Research Institute of Organic Agriculture

Drought events are becoming increasingly frequent and intense, posing major challenges to crop productivity. Beyond direct water stress, drought can indirectly affect plants by enhancing herbivore performance. While arbuscular mycorrhizal fungi (AMF) have been proposed to alleviate drought stress and to enhance plant resistance to herbivory, their role in mediating plant responses to the two combined pressures remains poorly understood. Here, we examined the individual and interactive effects of drought, AMF colonisation, and herbivory by Spodoptera exigua on maize (Zea mays) performance by combining a semi-field experiment with growth chamber assays. Drought reduced maize biomass (by 21.5%) and chlorophyll content (by 8.2%), while AMF improved reproductive traits. In particular, AMF colonisation increased the number of ears (from 1.1 to 1.4) and ear length (from 22.5 to 24.3 cm). Interestingly, drought transiently decreased DIMBOA-Glc levels in maize leaves, an effect that was exacerbated under AMF colonisation. Consistently, drought increased leaf herbivore performance by 32%. However, AMF colonisation mitigated the drought-induced increase in herbivore performance, even though leaf damage levels remained similar, indicating a post-ingestive resistance effect. This study highlights the need to consider multi-stressor interactions to harness AMF benefits in agriculture under increasing drought pressure.

Background: Livestock production contributes to the emergence and spread of antimicrobial resistance (AMR), with pig farming accounting for a large share of veterinary antibiotic use. Manure application to fields can release drug-resistant bacteria and AMR genes into the environment, creating potential transmission routes to humans. Mobile genetic elements such as plasmids and transposons facilitate horizontal transfer of AMR genes between bacteria, including pathogens. However, quantitative data on the manure resistome and its links to antibiotic use remain limited. Shotgun metagenomics provides broad insights into microbiota and AMR composition, with long-read sequencing offering improved resolution of the genomic context of AMR genes. Here, we applied long-read shotgun metagenomics to investigate the diversity, abundance, and mobility potential of AMR genes in 24 manure samples from 14 Swiss pig farms with documented antibiotic use. Results: Across 24 manure samples, 225 distinct AMR genes were detected, with tetracycline resistance genes being most prevalent. Manure samples from farms reporting the highest recent antibiotic use contained greater AMR gene abundance and richness. Metagenomic assemblies revealed that 77% of AMR genes with resolved flanking regions were located near transposases, recombinases, integrases, or relaxases, suggesting high transfer potential. The tigecycline resistance gene tet(X6) and related variants were identified in 21 of 24 samples, frequently embedded within mobile genetic elements. Two samples contained complete gene clusters of the vancomycin resistance determinant vanB, one of which was part of the conjugative transposon Tn1549. In one sample, a single highly abundant plasmid encoding beta-lactam and aminoglycoside resistance accounted for 42% of the total AMR gene load. Conclusions: Pig manure is a reservoir of diverse and mobile AMR genes, including those conferring resistance to critically important antibiotics. Long-read metagenomics adds valuable genomic context, supporting AMR monitoring and risk assessment within a One Health framework.

Land consolidation, especially when conducted in participatory processes, can improve the spatial and ownership structures of fragmented rural areas and thereby increase the economic viability of farms, reduce carbon footprints, and slow the spread of weeds. However, the community characteristics that enable land consolidation processes, and the factors that influence the fairness and acceptance of the outcomes, which should therefore be included in the processes, are insufficiently understood. Our research aimed to identify which factors should be considered and which factors influence a community's ability to carry out land consolidation. We followed the concept of sustainable landscape development when applying focus group interviews in four provinces in Poland that were undergoing land consolidation processes. The results show that social dynamics, including the attachment to place associated with the embeddedness of agricultural land in the culture and history of the local community, the quality of social capital, attitudes towards nature, and the ability to perceive the benefits of developing nature-based solutions, along with prospects for agricultural development, are particularly relevant to achieving fair and accepted outcomes. We conclude that social dynamics, with factors such as place attachment and social capital, although challenging, should be added to functional considerations for inclusion in processes of land consolidation is to contribute to sustainable landscape development.