Harpin proteins produced by plant-pathogenic Gram-negative bacteria are the venerable player in regulating bacterial virulence and inducing plant growth and defenses. A major gap in these effects is plant sensing linked to cellular responses, and plant sensor for harpin Hpa1 from rice bacterial blight pathogen points to plasma membrane intrinsic protein (PIP). Here we show that Arabidopsis AtPIP1;4 is a plasma membrane sensor of Hpa1 and plays a dual role in plasma membrane permeability of CO2 and H2O. In particular, AtPIP1;4 mediates CO2 transport with a substantial contribute to photosynthesis and further increases this function upon interacting with Hpa1 at the plasma membrane. As a result, leaf photosynthesis rates are increased and the plant growth is enhanced in contrast to the normal process without Hpa1-AtPIP1;4 interaction. Our findings demonstrate the first case that plant sensing of a bacterial harpin protein is connected with photosynthetic physiology to regulate plant growth.

Soils are the foundation of all terrestrial ecosystems 1 . However, unlike for plants and animals, a global assessment of the hotspots for soil nature conservation is still lacking 2 . This hampers our ability to establish nature conservation priorities for the multiple dimensions supporting the soil system: from soil biodiversity to ecosystem services. Here, we conducted a global field survey including biodiversity (archaea, bacteria, fungi, protists, and invertebrates) and function (critical for six ecosystem services) observations within 615 composite topsoil samples from a standardized survey in all continents, to identify global hotspots for soil nature conservation.We found that each of the different soil ecological dimensions (i.e., soil species richness [alpha diversity, measured as ASVs], community dissimilarity, and ecosystem services) peaked in contrasting regions of the planet, and were associated with different environmental factors.Temperate ecosystems showed the highest species richness, while community dissimilarity peaked in the tropics, and colder high-latitudinal ecosystems were identified as hotspots of ecosystem services. These findings highlight the complexities of simultaneously protecting multiple soil ecological dimensions. We further show that most of these hotspots are not properly covered by protected areas (over 70%), and are vulnerable in the context of multiple global change scenarios. This first global estimation of soil nature conservation priorities, highlights the fundamental importance of accounting for the multidimensionality of soil biodiversity and ecosystem services to conserve soils for future generations. Main text:Soils are essential to support terrestrial life on the planet 1 . They are home to diverse assemblages of organisms across all major lineages of life from bacteria to invertebrates, and provide multiple ecosystem services such as soil fertility, carbon (C) storage, waste decomposition, pest control, and water retention 3-5 that are critical for food production and human well-being 6-8 . However, soils are also highly vulnerable to anthropogenic disturbances such as climate change 9,10 and land use intensification (e.g., land-use change, pollution, and erosion 11,12 ). For an adequate conservation of soils, it is critical to consider and protect the

While the contribution of biodiversity to supporting multiple ecosystem functions is well-established in natural ecosystems, the relationship of the above and belowground diversity with ecosystem multifunctionality remains virtually unknown in urban greenspaces. Here, we conducted a standardized survey of urban greenspaces from 56 municipalities across six continents, aiming to investigate the relationships of plant and soil biodiversity (diversity of bacteria, fungi, protists, and invertebrates, and metagenomics-based functional diversity) with 18 surrogates of ecosystem functions from nine ecosystem services. We found that soil biodiversity across biomes was significantly and positively correlated with multiple dimensions of ecosystem functions, and contributed to key ecosystem services such as microbial-driven carbon pools, organic matter decomposition, plant productivity, nutrient cycling, water regulation, plant-soil mutualism, plant pathogen control, and antibiotic resistance regulation. Plant diversity only indirectly influenced multifunctionality in urban greenspaces via changes in soil conditions that were associated with soil biodiversity. These findings were maintained after controlling for climate, spatial context, soil properties, vegetation, and management practices. This study provides solid evidence that conserving soil biodiversity in urban greenspaces is key to support multiple dimensions of ecosystem functioning, which is critical for the sustainability of urban ecosystems and human wellbeing.

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