Bacterial type VI secretion systems (T6SSs) are molecular weapons designed to deliver toxic effectors into prey cells. These nanomachines have an important role in inter-bacterial competition and provide advantages to T6SS active strains in polymicrobial environments. Here we analyze the genome of the biocontrol agent Pseudomonas putida KT2440 and identify three T6SS gene clusters (K1-, K2- and K3-T6SS). Besides, 10 T6SS effector\uffe2\uff80\uff93immunity pairs were found, including putative nucleases and pore-forming colicins. We show that the K1-T6SS is a potent antibacterial device, which secretes a toxic Rhs-type effector Tke2. Remarkably, P. putida eradicates a broad range of bacteria in a K1-T6SS-dependent manner, including resilient phytopathogens, which demonstrates that the T6SS is instrumental to empower P. putida to fight against competitors. Furthermore, we observed a drastically reduced necrosis on the leaves of Nicotiana benthamiana during co-infection with P. putida and Xanthomonas campestris. Such protection is dependent on the activity of the P. putida T6SS. Many routes have been explored to develop biocontrol agents capable of manipulating the microbial composition of the rhizosphere and phyllosphere. Here we unveil a novel mechanism for plant biocontrol, which needs to be considered for the selection of plant wardens whose mission is to prevent phytopathogen infections.
", "keywords": ["PROTEIN SECRETION", "Nicotiana", "0301 basic medicine", "570", "INTESTINAL INFLAMMATION", "05 Environmental Sciences", "VIBRIO-CHOLERAE", "Environmental Sciences & Ecology", "VI SECRETION SYSTEM", "Xanthomonas campestris", "Microbiology", "03 medical and health sciences", "Bacterial Proteins", "10 Technology", "Plant Diseases", "0303 health sciences", "Science & Technology", "Ecology", "Pseudomonas putida", "ROOT MICROBIOME", "Gene Expression Regulation", " Bacterial", "06 Biological Sciences", "Type VI Secretion Systems", "GENOMIC ANALYSIS", "Biological Control Agents", "ESCHERICHIA-COLI", "EFFECTORS", "IMMUNITY PROTEINS", "Original Article", "HOST-RANGE", "Life Sciences & Biomedicine"]}, "links": [{"href": "http://www.nature.com/articles/ismej2016169.pdf"}, {"href": "https://doi.org/10.1038/ismej.2016.169"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/The%20ISME%20Journal", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1038/ismej.2016.169", "name": "item", "description": "10.1038/ismej.2016.169", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1038/ismej.2016.169"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2017-01-03T00:00:00Z"}}, {"id": "10.1111/1462-2920.13956", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-02T16:18:48Z", "type": "Journal Article", "created": "2017-10-13", "title": "Type VI secretion systems in plant-associated bacteria", "description": "SummaryThe type VI secretion system (T6SS) is a bacterial nanomachine used to inject effectors into prokaryotic or eukaryotic cells and is thus involved in both host manipulation and interbacterial competition. The T6SS is widespread among Gram\uffe2\uff80\uff90negative bacteria, mostly within the Proteobacterium Phylum. This secretion system is commonly found in commensal and pathogenic plant\uffe2\uff80\uff90associated bacteria. Phylogenetic analysis of phytobacterial T6SS clusters shows that they are distributed in the five main clades previously described (group 1\uffe2\uff80\uff935). The even distribution of the system among commensal and pathogenic phytobacteria suggests that the T6SS provides fitness and colonization advantages in planta and that the role of the T6SS is not restricted to virulence. This manuscript reviews the phylogeny and biological roles of the T6SS in plant\uffe2\uff80\uff90associated bacteria, highlighting a remarkable diversity both in terms of mechanism and function.
", "keywords": ["PROTEIN SECRETION", "0301 basic medicine", "570", "VIBRIO-CHOLERAE", "PATHOGENIC BACTERIA", "Microbiology", "03 medical and health sciences", "Bacterial Proteins", "Proteobacteria", "Phylogeny", "Plant Diseases", "2. Zero hunger", "0303 health sciences", "Science & Technology", "Virulence", "PSEUDOMONAS-AERUGINOSA", "Minireviews", "Plants", "Type VI Secretion Systems", "IN-SILICO ANALYSIS", "AGROBACTERIUM-TUMEFACIENS", "INTERBACTERIAL COMPETITION", "GENOMIC ANALYSIS", "EFFECTORS", "VIRULENCE", "Life Sciences & Biomedicine", "0605 Microbiology"]}, "links": [{"href": "https://onlinelibrary.wiley.com/doi/pdf/10.1111/1462-2920.13956"}, {"href": "https://doi.org/10.1111/1462-2920.13956"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Environmental%20Microbiology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1111/1462-2920.13956", "name": "item", "description": "10.1111/1462-2920.13956", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1111/1462-2920.13956"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2017-11-10T00:00:00Z"}}, {"id": "10.1111/nph.15230", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-02T16:19:17Z", "type": "Journal Article", "created": "2018-05-28", "title": "Partner communication and role of nutrients in the arbuscular mycorrhizal symbiosis", "description": "Contents Summary 1031 I. Introduction 1031 II. Interkingdom communication enabling symbiosis 1032 III. Nutritional and regulatory roles for key metabolites in the AM symbiosis 1035 IV. The plant\uffe2\uff80\uff93fungus genotype combination determines the outcome of the symbiosis 1039 V. Perspectives 1039 Acknowledgements 1041 References 1041
SummaryThe evolutionary and ecological success of the arbuscular mycorrhizal (AM) symbiosis relies on an efficient and multifactorial communication system for partner recognition, and on a fine\uffe2\uff80\uff90tuned and reciprocal metabolic regulation of each symbiont to reach an optimal functional integration. Besides strigolactones, N\uffe2\uff80\uff90acetylglucosamine\uffe2\uff80\uff90derivatives released by the plant were recently suggested to trigger fungal reprogramming at the pre\uffe2\uff80\uff90contact stage. Remarkably, N\uffe2\uff80\uff90acetylglucosamine\uffe2\uff80\uff90based diffusible molecules also are symbiotic signals produced by AM fungi (AMF) and clues on the mechanisms of their perception by the plant are emerging. AMF genomes and transcriptomes contain a battery of putative effector genes that may have conserved and AMF\uffe2\uff80\uff90 or host plant\uffe2\uff80\uff90specific functions. Nutrient exchange is the key feature of AM symbiosis. A mechanism of phosphate transport inside fungal hyphae has been suggested, and first insights into the regulatory mechanisms of root colonization in accordance with nutrient transfer and status were obtained. The recent discovery of the dependency of AMF on fatty acid transfer from the host has offered a convincing explanation for their obligate biotrophism. Novel studies highlighted the importance of plant and fungal genotypes for the outcome of the symbiosis. These findings open new perspectives for fundamental research and application of AMF in agriculture.
