Biology subjects

Peltier, E.

Publications and source records attributed to Peltier, E..

9 recordsLinked to original sources

bioRxiv2026

A Bayesian multidimensional approach to decipher the genetic basis of dynamic phenotypes in multiple species

Deciphering the genetic architecture of complex quantitative phenotypes remains challenging in quantitative genetics. These traits not only depend of multiple genetic factors but are also established over time and environments. Although quantitative genetics has investigated the genetic determinism of phenotypic plasticity in contrasted environmental conditions, the time related phenotypic plasticity has received less attention. Here we proposed a multivariate Bayesian framework, the Bayesian Varying Coefficient Model, designed for analysing the genetic architecture of the time related phenotypic plasticity by a multilocus approach. We applied the BVCM to time series phenotypes measured at various time scales (daily, monthly, yearly) across a diverse set of biological species. We included in this study: yeast (Saccharomyces cerevisiae), fungi (Fusarium graminearum), eucalyptus (Eucalyptus urophylla x E. grandis), and sweet cherry tree (Prunus avium). The BVCM results were compared with those obtained with a known genome-wide association method carried out time by time. For all species and traits, the BVCM was able to detect the major QTL identified by marker-trait association methods and revealed additional genetic regions of weak effect. It also increased the phenotypic variance explained for most of the phenotypes considered. It revealed dynamic QTLs with transitory, increasing or decreasing effects over time. By considering both the temporal and genetic multivariate structures in a single statistical model, we increased our understanding of the genetic architecture of complex traits notably by reducing the issue of missing heritability. More broadly, this work raises the foundation for extended applications in functional genomics, evolutionary ecology, and crop breeding programs, in which time-related phenotypic plasticity remains crucial for predicting and selecting key quantitative complex traits. Key messageBy capturing the genetic factors influencing the time related phenotypic plasticity, our approach contributes to a deeper understanding of the dynamic nature of genotype-phenotype relationships.

genetics↗

bioRxiv2023

Up-regulation of Retrograde Response in yeast increases glycerol and reduces ethanol during wine fermentation

Nutrient signaling pathways play a pivotal role in regulating the balance between metabolism, growth and stress response depending on the available food supply. They are key factor for the biotechnological success of the yeast Saccharomyces cerevisiae during food-producing fermentations. One such pathway is the Retrograde Response, which controls the use of carbon backbones for the synthesis of amino acids derived from alpha-ketoglutarate, such as glutamate and lysine. The repressor MKS1 is linked to the TORC1 complex and negatively regulates this pathway. Deletion of MKS1 on a variety of industrial strains causes an increase in glycerol in winemaking, brewing and baking conditions. This increase is accompanied by a reduction in ethanol production in grape juice fermentations in four commercial wine strains. Interestingly, this does not lead to an increase in volatile acidity, as the levels of acetic acid actually decrease. Aeration during winemaking usually increases acetic acid levels, but this effect is reduced in the MKS1 mutant. Although there is an improvement in the metabolites of oenological interest, it comes at a cost, as the mutant showed slower fermentation kinetics when grown in grape juice, malt, and laboratory media using glucose, sucrose, and maltose as carbon sources. The deletion of RTG2, an activator of the Retrograde Response that acts as an antagonist of MKS1, also results in a defect in wine fermentation speed. These findings suggest that the deregulation of this pathway causes a fitness defect. Therefore, manipulating the repressor MKS1 is a promising approach to modulate yeast metabolism and produce low-ethanol drinks.

microbiology↗

bioRxiv2021

Lessons from the meiotic recombination landscape of the ZMM deficient budding yeast Lachancea waltii

Meiotic recombination has been deeply characterized in a few model species only, notably in the budding yeast Saccharomyces cerevisiae. Interestingly, most members of the ZMM pathway that implements meiotic crossover interference in S. cerevisiae have been lost in Lachancea yeast species after the divergence of Lachancea kluyveri from the rest of the clade. This suggests major differences in the control of crossover distribution. After investigating meiosis in L. kluyveri, we determined the meiotic recombination landscape of Lachancea waltii and identified several characteristics that should help understand better the underlying mechanisms. Such characteristics include systematic regions of loss of heterozygosity (LOH) in L. waltii hybrids, compatible with dysregulated Spo11-mediated DNA double strand breaks (DSB) independently of meiosis. They include a higher recombination rate in L. waltii than in L. kluyveri despite the lack of multiple ZMM pro-crossover factors. L. waltii exhibits an elevated frequency of zero-crossover bivalents as L. kluyveri but opposite to S. cerevisiae. L. waltii gene conversion tracts lengths are comparable to those observed in S. cerevisiae and shorter than in L. kluyveri despite the lack of Mlh2, a factor limiting conversion tracts size in S. cerevisiae. L. waltii recombination hotspots are not shared with either S. cerevisiae or L. kluyveri, showing that meiotic recombination hotspots can evolve at a rather limited evolutionary scale within budding yeasts. Finally, in line with the loss of several ZMM genes, we found only residual crossover interference in L. waltii likely coming from the modest interference existing between recombination precursors. Significance statementStudying non-model species is relevant to understand better biological processes by shedding light on their evolutionary variations. Here we chose the non-model budding yeast Lachancea waltii to study meiotic recombination. In sexually reproducing organisms, meiotic recombination shuffles parental genetic combinations notably by crossovers that cluster in hotspots at the population level. We found remarkable variations compared to both the canonical Saccharomyces cerevisiae model and another close relative Lachancea kluyveri. Such variations notably include the loss in L. waltii of a layer of regulation of crossover distribution that is otherwise conserved in budding yeasts and mammals. They also include the lack of conservation of crossover hotspots across the Lachancea species while crossover hotspots are remarkably stable across the Saccharomyces species. Highlights- Extensive LOH events in L. waltii intraspecific hybrids - No conservation of the recombination hotspots across the Lachancea genus - Reduced but not suppressed crossover interference in the absence of the ZMM pathway - Similar gene conversion tract lengths in L. waltii, S. cerevisiae, and L. kluyveri despite the lack of MLH2 in L. waltii

