Grape Genome Research Articles

Genome-Wide Analysis of Multidrug and Toxic Compound Extruction Transporters in Grape.

Grape (Vitis vinifera L.) is an important fruit crop in the world. It is used as a table grape and is also used for raisin and wine production. Grape berries accumulate secondary metabolites, such as anthocyanins, tannins, and resveratrol, which are known as functional compounds for human health. Multidrug and toxic compound extrusion transporter (MATEs) transport secondary metabolites. MATEs also transport other solutes, including organic acids, and toxic xenobiotics, depending on cation gradient and play various roles in plants. MATE comprises 300–500 amino acid residues and possesses a MATE domain and 8–12 transmembrane domains. In the present study, 59 MATE genes were identified in the grape genome, and phylogenetic analysis revealed the presence of four groups of grape MATEs (Group 1–4). Their information, such as gene structures, protein motifs, predicted subcellular localizations, and gene IDs of four genome annotations, that is, CRIBI v1, CRIBI v2, Genoscope, and Vcost v3, were annotated. The transport substrates and physiological functions of grape MATEs were estimated based on their homology with the analyzed MATEs in other plant species. Group 1 may transport toxic compounds and alkaloids, Group 2 may transport polyphenolic compounds, Group 3 may transport organic acids, and Group 4 may transport plant hormones related to signal transduction. In addition to the known anthocyanin transporters, VvMATE37 and VvMATE39, a novel anthocyanin transporter, VvMATE38 in Group 2, was suggested as a key transporter for anthocyanin accumulation in grape berry skin. VvMATE46, VvMATE47, and VvMATE49 in Group 3 may contribute to Al3+ detoxification and Fe2+/Fe3+ translocation via organic acid transport. This study provides helpful and fundamental information for grape MATE studies and resolves the confusion of gene IDs in different genome annotations.

Role of SnRK2s in grape berry development and stress response

Even though abscisic acid (ABA) plays a significant role in fruit growth and responses to a variety of environmental stimuli, the signaling mechanisms that underpin these activities are unknown. role. In present study, we identified seven sucrose non-fermenting-1-related protein kinases 2 (SnRK2s) from the grape (Vitis vinifera L.) genome, which may localized in the nucleus, membrane, and cytoplasm. The overexpression (OE) of VvSnRK2s showed that VvSnRK2.2 and VvSnRK2.7 promoted the ripening process in strawberries on molecular and physiological levels (fruit weight, berry firmness, cell wall composition, total soluble sugar, titratable acid, pigments, phenolic compounds), furthermore, VvSnRK2.3 and VvSnRK2.6 induced strong resistance in strawberry fruits to B. cinerea. Only VvSnRK2.2 and VvSnRK2.7 were found to interact with VvMYB24, a positive regulator of grape berry ripening. Additionally, VvSnRK2s interact with VvABF1 (an ABA-responsive factor) and VvABI1 (ABA insensitive 1) to mediate the ABA signalling pathway. VvSnRK2s respond to different hormonal treatments and abiotic stresses to improve plant stress resistance. Collectively, our results demonstrated that VvSnRK2.2 and VvSnRK2.7 are positive regulators grape berry development and ripening, while, VvSnRK2.3 and VvSnRK2.6 mediate grape resistance against B. cinerea.

Genome-wide identification and expression analysis of magnesium transporter gene family in grape (Vitis vinifera)

BackgroundMagnesium ion is one of the essential mineral elements for plant growth and development, which participates in a variety of physiological and biochemical processes. Since there is no report on the research of magnesium ion transporter in grape, the study of the structure and function of magnesium ion transporters (MGT) is helpful to understand the dynamic balance mechanism of intracellular magnesium ions and their inter- or intra-cellular activities.ResultIn this study, we identified the members of MGT protein family in grape and performed the phylogenetic and expression analysis. We have identified nine VvMGT genes in grape genome, which are distributed on eight different chromosomes. Phylogenetic analysis showed that MGT family members of grapes were divided into five subfamilies and had obvious homology with Arabidopsis, maize, and pear. Based on transcriptome data from the web databases, we analyzed the expression patterns of VvMGTs at different development stages and in response to abiotic stresses including waterlogging, drought, salinity, and copper. Using qRT-PCR method, we tested the expression of grape VvMGTs under magnesium and aluminum treatments and found significant changes in VvMGTs expression. In addition, four of the MGT proteins in grape were located in the nucleus.ConclusionOverall, in this study we investigated the structural characteristics, evolution pattern, and expression analysis of VvMGTs in depth, which laid the foundation for further revealing the function of VvMGT genes in grape.

