Biology subjects

Aubourg, S.

Publications and source records attributed to Aubourg, S..

4 recordsLinked to original sources

bioRxiv2025

Transcriptomic analysis of genotypes derived from Rosa wichurana unveils molecular mechanisms associated with quantitative resistance to Diplocarpon rosae

Black spot disease, caused by the hemibiotrophic fungus Diplocarpon rosae, is a major foliar disease of garden roses. Resistant cultivars offer an alternative to fungicides, but the genetic basis of resistance is not well known. Understanding these mechanisms is essential for the effective and durable deployment of resistant cultivars. A hybrid of Rosa wichurana (RW) exhibits quantitative resistance to black spot. Analysis of an F1 progeny from a cross between RW and the susceptible cultivar Rosa chinensis Old Blush showed that RWs resistance mainly involves two Quantitative Trait Loci (QTLs), on linkage groups 3 (B3) and 5 (B5). This study aimed to better characterize the molecular mechanisms underlying these QTLs. RNA sequencing was performed on inoculated and non-inoculated samples of RW and four F1 genotypes with different QTL combinations, at 0, 3, and 5 days post-inoculation (dpi). The comparison of inoculated and non-inoculated samples revealed that most genes were differentially expressed at 3 dpi. For all the genotypes, we observed shifts in expression of genes involved in plant defense, as well as genes participating in hormonal pathways and calcium-mediated signaling. Genotypes harboring QTL B3 showed "classic" defense responses involving pathogen recognition, signaling, ROS production, callose deposition, and localized cell death. In contrast, QTL B5 was associated with few shared DEGs, making it harder to define its role. The quantitative nature of RWs resistance may result in this complex regulation of gene expression. Key messageTwo QTLs derived from Rosa wichurana contribute differently to rose black spot resistance, with QTL B3 linked to classical defense responses and QTL B5 suggesting a more complex regulatory mechanism.

plant biology↗

bioRxiv2022

The PROSCOOP10 gene encodes two extracellular hydroxylated peptides and impacts flowering time in Arabidopsis

AO_SCPLOWBSTRACTC_SCPLOWThe Arabidopsis PROSCOOP genes belong to a family predicted to encode secreted propeptides which undergo maturation steps to produce peptides named SCOOP. Some of them are involved in defence signalling through their perception by a receptor complex including MIK2, BAK1 and BKK1. Here, we focused on the PROSCOOP10 gene which is highly and constitutively expressed in the aerial organs. The MS/MS analyses of leaf apoplastic fluids allowed the identification of two distinct peptides, named SCOOP10#1 and SCOOP10#2, covering two different regions of PROSCOOP10. They both possess the canonical S-X-S family motif and have hydroxylated prolines. This identification in apoplastic fluids confirms for the first time the biological reality of SCOOP peptides. NMR and molecular dynamics studies showed that the SCOOP10 peptides, although largely unstructured in solution, tend to assume a hairpin-like fold exposing the two serine residues previously identified as essential for the peptide activity. Furthermore, PROSCOOP10 mutations led to an early flowering phenotype and an increased expression of the floral integrators SOC1 and LEAFY, consistent with the transcription of PROSCOOP10 in several mutants displaying an early or late flowering phenotype. These results suggest a role of PROSCOOP10 in flowering time, illustrating the functional complexity of the PROSCOOP family. HO_SCPLOWIGHLIGHTC_SCPLOWThe PROSCOOP10 gene encodes two post-translationally modified extracellular SCOOP10 peptides and acts upstream of SOC1 and LFY to delay flowering.

plant biology↗

bioRxiv2019

An Erwinia amylovora inducible promoter for intragenic improvement of apple fire blight resistance

Intragenesis is an important alternative to transgenesis to produce modified plants containing native DNA only. A key point to develop such a strategy is the availability of regulatory sequences controlling the expression of the gene of interest. With the aim of finding apple gene promoters either inducible by the fire blight pathogen Erwinia amylovora (Ea) or moderately constitutive, we focused on polyphenoloxidase genes (PPO). These genes encode oxidative enzymes involved in many physiological processes and have been previously shown to be up-regulated during the Ea infection process. We found ten PPO and two PPO-like sequences in the apple genome and characterized the promoters of MdPPO16 (pPPO16) and MdKFDV02 PPO-like (pKFDV02) for their potential as Ea-inducible and low-constitutive regulatory sequences respectively. Expression levels of reporter genes fused to these promoters and transiently or stably expressed in apple were quantified after various treatments. Unlike pKFDV02 which displayed a variable activity, pPPO16 allowed a fast and strong expression of transgenes in apple following Ea infection in a Type 3 Secretion System dependent manner. Altogether our results indicate that pKFDV02 did not keep its promises as a constitutive and weak promoter whereas pPPO16, the first Ea-inducible promoter cloned from apple, can be a useful component of intragenic strategies to create fire blight resistant apple genotypes. Key messagepPPO16, the first Ea-inducible promoter cloned from apple, can be a useful component of intragenic strategies to create fire blight resistant apple genotypes.

bioengineering↗

bioRxiv2018

A high-quality sequence of Rosa chinensis to elucidate genome structure and ornamental traits

Rose is the worlds most important ornamental plant with economic, cultural and symbolic value. Roses are cultivated worldwide and sold as garden roses, cut flowers and potted plants. Rose has a complex genome with high heterozygosity and various ploidy levels. Our objectives were (i) to develop the first high-quality reference genome sequence for the genus Rosa by sequencing a doubled haploid, combining long and short read sequencing, and anchoring to a high-density genetic map and (ii) to study the genome structure and the genetic basis of major ornamental traits.\n\nWe produced a haploid rose line from R. chinensis Old Blush and generated the first rose genome sequence at the pseudo-molecule scale (512 Mbp with N50 of 3.4 Mb and L75 of 97). The sequence was validated using high-density diploid and tetraploid genetic maps. We delineated hallmark chromosomal features including the pericentromeric regions through annotation of TE families and positioned centromeric repeats using FISH. Genetic diversity was analysed by resequencing eight Rosa species. Combining genetic and genomic approaches, we identified potential genetic regulators of key ornamental traits, including prickle density and number of flower petals. A rose APETALA2 homologue is proposed to be the major regulator of petals number in rose. This reference sequence is an important resource for studying polyploidisation, meiosis and developmental processes as we demonstrated for flower and prickle development. This reference sequence will also accelerate breeding through the development of molecular markers linked to traits, the identification of the genes underlying them and the exploitation of synteny across Rosaceae.

genomics↗