Differential gene expression during nitrogen starvation of Anthoceros punctatus and establishment of its symbiosis with Nostoc punctiforme

Starvation for combined nitrogen (N) is a key abiotic signal for the initiation of the symbiotic association between plants and nitrogen-fixing filamentous cyanobacteria. The gene expression pattern during the time course of combined N-starvation of A. punctatus in the absence and presence of the model nitrogen-fixing symbiotic partner N. punctiforme was determined by Poly-A enriched paired-end RNA sequencing. Our standard time course consists of six sampling points 0, 2, 5, 7, 10, 14, and 28 days after the N-stepdown, with one of the cultures co-inoculated with A. punctatus and N. punctiforme on day 0 and the other with A. punctatus alone. The RNA-Seq analysis was conducted to compare the effect of nitrogen starvation and an adaptation to that conditions in A. punctatus with or without N. punctiforme.