genetics↗

bioRxiv2021

Evolution of quantitative trait locus hotspots in yeast species

Dissecting the genetic basis of complex trait remains a real challenge. The budding yeast Saccharomyces cerevisiae has become a model organism for studying quantitative traits, successfully increasing our knowledge in many aspects. However, the exploration of the genotype-phenotype relationship in non-model yeast species could provide a deeper insight into the genetic basis of complex traits. Here, we have studied this relationship in the Lachancea waltii species which diverged from the S. cerevisiae lineage prior to the whole-genome duplication. By performing linkage mapping analyses in this species, we identified 86 quantitative trait loci (QTL) affecting growth fitness in a large number of conditions. The distribution of these loci across the genome has revealed two major QTL hotspots. A first hotspot corresponds to a general fitness QTL, impacting a wide range of conditions. By contrast, the second hotspot highlighted a fitness trade-off with a disadvantageous allele for drug-free conditions which proved to be advantageous in the presence of several drugs. Finally, the comparison of the detected QTL in L. waltii with those which had been previously identified for the same traits in a closely related species, Lachancea kluyveri, clearly revealed the absence of interspecific conservation of these loci. Altogether, our results expand our knowledge on the variation of the QTL landscape across different yeast species.

genetics↗

bioRxiv2021

Flor yeasts rewire the central carbon metabolism during wine alcoholic fermentation

The identification of natural allelic variations controlling quantitative traits could contribute to decipher metabolic adaptation mechanisms within different populations of the same species. Such variations could result from man-mediated selection pressures and participate to the domestication. In this study, the genetic causes of the phenotypic variability of the central carbon metabolism Saccharomyces cerevisiae were investigated in the context of the enological fermentation. Carbon dioxide and glycerol production as well as malic acid consumption modulate the fermentation yield revealing a high level of genetic complexity. Their genetic determinism was found out by a multi environment QTL mapping approach allowing the identification of 14 quantitative trait loci from which 8 of them were validated down to the gene level by genetic engineering. Most of the validated genes had allelic variations involving flor yeast specific alleles. Those alleles were brought in the offspring by one parental strain that is closely related to the flor yeast genetic group while the second parental strain is part of the wine group. The causative genes identified are functionally linked to quantitative proteomic variations that would explain divergent metabolic features of wine and flor yeasts involving the tricarboxylic acid cycle (TCA), the glyoxylate shunt and the homeostasis of proton and redox cofactors. Overall, this work led to the identification of genetic factors that are hallmarks of adaptive divergence between flor yeast and wine yeast in the wine biotope. These alleles can also be used in the context of yeast selection to improve oenological traits linked to fermentation yield.

genetics↗

bioRxiv2021

QTL mapping: an innovative method for investigating the genetic determinism of yeast-bacteria interactions in wine

The two most commonly used wine microorganisms, Saccharomyces cerevisiae yeast and Oenococcus oeni bacteria, are responsible for completion of alcoholic and malolactic fermentation (MLF), respectively. For successful co-inoculation, S. cerevisiae and O. oeni must be able to complete fermentation, however, this relies on compatibility between yeast and bacterial strains. For the first time, Quantitative Trait Loci (QTL) analysis was used to elucidate whether S. cerevisiae genetic makeup can play a role in the ability of O. oeni to complete MLF. Assessment of 67 progeny of an S. cerevisiae SBxGN cross, co-inoculated with a single O. oeni strain, SB3, revealed a major QTL linked to MLF completion by O. oeni. This QTL encompassed a well-known translocation, XV-t-XVI, that results in increased SSU1 expression and is functionally linked with numerous phenotypes including lag phase duration and sulfite export and production. A reciprocal hemizygosity assay was performed to elucidate the effect of the gene SSU1 in the SBxGN background. Our results instead revealed a strong effect of SSU1 haploinsufficiency on O. oenis ability to complete malolactic fermentation during co-inoculation, and paves the way for the implementation of QTL mapping projects for deciphering the genetic bases of microbial interactions. Key pointsFor the first time QTL analysis has been used to study yeast-bacteria interactions. A QTL encompassing a translocation, XV-t-XVI, was linked to MLF outcomes. S. cerevisiae SSU1 haploinsufficiency positively impacted MLF by O. oeni.

microbiology↗

bioRxiv2019

Natural allelic variations of Saccharomyces cerevisiae impact stuck fermentation due to the combined effect of ethanol and temperature; a QTL-mapping study.