Systematic analysis reveals O-methyltransferase gene family members involved in flavonoid biosynthesis in grape

O-methyltransferases (OMTs) are an important group of enzymes involved in the methylation of various secondary metabolites, including flavonoids. However, the features and functions of OMTs have not been comprehensively studied in grape (Vitis vinifera), a rich source of methylated flavonoids. Here, 47 OMT members were identified in grape genome. They were unevenly distributed on grape chromosomes and some genes were tandem duplicated, indicating the role of duplication processes in the expansion of this gene family. Based on the phylogenetic relationship, these OMTs were clustered into CCoAOMT and COMT subclades, which were further supported by the results of conserved motif and gene structure analysis. Correlation analysis revealed that three members (VvCCoAOMT1, VvCCoAOMT4, and VvCOMT1) were potentially involved in the synthesis of most methylated flavonoids in the berry skins. Expression profiling based on RNA-seq data and qRT-PCR experiments indicated that VvCCoAOMT1 and VvCCoAOMT4 had specific and high expression in berry skins, and responded to abscisic acid and high temperature treatments; and that VvCOMT1 expression was significantly induced during berry development and UVC treatment. Cis-regulatory element analysis suggested important roles of OMTs in growth, development, and defense against stresses. We further demonstrated the transcriptional regulation of VvCCoAOMT4 by VvMYBA1, a master regulator of grape berry anthocyanin, and verified the protein localization of VvCCoAOMT4 in membrane and nucleus. These findings facilitate a better understanding of the characteristics of OMT gene family, especially of the potential members involved in the formation of O-methylated flavonoids in grape.

Genome-Wide Identification and Characterization of DnaJ Gene Family in Grape (Vitis vinifera L.)

Grape production in southern China suffers great loss due to various environmental stresses. To understand the mechanism of how the grape plants respond to these stresses is an active area of research in developing cultivation techniques. Plant stress resistance is known to rely on special proteins. Amongst them, DnaJ protein (HSP40) serves as co-chaperones of HSP70, playing crucial roles in various stress response. However, the DnaJ proteins encoded by the DnaJ gene family in Vitis vinifera L. have not been fully described yet. In this study, we identified 78 VvDnaJs in the grape genome that can be classified into three groups—namely, DJA, DJB, and DJC. To reveal the evolutionary and stress response mechanisms for the VvDnaJ gene family, their evolutionary and expression patterns were analyzed using the bioinformatic approach and qRT-PCR. We found that the members in the same group exhibited a similar gene structure and protein domain organization. Gene duplication analysis demonstrated that segmental and tandem duplication may not be the dominant pathway of gene expansion in the VvDnaJ gene family. Codon usage pattern analysis showed that the codon usage pattern of VvDnaJs differs obviously from the monocotyledon counterparts. Tissue-specific analysis revealed that 12 VvDnaJs present a distinct expression profile, implying their distinct roles in various tissues. Cis-acting element analysis showed that almost all VvDnaJs contained the elements responsive to either hormones or stresses. Therefore, the expression levels of VvDnaJs subjected to exogenous hormone applications and stress treatments were determined, and we found that VvDnaJs were sensitive to hormone treatments and shade, salt, and heat stresses, especially VIT_00s0324g00040. The findings of this study could provide comprehensive information for the further investigation on the genetics and protein functions of the DnaJ gene family in grape.

Systematical characterization of VvCP gene in Vitis vinifera, and potential functions of VvCPs in the biosynthesis of Scripusin A

Cationic peroxidase is a crucial enzyme in plant defense systems and antioxidant activity. The Vitis vinifera Cationic peroxidase (VvCP) gene family, however, has yet to be fully characterized. We carefully evaluated many VvCP genes, including identification, phylogenetic analysis and categorization, and qRT-PCR analysis of VvCP expression to uncover the function of the VvCP family genes. The bioinformatics findings revealed that the nine VvCPs found in the wine grape genome could be grouped into four groupings based on gene structure, conserved motifs, chromosomal position, and cis-elements. Under UV-B stress, the expression levels and patterns differ, according to an RT-qPCR experiment (different times and parts). VvCPs was discovered to be the primary gene in the Scirpusin A biosynthesis pathway in a prior transcriptome investigation. Subsequent the UHPLC-QTOF-MS2 data confirmed that the VvCP11 gene catalyzed the synthesis of ε-viniferins to Scirpusin A. The findings will aid future research into the function and regulatory mechanism of the cationic peroxidase gene in wine grapes, as well as contribute to the development of novel Vitis vinifera (V. vinifera) types.

