Explore the vast range of titles available.

The scent of roses (Rosa x hybrida) is composed of hundreds of volatile molecules. Monoterpenes represent up to 70% percent of the scent content in some cultivars, such as the Papa Meilland rose. Monoterpene biosynthesis in plants relies on plastid-localized terpene synthases. Combining transcriptomic and genetic approaches, we show that the Nudix hydrolase RhNUDX1, localized in the cytoplasm, is part of a pathway for the biosynthesis of free monoterpene alcohols that contribute to fragrance in roses. The RhNUDX1 protein shows geranyl diphosphate diphosphohydrolase activity in vitro and supports geraniol biosynthesis in planta.

Most phytophagous insect species exhibit a limited diet breadth and specialize on a few or a single host plant. In contrast, some species display a remarkably large diet breadth, with host plants spanning several families and many species. It is unclear, however, whether this phylogenetic generalism is supported by a generic metabolic use of common host chemical compounds (‘metabolic generalism’) or alternatively by distinct uses of diet-specific compounds (‘multi-host metabolic specialism’)? Here, we simultaneously investigated the metabolomes of fruit diets and of individuals of a generalist phytophagous species, Drosophila suzukii , that developed on them. The direct comparison of metabolomes of diets and consumers enabled us to disentangle the metabolic fate of common and rarer dietary compounds. We showed that the consumption of biochemically dissimilar diets resulted in a canalized, generic response from generalist individuals, consistent with the metabolic generalism hypothesis. We also showed that many diet-specific metabolites, such as those related to the particular color, odor, or taste of diets, were not metabolized, and rather accumulated in consumer individuals, even when probably detrimental to fitness. As a result, while individuals were mostly similar across diets, the detection of their particular diet was straightforward. Our study thus supports the view that dietary generalism may emerge from a passive, opportunistic use of various resources, contrary to more widespread views of an active role of adaptation in this process. Such a passive stance towards dietary chemicals, probably costly in the short term, might favor the later evolution of new diet specializations. Most insects that feed on green plants are specialists, meaning that they feed on just a narrow range of plant species. This reduces competition, especially if the host plant contains chemical deterrents that are toxic to other insects. But specialists cannot easily switch to feed on other plants, making them vulnerable to changes in the availability of the particular food type that they eat. Generalist insects, on the other hand, are able to consume a wide range of diets. This makes them more robust to changes in food availability, but it is unclear how these insects deal with the wider range of chemical compositions of their food. Do they convert food into energy using the same chemical process, or metabolism, for all the different things they eat? Or do generalists have a specific metabolic pathway for each food type? To answer this question, Olazcuaga, Baltenweck et al. studied the metabolism of a generalist fruit fly species. The team compared four types of fruit (blackcurrant, cherry, cranberry and strawberry) and isolated separate groups of flies so that they each ate only one type of fruit. By comparing the chemical composition of the flies with that of the fruit they ate, they were able to work out how each fruit type was metabolised. They found that the flies converted food into energy using the same process regardless of the type of fruit they ate. This lack of a specialist metabolic pathway for each fruit type meant that some chemicals were not metabolised and accumulated in the fly’s body instead. This build-up of unprocessed chemicals is likely to be harmful to the fly. The results of Olazcuaga, Baltenweck et al. suggest that generalist insects do not actively adapt their metabolism to new food types. It’s more likely that they try different types of food as the opportunity arises, regardless of the fact that some of the food will not be converted into energy and may harm them long term. These findings are important because they give us an insight into how the chemistry of a plant can shape the physiology of the organisms that consume it, and vice-versa. These insights are a crucial step in developing sustainable agriculture practices that must consider tackle how plants are pollinated, how plant seeds are dispersed and what type of pest control to use.

Background A key step in domestication of the grapevine was the transition from separate sexes (dioecy) in wild Vitis vinifera ssp. sylvestris ( V. sylvestris ) to hermaphroditism in cultivated Vitis vinifera ssp. sativa ( V. vinifera ). It is known that V. sylvestris has an XY system and V. vinifera a modified Y haplotype (Yh) and that the sex locus is small, but it has not previously been precisely characterized. Results We generate a high-quality de novo reference genome for V. sylvestris , onto which we map whole-genome re-sequencing data of a cross to locate the sex locus. Assembly of the full X, Y, and Yh haplotypes of V. sylvestris and V. vinifera sex locus and examining their gene content and expression profiles during flower development in wild and cultivated accessions show that truncation and deletion of tapetum and pollen development genes on the X haplotype likely causes male sterility, while the upregulation of a Y allele of a cytokinin regulator ( APRT3 ) may cause female sterility. The downregulation of this cytokinin regulator in the Yh haplotype may be sufficient to trigger reversal to hermaphroditism. Molecular dating of X and Y haplotypes is consistent with the sex locus being as old as the Vitis genus, but the mechanism by which recombination was suppressed remains undetermined. Conclusions We describe the genomic and evolutionary characterization of the sex locus of cultivated and wild grapevine, providing a coherent model of sex determination in the latter and for transition from dioecy to hermaphroditism during domestication.

