Biology subjects

Porcher, A.

Publications and source records attributed to Porcher, A..

3 recordsLinked to original sources

bioRxiv2026

Sugar metabolism drives shoot branching by repressing BRC1 through miR319-targeted TCP4 in Rosa.

The coupling between sugar availability and shoot branching is well established, yet the underlying molecular mechanisms remain largely unknown. Here, using genome-wide profiling, we characterized the sugar signalling pathways by identifying 10 miRNAs repressed by glycolysis, the tricarboxylic acid (TCA) cycle, and/or the oxidative pentose phosphate pathway (OPPP) in rose buds. Focusing on RhmiR319, a miRNA repressed under active sugar metabolism, we demonstrate that disruption of both glycolysis/the TCA cycle and the OPPP induces the RhmiR319 accumulation, leading to the concomitant repression of its targets, RhTCP4a and RhTCP4b. We additionally reveal that the miR319/TCP4 module regulates shoot branching in Arabidopsis, as miR319 overexpression impairs shoot branching, whereas TCP4 promotes it. Altered branching patterns in Rose and Arabidopsis were associated with the expression of the branching integrator BRC1. Finally, we provide molecular evidence supporting that RhTCP4a/b directly binds to the RhBRC1 promoter and represses its transcription. Together, these results establish the miR319-TCP4-BRC1 regulatory module as a key component in the regulation of shoot branching in response to sugar status. We propose that the miR319-TCP4-BRC1 module is conserved between annual and perennial species and may integrate multiple hormonal and metabolic signals to shape shoot branching in plants.

plant biology↗

bioRxiv2026

Unstructured regions differentially modulate the activation of RBOHD and RBOHH

Reactive oxygen species (ROS) produced by plant NADPH oxidases (RBOHs) must be precisely controlled in their concentration and spatial distribution to support diverse developmental and stress responses. RBOHs are activated by Ca2+ binding and phosphorylation, yet how internal regulatory domains within RBOHs have evolved to translate these inputs into precise levels of ROS production remains unclear. To address this, we performed phylogenetic analyses to define RBOH subfamilies and identify protein regions underlying functional diversification. This analysis revealed that the most variable regions across land-plant RBOHs are two unstructured regions in the N-terminus, UR1 and UR2, which flank the EF-hand Ca2+-binding domain (EFD). We dissected the roles of these regions in Arabidopsis RBOHD, which is central to plant immunity, and in RBOHH, which drives pollen tube elongation and exhibits high Ca2+-induced ROS production. Our analyses revealed that UR1 plays opposing roles in these RBOHs: in RBOHD, UR1 functions as an autoinhibitory module that restrains Ca2+-mediated activation, whereas in RBOHH, UR1 is essential for Ca2+-dependent activation and has coevolved with the EFD to maximize Ca2+-induced ROS production. We further uncovered divergent regulatory roles for UR2. In RBOHD, but not in RBOHH, phosphorylation of UR2 stabilizes an -helical conformation that promotes interaction with the catalytic domain required for enzymatic activation. Furthermore, unlike in RBOHH, the EFD of RBOHD has coevolved with UR2 to maximize phosphorylation-induced activity. Together, our results show how evolution of unstructured regulatory regions adapts a conserved enzymatic core to distinct demands of immune signaling and polarized growth.

plant biology↗

bioRxiv2023

Identification of cambium stem cell factors and their positioning mechanism

Wood constitutes the majority of terrestrial biomass. Composed of xylem, it arises from one side of the vascular cambium, a bifacial stem cell niche that also produces phloem on the opposing side. It is currently unknown which molecular factors endow cambium stem cell identity. Here we show that TDIF ligand-activated PXY receptors promote the expression of CAMBIUM AINTEGUMENTA-LIKE (CAIL) transcription factors to define cambium stem cell identity in the Arabidopsis root. By sequestrating the phloem-originated TDIF, xylem-dependent PXY confines the TDIF signaling front, resulting in the activation of CAIL expression and stem cell identity in only a narrow domain. Our findings show how signals emanating from cells on opposing sides ensure robust yet dynamically adjustable positioning of a bifacial stem cell.

plant biology↗