## 3 Results
### Composition of Fungal Microbiota on Unripe and Ripe Sea Buckthorn Berries  
A total of four phyla, 69 orders, and 144 families were identified in the present study (Table S1). Based on the average abundance analysis, the dominating phyla on both sea buckthorn samples were Ascomycata (85.0% for UB and 97.6% for RB, respectively) followed by the Basidiomycota (10.6% and 1.7% in UB and RB, respectively) and other fungi (Figure 2A; Table S1). The impact of ripening on the fungal microorganism community was notable starting at the class level. Dothdeomycetes were present in large numbers in both samples (54.0% for UB and 44.6% for RB, respectively) (Figure 2B). However, on unripe berries (UB) the most abundant classes were Taphrinomycetes (18.4%) and Tremellomycetes (7.6%) when in RB samples Saccharomyces (47.6%) prevailed. At the family level, in UB samples we found dominating Aureobasidiaceae and Taphrinaceae, while RB samples were prevalent by Aureobasidiaceae and Metschnikowiaceae (Figure 2C). In total, 196 genera were identified in this study; the most abundant were _Aureobasidium_ (31.4%), _Taphrina_ (18.4%), and _Cidasporium_ (8.1%) for UB samples, and _Metschnikowia_ (44.5%) with _Aureobasidium_ (40.6%) for RB samples (Figure 2D).  
Figure 1: Principal coordinate analysis (PCoA) of the relative abundance of fungal microorganism amplicon sequence variants (ASVs) associated with unripe (UB) and ripe (RB) sea buckthorn berries. PCoA plot is based on unweighted UniFrac distance metrics.  
The Venn diagram presents the distribution of unique fungal ASVs in UB and RB samples (Figure 3). A total of 887 unique ASVs found in this study, 198 were shared by both UB and RB samples, while 493 ASVs were exclusive to UB and 196 to RB samples, respectively.  
A heatmap diagram illustrates the distribution of the most abundant fungal ASVs (Figure 4). Hierarchical cluster analysis showed that the microbial community structure displays different patterns  
Figure 3: Venn diagram illustrating the number of unique and shared amplicon sequence variants (ASVs) among sea buckthorn samples at different ripening stages. UB – unripe sea buckthorn berries, RB – ripe berries.  
Figure 2: Fungal microorganism community distribution on sea buckthorn unripe (UB) and ripe (RB) berries. Relative abundance of sequences classified at the phylum (**A**), class (**B**), family (**C**), and genus (**D**) level. The taxonomic groups comprising less than 1% of the total composition were assigned to “Other”.  
between UB and RB groups, while samples collected within the same ripening stage feature similar community structure. The core microbiomes detected in both samples comprised of ASV1 and ASV3 assigned to _Aureobasidium pullulans_ (Figure 4; Table S2). At the beginning of ripening, besides the _Aureobasidium pullulans_ the most abundant ASVs were ASV4 (7.6%) and ASV14 (2.4%) (both _Taphrina carpiin_), ASV10 (4.7%) (Taphrina), ASV6 (6.8%) (_Cladosporium_), and ASV20 (1.6%) (_Filobasidium wieringae_). During the ripening of the berries, their prevalence diminished to less than 1%. A dramatic change was observed between the beginning and the end of the ripening period, mainly due to the increase of fungal microorganisms belonging to _Metschnikovia spp_. (ASVs 2, 5, 7, 9, 11, 22, and 30). The overall abundance of ASVs assigned to _Metschnikovia_ in RB berries reached 44%, while on the unripe berries they consisted only 0.7%.