Effect of combined nitrogenous nutrition and CO2 concentration in biomass and gene expression profile in Pinus pinaster

Abstract

Carbon dioxide (CO2) in high concentration is beneficial for crop development, but due to the reduction of photorespiration in C3 plants, there is less reducing power available for nitrate (NO3-) reduction and later nitrogen assimilation compared to ammonium (NH4+) nutrition. To overcome this problem, research is focusing on NH4+ nutrition, because its assimilation is less expensive in terms of energy (Bloom, 2015). Knowing how plants manage NH4+ toxicity by gene expression and enzymatic pathways activation, will result in a novel set of molecular mechanisms that could be applied in crops in the near future, solving the problem of photorespiration reduction and nitrogen use efficiency (South et al., 2018). In this work we studied the growth of Pinus pinaster (Aiton) seedlings in 400 and 720 ppm CO2 concentrations and under NO3- and NH4+ nutrition, due to the tolerance that conifers have for NH4+ (Marino et al., 2022). Results show that during the early development, the combination of high CO2 concentration and NH4+ leads to an increase in biomass of the seedling and growth rates. To further investigate the set of genes differentially regulated in these conditions of nitrogen nutrition and CO2 concentration, we analysed the data from RNA-seq experiments from different organs of 2 months seedlings growth in 400 and 720 ppm of CO2 and different nitrogen nutrition (8 mM NH4+ or 8 mM NO3-).