Biology subjects

Divol, F.

Publications and source records attributed to Divol, F..

5 recordsLinked to original sources

bioRxiv2024

Autoregulation of cluster root and nodule development by white lupin CCR1 receptor-like kinase

Root development is controlled by local and systemic regulatory mechanisms that optimize mineral nutrient uptake and carbon allocation. The Autoregulation of Nodulation (AoN) pathway defines a negative regulation of nodule development in Legumes as a way to regulate the costly production of nitrogen-fixing organs. This pathway is defined as a response to symbiotic interaction and has been shown to also control root formation to some extent. However, it remains unclear if root and nodule development are under coordinated genetic regulation. Here, we identified mutants with altered root development in white lupin, constitutively producing specialized lateral roots called cluster roots. We showed that the CCR1 receptor-kinase negatively regulates cluster root and nodule development and targets common molecular modules such as NIN/LBD16-NFYA, defining a novel pathway that we named Autoregulation of Development (AoDev). AoDev defines a negative systemic pathway controlling several types of root organ development, independently of symbiotic partners and nutrient availability.

plant biology↗

bioRxiv2021

Auxin and pectin remodeling interplay during rootlet emergence in white lupin

Secondary root emergence is a crucial trait that shapes the plants underground system. Virtually every developmental step of root primordium morphogenesis is controlled by auxin. However, how the hormone controls cell separation in primordium-overlaying tissues through wall loosening is poorly understood. Here, we took advantage of white lupin and its spectacular cluster root development to assess the contribution of auxin to this process. We show that auxins positive role on rootlet emergence is associated with an upregulation of cell wall pectin modifying and degrading genes. Downregulation of a pectinolytic enzyme gene expressed in cells surrounding the primordium resulted in delayed emergence. Pectins were demethylesterified in the emergence zone and auxin treatment further enhanced this effect. Additionally, we report specific rhamnogalacturonan-I modifications during cortical cell separation. In conclusion, we propose a model in which auxin has a dual role during rootlet emergence: Firstly, through active pectin demethylesterification and secondly by regulating the expression of cell wall remodeling enzymes.

plant biology↗

bioRxiv2020

Pangenome of white lupin provides insights into the diversity of the species

BackgroundWhite lupin is an old crop with renewed interest due to its seed high protein content and high nutritional value. Despite a long domestication history in the Mediterranean basin, modern breeding efforts have been fairly scarce. Recent sequencing of its genome has provided tools for further description of genetic resources but detailed characterization is still missing. ResultsHere, we report the genome sequencing of several accessions that were used to establish a white lupin pangenome. We defined core genes that are present in all individuals and variable genes that are absent in some and may represent a gene pool for stress adaptation. We believe that the identification of novel genes, together with a more comprehensive reference sequence, represents a significant improvement of the white lupin genetic resources. As an example, we used this pangenome to identify selection footprints and to provide a candidate gene for one of the main QTLs associated with late flowering in Ethiopian lupin types. A 686 nucleotide deletion was identified in exon 3 of the LaFTa1 (Lupinus albus Flowering Time a1) gene that suggests a molecular origin for this trait of importance, defining the need for vernalization in some lupins. ConclusionsThe white lupin pangenome provides a novel genetic resource to better understand how domestication has shaped the genomic variability amongst this crop. It will be of major importance for breeders to select new breeding traits and incorporate them into new, more efficient and robust cultivars in order to face a growing demand for plant protein sources, notably in Europe.

plant biology↗

bioRxiv2020

Developmental atlas of white lupin cluster roots

During the course of evolution, plants have developed various strategies to improve micronutrient acquisition, such as cluster roots. These spectacular structures are dedicated to efficient phosphate remobilization and acquisition. When exposed to Pi-limitation, white lupin forms cluster roots made of dense clusters of short specialized roots, called rootlets. Although the physiological activity of rootlets has been well studied, their development remains poorly described. Here, we provide a developmental atlas of white lupin early rootlet development, using molecular markers derived from the model plant Arabidopsis. We first focused on cell division patterns to determine which cells contribute to the rootlet primordium. Then, we identified homologs of previously described tissue specific genes based on protein sequence analysis and also using detailed transcriptomic data covering rootlet development. This study provides a comprehensive description of the developmental phases of rootlet formation, highlighting that rootlet primordium arises from divisions in pericycle, endodermis and cortex. We describe that rootlet primordium patterning follows eight stages during which tissue differentiation is established progressively. HighlightWhite lupin cluster roots consist in the formation of numerous rootlets whose development can be divided in 8 stages and involves divisions in the pericycle, endodermis and cortex.

plant biology↗

bioRxiv2019

Genome sequence of the cluster root forming white lupin

White lupin (Lupinus albus L.) is a legume that produces seeds recognized for their high protein content and good nutritional value (lowest glycemic index of all grains, high dietary fiber content, and zero gluten or starch)1-5. White lupin can form nitrogen-fixing nodules but has lost the ability to form mycorrhizal symbiosis with fungi6. Nevertheless, its root system is well adapted to poor soils: it produces cluster roots, constituted of dozens of determinate lateral roots that improve soil exploration and phosphate remobilization7. As phosphate is a limited resource that comes from rock reserves8, the production of cluster roots is a trait of interest to improve fertilizers efficiency. Using long reads sequencing technologies, we provide a high-quality genome sequence of a modern variety of white lupin (2n=50, 451 Mb), as well as de novo assemblies of a landrace and a wild relative. We describe how domestication impacted soil exploration capacity through the early establishment of lateral and cluster roots. We identify the APETALA2 transcription factor LaPUCHI-1, homolog of the Arabidopsis morphogenesis coordinator9, as a potential regulator of this trait. Our high-quality genome and companion genomic and transcriptomic resources enable the development of modern breeding strategies to increase and stabilize yield and to develop new varieties with reduced allergenic properties (caused by conglutins10), which would favor the deployment of this promising culture.

genomics↗