Background: Hydrophilic compounds, such as amino acids, organic acids and sugars, among others, are present in large amounts in plant cells. The analysis and quantification of these major hydrophilic compounds are particularly relevant in plant science because they have a considerable impact on the quality of plant-derived products and on plant–pathogen relationships. Our objective was to develop and validate a complete analysis workflow combining a water-based extraction procedure with a fast separation using hydrophilic interaction liquid chromatography coupled to high-resolution mass spectrometry (HILIC-HRMS) for quantitative analysis of hydrophilic compounds in plant tissues. Results: Water-based microwave-assisted extraction (MAE) methods for hydrophilic compounds were compared using HILIC-HRMS. The newly developed method involved 20 s MAE time followed by a 10 min HILIC-HRMS analysis. This bioanalytical method was validated for 24 polar metabolites, including amino acids, organic acids, and sugars, to ensure the reliability of analytical results: selectivity, limits of detection and quantification, calibration range and precision. Depending on the compounds, quantification limit was as low as 0.10 µM up to 4.50 µM. Between-run RSDs evaluated on Vitis vinifera and Arabidopsis samples were all below 20% except for three compounds. Conclusions: A water-based MAE method, coupled with HILIC-HRMS, was developed for the absolute quantification of free amino acids, organic acids, and sugars in plant tissues. Its effectiveness was demonstrated in both lignified plants, such as Vitis vinifera, and non-lignified plants, such as Arabidopsis. This method is suitable for medium- to high-throughput analysis of key polar metabolites from small amounts of plant material.

Background Plant color variation is due not only to the global pigment concentration but also to the proportion of different types of pigment. Variation in the color spectrum may arise from secondary modifications, such as hydroxylation and methylation, affecting the chromatic properties of pigments. In grapes ( Vitis vinifera L.), the level of methylation modifies the stability and reactivity of anthocyanin, which directly influence the color of the berry. Anthocyanin methylation, as a complex trait, is controlled by multiple molecular factors likely to involve multiple regulatory steps. Results In a Syrah × Grenache progeny, two QTLs were detected for variation in level of anthocyanin methylation. The first one, explaining up to 27% of variance, colocalized with a cluster of Myb-type transcription factor genes. The second one, explaining up to 20% of variance, colocalized with a cluster of O- methyltransferase coding genes (AOMT). In a collection of 32 unrelated cultivars, MybA and AOMT expression profiles correlated with the level of methylated anthocyanin. In addition, the newly characterized AOMT2 gene presented two SNPs associated with methylation level. These mutations, probably leading to a structural change of the AOMT2 protein significantly affected the enzyme specific catalytic efficiency for the 3'- O- methylation of delphinidin 3-glucoside. Conclusion We demonstrated that variation in methylated anthocyanin accumulation is susceptible to involve both transcriptional regulation and structural variation. We report here the identification of novel AOMT variants likely to cause methylated anthocyanin variation. The integration of QTL mapping and molecular approaches enabled a better understanding of how variation in gene expression and catalytic efficiency of the resulting enzyme may influence the grape anthocyanin profile.

Stilbenes are a small family of phenylpropanoids produced in a number of unrelated plant species, including grapevine (Vitis vinifera). In addition to their participation in defense mechanisms in plants, stilbenes, such as resveratrol, display important pharmacological properties and are postulated to be involved in the health benefits associated with a moderate consumption of red wine. Stilbene synthases (STSs), which catalyze the biosynthesis of the stilbene backbone, seem to have evolved from chalcone synthases (CHSs) several times independently in stilbene-producing plants. STS genes usually form small families of two to five closely related paralogs. By contrast, the sequence of grapevine reference genome (cv PN40024) has revealed an unusually large STS gene family. Here, we combine molecular evolution and structural and functional analyses to investigate further the high number of STS genes in grapevine. Our reannotation of the STS and CHS gene families yielded 48 STS genes, including at least 32 potentially functional ones. Functional characterization of nine genes representing most of the STS gene family diversity clearly indicated that these genes do encode for proteins with STS activity. Evolutionary analysis of the STS gene family revealed that both STS and CHS evolution are dominated by purifying selection, with no evidence for strong selection for new functions among STS genes. However, we found a few sites under different selection pressures in CHS and STS sequences, whose potential functional consequences are discussed using a structural model of a typical STS from grapevine that we developed.

Resistance of carrot to Alternaria leaf blight (ALB) caused by Alternaria dauci is a complex and quantitative trait. Numerous QTL for resistance (rQTLs) to ALB have been identified but the underlying mechanisms remain largely unknown. Some rQTLs have been recently proposed to be linked to the flavonoid content of carrot leaves. In this study, we performed a metabolic QTL analysis and shed light on the potential mechanisms underlying the most significant rQTL, located on carrot chromosome 6 and accounting for a large proportion of the resistance variation. The flavonoids apigenin 7- O -rutinoside, chrysoeriol 7- O -rutinoside and luteolin 7- O -rutinoside were identified as strongly correlated with resistance. The combination of genetic, metabolomic and transcriptomic approaches led to the identification of a gene encoding a bHLH162-like transcription factor, which may be responsible for the accumulation of these rutinosylated flavonoids. Transgenic expression of this bHLH transcription factor led to an over-accumulation of flavonoids in carrot calli, together with significant increase in the antifungal properties of the corresponding calli extracts. Altogether, the bHLH162-like transcription factor identified in this work is a strong candidate for explaining the flavonoid-based resistance to ALB in carrot.

