Protein degradation in the auxin response.

The signaling molecule auxin sits at the nexus of plant biology and coordinates essentially all growth and developmental processes in plants. Auxin molecules are transported throughout plant tissues and are capable of evoking highly specific physiological responses in plant cells by inducing various molecular pathways. In many of these pathways, proteolysis plays a crucial role for correct physiological responses. This review provides a chronology of the discovery and characterisation of the auxin receptor, which is a fascinating example of separate research trajectories ultimately converging on the discovery of a core auxin signaling hub which relies on degradation of a family of transcriptional inhibitor proteins - the Aux/IAAs. Beyond describing the "classical" proteolysis-driven auxin response system, we explore more recent examples of the interconnection of proteolytic systems, which target a range of other auxin signaling proteins, and auxin response. By highlighting these emerging concepts, we provide potential future directions to further investigate the role of protein degradation within the framework of auxin response.

Synthetic bacterial community derived from a desert rhizosphere confers salt stress resilience to tomato in the presence of a soil microbiome.

The root bacterial microbiome is important for the general health of the plant. Additionally, it can enhance tolerance to abiotic stresses, exemplified by plant species found in extreme ecological niches like deserts. These complex microbe-plant interactions can be simplified by constructing synthetic bacterial communities or SynComs from the root microbiome. Furthermore, SynComs can be applied as biocontrol agents to protect crops against abiotic stresses such as high salinity. However, there is little knowledge on the design of a SynCom that offers a consistent protection against salt stress for plants growing in a natural and, therefore, non-sterile soil which is more realistic to an agricultural setting. Here we show that a SynCom of five bacterial strains, originating from the root of the desert plant Indigofera argentea, protected tomato plants growing in a non-sterile substrate against a high salt stress. This phenotype correlated with the differential expression of salt stress related genes and ion accumulation in tomato. Quantification of the SynCom strains indicated a low penetrance into the natural soil used as the non-sterile substrate. Our results demonstrate how a desert microbiome could be engineered into a simplified SynCom that protected tomato plants growing in a natural soil against an abiotic stress.