Biology subjects

Goulet, C.

Publications and source records attributed to Goulet, C..

7 recordsLinked to original sources

bioRxiv2026

Volatile profiling and estimated odor-activity analysis of commercial drug-type cannabis accessions

Volatile organic compounds (VOCs) define the distinctive aroma of cannabis and critically influence consumer preference, cultivar authentication, and breeding programs. However, systematic characterization of VOC diversity across commercial drug-type cultivars remains limited. This study presents a comprehensive volatilomics-based phenotypic characterization of 165 commercial drug-type cannabis accessions using gas chromatography with flame ionization detection and mass spectrometry (GC-FID/MS). We identified 61 high-confidence VOCs assigned to three biosynthetic classes: terpenoids (n = 45), fatty acid-derived volatiles (n = 12) and amino acid-derived volatiles (n = 4), resolved into 12 subclasses. Analysis of variance revealed highly significant among-accession differences for all compounds (p < 0.001; 2 = 0.67-0.97), with repeatability estimates averaging 0.81 (range 0.50-0.95). Unsupervised clustering partitioned accessions into three distinct chemotypes (n = 90, 53, and 22), supported by principal component and t-SNE analyses. Machine learning-based feature selection identified a consensus panel of 12 discriminative compounds (camphene, -fenchene, sabinene, -terpinene, ({+/-})-limonene, -humulene, linalool, endo-fenchol, {Delta}3-carene, -thujene, {gamma}-terpinene and -phellandrene) that recovered the chemotype assignment of 32 of 33 held-out accessions. Estimated odor-activity screening ranked prenylthiol, -pinene, ({+/-})-limonene, linalool and myrcene highest among the odor-active compounds. All three chemotypes shared a prenylthiol-dominated core (67-77% of summed OAV) and were distinguished by the extent and nature of terpenoid modulation of that core: minimally modulated (Cluster ZERO), citrus-floral modulated (Cluster ONE) and pine-terpenic modulated (Cluster TWO). These findings indicate that volatile diversity in this panel can be summarized by three reproducible chemotypes, providing a quantitative basis for accession characterization and a foundation for future breeding and quality-assessment studies.

plant biology↗

bioRxiv2025

Gene editing of Nicotiana benthamiana architecture for space-efficient production of recombinant proteins in controlled environments

Indoor vertical farming (VF) offers several practical advantages for the cultivation of plant protein bio-factories, including plant uniformity, product consistency, water/nutrient recycling and production cycles on a year-round basis. Much progress has been achieved in recent years toward the development of innovative systems for artificial lighting, automated irrigation, plant handling, environment control and space use optimization in VF systems. Here, we used a CRISPR-Cas9 gene editing approach to generate mutant lines of transient protein expression host Nicotiana benthamiana presenting a compact, space-efficient phenotype compared to the so-called LAB strain commonly used for protein production. Our strategy consisted of altering apical dominance by suppressing the biosynthesis of strigolactone, a negative regulator of axillary bud outgrowth-promoting cytokinins. Strigolactone-depleted lines were generated by knocking-down the expression of either Carotenoid cleavage dioxygenase 7 (CCD7) or Carotenoid cleavage dioxygenase 8 (CCD8), two key enzymes of the metabolic pathway leading to strigolactone synthesis. Knocking-down the genes of either enzyme had no impact on the overall growth rate of the plant but drastically influenced its leaf proteome, auxin/cytokinin ratio and overall architecture. More specifically, the {Delta}CCD mutants exhibited altered glycolytic and malate-processing enzyme fluxes driving the production of pyruvate and cytokinins in leaf tissue, an axillary growth-oriented development pattern and, most importantly, a spatial footprint reduced by 45% to 50% compared to the LAB strain. Most importantly, recombinant protein yields per plant were maintained in the mutant lines, as here illustrated for the model protein GFP and for rituximab, a chimeric monoclonal antibody of confirmed clinical value in humans. Our data demonstrate the usefulness of {Delta}CCD7 and {Delta}CCD8 knockout leading to strigolactone depletion for the generation of compact, space-efficient N. benthamiana lines well suited to VF systems intended for biopharmaceutical production.

plant biology↗

bioRxiv2024

Tomato cystatin SlCYS8 as a trigger of drought tolerance and tuber yield in potato