Grape Small Auxin Upregulated RNA (SAUR) 041 Is a Candidate Regulator of Berry Size in Grape.

Grape (Vitis vinifera) is an important horticultural crop that can be used to make juice and wine. However, the small size of the berry limits its yield. Cultivating larger berry varieties can be an effective way to solve this problem. As the largest family of auxin early response genes, SAUR (small auxin upregulated RNA) plays an important role in the growth and development of plants. Berry size is one of the important factors that determine grape quality. However, the SAUR gene family’s function in berry size of grape has not been studied systematically. We identified 60 SAUR members in the grape genome and divided them into 12 subfamilies based on phylogenetic analysis. Subsequently, we conducted a comprehensive and systematic analysis on the SAUR gene family by analyzing distribution of key amino acid residues in the domain, structural features, conserved motifs, and protein interaction network, and combined with the heterologous expression in Arabidopsis and tomato. Finally, the member related to grape berry size in SAUR gene family were screened. This genome-wide study provides a systematic analysis of grape SAUR gene family, further understanding the potential functions of candidate genes, and provides a new idea for grape breeding.

Identification of grape H3K4 genes and their expression profiles during grape fruit ripening and postharvest ROS treatment

Fruit development is modified by different types of epigenetics. Histone methylation is an important way of epigenetic modification. Eight genes related to H3K4 methyltransferase, named VvH3K4s, were identified and isolated from the grape genome based on conserved domain analysis, which could be divided into 3 categories by the phylogenetic relationship. Transcriptome data showed that VvH3K4–5 was obviously up-regulated during fruit ripe, and its expression level was significantly different between ‘Kyoho’ and ‘Fengzao’. The VvH3K4s promoters contains cis-acting elements of in response to stress, indicating that they may be involved in the metabolic pathways regulated by ROS signaling. The subcellular localization experiment and promoter activity analysis experiment on VvH3K4–5 showed that VvH3K4s may be regulated by H2O2. With H2O2 and Hypotaurine treatment, it was found that the expression pattern of most genes was opposite, and the expression level showed different expression trend with the extension of treatment time.

Genome-wide analysis of the SCPL gene family in grape (Vitis vinifera L.)

Serine carboxypeptidase-like (SCPL) proteins are a group of acyltransferase enzymes that have important roles in plant growth, development, and stress responses. Although SCPL proteins have been studied in many plants, the biological functions of SCPL genes in grape are still unknown. In this study, 59 putative SCPL proteins were identified from the grape genome. A bioinformatics analysis, including chromosomal locations, exon/intron structures, phylogeny, cis-elements, and conserved motifs, was performed for the gene family. The phylogenetic analysis revealed that VvSCPL proteins could be classified into three groups, with the gene motifs in each group showing high similarity levels. The number of exons in the VvSCPL genes ranged from 1 to 19, suggesting significant variations among grape SCPL genes. The expression of the VvSCPL genes, as assessed by RNA sequencing (RNA-seq) and quantitative real-time PCR, showed that most VvSCPL genes responded to drought- and waterlogging-stress treatments, which indicated their roles in abiotic stress responses. The results provide useful information for further study of SCPL genes in grape.

Molecular cloning and expression analysis of hydrogen peroxide sensors under H2O2 and ROS inhibitor treatment in ‘Kyoho’ grape berry

Hydrogen peroxide is an important factor involved in the senescence and quality deterioration of postharvest fruit. However, few studies have examined hydrogen peroxide sensors and their expression patterns in grape. Here, postharvest grape berries were treated with H2O2 and the ROS inhibitor hypotaurine (HT). HT reduced the H2O2 content by increasing ROS-scavenging enzyme activity, whereas H2O2 accelerated senescence. Four hydrogen peroxide sensors (VvHPCA1, 2, 3, and 4) were identified and isolated from the grape genome. Sequence analysis indicated that VvHPCAs shared a conserved structure, including the LRR-RK and hydrogen peroxide (HP) domains, with other homologous hydrogen peroxide sensor genes. Furthermore, the expression patterns of the four VvHPCAs were investigated under H2O2 and HT treatment in grape. The expression levels of the four VvHPCAs were lower in grape berries treated with HT than in grape berries treated with H2O2 or water treatment (Control) in at least one of the sampling points during storage. VvHPCAs are cytomembrane proteins with stress-responsive cis-acting elements in their promoters, indicating that these four identified VvHPCAs might function as hydrogen peroxide sensors in grape and regulate hydrogen peroxide signaling and metabolism. Thus, VvHPCAs are capable of responding to postharvest ROS stress. These findings provided new insight into the function of these four VvHPCAs, which are potential candidate genes involved in regulating ROS stress in grape.

