Emerging plant viruses are a threat worldwide. Studying their life cycles in details is a prerequisite to reveal alternative control strategies. We will target the family Nanoviridae for both practical and fundamental reasons: i) it represents a huge threat for Musaceae crop (genus Babuvirus) and for legumes (genus Nanovirus), and ii) it has adopted the enigmatic “multipartite” organization, with its genome composed of several nucleic acid segments each encapsidated individually. Nanoviruses being multipartite viruses with the highest number of genome segments described thus far, they are perfect models to investigate processes that might be specific to this viral genomic architecture most frequently adopted by plant viruses. In particular, how such viruses can efficiently infect a high proportion of cells/hosts with at least one copy of each of their numerous genome segments remains elusive. It is deemed impossible in the literature that actually questions the conceptual frame with which we try to comprehend the multipartite viral systems. Consistently, we recently showed that a nanovirus do not function in a way that fits the current concepts in virology. The virus spreads distinct genome segments in distinct individual cells of the host. These segments functionally complement across cells and thereby define a pluricellular way of life. This unprecedented discovery in virology now requires in depth investigation to decipher the mechanisms allowing such a surprising viral lifestyle. More specifically the Krenz group analyzes the viral proteins role during virus-host interactions, while the Blanc group studies the within-host viral population dynamics and the virus-vector interactions during plant-to-plant transmission. Through this project, we will join forces to study the full lifecycle. We propose to decipher the biochemical and biological properties of various nanoviral gene products interacting with host plants and aphid vectors. We aim to understand how distinct viral genome segments initially expressed in distinct plant cells actually function, how they can communicate and complement at a distance and at a supra-cellular scale. We will analyze the properties of the viral gene products with a focus on those with yet unknown function, and on properties that could be involved in trafficking among cells for complementation. Likewise, we will strive to understand how virus particles successfully travel through the body of their aphid vectors, ensuring that all segments are acquired, transported across aphid’s cell barriers, and inoculated together. Thus, beyond the urgent need to better understand the biology of nanoviruses, an emerging threat worldwide, another ambitious goal of this project is to decipher the means by which a multipartite virus can sustain a pluricellular lifestyle, and thereby definitely coin this discovery as a new research horizon in plant virology and beyond.

Microbiomes comprise communities of microorganisms (i.e., microbiota that includes bacteria, archaea, protists, fungi and microalgae) and their "theatre of activity" (i.e., structural elements, metabolites, signal molecules, mobile genetic elements, as well as surrounding environmental conditions). Microbiomes play a key role in maintaining life on Earth by providing a range of essential ecosystem services and are indispensable for the health of plants, animals and humans. Thus, there is a wide consensus that by harnessing microbiome functions society would be better placed to tackle global challenges such as food security, health and wellbeing, food waste management, and climate change mitigation. To facilitate the science necessary to achieve key advances in microbiome research, methodologies and technologies to capture or create, ensure stable long-term maintenance, and experimentally perturb microbiomes are required. Research infrastructures currently lack optimized methodologies and technologies to preserve and provide access to microbiome samples and massive amounts of associated data MICROBE is designed to address these issues by building upon and connecting: (1) technical solutions for microbiome preservation, propagation and functionality assessment, (2) novel ecological concepts (i.e. “core microbiome” and “microbial keystone taxa”), and (3) data infrastructures. In addition, MICROBE will address essential framework issues such as standardization, ethical and legal requirements and new business opportunities. Participation of relevant European research infrastructures, i.e., BBMRI-ERIC, MIRRI, ELIXIR and EMBRC-ERIC, to ensure that community needs are properly addressed and that developed solutions are efficiently taken up by the infrastructures themselves and by their user communities. Long term ambition is to ensure widespread uptake in microbiome research communities and thus support the development of novel microbiome-based applications.