Biology subjects

Vladimirtsev, D.

Publications and source records attributed to Vladimirtsev, D..

3 recordsLinked to original sources

bioRxiv2025

Cytosolic Ca2+ as a universal signal for rapid root growth regulation

Roots must continuously adapt their growth and have evolved the ability to rapidly respond to diverse environmental and hormonal cues, including the phytohormone auxin. Auxin-induced cellular responses involve membrane depolarization, cytosolic calcium (Ca{superscript 2}) elevation, and extracellular pH increase, but how these processes lead to rapid growth regulation remains unclear. Here, we show that cytosolic Ca{superscript 2} acts as a universal signal integrating diverse cues for rapid regulation of root growth. Using live imaging, microfluidics, and optogenetics in Arabidopsis, we demonstrate that a swift rise in cytosolic Ca{superscript 2} is the primary target of auxin signaling affecting growth inhibition. Disruption of Ca{superscript 2} influx abolishes these responses, whereas light-gated Ca{superscript 2} influx from the apoplast or endoplasmic reticulum stores inhibits growth. Multiple unrelated stimuli--including auxin, extracellular ATP, RALF peptides, and hydrogen peroxide--converge on this Ca{superscript 2}-dependent mechanism. Cytosolic Ca{superscript 2} elevation thus represents a necessary and sufficient step for rapid growth inhibition, revealing a unifying principle of root signaling.

plant biology↗

bioRxiv2025

Calcium-triggered apoplastic ROS bursts balance gravity and mechanical signals to navigate soil

Reactive oxygen species (ROS) have been implicated repeatedly in multiple signaling processes in plants but the underlying mechanisms and roles remain enigmatic. Here, we developed live imaging of apoplastic ROS at the root surface. Different signals, including auxin, extracellular ATP and RALF1 peptide, all induce cytosolic calcium transients and apoplastic ROS bursts. Genetic and optogenetic manipulations identified calcium transients as necessary and sufficient for ROS bursts via activation of NADPH oxidases RBOHC and RBOHF. Apoplastic ROS bursts are not required but rather limit the gravity-induced root bending. Root bending is sensed by stretch-activated calcium channel MCA1 leading to NADPH oxidase activation at the stretched side. The resulting ROS production stiffens cell wall for better soil penetration. Apoplastic ROS thus provides a means to balance tissue flexibility and stiffness to efficiently navigate soil.

plant biology↗

bioRxiv2025

Armadillo Repeat Only Proteins Are Crucial for the Function of Plant CNGC Channels

The versatile Ca2+ signaling system governs plant responses to a wide array of environmental and developmental cues. CYCLIC NUCLEOTIDE-GATED CHANNELS (CNGCs) trigger cellular responses to diverse signals, including phytohormones, biotic and abiotic stresses; and as such their activity is tightly controlled. Unlike their animal paralogs, plant CNGCs does not seem to be gated by cyclic nucleotides, and the mechanism of their activation remains unresolved. Here we report ARMADILLO REPEAT ONLY (ARO) proteins as novel, plant-specific, and essential activators of plant CNGCs. Reciprocal proximity labeling revealed interactions between all sporophytic CNGCs and AROs. Loss-of-function aro mutants fail to induce Ca2+ transients in response to known CNGC-triggering stimuli. Structural modeling, mutational analysis, and electrophysiological data show that AROs assemble into a complex with CNGC tetramers by interaction with the conserved Calmodulin-binding IQ domain. AROs represent CNGC activators, competing with Calmodulins, showcasing an evolutionarily unique solution to regulation of calcium signaling in plants.

plant biology↗