Current climate change scenarios predict an increased incidence of drought episodes likely to affect potato crops worldwide. Potato exhibits a low-density, shallow root system that makes it particularly vulnerable to water shortage and any successful attempt to implement drought tolerance in cultivated potato varieties is potentially relevant from an agronomic standpoint. In this study, we assessed the potential of tomato cystatin SlCYS8 to promote drought tolerance in SlCYS8-expressing potato lines by induction of stress-related pleiotropy. Up to now, protease inhibitors of the cystatin protein superfamily have been mostly considered as biotechnological tools to engineer pest or pathogen resistance in crops, but several recent studies have also revealed a possible link between abiotic stress tolerance and these regulatory proteins in leaf tissue. SlCYS8-expressing plantlets grown on culture medium containing the drought mimic polyethylene glycol (PEG) exhibited an elevated root-to-shoot ratio, an indicator of drought tolerance in potato. A similar conclusion could be drawn with greenhouse-grown acclimated plants, confirming a relative root growth-promoting effect for the recombinant inhibitor upon water deficit. SlCYS8-potato lines also showed a high tuber yield compared to the control line under both limiting and non-limiting water regimes, suggesting an improved efficiency of the primary metabolism and the avoidance of a growth- stress response tradeoff in the modified lines. Accordingly, SlCYS8 expression was associated with a stress response-oriented proteome in leaves likely explained by pleiotropic effects of the recombinant cystatin driving the constitutive expression of stress-related proteins and the upregulation of primary metabolism-associated proteins. Overall, these data suggest the potential of cystatins as molecular triggers of tuber biomass production and drought resilience in potato. Complementary studies will be warranted to assess tuber yield of the SlCYS8-lines under different water regimes in field conditions.

plant biology↗

bioRxiv2023

Can leafhoppers help us trace the impact of climate change on agriculture?

SUMMARYClimate change is reshaping agriculture and insect biodiversity worldwide. With rising temperatures, insect species with narrow thermal margins are expected to be pushed beyond their thermal limits, and losses related to herbivory and diseases transmitted by them will be experienced in new regions. Several previous studies have investigated this phenomenon in tropical and temperate regions, locally and globally; however, here, it is proposed that climate changes impact on agriculture can be traced through the study of Nearctic migratory insects, specifically leafhoppers. To test this hypothesis, leafhoppers in strawberry fields located in the province of Quebec, eastern Canada, were evaluated. The strawberry-leafhopper pathosystem offers a unique opportunity because leafhoppers can transmit, among other diseases, strawberry green petal disease (SbGP), which is associated with pathogenic phytoplasmas. Here, we found that in the last ten years, the number of leafhoppers has been increasing in correspondence with the number of SbGP cases detected in eastern Canada, reporting for the first time ten species new to eastern Canada and two to the country, although the leafhopper diversity has been seriously affected. Our model using more than 34 000 leafhoppers showed that their abundance is influenced by temperature, a factor that we found also influences the microbiome associated with Macrosteles quadrilineatus, which was one of the most abundant leafhoppers we observed. One of our most striking findings is that none of the insecticides used by strawberry growers can control leafhopper incidence, which could be linked to microbiome changes induced by changing temperatures. We suggest that Nearctic leafhoppers can be used as sentinels to trace the multilayered effects of climate change in agriculture. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=185 SRC="FIGDIR/small/544773v1_ufig1.gif" ALT="Figure 1"> View larger version (77K): org.highwire.dtl.DTLVardef@e984eorg.highwire.dtl.DTLVardef@3146a9org.highwire.dtl.DTLVardef@1160b9aorg.highwire.dtl.DTLVardef@53c39c_HPS_FORMAT_FIGEXP M_FIG C_FIG IN BRIEFThe current climate crisis is reshaping insect biodiversity and abundance, but little is known about the direct effect of this phenomenon on agriculture. In this study, we explored leafhoppers, a group of agriculturally important insect pests and disease vectors, as sentinels of the effect of climate change on agriculture. Our findings indicate that this group of insects can help us to understand the effect of the current climate crisis on insect invasions, diversity, abundance, disease dynamics and insecticide resistance and to take quick action to ensure food security while achieving more sustainable agriculture. HIGHLIGHTSO_LIMigratory leafhoppers benefit from temperature increases C_LIO_LILeafhopper-transmitted diseases have increased in the last decade C_LIO_LINew non-migratory leafhoppers can be found now in Nearctic regions C_LIO_LILeafhopper insecticide resistance could be linked to the insect microbiome C_LI

ecology↗

bioRxiv2022

Structural variations in the phytoene synthase 1 gene affect carotenoid accumulation in tomato fruits and result in bicolor and yellow phenotypes

