A light life together: photosensing in the plant microbiota

Abstract

Bacteria and fungi of the plant microbiota can be phytopathogens, parasites or symbionts that establish mutually advantageous relationships with plants. They are often rich in photoreceptors for UVA–Visible light, and in many cases, they exhibit light regulation of growth patterns, infectivity or virulence, reproductive traits, and production of pigments and of metabolites. In addition to the light-driven effects, often demonstrated via the generation of photoreceptor gene knock-outs, microbial photoreceptors can exert effects also in the dark. Interestingly, some fungi switch their attitude towards plants in dependence of illumination or dark conditions in as much as they may be symbiotic or pathogenic. This review summarizes the current knowledge about the roles of light and photoreceptors in plant-associated bacteria and fungi aiming at the identification of common traits and general working ideas. Still, reports on light-driven infection of plants are often restricted to the description of macroscopically observable phenomena, whereas detailed information on the molecular level, e.g., protein–protein interaction during signal transduction or induction mechanisms of infectivity/virulence initiation remains sparse. As it becomes apparent from still only few molecular studies, photoreceptors, often from the red- and the blue light sensitive groups interact and mutually modulate their individual effects. The topic is of great relevance, even in economic terms, referring to plant-pathogen or plant-symbionts interactions, considering the increasing usage of artificial illumination in greenhouses, the possible light-regulation of the synthesis of plant-growth stimulating substances or herbicides by certain symbionts, and the biocontrol of pests by selected fungi and bacteria in a sustainable agriculture.

Neuronal Coherence Agent for Shared Intentionality: A Hypothesis of Neurobiological Processes Occurring during Social Interaction

“…The protein molecules play essential roles in photoreceptors, which regulate motility in bacteria, thereby contributing to the community phototaxis in bacteria [48]. The review on plantassociated bacteria reported the observation of protein-protein interactions between the photoreceptors in bacteria during signal transduction which was identified as a common trait for all [49]. Photoreceptors interact with each other and mutually modulate their individual effects [49].…”

Mycorrhiza-Induced Resistance against Foliar Pathogens Is Uncoupled of Nutritional Effects under Different Light Intensities

“…Besides the effects on plant growth and defense, light may also have a direct impact on the microbes [ 44 , 45 , 46 , 47 ]. Although a considerable impact of light on plant–microbe interactions is to be expected, this has been poorly explored [ 48 , 49 ]. Several studies have addressed the impact of light intensity on mycorrhizal establishment, usually relating low light intensities with reductions of mycorrhizal colonization [ 34 , 35 , 50 ].…”

Monochromic Radiations Provided by Light Emitted Diode (LED) Modulate Infection and Defense Response to Fire Blight in Pear Trees

“…This practice is strongly consolidated, and, for this reason, microbial culture equipment (static and shaken incubators) is not provided with a light control system in the standard configuration. In contrast, there are several studies on non-photosynthetic bacteria associated with humans, plants, and animals (i.e., Pseudomonas aeruginosa , Pseudomonas syringae, and Xanthomonas ) indicating that chemical (quorum sensing), and light (photosensing) signals affect the growth pattern, infectivity, and virulence of these bacteria through common regulatory pathways [ 30 , 52 ] Data presented in this work provide the first evidence that the spectral distribution of the light affects the growth of E. amylovora under laboratory conditions. This preliminary result provides novel prospects in studying the impact of spectral quality on the lifestyle of this phytopathogen and its interactions with the plant host.…”