The strict relationships between bacteria and plants represents one of the major facets of terrestrial ecology. Depending on the type of interaction and amount of metabolic advantage one organism can obtain from such relationships, these are classified as mutualistic, commensal or parasitic interactions. Within this context, Pseudomonas and Xanthomonas are bacterial genera with a worldwide spread, capable of establishing all of the above mentioned interactions with plants. Therefore, they represent good models for studying different lifestyles and, accordingly, deciphering distinct evolutionary trajectories followed by different lineages of a single genus to infect and/or to establish a mutualistic relationships with the plant. Some members of these two genera are regulated pests that are recognized as economically major threats for their host crop(s) both in temperate and tropical environments.

This Research Topic is dedicated In Memoriam of Dr. Nicola Sante Iacobellis who contributed to the conception of this article collection † This Research Topic collects the selected contributions to the 14th International Conference on Plant Pathogenic Bacteria (14th ICPPB), “The Impact of Plant Pathogenic Bacteria on Global Plant Health”, which was held in Assisi (Italy) from July 3 to 8, 2022. Occurrence of bacterial disease in plant is the result of complex interaction between host, bacterium and environment. The mechanisms by which bacteria cause shifts in the biochemical and physiological processes required for the plant life cycle as well as the mechanisms by which hosts prevent or respond or defend against attack by bacteria are the central themes of this Research Topic.

This open access book offers the first comprehensive account of the pan-genome concept and its manifold implications. The realization that the genetic repertoire of a biological species always encompasses more than the genome of each individual is one of the earliest examples of big data in biology that opened biology to the unbounded. The study of genetic variation observed within a species challenges existing views and has profound consequences for our understanding of the fundamental mechanisms underpinning bacterial biology and evolution. The underlying rationale extends well beyond the initial prokaryotic focus to all kingdoms of life and evolves into similar concepts for metagenomes, phenomes and epigenomes. The book’s respective chapters address a range of topics, from the serendipitous emergence of the pan-genome concept and its impacts on the fields of microbiology, vaccinology and antimicrobial resistance, to the study of microbial communities, bioinformatic applications and mathematical models that tie in with complex systems and economic theory. Given its scope, the book will appeal to a broad readership interested in population dynamics, evolutionary biology and genomics.

Type IV secretion systems (T4SSs) are highly versatile membrane-associated transporter machines used by Gram-negative and Gram-positive bacteria to deliver substrate molecules to a large variety of target cells. This volume summarizes our current knowledge of the large variety and structural diversity of T4SSs in pathogenic Escherichia, Agrobacterium, Legionella, Coxiella, Bartonella, Helicobacter, Enterococcus and other species. Divided into 13 chapters contributed by leading experts, it presents findings that significantly enhance our understanding of how various pathogens manipulate host cell functions to trigger bacterial uptake, promote intracellular growth, suppress defense mechanisms and of how bacteria spread antibiotic resistances, thus facilitating bacterial colonization and disease development. The book is an invaluable source of information for researchers and clinicians.

Acetobacter. Actinomyces. Aerobacter. Agrobacterium. Aplanobacter. Aplanobacterium. Arthrobacter. Bacillus. Bacterium. Burkholderiella. Chlorobacter. Chromobacterium. Clavibacter. Clostridium. Coccus. Corynebacterium. Curtobacterium. Diplococcus. Empedobcter. Enterobacter. Erwinia. Eubacterium. Flavobacterium. Gluconobacter. Innominatus. Kurthia. Methanobacterium. Methanobrevibacter. Micrococcus. Mycobacterium. Norcadia. Pectobacterium. Phytobacter. Phytobacterium. Phytomonas. Polyangium. Polymonas. Proteus. Psudobacterium. Pseudomonas. Rhodococcus. Serratia. Spiroplasma. Streptomyces. Xanthomonas. Host-pathogen index. Frequently cited references.