Biology subjects

Creff, A.

Publications and source records attributed to Creff, A..

7 recordsLinked to original sources

bioRxiv2025

APETALA2 controls seed growth by regulating outer integument mechanical identity during seed coat differentiation

Organ morphogenesis requires differentiating cells to acquire mechanical properties that precisely regulate growth. In Arabidopsis thaliana, seed size and shape are largely controlled by the outer integument of the seed coat, whose two layers develop distinct mechanical behaviors critical for growth regulation. Here, we show that the cell identity factor APETALA2 (AP2) both promotes and restricts seed growth by coordinating the post-fertilization differentiation of these layers into distinct seed coat tissues. AP2 drives layer-specific remodeling of cell wall composition, notably affecting pectin and xyloglucan, thereby establishing contrasting mechanical properties between the two layers. Unexpectedly, these changes in wall composition and mechanics do not alter mechanosensitive responses, revealing a surprising uncoupling between cell wall remodeling and mechanotransduction. Our findings identify AP2 as a key coordinator of tissue-specific mechanical differentiation during organ morphogenesis.

plant biology↗

bioRxiv2025

An embryo-derived peptide signal directs endosperm polarity in Arabidopsis

Angiosperm seed formation requires the coordinated development of the products of double fertilization, the embryo and the endosperm. The endosperm mediates efficient nutrient transfer from surrounding maternal tissues to the developing embryo. This function requires a polarized tissue organization, which manifests as early polar gene expression and polar cellularization dynamics. We show that the receptor kinase HAIKU2 acts in coordination with the transcription factor WRKY10/MINISEED3 to ensure robust endosperm polarity establishment through the activity of the homeodomain transcription factors WUSCHEL-RELATED HOMEOBOX 8 and 9. This process depends on egg cell fertilization and is mediated through the peptide PATHOGEN-INDUCED PEPTIDE-LIKE 7, which acts as a HAIKU2 ligand. Our results reveal how a molecular paracrine dialogue between the embryo and endosperm ensures optimal seed developmental coordination.

plant biology↗

bioRxiv2024

Long-term high temperatures affect seed maturation and seed coat integrity in Brassica napus

Temperatures above the optimum growth threshold affect seed development, accelerating embryo development and producing seeds with ruptured seed coats. However, the underlying mechanisms of this effect remain unclear. To investigate temperature-induced seed coat rupture, we used a multidisciplinary approach combining detailed phenotyping, transcriptomics, histology, immunolabelling, cell wall profiling and nanoindentation-based mechanics of the seed coat in oilseed rape (Brassica napus). Our data reveal that high temperatures accelerate embryo growth, resulting in larger embryos without a compensatory increase in overall seed size. This rapid embryo expansion may exert elevated mechanical stress on the seed coat cells, significantly thinning the seed coat layers. Concurrently, prolonged exposure to high temperatures drives premature biochemical maturation of the seed coat, characterized by accumulation of demethylesterified pectin. Nanoindentation analysis demonstrated that these changes may have compromised the structural integrity of seed coat cell walls. Ultimately, the weakened seed coat may not withstand the internal tension imposed by the fast-growing embryo, leading to seed coat rupture and reduced seed quality. Our work on seed maturation and the mechanism of heat-induced seed coat rupture provides valuable insights for future research into breeding thermotolerant Brassica napus, crucial in the context of a changing climate. HIGHLIGHTSO_LIGrowth of Brassica napus under long-term high temperatures accelerated embryo growth and led to seed coat rupture in approximately half of the seeds. C_LIO_LIPathways linked to cell wall modification were found to be significantly differentially regulated at high temperatures, accompanied by increased pectin demethylesterification in the seed coat. C_LIO_LIA lower reduced modulus and hardness indicate that the surface of HT seeds is mechanically more compliant and softer. Together with the reduced thickness of the seed coat layers, such a seed coat, as a whole structure, is mechanically weaker and less able to resist deformation imposed by embryo growth, resulting in seed coat rupture. C_LI

