Intraspecific recurrent selection in V. vinifera is an effective method for breeding of high quality, disease-, cold-, and drought-resistance grapes. Exploring the optimal treatment methods for grape (V. vinifera) seeds can help to accelerate the process of intraspecific recurrent selection and improve breeding efficiency. In this study, seeds of six V. vinifera varieties were used as experimental materials, and the germination and seedling formation characteristics were studied by single factor treatment and orthogonal compound treatment, respectively. To do this, stratification, chemical substances, beak cutting, and pre-germination treatments were tested, and the optimal treatment combination was determined for each variety. The results indicated that the optimal conditions obtained in the orthogonal experiments were not completely consistent with those in the single-factor experiments. Single factor experiment results demonstrated that two stratification methods (chilling gauze-storage and chilling sand-storage) and two pre-germination methods (pre-germination in petri dishes and pre-germination in a bean sprouter) vary in effectiveness for different varieties. gibberellin acid (GA3) soaking and beak-cutting promote the germination and seedling rate of the tested varieties. Orthogonal test results demonstrate that, for Dunkelfelder and Cabernet Sauvignon, the optimal treatment combination was chilling sand-storage + GA3 soaking seed + beak cutting + pre-germination in petri dishes. For Meili, the optimal treatment combination was chilling sand-storage + acetic acid (HAc) soaking seed + beak cutting + pre-germination in petri dishes. For Ecolly, the optimal treatment combination was chilling sand-storage + GA3 soaking seed + beak cutting + pre-germination in a bean sprouter. For Garanior, the optimal treatment combination was chilling sand-storage + HAc soaking seed + no beak cutting + pre-germination in petri dishes. For Marselan, the optimal treatment combination was chilling gauze-storage + GA3 soaking seed + beak cutting + pre-germination in a bean sprouter. This study identified the optimal conditions for seed germination and seedling formation of six grape varieties, which will facilitate future work to characterize the seed germination and seedling formation of seeds obtained by intraspecific hybridization of these varieties. This work also provides a reference for addressing problems of low seed germination rate and suboptimal seedling formation for better utilization of grape germplasms.

Low temperature is an important factor limiting plant growth. Most cultivars of Vitis vinifera L. are sensitive to low temperatures and are at risk of freezing injury or even plant death during winter. In this study, we analyzed the transcriptome of branches of dormant cv. Cabernet Sauvignon exposed to several low-temperature conditions to identify differentially expressed genes and determine their function based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG)enrichment analyses. Our results indicated that exposure to subzero low temperatures resulted in damage to plant cell membranes and extravasation of intracellular electrolytes, and that this damage increased with decreasing temperature or increasing duration. The number of differential genes increased as the duration of stress increased, but most of the common differentially expressed genes reached their highest expression at 6 h of stress, indicating that 6 h may be a turning point for vines to tolerate extreme low temperatures. Several pathways play key roles in the response of Cabernet Sauvignon to low-temperature injury, namely: (1) the role of calcium/calmodulin-mediated signaling; (2) carbohydrate metabolism, including the hydrolysis of cell wall pectin and cellulose, decomposition of sucrose, synthesis of raffinose, and inhibition of glycolytic processes; (3) the synthesis of unsaturated fatty acids and metabolism of linolenic acid; and (4) the synthesis of secondary metabolites, especially flavonoids. In addition, pathogenesis-related protein may also play a role in plant cold resistance, but the mechanism is not yet clear. This study reveals possible pathways for the freezing response and leads to new insights into the molecular basis of the tolerance to low temperature in grapevine.

Downy mildew is a major disease that severely restricts the healthy and sustainable development of the global grape and wine industry, so there is significant interest in breeding high-quality disease-resistant varieties. In this study, hybridization was carried out between two disease-resistant and four high-quality varieties for eight hybrid combinations. The downy mildew resistance of 6 hybrid parents and 350 hybrid F1 progeny was determined by the leaf disc inoculation test, and the frequency distribution of the disease resistance grades was analyzed for the different populations. Agarose gel electrophoresis and disease resistance identification were used to screen SSR molecular markers of the tested hybrids for resistance to downy mildew. The results showed that minor disease-resistance genes in V. vinifera varieties were the main determinant of the variation in disease susceptibility among different varieties. V. vinifera resistance to downy mildew is inherited by a quantitative trait controlled by multiple genes. Intraspecific hybridization of V. vinifera can be applied to breed suitable intermediate materials or new types of disease resistance. The screening and verification of simple-sequence repeats (SSR) as molecular markers revealed that UDV-304, UDV-305, and UDV-737 could be used as standard markers for the identification of downy mildew resistance of hybrid progeny of Ecolly and Cabernet Sauvignon, UDV-305 could be used for the hybrid progeny of Meili and Cabernet Sauvignon, and VMC8g9 could be used for the hybrid progeny of Ecolly or Meili and Dunkelfelder. The disease-resistant progeny selected in this study can be used as intermediate materials for the breeding of new high-quality, disease-resistant varieties by intraspecific recurrent selection in V. vinifera. The screened standard markers can be utilized for rapid batch identification of hybrid progeny of different hybrid combinations to facilitate molecular marker-assisted breeding.