Interactions among Floral Traits, Pollinator Visitation, and Flower-Associated Fungi in European Genotypes of Fragaria vesca

Flowers are sites of interaction among plants, flower visitors and microorganisms, yet these relationships are often studied separately. Flower-visiting insects can transport microorganisms among flowers, providing a potential link between floral display, microbial arrival and subsequent fruit health and shelf life. This pathway may be particularly relevant in strawberry because Aureobasidium pullulans has demonstrated antagonistic potential against plant pathogens, whereas Botrytis cinerea causes grey mould and contributes to postharvest fruit deterioration. This thesis examined 42 wild strawberry (Fragaria vesca) genotypes originating from different European regions and grown under shared net-house conditions in Alnarp, Sweden, to determine whether floral-display variation was associated with geographic origin, flower visitation, culture-based fungal abundance and fruit shelf life. Floral display was described using three traits: petal size, inflorescence exsertion and the average weekly number of open flowers. These traits varied among genotypes and formed distinct multidimensional display groups, although the groups were not clearly structured by geographic region. Visitor activity during the scheduled daytime observations was low. Only nine visits were recorded, which meant that relationships between floral traits and pollinator visitation could not be tested statistically. In the main floral-trait analysis, total culture-based fungal abundance was positively associated with petal size and negatively associated with the number of open flowers. Inflorescence exsertion and floral-display group were not significant predictors of total fungal abundance, suggesting that individual traits captured more of the relevant variation than the broader display groups. Culture-based A. pullulans abundance showed no clear association with floral traits or floral-display groups, and presumptive B. cinerea colonies were uncommon. Fruit shelf life differed among harvest batches, but there was little evidence that it was associated with floral-display group or geographic region. Together, these results suggest that floral-display variation in F. vesca is linked to culturable flower-associated fungi mainly through specific traits rather than through overall display type. However, because pollinator visitation was rare and fungal detection was culture-based, the study could not determine whether these fungal patterns reflected visitor-mediated dispersal, environmental deposition or differences in fungal establishment. More intensive visitor observations, including nocturnal surveys, together with systematic molecular sampling would be needed to test these pathways directly. Few recorded visits prevented direct testing of the proposed links among floral display, pollinators, flower-associated microbes and fruit shelf life.