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The provision of probiotics benefits the health of a wide range of organisms, from humans to animals and plants. Probiotics can enhance stress resilience of endangered organisms, many of which are critically threatened by anthropogenic impacts. The use of so-called 'probiotics for wildlife' is a nascent application, and the field needs to reflect on standards for its development, testing, validation, risk assessment, and deployment. Here, we identify the main challenges of this emerging intervention and provide a roadmap to validate the effectiveness of wildlife probiotics. We cover the essential use of inert negative controls in trials and the investigation of the probiotic mechanisms of action. We also suggest alternative microbial therapies that could be tested in parallel with the probiotic application. Our recommendations align approaches used for humans, aquaculture, and plants to the emerging concept and use of probiotics for wildlife.

Symbiotic cnidarians such as corals and anemones form highly productive and biodiverse coral reef ecosystems in nutrient-poor ocean environments, a phenomenon known as Darwin's paradox. Resolving this paradox requires elucidating the molecular bases of efficient nutrient distribution and recycling in the cnidarian-dinoflagellate symbiosis. Using the sea anemone Aiptasia, we show that during symbiosis, the increased availability of glucose and the presence of the algae jointly induce the coordinated up-regulation and relocalization of glucose and ammonium transporters. These molecular responses are critical to support symbiont functioning and organism-wide nitrogen assimilation through glutamine synthetase/glutamate synthase-mediated amino acid biosynthesis. Our results reveal crucial aspects of the molecular mechanisms underlying nitrogen conservation and recycling in these organisms that allow them to thrive in the nitrogen-poor ocean environments.

Life in arid regions and, in particular, hot deserts is often limited due to their harsh environmental conditions, such as large temperature fluctuations and low amounts of water. These extreme environments can influence the microbial community present on the surface sands and any rhizosphere members surrounding desert plant roots. The Jizan desert area, located in Saudi Arabia, supports particular vegetation that grows in the large sandy flat terrain. We examined five different samples, four from the rhizosphere of pioneer plants plus a surface sand sample, and used pyrosequencing of PCR-amplified V1-V3 regions of 16S rDNA genes from total extracted DNA to reveal and compare the bacterial population diversity of the samples. The results showed a total of 3,530 OTUs in the five samples, calculated using ≥ 97% sequence similarity levels. The Chao1 estimation of the bacterial diversity fluctuated from 637 to 2,026 OTUs for a given sample. The most abundant members found in the samples belong to the Bacteroidetes, Firmicutes and Proteobacteria phyla. This work shows that the Jizan desert area of Saudi Arabia can contain a diverse bacterial community on the sand and surrounding the roots of pioneer desert plants. It also shows that desert sand microbiomes can vary depending on conditions, with broad implications for sandstone monument bacterial communities

Programmed cell death (PCD) is a common host response to microbial infection [1-3]. In plants, PCD is associated with immunity to biotrophic pathogens, but it can also promote disease upon infection by necrotrophic pathogens [4]. Therefore, plant cell-suicide programs must be strictly controlled. Here we demonstrate that the Arabidopsis thaliana Brassinosteroid Insensitive 1 (BRI1)-associated receptor Kinase 1 (BAK1), which operates as a coreceptor of BRI1 in brassinolide (BL)-dependent plant development, also regulates the containment of microbial infection-induced cell death. BAK1-deficient plants develop spreading necrosis upon infection. This is accompanied by production of reactive oxygen intermediates and results in enhanced susceptibility to necrotrophic fungal pathogens. The exogenous application of BL rescues growth defects of bak1 mutants but fails to restore immunity to fungal infection. Moreover, BL-insensitive and -deficient mutants do not exhibit spreading necrosis or enhanced susceptibility to fungal infections. Together, these findings suggest that plant steroid-hormone signaling is dispensable for the containment of infection-induced PCD. We propose a novel, BL-independent function of BAK1 in plant cell-death control that is distinct from its BL-dependent role in plant development.

Signal transduction, protein phosphorylation

Plants are exposed to a wide variety of extracellular stimuli and employ a broad set of signaling pathways to give the appropriate response. M itogen a ctivated p rotein k inases (MAPKs) play an important role in the signal transduction of yeast and animals and increasing evidence suggests a similar role of MAPKs in the signal transduction of plants. MAPKs employ their function as part of protein kinase cascades, composed of a MAPK, a M AP Kk inase (MKK), and a M AP Kk inase k inase (MKKK). MKKKs activate MKKs by phosphorylation of conserved threonine or serine residues, and subsequently MKKs activate the MAPKs by phosphorylation of highly conserved tyrosine and threonine residues.The introduction gives a brief overview of the MAPK cascades employed by yeast and animals and a more extensive overview of our current knowledge about the function of MAPK cascades in plants. To get an overview of the plant MAPKs and their functions the known plant MAPKs were classified and the analyses of all isolated full-length plant MAPK sequences reveals that they can be divided into at least five distinct subfamilies (Chapter 2). For some of these groups it could be shown that MAPKs with similar sequences also perform similar functions. In addition, analysis of e xpressed s equence t ags (ESTs) and partial cDNAs coding for MAPKs revealed the existence of a new plant MAPK subfamily.The goal of the research described in this thesis was to provide insight in the role of several plant MAPKs in stress responses of plants. One of the most severe environmental stresses to which plants can be exposed is wounding. It can be the result of physical injury, herbivore or pathogen attack and induces a wide range of responses, in general involving the induction of genes active in healing and defense processes. In chapter 3 the involvement of a MAPK in the wound response of alfalfa is discussed. It could be shown that wounding activates the alfalfa s tress a ctivated M AP K (SAMK) both at the post