plant biology↗

bioRxiv2021

Endosperm turgor pressure both promotes and restricts seed growth and size

Organ size depends on complex biochemical and mechanical interactions between cells and tissues. Here, we investigate the control of seed size, a key agronomic trait, by mechanical interactions between two compartments: the endosperm and the testa. By combining experiments with computational modelling, we tested an incoherent mechanical feedforward loop hypothesis in which pressure-induced stresses play two antagonistic roles; directly driving seed growth, but indirectly inhibiting it through mechanosensitive stiffening of the seed coat. We show that our model can recapitulate wild type growth patterns and explain the small seed phenotype of the haiku2 mutant. Our work further reveals that the developmental regulation of endosperm pressure is needed to prevent a precocious reduction of seed growth rate induced by force-dependent seed coat stiffening.

plant biology↗

bioRxiv2019

ROS production by localized SCHENGEN receptor module drives lignification at subcellular precision

Production of reactive-oxygen species (ROS) by NADPH oxidases (NOXs) impacts many processes in animals and plants and many plant receptor pathways involve rapid, NOX-dependent increases of ROS. Yet, their general reactivity has made it challenging to pinpoint the precise role and direct cellular targets of ROS. A well-understood ROS target in plants are lignin peroxidases in the cell wall. Lignin can be deposited with exquisite spatial control, but the underlying mechanisms have remained elusive. Here we establish a full kinase signaling relay that exerts direct, spatial control over ROS production and lignification within the cell wall. We show that polar localization of a single kinase component is crucial for pathway function. Our data indicates that an intersection of more broadly localized components allows for micrometer-scale precision of lignification and that this system is triggered through initiation of ROS production as a critical peroxidase co-substrate.

plant biology↗

bioRxiv2018

A stress-response-related inter-compartmental signalling pathway regulates embryonic cuticle integrity in Arabidopsis

The embryonic cuticle is necessary for normal seed development and seedling establishment in Arabidopsis. Although mutants with defective embryonic cuticles have been identified, neither the deposition of cuticle material, nor its regulation, has been described during embryogenesis. Here we use electron microscopy, lipid staining and permeability assays to show that cuticle deposition initiates de novo in patches on globular embryos. By combining these techniques with genetics and gene expression analysis, we show that successful patch coalescence to form a continuous cuticle requires a signalling involving the endosperm-specific subtilisin protease ALE1 and the receptor kinases GSO1 and GSO2, which are expressed in the developing embryonic epidermis. Transcriptome analysis shows that this pathway regulates stress-related gene expression in seeds. Consistent with these findings we show genetically, and through activity analysis, that the stress-associated MPK6 protein acts downstream of GSO1 and GSO2 in the developing embryo. We propose that a stress-related signalling pathway has been hijacked in some angiosperm seeds through the recruitment of endosperm-specific components. Our work reveals the presence of an inter-compartmental dialogue between the endosperm and embryo that ensures the formation of an intact and functional cuticle around the developing embryo through an \"auto-immune\" type interaction.

plant biology↗

bioRxiv2018

In vivo phosphatidylserine variations steer Rho GTPase signaling in a cell-context dependent manner

AbstractRho GTPases are master regulators of cell signaling, but how they are regulated depending on the cellular context is unclear. Here, we show that the phospholipid phosphatidylserine acts as a developmentally-controlled lipid rheostat that tunes Rho GTPase signaling in Arabidopsis. Live super-resolution single molecule imaging revealed that RHO-OF-PLANT6 (ROP6) is stabilized by phosphatidylserine into plasma membrane (PM) nanodomains, which is required for auxin signaling. Furthermore, we uncovered that the PM phosphatidylserine content varies during plant root development and that the level of phosphatidylserine modulates the quantity of ROP6 nanoclusters induced by auxin and hence downstream signaling, including regulation of endocytosis and gravitropism. Our work reveals that variations in phosphatidylserine levels are a physiological process that may be leveraged to regulate small GTPase signaling during development.\n\nOne Sentence SummaryPhosphatidylserine acts as a developmentally-controlled lipid rheostat that regulates cellular auxin sensitivity and plant development.

plant biology↗