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.

Regulatory gateways for cell-specific gene expression in C4 leaves with Kranz anatomy.

C photosynthesis is a carbon-concentrating mechanism that increases delivery of carbon dioxide to RuBisCO and as a consequence reduces photorespiration. The C pathway is therefore beneficial in environments that promote high photorespiration. This pathway has evolved many times, and involves restricting gene expression to either mesophyll or bundle sheath cells.

Ancestral light and chloroplast regulation form the foundations for C gene expression.

C photosynthesis acts as a carbon concentrating mechanism that leads to large increases in photosynthetic efficiency. The C pathway is found in more than 60 plant lineages but the molecular enablers of this evolution are poorly understood. In particular, it is unclear how non-photosynthetic proteins in the ancestral C system have repeatedly become strongly expressed and integrated into photosynthesis gene regulatory networks in C leaves.