IMPLiCIT

Although the role of pollinators is now widely recognized as essential for agricultural productivity and biodiversity conservation, the mechanisms through which the biological fertility of soil can influence plant attractiveness, the quality of floral resources and, consequently, the behaviour and health of pollinating insects remain only partially understood. The PRIN project IMPLiCIT – Improving soil-plant-insect interactions to promote pollinators, funded within the framework of the NRRP, addressed this knowledge gap by investigating the interactions among soil, plants and pollinators, using sunflower (Helianthus annuus) as a model crop. The project brought together complementary expertise in agricultural microbiology, applied entomology, chemical ecology, plant physiology and analytical chemistry, involving the Free University of Bolzano, the University of Bologna and the University of Padova. Its main objective was to understand whether and how soil microbiota and the application of beneficial microorganisms can modulate plant physiology, the emission of volatile organic compounds, the composition of nectar and pollen and, ultimately, plant interactions with honeybees and other pollinators.

Results achieved

The project produced relevant evidence on the role of soil microbiota in regulating plant traits involved in pollinator attraction and nutrition. Hybrid and non-hybrid sunflower varieties with comparable phenological and agronomic characteristics were selected, and microbial strains with potential PGPB activity were identified, including strains belonging to the genera Bacillus, Pseudomonas, Apilactobacillus and Lactiplantibacillus. Field trials carried out over two growing seasons showed that microbial inoculation did not induce detectable short-term changes in the physicochemical properties of bulk soil, but it could significantly influence the composition of rhizosphere and endosphere microbial communities.

In terms of plant physiology and floral chemistry, microbial treatments modified several photosynthetic and spectral parameters, with genotype-dependent responses. The analysis of volatile organic compounds revealed complex profiles, mainly dominated by monoterpenes and sesquiterpenes, and showed that inocula based on Bacillus and Lactobacillus can significantly alter the volatile bouquet of sunflower. Honeybees were able to perceive key compounds such as α-pinene, sabinene, limonene and DMNT, suggesting that microbiota-induced modifications may affect pollinator recognition and preference. Field observations also indicated differences in pollinator visitation and diversity depending on sunflower variety and microbial treatment.

The project also characterized the composition of nectar, pollen and floral microbiota, highlighting a strong effect of plant genotype on the nutritional quality of floral resources, particularly on the amino acid profile of pollen. Some microorganisms isolated from nectar and pollen showed potential interest for honeybee health, with strain-specific effects on vitellogenin expression. Overall, IMPLiCIT demonstrated that soil microbial biodiversity is a functional component of plant-pollinator interactions and laid the groundwork for sustainable agricultural strategies based on beneficial microorganisms, aimed at improving soil functionality, the quality of floral resources and pollination ecosystem services.

D.D. del MUR n. 104 del 02/02/2022

Codice progetto MUR: 2022NMAPEL

CUP: J53D23006680006

Coordinatore di progetto: Libera Università di Bolzano

Ruolo UNIBO: RL

Research areas: Agro-environmental and food microbiology

Scientific officer: Diana Di Gioia

Duration: 05/10/2023 - 05/10/2025

Research group: Diana Di Gioia, Daniele Alberoni, Chiara Braglia.