Genome-wide characterization and analysis of bHLH transcription factors related to anthocyanin biosynthesis in spine grapes (Vitis davidii)

As one of the largest transcription factor family, basic helix-loop-helix (bHLH) transcription factor family plays an important role in plant metabolism, physiology and growth. Berry color is one of the important factors that determine grape quality. However, the bHLH transcription factor family’s function in anthocyanin synthesis of grape berry has not been studied systematically. We identified 115 bHLH transcription factors in grape genome and phylogenetic analysis indicated that bHLH family could be classified into 25 subfamilies. First, we screened six candidate genes by bioinformatics analysis and expression analysis. We found one of the candidate genes VdbHLH037 belonged to III (f) subfamily and interacted with genes related to anthocyanin synthesis through phylogenetic analysis and interaction network prediction. Therefore, we speculated that VdbHLH037 participated in the anthocyanin synthesis process. To confirm this, we transiently expressed VdbHLH037 in grape and Arabidopsis transformation. Compared with the control, transgenic materials can accumulate more anthocyanins. These results provide a good base to study the function of the VdbHLH family in anthocyanin synthesis of grape berry.

Optimizing the CRISPR/Cas9 system for genome editing in grape by using grape promoters

The efficacy of the CRISPR/Cas9 system in grapevine (Vitis vinifera L.) has been documented, but the optimization of this system, as well as CRISPR/Cas9-mediated multiplex genome editing, has not been explored in this species. Herein, we identified four VvU3 and VvU6 promoters and two ubiquitin (UBQ) promoters in grapevine and demonstrated that the use of the identified VvU3/U6 and UBQ2 promoters could significantly increase the editing efficiency in grape by improving the expression of sgRNA and Cas9, respectively. Furthermore, we conducted multiplex genome editing using the optimized CRISPR/Cas9 vector that contained the conventional multiple sgRNA expression cassettes or the polycistronic tRNA-sgRNA cassette (PTG) by targeting the sugar-related tonoplastic monosaccharide transporter (TMT) family members TMT1 and TMT2, and the overall editing efficiencies were higher than 10%. The simultaneous editing of TMT1 and TMT2 resulted in reduced sugar levels, which indicated the role of these two genes in sugar accumulation in grapes. Moreover, the activities of the VvU3, VvU6, and UBQ2 promoters in tobacco genome editing were demonstrated by editing the phytoene desaturase (PDS) gene in Nicotiana benthamiana leaves. Our study provides materials for the optimization of the CRISPR/Cas9 system. To our knowledge, our simultaneous editing of the grape TMT family genes TMT1 and TMT2 constitutes the first example of multiplex genome editing in grape. The multiplex editing systems described in this manuscript expand the toolbox of grape genome editing, which would facilitate basic research and molecular breeding in grapevine.

Identification, characterization and functional analysis of grape (Vitis vinifera L.) mitochondrial transcription termination factor (mTERF) genes in responding to biotic stress and exogenous phytohormone

BackgroundMitochondrial transcription termination factor (mTERF) is a large gene family which plays a significant role during plant growth under various environmental stresses. However, knowledge of mTERF genes in grapevine (Vitis L.) is limited.ResultsIn this research, a comprehensive analysis of grape mTERF (VvmTERF) genes, including chromosome locations, phylogeny, protein motifs, gene structures, gene duplications, synteny analysis and expression profiles, was conducted. As a result, a total of 25 mTERF genes were identified from the grape genome, which are distributed on 13 chromosomes with diverse densities and segmental duplication events. The grape mTERF gene family is classified into nine clades based on phylogenetic analysis and structural characteristics. These VvmTERF genes showed differential expression patterns in response to multiple phytohormone treatments and biotic stresses, including treatments with abscisic acid and methyl jasmonate, and inoculation of Plasmopara viticola and Erysiphe necator.ConclusionsThese research findings, as the first of its kind in grapevine, will provide useful information for future development of new stress tolerant grape cultivars through genetic manipulation of VvmTERF genes.

