Introgressions of Vitis rotundifolia Michx. to obtain grapevine genotypes with complex resistance to biotic and abiotic stresses

Vitis rotundifolia Michx. is one of the species of the family Vitaceae, with resistance to both biotic and abiotic stresses. The present study reports new scientific knowledge about the inheritance of resistance to downy mildew, powdery mildew and frost by V. vinifera varieties from V. rotundifolia. Recombinant lines of three hybrid populations from the crossing of the maternal genotype ♀M. 31-77-10 with V. rotundifolia hybrids were used as the object of the study. As a result of laboratory screening, more than 40 % of recombinants of the ♀M. 31-77-10× ×[DRX-M5-734+DRX-M5-753+DRX-M5-790] population showed a high degree of frost resistance (–24 °C), while 6 % of transgressive recombinants were characterized by a very high degree of resistance (–27 °С). The maternal genotype ♀M. 31-77-10 does not carry alleles of resistance to powdery mildew at the Run1 locus and in the field suffers from powdery mildew much more than the paternal genotypes. The prevalence of powdery mildew on vegetative organs in the three recombinant populations over the years varies on average between 3.2–17.1, 0.3–17.7 and 0.6–5.2 %, respectively. As a result, almost all recombinant genotypes that received a resistant allele from the paternal genome are highly resistant to powdery mildew.

Comparison of Salt Exclusion in Muscadine and Interspecific Hybrid Grapes Using a Greenhouse Screening Procedure

Bunch grapes (Euvitis) are classified as moderately salt-tolerant. However, little is known about the salt tolerance of muscadine grapes (Vitis rotundifolia). The objective of this research was to evaluate the salt exclusion capacity of muscadine grapes relative to common bunch grape rootstocks and hybrid winegrapes using a greenhouse screening assay. In two separate experiments, 31 muscadine, six bunch grape rootstocks, and five hybrid winegrape cultivars were irrigated daily with a 25-mm sodium chloride salt solution for a period of 14 d, followed by a destructive harvest to determine sodium (Na) and chloride (Cl) concentrations in root and shoot tissues. Generally, the muscadines studied exhibited a greater range of salt concentration relative to bunch grape rootstocks. Total tissue (shoot and root) salt varied by 250% and 430% across muscadines and by 180% and 190% across bunch grape rootstocks for Na and Cl, respectively. Despite the wider range, muscadine grapes expressed significantly less leaf necrosis than the bunch grape rootstocks. The most effective salt-excluding muscadines, ‘Janebell’, ‘Scuppernong’, ‘Late Fry’, and ‘Eudora’, were not distinguishable from the bunch grape rootstocks [‘Paulsen 1103’ (1103P), ‘Ruggeri 140’ (140Ru), ‘Schwarzmann’, ‘Millardet et de Grasset 101-14’ (101-14 Mgt.), ‘Millardet et de Grasset 420A’ (420A), and ‘Matador’]. Overall, there was no discernable difference between the salt exclusion capacity of muscadine and bunch grapes. The hybrid winegrape ‘Blanc Du Bois’ displayed poor Na and Cl exclusion properties but showed only moderate leaf necrosis symptoms. In both experiments, ‘Blanc Du Bois’ accumulated more than two-fold higher root and shoot concentrations of Na and Cl compared with the best-performing rootstocks (1103P, 140Ru, 101-14 Mgt.), suggesting that ‘Blanc Du Bois’ could benefit from grafting if salinity is a limiting factor.

Genome assembly of Vitis rotundifolia Michx. using third-generation sequencing (Oxford Nanopore Technologies)

The immune North American grapevine species Vitis rotundifolia Michaux (subgen. Muscadinia Planch.) is regarded as a potential donor of disease resistance genes, withstanding such dangerous diseases of grapes as powdery and downy mildews. The cultivar ‘Dixie’ is the only representative of this species preserved ex situ in Russia: it is maintained by the N.I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR) in the orchards of its branch, Krymsk Experiment Breeding Station. Third-generation sequencing on the MinION platform was performed to obtain information on the primary structure of the cultivar’s genomic DNA, employing also the results of Illumina sequencing available in databases. A detailed description of the technique with modifications at various stages is presented, as it was used for grapevine genome sequencing and whole-genome sequence assembly. The modified technique included the main stages of the original protocol recommended by the MinION producer: 1) DNA extraction; 2) preparation of libraries for sequencing; 3) MinION sequencing and bioinformatic data processing; 4) de novo whole-genome sequence assembly using only MinION data or hybrid assembly (MinION+Illumina data); and 5) functional annotation of the whole-genome assembly. Stage 4 included not only de novo sequencing, but also the analysis of the available bioinformatic data, thus minimizing errors and increasing precision during the assembly of the studied genome. The DNA isolated from the leaves of cv. ‘Dixie’ was sequenced using two MinION flow cells (R9.4.1).

