Next-generation ABACUS biosensors reveal cellular ABA dynamics driving root growth at low aerial humidity.

The plant hormone abscisic acid (ABA) accumulates under abiotic stress to recast water relations and development. To overcome a lack of high-resolution sensitive reporters, we developed ABACUS2s-next-generation Förster resonance energy transfer (FRET) biosensors for ABA with high affinity, signal-to-noise ratio and orthogonality-that reveal endogenous ABA patterns in Arabidopsis thaliana. We mapped stress-induced ABA dynamics in high resolution to reveal the cellular basis for local and systemic ABA functions.

Arabidopsis sirtuins and poly(ADP-ribose) polymerases regulate gene expression in the day but do not affect circadian rhythms.

Nicotinamide-adenine dinucleotide (NAD) is involved in redox homeostasis and acts as a substrate for NADases, including poly(ADP-ribose) polymerases (PARPs) that add poly(ADP-ribose) polymers to proteins and DNA, and sirtuins that deacetylate proteins. Nicotinamide, a by-product of NADases increases circadian period in both plants and animals. In mammals, the effect of nicotinamide on circadian period might be mediated by the PARPs and sirtuins because they directly bind to core circadian oscillator genes.

BIG Regulates Dynamic Adjustment of Circadian Period in .

Circadian clocks drive rhythms with a period near 24 h, but the molecular basis of the regulation of the period of the circadian clockis poorly understood. We previously demonstrated that metabolites affect the free-running period of the circadian oscillator of Arabidopsis (), with endogenous sugars acting as an accelerator and exogenous nicotinamide acting as a brake. Changes in circadian oscillator period are thought to adjust the timing of biological activities through the process of entrainment, in which the circadian oscillator becomes synchronized to rhythmic signals such as light and dark cycles as well as changes in internal metabolism.

Inhibition of auxin transport and auxin signaling and treatment with far red light induces root coiling in the phospholipase-A mutant ppla-I-1. Significance for surface penetration?

When grown on a non-penetretable at a surface angle of 45°, Arabidopsis roots form wave-like structures and, in wild type rarely, but in certain mutants the tip root even may form circles. These circles are called coils. The formation of coils depends on the complex interaction of circumnutation, gravitropism and negative thigmotropism where - at least - gravitropism is intimately linked to auxin transport and signaling.

POLYAMINE OXIDASE2 of Arabidopsis contributes to ABA mediated plant developmental processes.

Polyamines (PA) are catabolised by two groups of amine oxidases, the copper-binding amine oxidases (CuAOs) and the FAD-binding polyamine oxidases (PAOs). Previously, we have shown that CuAO1 is involved in ABA associated growth responses and ABA- and PA-mediated rapid nitric oxide (NO) production. Here we report the differential regulation of expression of POLYAMINE OXIDASE2 of Arabidopsis (AtPAO2) in interaction with ABA, nitrate and ammonium.