Biology subjects

Vandenbussche, M.

Publications and source records attributed to Vandenbussche, M..

7 recordsLinked to original sources

bioRxiv2026

The FUL-SHP-AP2 module regulates fruit development in petunia

Fruit development is a typical angiosperm feature that greatly facilitates seed dispersal. Despite extensive studies on the gene regulatory network underlying pod shattering in the dry Arabidopsis fruit and the ripening process in the fleshy tomato fruit, it is yet unclear if a conserved regulatory network acts in early fruit development. Here, we investigated the roles of Petunia x hybrida (petunia) FRUITFULL (FUL), SHATTERPROOF (SHP) and APETALA 2 (AP2) homologs, three types of transcription factors repeatedly associated with fruit development and/or ripening. Petunia is closely related to tomato but produces dry dehiscent fruits like Arabidopsis. Our functional analysis revealed that the three petunia FUL-like genes, PETUNIA FLOWERING GENE (PFG), FLORAL BINDING PROTEIN 26 (FBP26) and FBP29, redundantly regulate endocarp development. They promote the formation of regularly shaped inner endocarp cells, probably via auxin/brassinosteroid signalling and cell wall modification. Furthermore, we discovered that the SHP-like gene FLORAL BINDING PROTEIN 6 (FBP6) has an opposite role, promoting more mesocarp-shaped endocarp cells, indicating that the FUL-like and SHP-like genes act antagonistically in early pericarp development. Finally, we show that the AP2-like genes REPRESSOR OF B-FUNCTION 1 (ROB1), ROB2 and ROB3 are crucial factors in petunia fruit development. rob1 rob2 rob3 mutants completely fail to dehisce and show major defects in pericarp patterning. The ROB transcription factors repress the activity of the FUL-like genes, and have, together with FBP6, an opposite effect on auxin and brassinosteroid signalling genes. Our study suggests that a module consisting of antagonistically acting TFs, including co-orthologs of AP2, FUL and SHP, regulates early pericarp patterning, at least partially via auxin and brassinosteroids.

plant biology↗

bioRxiv2025

Spatial specificity of MADS-box transcription factors in floral organs

HighlightMADS-box transcription factors specify the identity of floral organs at the primordia stage, but they also have late and spatially-restricted roles in developing or mature floral organs, which we explore in this review. Floral homeotic genes, most of them encoding MADS-box transcription factors, are classically pictured as early specifiers of floral organ identity, as implied by the famous ABC model. Yet, floral homeotic genes remain expressed throughout floral organ development, sometimes with a cell type-specific expression pattern, and late functions have been firmly established for some of these genes. Here, we review how floral homeotic MADS-box genes are expressed in floral organs during their development, highlighting general trends for their spatial or temporal-specific expression, in particular for B-class genes in petals that are systematically distally-enriched. We focus on chosen examples from the literature to discuss the different roles associated with this specific expression, and we then explore the possible molecular mechanisms by which MADS-box transcription factors can adopt spatially or temporally restricted functions in floral organs, either by a simple restriction of their presence, or by a different mode of action in given cell types. Altogether, this review highlights that late roles of floral MADS-box transcription factors have been largely unexplored, and that these regulators might have multiple different functions according to the cell types in which they are present.

plant biology↗

bioRxiv2025

EPP1 is an ancestral component of the plant Common SymbiosisPathway

The success of plants on land has been enabled by mutualistic intracellular associations with microbes for 450 million years (Delaux and Schornack 2021). Because of their intracellular nature, the establishment of these interactions requires tight regulation by the host plants. In particular, three genes - SYMRK, CCaMK and CYCLOPS - form the core of an ancestral common symbiosis pathway (CSP) for intracellular symbioses, and are conserved since the most recent common ancestor of land plants (Radhakrishnan et al. 2020; Delaux et al. 2015; Wang et al. 2010; Parniske 2008). Here, we describe EPP1 as a fourth gene committed to the CSP. Among land plants, EPP1 is conserved only in species able to associate with at least one type of intracellular symbiont. We found that loss-of-function epp1 mutants or EPP1 knock-down lines in four clades of land plants - legumes, Solanaceae, monocots and bryophytes - are all impaired in their ability to associate with arbuscular mycorrhizal fungi. We discovered that the plasma membrane-localized receptor-like SYMRK phosphorylates EPP1 on a conserved serine residue and that this phosphorylation is essential for symbiosis. Using a gain-of-function approach, we demonstrate that EPP1 is upstream of the nuclear kinase CCaMK. We propose that EPP1 is an ancestral component of the essential pathway that has regulated plant symbiosis for half a billion years.

plant biology↗

bioRxiv2024

A new group of LysM-RLKs involved in symbiotic signal perception and arbuscular mycorrhiza establishment