Genome-wide identification and characterisation of phenylalanine ammonia-lyase gene family in grapevine

ABSTRACT Phenylalanine ammonia-lyase (PAL) is a rate-limiting enzyme of phenylpropanoid biosynthesis in plants that synthesise many ubiquitous key compounds, including phenolic acids, flavonoids, lignins, and stilbenes. The first draft of the full grape genome assembly was released, but systematic analysis of the PAL family has not been completed in detail. In this study, 15 PALs were identified in the grape genome. Grape PALs are distributed on 6 chromosomes, and 9 PALs are distributed on chromosome 16, in which most of the 2 downstream genes, including chalcone synthase (CHS) and stilbene synthase (STS). Promoter analysis revealed that there were many cis-acting elements in the promoter regions to respond to light, phytohormone, and stress. According to transcriptome-data analysis, VvPALs have extensive expression patterns in various tissues and developmental stages in response to various stresses. Dynamic expression patterns of PAL1/2/3/5 were observed in different developmental stages of 4 grape varieties on the basis of qRT-PCR analysis, and suggested that PALs are involved in a complex mechanism to modulate in anthocyanin biosynthesis. Comprehensive analysis of PALs offers a basis for further understanding the physiological functions of PALs during grape development and their potential role to respond the various stimuli.

Genome-wide identification of cytokinin oxidases/dehydrogenase (CKXs) in grape and expression during berry set

Cytokinin oxidase/dehydrogenase (CKX) is a flavoenzyme, which irreversibly degrades the cytokinins and plays an important role in plant growth and development. They have been identified in many plants, but little is known in grape. Also, how CKXs meditated cytokinin signal pathway in grape berry set process is unclear. In this study, a total of 8 VvCKX gene family members (GFMs) were identified from ‘Kyoho’ grape genome, which divided into four group (group I, II, III, IV) based on phylogenetic analysis. Further structural analysis found that all VvCKXs had 3–5 intron and VvCKX GFMs that clustered together according to a phylogenetic tree had similar motif. The CKX GFMs had two highly conserved domains: an oxidase FAD-binding domain and a cytokinin dehydrogenase 1, FAD/cytokinin binding domain. In addition, the 8 VvCKX GFMs distributed on 6 chromosome and chromosome mapping indicated that three group genes of VvCKX were identified segment duplication genes. Growth and development, light response, phytohormone responsive and abiotoc elements were identified from the cis-regulatory elements analysis of VvCKX GFMs. The expression profiles of VvCKX GFMs in different organs suggested that VvCKX4 and VvCKX8 had highly expression in inflorescence and may play important role in grape berry set. Furthermore, the expression of VvCKX GFMs following application of N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU) showed that the majority of VvCKX GFMs were up-regulated, especially VvCKX4, VvCKX6 and VvCKX8. But VvCKX5 was consistently down-regulated. These results indicate that VvCKX GFMs may play important role in the set of grape berries. Our results provide valuable information for future studies on the functional characteristics of VvCKX GFMs in grape berry set.

Molecular Markers, Yield Performance and Berry Sensory Attributes in 10 Grape Cultivars Cultivated in Assiut Governorate

Yield performance and berry sensory attributes in 10 grape cultivars were studied under Assiut conditions. In addition, the genetic variability and relationships among these cultivars were determined based on RAPD and SRAP molecular markers. Genetic variations were observed between the tested cultivars in all studied traits of yield and yield components as well as in berry sensory attributes. 100 sites of grape genome were amplified by RAPD and SRAP primers and used to study the interrelationships between 10 grape cultivars. The highest interrelationships were found between “Black Muscat and Provano”, “Palomino and Bez El-Naka”, and between “Palomino and Ruby Seedless”. The lowest relatedness was found between Beauty Seedless and the other nine grape cultivars. The phenotypic data and molecular markers were effective in estimating the genetic variability between grape cultivars. The study indicated the presence of abundant genetic variability among some of the important commercial grape cultivars. Significant positive correlation was found between the phenotypic and genotypic distance indicated that the studied RAPD and SRAP markers were able to bind to effective regions in the genome.

ABA signaling pathway genes and function during abiotic stress and berry ripening in Vitis vinifera.