", "keywords": ["0301 basic medicine", "2. Zero hunger", "0303 health sciences", "Nitrogen", "Phosphorus", "Plants", "15. Life on land", "symbiosis", "lipids", "03 medical and health sciences", "nutrients", "Mycorrhizae", "arbuscular mycorrhizal fungi (AMF)", "Metabolome", "natural variation", "signalling", "Symbiosis", "effectors", "phosphate"]}, "links": [{"href": "https://iris.unito.it/bitstream/2318/1667502/1/Pre-print%20IRIS_%20review%20New%20Phytol%202018.pdf"}, {"href": "https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/nph.15230"}, {"href": "https://doi.org/10.1111/nph.15230"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/New%20Phytologist", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1111/nph.15230", "name": "item", "description": "10.1111/nph.15230", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1111/nph.15230"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2018-05-28T00:00:00Z"}}, {"id": "10261/346836", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-02T16:24:48Z", "type": "Journal Article", "created": "2021-12-08", "title": "Marchantia polymorpha model reveals conserved infection mechanisms in the vascular wilt fungal pathogen Fusarium\u2009oxysporum", "description": "Summary
Root\uffe2\uff80\uff90infecting vascular fungi cause wilt diseases and provoke devastating losses in hundreds of crops. It is currently unknown how these pathogens evolved and whether they can also infect nonvascular plants, which diverged from vascular plants over 450 million years ago.
We established a pathosystem between the nonvascular plant Marchantia polymorpha (Mp) and the root\uffe2\uff80\uff90infecting vascular wilt fungus Fusarium oxysporum (Fo). On angiosperms, Fo exhibits exquisite adaptation to the plant xylem niche as well as host\uffe2\uff80\uff90specific pathogenicity, both of which are conferred by effectors encoded on lineage\uffe2\uff80\uff90specific chromosomes.
Fo isolates displaying contrasting lifestyles on angiosperms \uffe2\uff80\uff93 pathogenic vs endophytic \uffe2\uff80\uff93 are able to infect Mp and cause tissue maceration and host cell killing. Using isogenic fungal mutants we define a set of conserved fungal pathogenicity factors, including mitogen activated protein kinases, transcriptional regulators and cell wall remodelling enzymes, that are required for infection of both vascular and nonvascular plants. Markedly, two host\uffe2\uff80\uff90specific effectors and a morphogenetic regulator, which contribute to vascular colonisation and virulence on tomato plants are dispensable on Mp.
Collectively, these findings suggest that vascular wilt fungi employ conserved infection strategies on nonvascular and vascular plant lineages but also have specific mechanisms to access the vascular niche of angiosperms.
The non-vascular plantMarchantia polymorphahas emerged as a valuable model for studying evolutionarily conserved microbial infection strategies and plant immune responses. However, only a handful of fungal pathogens ofMarchantiahave been described so far. Here we establish a new pathosystem using the root-infecting vascular wilt fungusFusarium oxysporum. On angiosperms, this fungus exhibits exquisite adaptation to the plant vascular niche and host-specific pathogenicity, both of which are conferred by lineage-specific effectors secreted during growth in the xylem. We show thatF. oxysporumisolates with different lifestyles - pathogenic or endophytic - are able to infect this non-vascular liverwort causing tissue maceration and plant cell killing. Similar to bacterial pathogens,F. oxysporuminduces a PAMP-triggered immune response inM. polymorpha. Analysis of isogenic fungal mutants established that infection ofMarchantiarequires conserved fungal pathogenicity mechanisms such as mitogen activated protein kinases, transcriptional regulators and cell wall remodeling enzymes. Remarkably, lineage-specific virulence effectors are dispensable for infection, most likely due to the absence of xylem tissue in this non-vascular plant. TheF. oxysporum-M. polymorphasystem provides new insights into the mechanism and evolution of pathogenic and endophytic fungus-plant interactions.Significance statementRoot-infecting vascular fungi cause wilt diseases and provoke devastating losses in hundreds of crops. It is currently unknown how these pathogens evolved and whether they infect non-vascular plants, which diverged from vascular plants over 450 million years ago. Here we show that two strains of the fungusFusarium oxysporumwith opposed lifestyles, causing either wilting and death or beneficial protection on tomato, produce similar disease symptoms on the non-vascular plantMarchantia polymorpha.We define a set of core fungal pathogenicity factors required on both vascular and non-vascular plants and show that host-specific effectors contributing to disease on tomato are dispensable onMarchantia. These findings suggest that systemic wilt disease evolved in fungal pathogens after the emergence of vascular land plants.