The genome sequence of the diploid and highly homozygous Vitis vinifera genotype PN40024 serves as the reference for many grapevine studies. Despite several improvements to the PN40024 genome assembly, its current version PN12X.v2 is quite fragmented and only represents the haploid state of the genome with mixed haplotypes. In fact, being nearly homozygous, this genome contains several heterozygous regions that are yet to be resolved. Taking the opportunity of improvements that long-read sequencing technologies offer to fully discriminate haplotype sequences, an improved version of the reference, called PN40024.v4, was generated. Through incorporating long genomic sequencing reads to the assembly, the continuity of the 12X.v2 scaffolds was highly increased with a total number decreasing from 2,059 to 640 and a reduction in N bases of 88%. Additionally, the full alternative haplotype sequence was built for the first time, the chromosome anchoring was improved and the number of unplaced scaffolds was reduced by half. To obtain a high-quality gene annotation that outperforms previous versions, a liftover approach was complemented with an optimized annotation workflow for Vitis. Integration of the gene reference catalogue and its manual curation have also assisted in improving the annotation, while defining the most reliable estimation of 35,230 genes to date. Finally, we demonstrated that PN40024 resulted from 9 selfings of cv. “Helfensteiner” (cross of cv. “Pinot noir” and “Schiava grossa”) instead of a single “Pinot noir”. These advances will help maintain the PN40024 genome as a gold-standard reference, also contributing toward the eventual elaboration of the grapevine pangenome.

A correlation between the toxicity of TH dose and oxidative damage in the brain of exposed embryos was shown by the induction of oxidative stress, inflammatory response, and the altered expressions of apoptotic and stress-related genes. [...]these authors have highlighted the properties of chicoric and rosmarinic acids as anti-apoptotic and anti-reactive oxygen species (ROS)-mediated damages by enhancing brain antioxidants and reducing cytokines and inflammatory mediators. On the following section, authors focus on rice, maize, soybean, wheat, and other crops applications of metabolomics, also highlighting its impact on the assessment of quality and metabolite variation of plant-derived products and food safety [5]. [6] evaluated the metabolic diversity and antioxidant activity of six false fruits of apple (Malus domestica) and five pear (Pyrus communis) cultivars, as tools to identify varieties with superior organoleptic properties and potential health benefits. Authors used both untargeted and targeted metabolomic approaches combining different techniques: nuclear magnetic resonance (NMR) spectroscopy, high-performance liquid chromatography with diode array detection (HPLC-DAD) and HPLC with electrospray ionization mass spectrometry (HPLC-ESI-MS).

Fomitiporia mediterranea (Fmed) is one of the main fungal species found in grapevine wood rot, also called “amadou,” one of the most typical symptoms of grapevine trunk disease Esca. This fungus is functionally classified as a white-rot, able to degrade all wood structure polymers, i.e., hemicelluloses, cellulose, and the most recalcitrant component, lignin. Specific enzymes are secreted by the fungus to degrade those components, namely carbohydrate active enzymes for hemicelluloses and cellulose, which can be highly specific for given polysaccharide, and peroxidases, which enable white-rot to degrade lignin, with specificities relating to lignin composition as well. Furthermore, besides polymers, a highly diverse set of metabolites often associated with antifungal activities is found in wood, this set differing among the various wood species. Wood decayers possess the ability to detoxify these specific extractives and this ability could reflect the adaptation of these fungi to their specific environment. The aim of this study is to better understand the molecular mechanisms used by Fmed to degrade wood structure, and in particular its potential adaptation to grapevine wood. To do so, Fmed was cultivated on sawdust from different origins: grapevine, beech, and spruce. Carbon mineralization rate, mass loss, wood structure polymers contents, targeted metabolites (extractives) and secreted proteins were measured. We used the well-known white-rot model Trametes versicolor for comparison. Whereas no significant degradation was observed with spruce, a higher mass loss was measured on Fmed grapevine culture compared to beech culture. Moreover, on both substrates, a simultaneous degradation pattern was demonstrated, and proteomic analysis identified a relative overproduction of oxidoreductases involved in lignin and extractive degradation on grapevine cultures, and only few differences in carbohydrate active enzymes. These results could explain at least partially the adaptation of Fmed to grapevine wood structural composition compared to other wood species, and suggest that other biotic and abiotic factors should be considered to fully understand the potential adaptation of Fmed to its ecological niche. Proteomics data are available via ProteomeXchange with identifier PXD036889.