High CO2 Triggers Preferential Root Growth of Arabidopsis thaliana Via Two Distinct Systems Under Low pH and Low N Stresses

Abstract

Biomass allocation between shoots and roots is an important strategy used by plants to optimize growth in various environments. Root to shoot mass ratios typically increase in response to high CO2, a trend particularly evident under abiotic stress. We investigated this preferential root growth (PRG) in Arabidopsis thaliana plants cultivated under low pH/high CO2 or low nitrogen (N)/high CO2 conditions. Previous studies have suggested that changes in plant hormone, carbon (C) and N status may be related to PRG. We therefore examined the mechanisms underlying PRG by genetically modifying cytokinin (CK) levels, C and N status, and sugar signaling, performing sugar application experiments and determining primary metabolites, plant hormones and expression of related genes. Both low pH/high CO2 and low N/high CO2 stresses induced increases in lateral root (LR) number and led to high C/N ratios; however, under low pH/high CO2 conditions, large quantities of C were accumulated, whereas under low N/high CO2 conditions, N was severely depleted. Analyses of a CK-deficient mutant and a starchless mutant, in conjunction with sugar application experiments, revealed that these stresses induce PRG via different mechanisms. Metabolite and hormone profile analysis indicated that under low pH/high CO2 conditions, excess C accumulation may enhance LR number through the dual actions of increased auxin and decreased CKs.

Nitrate reductase, nitrite reductase, glutamine synthetase, and glutamate synthase expression and activity in response to different nitrogen sources in nitrogen‐starved wheat seedlings

“…Ammonium uptake takes place by two constitutive ammonium transporters (LATS and HATS) and causes an increase in leaves ammonium content . These two transporters are highly responsive to the ammonium supply and are strongly repressed in the presence of high external ammonium supply as well as high internal glutamine content . Ammonium as a toxic substance downregulates ammonium uptake that could be related to its suppressive effects .…”

High Nitrate or Ammonium Applications Alleviated Photosynthetic Decline of Phoebe bournei Seedlings under Elevated Carbon Dioxide

“…Furthermore, the form of nitrogen can also affect photosynthetic characteristics and the metabolism of different nitrogen forms is different. Most studies have shown that eCO 2 is less conducive for the absorption and transformation of nitrate by plants compared with that of ammonium [32][33][34].…”

Increasing carbon availability stimulates growth and secondary metabolites via modulation of phytohormones in winter wheat

“…Growth modulation via IAA has also been observed under elevated [CO 2 ] in Arabidopsis (Hachiya et al , 2014) and in tomato seedlings (Wang et al , 2009), and during drought and low temperatures in rice ( Oryza sativa ) (Zhang et al , 2009; Du et al , 2013). …”

“…Elevated CO 2 increased carbohydrate and IAA concentrations and promoted growth in Arabidopsis thaliana (Teng et al , 2006; Hachiya et al , 2014) and tomato seedlings ( Solanum lycopersicum ; Wang et al , 2009) but reduced IAA concentrations in roots of sweet pepper ( Capsicum annuum ; Piñero et al , 2014). Niu et al (2011) showed that the auxin-dependent signalling pathway is required for enhancing root development under elevated CO 2 in Arabidopsis.…”