Molecular Mechanisms for Microbe Recognition and Defense by the Red Seaweed Laurencia dendroidea

Abstract

Marine bacteria are part of the healthy microbiota associated with seaweeds, but some species, such as Vibrio spp., are frequently associated with disease outbreaks, especially in economically valuable cultures. In this context, the ability of seaweeds to recognize microbes and, when necessary, activate defense mechanisms is essential for their survival. However, studies dedicated to understanding the molecular components of the immune response in seaweeds are rare and restricted to indirect stimulus. This work provides an unprecedentedly large-scale evaluation of the transcriptional changes involved in microbe recognition, cellular signaling, and defense in the red seaweed Laurencia dendroidea in response to the marine bacterium Vibrio madracius. By expanding knowledge about seaweed-bacterium interactions and about the integrated defensive system in seaweeds, this work offers the basis for the development of tools to increase the resistance of cultured seaweeds to bacterial infections.

The emission of volatile halocarbons by seaweeds and their response towards environmental changes

“…Seaweeds are able to detect pathogen invasion through cell-level recognition of signal molecules from the invading organism or their own cell wall. Such compounds, also known as elicitors, include oligosaccharides, peptidoglycans, and lipoteichoic acid (Amsler 2008;de Oliveira et al 2017). The brown seaweeds belonging to the families Laminariales, Desmarestiales, Ectocarpales, and Fucales, are able to rapidly detect the signals for defense elicited by simple addition of alginate oligosaccharides (Küpper et al 2002;Amsler 2008;Chance et al 2009).…”

Metabolic Complementarity Between a Brown Alga and Associated Cultivable Bacteria Provide Indications of Beneficial Interactions

“…Elucidating the interactions within microbial communities and how they affect host physiology is a complex task and requires an understanding of the dynamics within the microbiome and the host, as well as of possible interspecies interactions and/or metabolic exchanges that could occur between the partners. One way to dissect those interactions is via targeted co-culture experiments using culturable bacteria, and monitoring potential interaction, e.g., via transcriptomics (de Oliveira et al, 2017). This approach works particularly well for 1:1 or 1:2 interactions, but as the number of potentially interacting organisms increases, selecting the "right" bacterial consortia becomes a major bottleneck (Lindemann et al, 2016).…”

Increased Heat Resilience of Intraspecific Outbred Compared to Inbred Lineages in the Kelp Laminaria digitata: Physiology and Transcriptomics

“…Reduced expression of ALDH genes in H × S might therefore indicate either low levels of oxidative stress or a high tolerance capacity. In contrast, increased terpene biosynthesis in H × S, as indicated by expression of transcripts coding for hydroxymethylglutaryl-CoA synthase, might indicate defense reactions or increased antioxidant capacity (Fisch et al, 2003;de Oliveira et al, 2017). As protein-serine/threonine kinases are involved in stress-related signaling cascades (Graves et al, 1995;Bischof et al, 2019), the increased expression of related genes in H × S indicates a stronger response to heat stress than in S × H. The increased expression of other KEGG genes in H × S points toward measures of metabolic maintenance.…”