Lipo-chitooligosaccharides (LCO) and short-chain chitooligosaccharides (CO) are produced by arbuscular mycorrhizal fungi (AMF) and activate the plant symbiosis signalling pathway, which is essential for mycorrhiza formation. High affinity LCO receptors belonging to the LysM receptor-like kinase (LysM-RLK) phylogenetic group LYR-IA play a role in AM establishment, but no plant high affinity short-chain CO receptors have yet been identified. Here we studied members of the uncharacterized LYR-IB group, and found that they show high affinity for LCO, short- and long-chain CO, and play a complementary role with the LYR-IA LCO receptors for AM establishment. While LYR-IB knock out mutants had a reduced AMF colonization in several species, constitutive/ectopic expression in wheat increased AMF colonization. LYR-IB function is conserved in all tested angiosperms, but in most japonica rice a deletion creates a frameshift in the gene, explaining differences in AM phenotypes between rice and other monocot single LYR-IA mutants. In conclusion, we identified a class of LysM-RLK receptors in angiosperms with new biochemical properties and a role in both LCO and CO perception for AM establishment.

plant biology↗

bioRxiv2024

Conservation of symbiotic signalling across 450 million years of plant evolution

HighlightO_LIThe common symbiotic pathway is activated during arbuscular mycorrhizal symbiosis in Marchantia paleacea C_LIO_LIThe three core members of the common symbiotic pathway are essential for symbiosis in Marchantia paleacea C_LIO_LIThe molecular function of the CCaMK/CYCLOPS module is conserved across land plants C_LIO_LISymbiotic signalling has been conserved in plants for 450 million years C_LI The colonization of land by plants 450 million years ago revolutionized life on Earth1. The fossil record2 and genetic evidence in extant species3 suggest that this transition was facilitated by interactions with symbiotic arbuscular mycorrhizal (AM) fungi4. This ancestral symbiosis relied on the biosynthesis of chemicals by the host plant, both as signals5 and as nutrients3. In angiosperms, a signalling pathway involving the receptor-like kinase SYMRK/DMI26,7, the Calcium and Calmodulin-dependent protein kinase CCaMK/DMI38 and the transcription factor CYCLOPS/IPD39,10 has been described as the common symbiosis pathway (CSP), essential for the establishment of the AM symbiosis and the root-nodule symbiosis11. Phylogenetic and comparative phylogenomic analyses indicated an ancient origin of the CSP, present in all extant land plants forming intracellular symbioses12-15. Trans-complementation assays of the angiosperm mutants with orthologs from diverse species further indicated the conservation of the molecular function of the CSP across the embryophytes9,12,14-16. However, this correlative evidence did not allow testing the ancestral biological function of the CSP. In this study we demonstrate that SYMRK, CCaMK and CYCLOPS are essential for the colonization by AM fungi in bryophytes, indicating that plants have maintained a dedicated signalling pathway to support symbiotic interactions for 450 million years.

plant biology↗

bioRxiv2023

Role of the metallo-reductase FADING and vacuolinos in anthocyanin degradation in flowers and fruits.

Anthocyanins are vacuolar pigments that confer red-violet colors to plant tissues. Pigmentation patterns result from spatio-temporally regulated anthocyanin synthesis and degradation. Mutational inactivation of a conserved MYB-bHLH-WDrepeat-WRKY transcriptional complex (MBWW) causes degradation of anthocyanins and fading of flower color via a pathway that involves FADING (FA). Here we show that FA encodes a vacuolar membrane Fe-reductase-oxidase that promotes anthocyanin degradation. In wild type petals anthocyanins in the central vacuole (CV) are stable, because FA-GFP is upheld in small vacuoles (vacuolinos) and kept away from the CV, indicating that vacuolinos act as gatekeepers in protein trafficking. In cells lacking vacuolinos, including mbww- mutant petals, FA-GFP reaches the CV and triggers anthocyanin degradation. Virus-induced gene silencing (VIGS) of an FA-homolog in pepper fruits prevented the "fading" of anthocyanins during fruit maturation. These findings provide new insights to breed ornamental and food crops with increased anthocyanin-content and enhanced nutritional value of edible parts.

plant biology↗

bioRxiv2021

Cell layer-specific expression of the B-class MADS-box gene PhDEF drives petal tube or limb development in petunia flowers

Floral homeotic MADS-box transcription factors ensure the correct morphogenesis of floral organs, which are organized in different cell layers deriving from the meristematic L1, L2 and L3 layers. How cells from these distinct layers acquire their respective identity and coordinate their growth to ensure normal floral organ morphogenesis is unresolved. Here, we study petunia petals that form a limb and tube through congenital fusion, a complex morphology that coevolved with pollinators. We have identified petunia mutants expressing the B-class MADS-box gene PhDEF in the epidermis or in the mesophyll of the petal only, called wico and star respectively. Strikingly, wico flowers form a strongly reduced tube while their limbs are almost normal, while star flowers form a normal tube but very reduced and unpigmented limbs, showing that petunia petal morphogenesis is highly modular. Comparative transcriptome analysis of star, wico and wild-type petals revealed a strong down-regulation of the anthocyanin production pathway in star petals including its major regulator ANTHOCYANIN2 (AN2). We found that PhDEF directly binds to AN2 regulatory sequence in vitro by gel shift assay, and in vivo by chromatin immunoprecipitation, suggesting that PhDEF directly activates the petal pigmentation pathway by activating AN2. Altogether, we show that cell-layer specific homeotic activity in petunia petals differently impacts tube and limb development, revealing the relative importance of the different cell layers in the modular architecture of petunia petals.

plant biology↗