Genetius

The abstract proposes that microbial indole-3-acetic acid (IAA) enhances plant thermotolerance by regulating proline metabolism, coordinating early osmoprotective synthesis with later catabolism to support growth and redox balance during heat stress. This regulation is hypothesized to involve integration of auxin perception (HSP90‑TIR1), MAPK signaling (MPK‑IAA8), mitochondrial redox components (SSR1, HSCA2) and interactions with abscisic acid and ethylene, offering a framework for using auxin‑producing microbes to boost heat resilience.

The study characterizes the endophytic fungus Penicillium melinii, isolated from Arabidopsis thaliana roots, as a plant‑growth‑promoting agent that enhances root architecture and biomass across Arabidopsis, quinoa, and tomato. Integrated phenotypic, transcriptomic, and hormonal analyses reveal that the fungus stimulates auxin‑related pathways and modest stress responses, leading to increased tomato yield in field trials, underscoring its value as a model for root development and a sustainable biostimulant.

The study demonstrates that salinity stress induces a photomorphogenic‑like response in dark‑grown Arabidopsis thaliana seedlings, resulting in reduced apical hook curvature and impaired soil emergence. This phenotype is linked to disrupted asymmetric epidermal cell elongation, decreased auxin signaling and PIN3 abundance on the hook’s concave side, repression of BBX28 expression, and loss of a spatial COP1 gradient, highlighting spatial regulation as a key factor in stress‑affected seedling development.

The study elucidates the SPL/NZZ‑dependent regulatory pathway governing megaspore mother cell (MMC) differentiation, revealing that SPL/NZZ directly targets genes and interacts with ovule‑identity MADS‑domain transcription factor complexes. Integration of multi‑omics data with genetic complementation and mutant analyses uncovers an auxin‑dependent downstream network that drives MMC formation.

The study demonstrates that very long chain sphingolipids in the outer membrane leaflet interdigitate with inner‑leaflet phosphatidylserine, forming a vertical bridge that organizes PS nanodomains and enables auxin‑induced activation of the Rho‑GTPase ROP6. Disruption of sphingolipid biosynthesis disperses these nanodomains, impairing ROP6 signaling, cytoskeletal dynamics, and directional growth, highlighting interleaflet coupling as a key mechanism linking membrane asymmetry to plant signal transduction.

The study demonstrates that a rapid increase in cytosolic Ca²⁺ is the primary and sufficient signal mediating auxin‑induced root growth inhibition in Arabidopsis. Using live imaging, microfluidics, and optogenetic control of Ca²⁺ influx, the authors show that blocking Ca²⁺ entry prevents growth responses, while light‑triggered Ca²⁺ influx from the apoplast or ER mimics inhibition, indicating that diverse stimuli converge on a Ca²⁺‑dependent mechanism.

The study uses an optogenetic ChannelRhodopsin 2 variant (XXM2.0) to generate defined cytosolic Ca²⁺ transients in Arabidopsis root cells, revealing that these Ca²⁺ signatures suppress auxin‑induced membrane depolarization, Ca²⁺ spikes, and auxin‑responsive transcription, leading to reversible inhibition of cell division and elongation. This demonstrates that optogenetically imposed Ca²⁺ signals act as dynamic regulators of auxin sensitivity in roots.

The study reveals that the endoplasmic reticulum‑associated degradation (ERAD) pathway governs the proteasome‑dependent turnover of PIN‑LIKES (PILS) auxin transport proteins under normal conditions, and that both internal and external cues modulate this process via the ERAD complex. These findings link ER protein homeostasis to auxin‑mediated growth regulation, highlighting a new mechanism by which plants adapt to environmental and developmental signals.

The study investigates how auxin regulates root cell elongation in Arabidopsis thaliana by modulating the transcription of pectin‑degrading polygalacturonases (PGRAs). Auxin down‑regulates PGRA1 expression to limit pectin remodeling, and mutants lacking PGRAs fail to enhance root growth when auxin levels are reduced, linking auxin signaling to cell‑wall modification.

The study reveals that cross‑talk between the ERECTA receptor pathway and auxin signaling determines the output of bilateral stem cell layers during secondary growth by phosphorylating the transcription factor AINTEGUMENTA (ANT). Phosphorylation of ANT biases stem cell activity toward the production of a single vascular cell type, thereby modulating root girth and overall biomass accumulation.