BackgroundFermentation completion is a major prerequisite in many industrial processes involving the bakery yeast Saccharomyces cerevisiae. Stuck fermentations can be due to the combination of many environmental stresses. Among them high temperature and ethanol content are particularly deleterious especially in bioethanol and red wine production. Although the genetic causes of temperature and/or ethanol tolerance were widely investigated in laboratory conditions, few studies investigated natural genetic variations related to stuck fermentations in high gravity matrixes.\n\nResultsIn this study, three QTLs linked to stuck fermentation in winemaking conditions were identified by using a selective genotyping strategy carried out on a backcrossed population. The precision of mapping allows the identification of two causative genes VHS1 and OYE2 characterized by stop-codon insertion. The phenotypic effect of these allelic variations was validated by Reciprocal Hemyzygous Assay in high gravity fermentations (>240 g/L of sugar) carried out at high temperatures (>28{degrees}C). Phenotypes impacted were related to the late stage of alcoholic fermentation during the stationary growth phase of yeast.\n\nConclusionsThe genes identified are related to molecular functions such as Programed Cell Death, ROS metabolism and respire-fermentative switch and were never related to fermentation efficiency. Our findings open new avenues for better understanding yeast resistance mechanisms involved in high gravity fermentations.

genetics↗

bioRxiv2018

A study of phenotypic plasticity of Saccharomyces cerevisiae in natural grape juices shed light on allelic variation under balanced selection.

The ability of a genotype to produce different phenotypes according to its surrounding environment is known as phenotypic plasticity. Within different individuals of the same species, phenotypic plasticity can vary greatly. This contrasted response is due to allelic variations and is caused by gene-by-environment interactions (GxE). Finding the genes and the cellular functions that interact with the environment is a current challenge for better understanding the genetic bases of phenotypic plasticity. In order to study the impact of natural allelic variations having a contrasted but relevant effect in a changing environment, we investigated the phenotypic response of the wine yeast Saccharomyces cerevisiae fermented in various grape juices. In this study we implemented a QTL mapping program using two independent offspring (~100 progeny) in order to investigate the molecular basis of yeast phenotypic response in a wine fermentation context. Thanks to high throughput sequencing approaches, both populations were genotyped, providing saturated genetic maps of thousands of markers. Linkage analyses allowed the detection of 78 QTLs including 21 with significant interaction with the nature of the fermented juice or fermentation conditions. Molecular dissection of a major QTL showed that the sulfite pump Ssu1p has a pleiotropic effect and impacts the phenotypic plasticity of several traits. Both alleles have positive effect according to external condition in phenotypes related to yeast fitness suggesting an example of balanced selection. All together these results pave the way for exploiting and deciphering the genetic determinism of phenotypic plasticity.

genetics↗

bioRxiv2017

Wine yeast phenomics: a standardized fermentation method for assessing quantitative traits of Saccharomyces cerevisiae strains in enological conditions.

This work describes the set up of a small scale fermentation methodology for measuring quantitative traits of hundreds of samples in an enological context. By using standardized screw cap vessels, the alcoholic fermentation kinetics of Saccharomyces cerevisiae strains were measured by following the weight loss over time. Preliminary results showed that the kinetic parameters measured are in agreement with those observed in larger scale vats. The small volume used did not impair any analysis of the strain performance. Indeed, this fermentation system was coupled with robotized enzymatic assays and 8 end-point metabolites of enological interest were measured accurately. Moreover, the vessel used offers the possibility to assay 32 volatiles compounds using a headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry approach. Data presented demonstrates that the shaking conditions significantly impacted the mean and the variance of kinetic parameters, primary metabolites, and the production of volatile compounds. This effect was likely due to an enhanced transfer of dissolved oxygen during the first hours of the alcoholic fermentation. To test the efficiency of this experimental design, the phenotypic response of 35 wine industrial starters was measured in five grape juices from the Bordeaux area. A multivariate analysis illustrated that strains were better discriminated by some grape must, than others. The technological performances as well as the phenotypic robustness of these strains was measured and discussed. The optimized methodology developed allows investigating multiple fermentation traits for numerous yeast strains and conditions and greatly contributes in achieving quantitative genetics studies as well as yeast selection programs.

microbiology↗