Abscisic acid (ABA) plays important roles in plant development and tolerance to abiotic stresses. Limited information is available regarding ABA signaling pathway genes in grape. In this study, 9 VvPYR/PYLs, 85 VvPP2Cs, 7 VvABIs, 7 VvSnRK2s, and 8 VvABFs were identified in the grape genome. Duplication analysis indicated that whole genome duplication might contribute to the expansion of these gene families. The comprehensive transcriptome analysis in various organs/tissues implied that most of these genes were tissue-specific, and few were environment-specific genes. Exogenous ABA treatment reduced the grape maturation period. VvPP2C59, VvPP2C60, VvPP2C66, and VvABF8 were all involved in tolerance to cold, heat, and drought stresses, revealing their crucial roles in regulating environmental stress responses. This work provides detailed information of ABA signaling pathway genes and new insights regarding their expression patterns during grape development and abiotic stress treatment.

The wild grape genome sequence provides insights into the transition from dioecy to hermaphroditism during grape domestication

BackgroundA 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.ResultsWe 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.ConclusionsWe 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.

Analysis of PYL Genes and Their Potential Relevance to Stress Tolerance and Berry Ripening in Grape

Abscisic acid (ABA) is an essential phytohormone that regulates plant growth and development, particularly in response to abiotic stress. The ABA receptor PYR/PYL/RCAR (PYL) family has been identified from some plant species. However, knowledge about the PYL family (VvPYLs) in grape (Vitis vinifera) is limited. This study aims to conduct genome-wide analyses of VvPYLs. We successfully identified eight PYL genes from the newest grape genome database. These VvPYLs could be divided into three subfamilies. Exon-intron structures were closely related to the phylogenetic relationship of the genes, and PYL genes that clustered in the same subfamily had a similar number of exons. VvPYL1, VvPYL2, VvPYL4, VvPYL7, and VvPYL8 were relatively highly expressed in roots. VvPYL1, VvPYL3, VvPYL7, and VvPYL8 were expressed in response to cold, salt, or polyethylene glycol stress. VvPYL6 was up-regulated by cold stress for 4 hours, and the expression of VvPYL2 was 1.74-fold greater than that of the control under cold stress. VvPYL8 was up-regulated 1.64-, 1.83-, and 1.90-fold compared with the control when treated with salt, PEG, or cold stress after 4 hours, respectively. Additionally, abiotic stress-inducible elements exist in VvPYL2, VvPYL3, VvPYL7, and VvPYL8, indicating that in these four genes, the response to abiotic stress may be regulated by cis-regulatory elements. The transcriptional levels of VvPYL1 and VvPYL8 significantly increased from fruit set to the ripening stage and decreased in the berry when treated by exogenous ABA. The eight VvPYL genes have diverse roles in grape stress responses, berry ripening, or development. This work provides insight into the role of VvPYL gene families in response to abiotic stress and berry ripening in grape.

Genome Resequencing, Improvement of Variant Calling, and Population Genomic Analyses Provide Insights into the Seedlessness in the Genus Vitis.

The seedlessness of grape derived from stenospermocarpy is one of the most prized traits of table or raisin grapes. It is controlled by a complex genetic system containing one dominant gene and multiple recessive genes. Here, we collected dense variation data from high-depth resequencing data of seeded, seedless, and wild relative grape genomes sequenced to > 37x mean depth. Variant calls were made using a modified variant calling pipeline that was suitable for highly diverse interspecific grape accessions. The modified pipeline enabled us to call several million more variants than the commonly recommended pipeline. The quality was validated by Sanger sequencing data and subsequently supported by the genetic population structure and the phylogenetic tree constructed using the obtained variation data, results of which were generally consistent with known pedigree and taxonomic classifications. Variation data enabled us to confirm a dominant gene and identify recessive loci for seedlessness. Incidentally, we found that grape cultivar Rizamat contains an ancestral chromosomal region of the dominant gene in Sultanina, a predominant seedlessness donor cultivar. Furthermore, we predicted new candidate causal genes including Vitvi01g00455, Vitvi08g01528, and Vitvi18g01237 associated with the recessive seedless-regulating loci, which showed high homology with genes that regulate seed development in Arabidopsis. This study provides fundamental insights relevant to variant calling from genome resequencing data of diverse interspecific hybrid germplasms such as grape and will accelerate future efforts aimed at crop improvement.