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Poplar trees use photoperiod as a precise seasonal indicator, synchronizing plant phenology with the environment. Daylength cue determines FLOWERING LOCUS T 2 (FT2) daily expression, crucial for shoot apex development and establishment of the annual growing period. However, limited evidence exists for the molecular factors controlling FT2 transcription and the conservation with the photoperiodic control of Arabidopsis flowering. We demonstrate that FT2 expression mediates growth cessation response quantitatively, and we provide a minimal data-driven model linking core clock genes to FT2 daily levels. GIGANTEA (GI) emerges as a critical inducer of the FT2 activation window, time-bound by TIMING OF CAB EXPRESSION (TOC1) and LATE ELONGATED HYPOCOTYL (LHY2) repressions. CRISPR/Cas9 loss-of-function lines validate these roles, identifying TOC1 as a long-sought FT2 repressor. Additionally, model simulations predict that FT2 downregulation upon daylength shortening results from a progressive narrowing of this activation window, driven by the phase shift observed in the preceding clock genes. This circadian-mediated mechanism enables poplar to exploit FT2 levels as an accurate daylength-meter., (© 2024. The Author(s).)

How gene activities and biomechanics together direct organ shapes is poorly understood. Plant leaf and floral organs develop from highly similar initial structures and share similar gene expression patterns, yet they gain drastically different shapes later-flat and bilateral leaf primordia and radially symmetric floral primordia, respectively. We analyzed cellular growth patterns and gene expression in young leaves and flowers of Arabidopsis thaliana and found significant differences in cell growth rates, which correlate with convergence sites of phytohormone auxin that require polar auxin transport. In leaf primordia, the PRESSED-FLOWER-expressing middle domain grows faster than adjacent adaxial domain and coincides with auxin convergence. In contrast, in floral primordia, the LEAFY-expressing domain shows accelerated growth rates and pronounced auxin convergence. This distinct cell growth dynamics between leaf and flower requires changes in levels of cell-wall pectin de-methyl-esterification and mechanical properties of the cell wall. Data-driven computer model simulations at organ and cellular levels demonstrate that growth differences are central to obtaining distinct organ shape, corroborating in planta observations. Together, our study provides a mechanistic basis for the establishment of early aerial organ symmetries through local modulation of differential growth patterns with auxin and biomechanics., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Pd-membranes are interesting in multiple ultra-pure hydrogen production processes, although they can suffer inhibition by certain species or abrasion under fluidization conditions in membrane reactors, thus requiring additional protective layers to ensure long and stable operation. The ability to incorporate intermediate and palladium films with enough adherence on both external and internal surfaces of tubular porous supports becomes crucial to minimize their complexity and cost. This study addresses the incorporation of CeO 2 and Pd films onto the internal side of PSS tubes for applications in which further protection could be required. The membranes so prepared, with a Pd-thickness around 12-15 μm, show an excellent mechanical resistance and similar performance to those prepared on the external surface. A good fit to Sieverts' law with an H 2 -permeance of 4.571 × 10 -3 mol m -2 s -1 Pa -0.5 at 400 °C, activation energy around 15.031 kJ mol -1 , and complete ideal perm-selectivity was observed. The permeate fluxes reached in H 2 mixtures with N 2 , He, or CO 2 decreased with dilution and temperature due to the inherent concentration-polarization. The presence of CO in mixtures provoked a higher decrease because of a further inhibition effect. However, the original flux was completely recovered after feeding again with pure hydrogen, maintaining stable operation for at least 1000 h.