Molecular marker-assisted selection (MAS) can significantly accelerate and improve the efficiency of the breeding process in seedless grape cultivars.  In this study, we developed the KASP_VviAGL11 and VviAGL11_410 markers based on a single nucleotide polymorphism (SNP) site (Chr18: 26889437 (A/C)) of the VviAGL11 gene, and compared them with previously reported SSR markers p3_VvAGL11 and 5U_VviAGL11 by testing 101 cultivars and 81 F₁ hybrid progenies.  The results showed that both of the proposed markers obtained 100% accuracy rates in detecting allele A, which was closely associated with the seedless trait in grapes, while p3_VvAGL11 and 5U_VviAGL11 had lower accuracy rates due to their tendency to produce false positives.  After careful evaluation of the technical advantages and disadvantages associated with these markers, we concluded that KASP_VviAGL11 was superior in terms of simplicity, cost-effectiveness, efficiency, and accuracy.  Thus, we optimized the process of molecular MAS for seedless grapes, focusing on the KASP_VviAGL11 marker as a central component, to provide key technical support for the development of new seedless grape cultivars.

Embryo rescue technology plays an important role in seedless grape breeding.  However, the efficiency of embryo rescue, including the embryo formation, germination, and seedling rates, is closely related to the parental genotypes, degree of abortion, growth medium, and plant growth regulators.  In this study, we investigated the effects of different concentrations of paclobutrazol (PAC), a plant growth regulator, and embryo collection times on the embryo formation, germination, and seedling rates for different hybrid combinations of grape breeding varieties used for their aroma and cold-resistance traits.  The results showed that the different PAC concentrations had varying impacts on the development of ovules and embryos from the different grape varieties.  The embryo formation rates of the ‘Sultanina Rose’בBeibinghong’ and ‘Kunxiang Seedless’בTaishan-2’ crosses were the highest under the 5.1 μmol L^–1 PAC treatment.  The 1.0 μmol L^–1 PAC treatment was optimal for the germination and seedling development of the ‘Sultanina Rose’בBeibinghong’ embryos, whereas the 0.2 μmol L^–1 PAC treatment induced the highest germination rate for the ‘Sultanina Rose’בKunxiang Seedless’ cross.  The optimal sampling times for each cross varied as 39 d after pollination (DAP) for the ‘Flame Seedless’בMuscat Hamburg’ cross, 46 DAP for the ‘Kunxiang Seedless’בBeibinghong’ cross, and 41 DAP for the ‘Ruby Seedless’בBeibinghong’ and ‘Fantasy Seedless’בShuangyou’ crosses.  Moreover, the medium modified with 0.5 g L^–1 of indole-3-butyric acid allowed the malformed seedlings to develop into plantlets and achieve larger progenies.  This study provides a useful basis for further studies into grape embryo rescue and could improve breeding efforts for new seedless grape varieties.