Project description:Many cyanobacteria can form nitrogen-fixing symbioses with a broad range of plant species. Unlike other plant-bacteria symbioses, little is understood about the immunological responses induced by plant cyanobionts (symbiotic cyanobacteria). Here, we used Arabidopsis thaliana suspension cell cultures as a model system to demonstrate that the model plant-symbiotic cyanobacteria, Nostoc punctiforme is capable of protecting against plant programmed cell death (PCD). We also profiled the early transcriptomic changes that were induced in response to conditioned medium (CM) from N. punctiforme cell cultures. Interestingly, the PCD reduction was preceded by the induction of genes associated with defence and immunity, the most striking of which were a number of WRKY-family transcription factors. Down-regulated included genes involved in the regulation of cell growth and differentiation. This work is the first to show that a cyanobacteria can regulate plant PCD and provides a useful transcriptome resource for studying early plant cell responses to symbiotic cyanobacteria.
Project description:We characterized the polyethylene glycol (PEG)-responding desiccome from the most geographically widespread Gram-positive nitrogen-fixing plant symbiont, i.e. Frankia alni, by next-generation proteomics.
Project description:Plant-cyanobacteria symbiosis is considered one of the pivotal events in the history of life. In this symbiosis, the cyanobacterium provides to the plant fixed nitrogen compounds and plant hormones and, in return, the plant provides to the cyanobacterium fixed carbon. Despite the large knowledge in the physiology and ecology of plant-cyanobacteria symbioses, little is known about the molecular mechanisms involved in the crosstalk between partners. It has been shown recently that Nostoc punctiforme is able to stablish an endophytic symbiosis with Oryza sativa. This finding opens a door to explore this symbiotic interaction as a sustainable alternative to nitrogen fertilization of paddy fields. However, molecular mechanisms behind Oryza-Nostoc endosymbiosis are still not clarified. To gain further insights, an LC-MS/MS based label-free quantitative technique was used to evaluate the differential proteomics under N. punctiforme treatment vs. control plants at 1 day and 7 days. Differential expression profiling reveals a significant number of proteins to be down-regulated or missing in both partners, while others were more abundant or only expressed when both partners were in contact. In N. punctiforme, the differential protein expression was primarily connected to primary metabolism, signal transduction and perception, transport of substances and photosynthesis. In O. sativa, the differential protein expression was connected to a wide range of biological functions regulating carbon and nitrogen metabolism and response to biotic and abiotic stresses.
