NAD Metabolism and Stress Responses in Plants

Nicotinamide adenine dinucleotide (NAD) and its phosphorylated form (NADP) lie at the heart of plant metabolism, serving both as redox cofactors in hundreds of enzymatic reactions and as signalling molecules coordinating growth and defence. Plants synthesise NAD de novo from aspartate via a series of enzymatic steps beginning with L-aspartate oxidase and including quinolinate synthase, while salvage pathways recycle nicotinamide and nicotinic acid intermediates. The distribution of NAD and NADP pools across chloroplasts, mitochondria and the cytosol underpins energy transduction during photosynthesis, respiration and biosynthetic processes. Fluctuations in the NADH/NAD+ ratio and in the size of the NADP(H) pool reflect cellular redox status, adjusting reactive oxygen species (ROS) scavenging systems and influencing thioredoxin-dependent regulatory circuits. Beyond classical bioenergetics, NAD metabolites interact with phytohormone networks—most notably abscisic acid and salicylic acid—to modulate stomatal behaviour, gene expression and stress signalling. Under drought, salinity, temperature extremes or pathogen attack, enzymes such as NAD kinases, Nudix hydrolases and glycerol-3-phosphate dehydrogenases dynamically regulate nicotinamide dinucleotide homeostasis, thereby sustaining cellular resilience. Advances in understanding this central hub offer routes to engineer crops with enhanced tolerance to environmental challenges and improved yield stability under changing climates.

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NAD Metabolism and Stress Responses in Plants publication trend

The graph below shows the total number of articles in nad metabolism and stress responses in plants across all publications each year (not limited to Nature Index journals).

Technical terms

Nicotinamide adenine dinucleotide (NAD): A central redox coenzyme that alternates between oxidised (NAD+) and reduced (NADH) forms, essential for electron transfer in metabolism.

NADP (nicotinamide adenine dinucleotide phosphate): A phosphorylated derivative of NAD, existing as NADP+ and NADPH, that provides reducing power for biosynthetic reactions and antioxidant defence.

L-aspartate oxidase: The enzyme catalysing the first step in de novo NAD biosynthesis, oxidising L-aspartate to iminoaspartate.

Quinolinate synthase: An enzyme that converts iminoaspartate and dihydroxyacetone phosphate into quinolinate, a key NAD precursor.

Reactive oxygen species (ROS): Chemically reactive molecules containing oxygen, generated as by-products of metabolism and implicated in stress signalling and damage.

Abscisic acid (ABA): A plant hormone that regulates stomatal closure, gene expression and adaptive responses to drought and salinity.

References

1. Inter-Organelle NAD Metabolism Underpinning Light Responsive NADP Dynamics in Plants. Frontiers in Plant Science (2019).
2. Genome-wide characterization of L-aspartate oxidase genes in wheat and their potential roles in the responses to wheat disease and abiotic stresses. Frontiers in Plant Science (2023).
3. Reciprocal regulation between nicotinamide adenine dinucleotide metabolism and abscisic acid and stress response pathways in Arabidopsis. PLOS Genetics (2020).
4. A cytosolic NAD+-dependent GPDH from maize (ZmGPDH1) is involved in conferring salt and osmotic stress tolerance. BMC Plant Biology (2019).