Tomato fruits normally accumulate large amounts of the red pigment lycopene in their chromoplasts. Some tomato cultivars (Solanum lycopersicum) show however distinct phenotypes, from a pure yellow hue to bicolor fruits with red and yellow sections. In this study, we show that alleles of the phytoene synthase 1 gene (PSY1), the first gene of carotenoid synthesis pathway, are responsible for the yellow, but also the bicolor phenotype. Introgression lines with the PSY1 allele from the green-fruited species S. habrochaites express less the enzyme, resulting in a bicolor phenotype. On the other hand, in tomato bicolor cultivars, the same coloration pattern is caused by a 3789 bp-deletion in the promoter region of PSY1. Since the deletion contains part of the 5UTR region of PSY1, translation efficiency is likely decreased resulting in a reduction of lycopene accumulation. Furthermore, we identified that the yellow ry phenotype is caused by a duplication and an inversion implicating PSY1 and the downstream neighbor gene. The genomic rearrangement change the end of PSY1 amino acid sequence. The fruits of yellow ry cultivars are still able in certain conditions to accumulate lycopene near the blossom-end of the fruit, though to a lesser extent than in bicolor cultivars. In contrast, fruits of the yellow r cultivars never present fleshy red sections. These cultivars have an insertion of a single long terminal repeat from the Rider transposon in the first exon of PSY1 resulting in a non-functional protein. These results demonstrate how multiple phenotypes can arise from structural variations in a key gene.

plant biology↗

bioRxiv2022

Hidden potential of the supporting scaffold as a structural module for plant cystatin design

Protein engineering approaches have been proposed to improve the inhibitory properties of plant cystatins towards herbivorous pest digestive Cys proteases, typically involving sequence alterations in the inhibitory loops and/or N-terminal trunk of the protein interacting with specific amino acid residues of the target protease. In this study, we assessed whether the loops-supporting frame, or scaffold, would represent a valuable structural module for cystatin function improvement. Twenty hybrid cystatins were designed in silico, consisting of the N-terminal trunk and two inhibitory loops of a given donor cystatin grafted onto the scaffold of an alternative, recipient cystatin. Synthetic genes for the hybrids were expressed in E. coli, and the resulting proteins assessed for their potency to inhibit model Cys protease papain and the digestive Cys proteases of Colorado potato beetle (Leptinotarsa decemlineata) used as an insect pest model. In line with the occurrence of positively selected amino acids presumably influencing inhibitory activity in the scaffold region of plant cystatins, grafting the N-terminal trunk and inhibitory loops of a given cystatin onto the scaffold of an alternative cystatin generally had an effect on the inhibitory potency of these function-related elements against Cys proteases. For instance, hybrid cystatins including the three structural elements of model tomato cystatin SlCYS8 grafted on the scaffold of cystatins from other plant families showed Ki values altered by up to 3-fold for papain, and inhibitory efficiencies increased by up to 8-fold against L. decemlineata cathepsin L-like proteases, compared to wild-type SlCYS8 bearing the original scaffold. Our data point to a significant influence of the cystatin scaffold on the inhibitory activity of the N-terminal trunk and protease inhibitory loops. They also suggest the potential of this structural element as a module for plant cystatin design to generate functional variability against Cys proteases, including the digestive proteases of herbivorous pests.

plant biology↗

bioRxiv2021

Harnessing the functional diversity of plant cystatins to design inhibitor variants highly active against herbivorous arthropod digestive proteases

Protein engineering approaches have been proposed to improve the inhibitory properties of plant cystatins against herbivorous arthropod digestive proteases. These approaches typically involve the site-directed mutagenesis of functionally relevant amino acids, the production and selection of improved inhibitory variants by molecular phage display procedures, or the design of bi/multifunctional translational fusions integrating one or several cystatin inhibitory domains. Here, we propose a new approach where the function-related structural elements of a cystatin are substituted by the corresponding elements of an alternative cystatin. Cys protease inhibitory assays were first performed with 20 representative plant cystatins and model Cys proteases, including herbivorous arthropod digestive proteases, to appreciate the extent of functional variability among plant cystatin protein family members. The most, and less, potent of these cystatins were then used as donors of structural elements to create hybrids of tomato cystatin SlCYS8 used as a model recipient inhibitor. Our data confirm the wide variety of cystatin protease inhibitory profiles among plant taxa. They also demonstrate the usefulness of these proteins as a pool of discrete structural elements for the design of cystatin variants with improved potency against herbivorous pest digestive Cys proteases.

plant biology↗