Arabidopsis Seedling Growth, Storage Lipid Mobilization, and Photosynthetic Gene Expression Are Regulated by Carbon:Nitrogen Availability

Abstract

The objective of the current work was to establish the degree to which the effects of carbon and nitrogen availability on Arabidopsis seedling growth and development are due to these nutrients acting independently or together. Growth of seedlings on low (0.1 mM) nitrogen results in a significant reduction of seedling and cotyledon size, fresh weight, chlorophyll, and anthocyanin content but a slight increase in endogenous sugars. The addition of 100 mM sucrose (Suc) to the nitrogen-depleted growth media results in a further reduction in cotyledon size and chlorophyll content and an overall increase in anthocyanins and endogenous sugars. Storage lipid breakdown is almost completely blocked in seedlings grown on low nitrogen and 100 mM Suc and is significantly inhibited when seedlings are grown on either low nitrogen or high Suc. Carbohydrate repression of photosynthetic gene expression can only be observed under low nitrogen conditions. Low (0.1 mM) nitrogen in the absence of exogenous carbohydrate results in a significant decrease in chlorophyll a/b-binding protein and ribulose bisphosphate carboxylase small subunit gene transcript levels. Thus, carbon to nitrogen ratio rather than carbohydrate status alone appears to play the predominant role in regulating various aspects of seedling growth including storage reserve mobilization and photosynthetic gene expression.

ABI4 Activates DGAT1 Expression in Arabidopsis Seedlings during Nitrogen Deficiency

“…Oil drops in seedlings often correlate with the inhibition of stored lipid breakdown. A previous study showed that simultaneously decreasing N concentration and adding exogenous sugar resulted in 80% of eicosenoic acid, a 20:1 fatty acid that is specific to seed oil, being maintained 6 d after germination, suggesting delayed degradation of storage oil (Martin et al, 2002). However, we found that genes involved in TAG biosynthesis and accumulation were increased when the N concentration was reduced from 60 to 0.1 mM.…”

“…Arabidopsis (Arabidopsis thaliana) seeds were sterilized and plated on MS medium with different concentrations of N and Suc as described by Martin et al (2002). The molar ratio of KNO 3 to NH 4 NO 3 was maintained in each medium as MS medium described by Murashige and Skoog (1962).…”

“…Nitrogen (N) and C are important nutrients and signals for plants. CN availability affects postgermination growth, chloroplast lipid metabolism, and TAG content in Arabidopsis (Arabidopsis thaliana) seedlings, demonstrating that nutrient supply is important for the regulation of lipid composition and turnover in plant leaves (Martin et al, 2002;Gaude et al, 2007).…”

Ethylene Insensitivity Results in Down-Regulation of Rubisco Expression and Photosynthetic Capacity in Tobacco

“…In Arabidopsis, external application of Suc or Glc results in a decreased level of chlorophyll a/b-binding protein mRNA (Martin et al, 2002;Moore et al, 2003). In contrast, we observed no change in the expression of CAB21 mRNA between ethylene-sensitive and insensitive plants (Fig.…”

The MYB182 Protein Down-Regulates Proanthocyanidin and Anthocyanin Biosynthesis in Poplar by Repressing Both Structural and Regulatory Flavonoid Genes

“…The sample was extracted with 1 mL of chloroform and centrifuged at 13,000 rpm for 5 min (Nemie-Feyissa et al, 2014). Anthocyanins were measured in the aqueous upper phase at 530 nm (modified from Martin et al, 2002).…”