Location: Sugarbeet and Potato ResearchTitle: Microbial small molecules – weapons of plant subversion
|STRINGLIS, IOANNIS - Utrecht University|
|ZHANG, HAO - Utrecht University|
|PIETERSE, CORNE - Utrecht University|
|DE JONGE, RONNIE - Utrecht University|
Submitted to: Natural Products Report
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2018
Publication Date: 5/14/2018
Citation: Stringlis, I., Zhang, H., Pieterse, C.M., Bolton, M.D., De Jonge, R. 2018. Microbial small molecules – weapons of plant subversion. Natural Product Reports. 35:410-433.
Interpretive Summary: In nature, plants are constantly bombarded with everything from fungal spores to various nematode and insect ‘nibblers.’ Despite this onslaught of microbes flying through the air or coursing underground, plant disease in natural ecosystems is rare. Field crops are also inundated with microbes, but only a select few pathogens have the required molecular mechanisms to cause disease in a particular crop. In contrast, some microbes provide a distinct benefit to plants including enhanced nutrient uptake and protection against pests and disease. Whether pathogenic or beneficial, microbes that colonize plant tissue must disarm the plant immune system to stay alive because plants will normally try to kill or subdue all potential invaders to stay healthy. In this review, we discuss the many strategies that pathogens and beneficial microbes utilize to communicate and disarm their plant host for their own benefit.
Technical Abstract: Plants live in close association with a myriad of microbes, most of which are harmless. However, the minority of microbes that are pathogens can severely impact crop quality and yield, thereby endangering food security. By contrast, beneficial microbes provide plants with important services, such as enhanced nutrient uptake and protection against pests and diseases. Like pathogens, beneficial microbes can modulate host immunity to efficiently colonize the nutrient-rich niches within and around the roots and aerial tissues of a plant, a phenomenon mirroring the establishment of commensal microbes in the human gut. Various ingenious mechanisms have been described by which pathogenic and beneficial microbes in the plant microbiome communicate with their host, including the delivery of immune-suppressive effector proteins and the production of phytohormones, toxins and other bioactive molecules. Plants signal to their associated microbes via exudation of photosynthetically fixed carbon sources, quorum-sensing mimicry molecules and selective secondary metabolites such as strigolactones and flavonoids. Molecular communication thus forms an integral part of the establishment of both beneficial and pathogenic host-microbe relations. Here, we review the current knowledge on microbial-derived small molecules that act as signalling compounds in this process. By means of large-scale genome comparisons of small molecule biosynthesis capabilities within the Pseudomonas genus, we display the biosynthetic potential of individual microbial genomes and the population as a whole, and highlight the increasingly fading barrier between detrimental and beneficial microbes.