New cold-resistant, seedless grapes developed using embryo rescue and marker-assisted selection

Embryo Rescue of Cold-hardy Table Grapes

“…In our study, germination ranged from 31.00% to 89.74% (Table 4). These results are comparable or superior to other values reported in the literature (Li et al, 2014(Li et al, , 2020bLiu et al, 2008;Zhu et al, 2020). Among the eight crosses tested, GE1972 and GE1974 had the greatest percentage of normal plantlets (40.44% and 43.59%, respectively).…”

“…Embryo rescue techniques have been studied primarily using V. vinifera cultivars and were developed to aid seedless table grape breeding under Mediterranean climate conditions with different phenological and developmental benchmarks than those in cold-hardy hybrid grape production and breeding programs like that of Minnesota. More recent reports using cold-hardy varieties (mostly from the University of Arkansas: 'Venus', 'Neptune', and 'Jupiter') have emerged from China (Guo et al, 2015;Liu et al, 2016;Zhu et al, 2020). Developing breeding program-specific embryo rescue techniques for extreme cold-hardy germplasm (USDA zone 4) in Minnesota was imperative to achieve the greatest number of surviving plants in a generally inefficient and laborious process.…”

“…Our study did not investigate embryo development specifically to reduce the handling of extracted embryos from the ovules. Based on the literature, many dates are proposed as optimal sampling times, varying from 39 to 70 d after flowering (Bharathy et al, 2003;Gray et al, 1990;Li et al, 2014Li et al, , 2015aLi et al, , 2020bLiu et al, 2008;Zhu et al, 2020). GDD can be a viable predictor for sampling time.…”

“…Grape breeders have crossed seedless pollen donors with seeded mother plants for decades to get a proportion of seedless offspring each generation to advance cultivar development (Gray et al, 1990;Li et al, 2020b). In some seeded  seedless crosses, less than 10% of the F 1 progeny are seedless; however, using two seedless parents, this value can reach 82% to 100% (Bharathy et al, 2005;Emershad et al, 1989;Ji et al, 2013;Ramming, 1990;Tian and Wang, 2008;Zhu et al, 2020). Bouquet and Danglot (1996) hypothesized that seedlessness results from the expression of three complementary recessive genes regulated by a dominant inhibitor gene, which they identified as the seedlessness (SDI) gene.…”

“…The success rate for embryo rescue through ovule culture in grape is low, but it can vary from 1% to 89% (Bharathy et al, 2005;Emershad et al, 1989;Ji et al, 2013;Yang et al, 2007;Zhu et al, 2020). The developmental progression through in vitro culture of an ovule to a normal seedling is influenced by genotype, cultural conditions, and embryo development in the artificial environment (Li et al, 2015b).…”