Interaction between CO2 levels and nitrogen nutrition in Pinus pinaster

The main objective of the present work is the transcriptomic analysis of the interaction between nitrogen nutrition and CO2 levels in maritime pine. For this purpose, seedlings were fertilized with nitrate or ammonium and grown in two different CO2 levels: normal (400 ppm) and high (720ppm). Pine seedlings were subdivided into four groups. The treatments were maintained one month. Two groups were irrigated with 40 mL of 8 mM NH4Cl once a week, the two remaining groups were supplied with 40 mL of 8 mM KNO3 once a week. Of the groups irrigated with each solution, one was maintained at 400 ppm CO2 and the other at 720 ppm CO2. Pools of 12 seedlings were harvested per each biological replicate. The three main organs (needles, stem and roots) were isolated and immediately frozen in liquid nitrogen. Total RNA was extracted for the 36 samples, which were sequenced on an Illumina NovaSeq 6000 as paired-end reads of 150 bp length.