063/index
https://www.impb.ru/index.php?id=div/lce/22-24-01063/index&lang=eng