Tolerance of Muscadine grapes (Vitis rotundifolia) to alkaline soil

Muscadine (Muscadinia rotundifolia) grapes have been used in grape variety and rootstock development due to their inherent pest and disease resistance, but little is known about their alkaline soil tolerance. In this study, Muscadine varieties, commercialrootstock and interspecific hybrid grape (Vitis spp.) cultivars were evaluated for alkaline soil tolerance under field conditions to determine the potential suitability of muscadines for rootstock development. Thirty-one muscadine and eleven interspecific hybridgrape cultivars were grown in a moderately alkaline soil (pH = 8.1) over a three-year period. Alkaline soil tolerance wasdetermined by relative vine vigour (shoot length), vine nutrient status (whole leaf tissue testing) and visual chlorosis. Additional data were collected on the timing of budbreak. Overall, the muscadines studied expressed low vigour and had greater chlorosissymptoms than the interspecific hybrid rootstocks (Paulsen 1103, Millardet et de Grasset 101-14, Millardet et de Grasset 420A,Ruggeri 140, Schwarzmann, and Matador). These parameters were not correlated with the concentration in any specific nutrient, although nutrient deficiencies (nitrogen, copper) and excesses (calcium, boron) were observed in the muscadine varieties.Overall, the muscadine grapes expressed poor alkaline soil tolerance compared to interspecific hybrid grape rootstocks (1103P, 101-14 MGt., 140Ru, Schwarzmann, 420A, and Matador), even the ones having poor alkaline soil tolerance (101-14 MGt., Schwarzmann) and own-rooted cultivars (Black Spanish, Blanc Du Bois, Dunstan’s Dream and Victoria Red). Nevertheless, some variability in chlorosis symptoms and nutrition was observed across the muscadine group, suggesting some interests to select Muscadine hybrid rootstocks less sensitive to iron chlorosis.

Leaf-tissue Nutrient Dynamics in Mature Muscadine Cultivars Carlos and Noble in Georgia and North Carolina

More than 3000 acres of commercial muscadine (Vitis rotundifolia) vineyards exist in the southeastern United States. The muscadine wine industry is generating an economic impact of $1 billion in North Carolina alone. Muscadines have been cultivated since the 1800s, but muscadine vineyard fertilizer programs, tissue sampling, and nutrient sufficiency ranges continue to be based on anecdotal knowledge. While seasonal changes in tissue nutrient concentration are well documented in bunch grape (Vitis vinifera), questions remain about the seasonal and cultivar-dependent dynamics of muscadine leaf tissue nutrient concentrations. The aim of this study was to assess temporal and cultivar-related differences in tissue nutrient concentration of mature commercially grown muscadines. Leaf tissue nutrient concentration of the muscadine cultivars Carlos and Noble were assessed in three vineyards (Piedmont North Carolina, north Georgia, and south Georgia) at bloom, véraison, and postharvest in 2018 and 2019. Our results show that nitrogen (N), phosphorus (P), and manganese (Mn) were generally above the recommended sufficiency ranges, with calcium increasing over the season—and N, P, and potassium decreasing over the season. ‘Carlos’ had significantly higher levels of N and P, compared with ‘Noble’, while ‘Noble’ showed higher Mn concentration than ‘Carlos’. With this evaluation, we demonstrate the need for a modification in muscadine tissue nutrient sufficiency ranges that are based on cultivar and vine growth stage.

Molecular Characterization and Phylogenetic Analysis of MADS-Box Gene VroAGL11 Associated with Stenospermocarpic Seedlessness in Muscadine Grapes

Reduced expression of MADS-box gene AGAMOUS-LIKE11 (VviAGL11) is responsible for stenospermocarpic seedlessness in bunch grapes. This study is aimed to characterize the VviAGL11 orthologous gene (VroAGL11) in native muscadine grapes (Vitis rotundifolia) at the molecular level and analyze its divergence from other plants. The VroAGL11 transcripts were found in all muscadine cultivars tested and highly expressed in berries while barely detectable in leaves. RT-PCR and sequencing of predicted ORFs from diverse grape species showed that AGL11 transcripts were conservatively spliced. The encoded VroAGL11 protein contains highly conserved MADS-MEF2-like domain, MADS domain, K box, putative phosphorylation site and two sumoylation motifs. The muscadine VroAGL11 proteins are almost identical (99%) to that of seeded bunch cultivar, Chardonnay, except in one amino acid (A79G), but differs from mutant protein of seedless bunch grape, Sultanina, in two amino acids, R197L and T210A. Phylogenetic analysis showed that AGL11 gene of muscadine and other Vitis species formed a separate clade than that of other eudicots and monocots. Muscadine grape cultivar “Jane Bell” containing the highest percentage of seed content in berry (7.2% of berry weight) had the highest VroAGL11 expression, but almost none to nominal expression in seedless cultivars Fry Seedless (muscadine) and Reliance Seedless (bunch). These findings suggest that VroAGL11 gene controls the seed morphogenesis in muscadine grapes like in bunch grape and can be manipulated to induce stenospermocarpic seedlessness using gene editing technology.

Comparison of the chemical diversity of Vitis rotundifolia and Vitis vinifera cv. ‘Cabernet Sauvignon’

Grapevine is one of the most important fruit plants in the world, mainly due to its grapes and related products, with a highly economic and cultural importance. Every year, vineyards are affected by several pathogen outbreaks and the only way to control them is through preventive applications of agrochemicals every 12 to 15 days. This approach is not sustainable and not always effective. The Vitis genus comprise different species that exhibit varying levels of resistance to pathogens, thus the understanding of the innate resistance/susceptibility mechanisms of these different Vitis species is crucial to cope with these threats. In this work, an untargeted metabolomics approach was followed, using Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR-MS), to analyse the metabolic chemical diversity of two Vitis species: Vitis rotundifolia (resistant to pathogens) and V. vinifera cv. ‘Cabernet Sauvignon’ (susceptible to pathogens). Chemical formulas from both Vitis were used to build Van Krevelen diagrams and compositional space plots, which do not require full metabolite identification and provide an easy comparison method. Based only on these visualization tools, it was shown that the V. rotundifolia metabolome is more complex than the metabolome of V. vinifera cv. ‘Cabernet Sauvignon’. Moreover, the regions that present a higher density are associated to lipids, polyketides and carbohydrates. Also, V. rotundifolia metabolome presented a higher ratio O/C compounds.