Insights into cross-kingdom plant pathogenic bacteria.

Morgan W B Kirzinger,Geetanchaly Nadarasah,John Stavrinides

doi:10.3390/genes2040980

Abstract

Plant and human pathogens have evolved disease factors to successfully exploit their respective hosts. Phytopathogens utilize specific determinants that help to breach reinforced cell walls and manipulate plant physiology to facilitate the disease process, while human pathogens use determinants for exploiting mammalian physiology and overcoming highly developed adaptive immune responses. Emerging research, however, has highlighted the ability of seemingly dedicated human pathogens to cause plant disease, and specialized plant pathogens to cause human disease. Such microbes represent interesting systems for studying the evolution of cross-kingdom pathogenicity, and the benefits and tradeoffs of exploiting multiple hosts with drastically different morphologies and physiologies. This review will explore cross-kingdom pathogenicity, where plants and humans are common hosts. We illustrate that while cross-kingdom pathogenicity appears to be maintained, the directionality of host association (plant to human, or human to plant) is difficult to determine. Cross-kingdom human pathogens, and their potential plant reservoirs, have important implications for the emergence of infectious diseases.

Highlights

Plant pathogenic bacteria are responsible for major economical losses in agricultural industries worldwide, prompting massive research efforts to understand their ecology, pathology and epidemiology
Human pathogens are studied almost exclusively for their detrimental impact on human health. Pathogens such as Escherichia coli, Listeria monocytogenes, and Campylobacter jejuni possess a diverse set of genetic factors that enable pathogenicity, ranging from specialized secretion systems to toxins and adhesins, all of which are involved in manipulating or circumventing the human immune system [10,11,12]
Burkholderia species, including Burkholderia cepacia, Burkholderia cenocepacia, Burkholderia ambifaria, and Burkholderia pyrrocinia were initially identified as inhabitants of agricultural soil, with some, like Burkholderia glathei being found in fossil soils in Germany [39]

Summary

Introduction

Plant pathogenic bacteria are responsible for major economical losses in agricultural industries worldwide, prompting massive research efforts to understand their ecology, pathology and epidemiology. Pathogens such as Escherichia coli, Listeria monocytogenes, and Campylobacter jejuni possess a diverse set of genetic factors that enable pathogenicity, ranging from specialized secretion systems to toxins and adhesins, all of which are involved in manipulating or circumventing the human immune system [10,11,12] We often consider these human pathogenic bacteria to be dedicated animal pathogens, causing disease and epidemics; yet, the constant interaction of human carriers with their environment predisposes these pathogens to alternative niches that include non-animal hosts. Signatures of host adaptation will be apparent in these determinants, which may include incremental mutations and genetic rearrangements, along with the acquisition of novel genetic elements that may contribute to virulence or host specificity [13] The identification of these genetic determinants in cross-kingdom pathogens with both human- and plant-pathogenic potential can provide a better understanding of the evolution of phytopathogenicity, as well as the role of plants as potential reservoirs for clinically relevant bacteria.

Plant Pathogens that Infect Humans

Human Pathogens that Can Infect Plants

Evolutionary Models

Findings

Conclusions