Immature Embryo Rescue and in Vitro Development Evaluation of Intraspecific Hybrids from Brazilian Seedless Grapevine“Superior×Thompson”Clones

The fruit production for export is an economically significant activity in the Valley of S?o Francisco River, especially in the irrigated lands of Petrolina-PE/Juazeiro-BA, Brazil. The development of new genetic material most suitable to the tropical climate and the demands of the consumer market have led to the selection of new seedless grapes cultivars. In this case, the use of the embryo rescue technique has produced satisfactory results for obtaining such materials, especially in the semiarid region. This study aimed to evaluate the in vitro development of intraspecific hybrids of grapevine (Vitis vinifera L.), derived from the rescue of immature embryos resultant from the crossing of “Superior Seedless” and “Thompson Seedless” Brazilian clones. To establish and develop the cultivation, the culture media was supplemented with 30 g/L sucrose, 0.1 g/L myo-inositol, 0.002 g/L glycine, 0.1 mg/L indoleacetic acid (IAA), 6.5 g/L of agar, adjusted pH to 5.7. The experiment was evaluated after 90 days. The variables measured were: number of nodes, number of leaves, plant height (cm), number of roots and length (cm) of the root system and internodes. The period of 60 days of in vitro culture of ovules resulted in the highest values of embryos (about 50%), as well as better characterized developmental stages with higher germination (47.3%). The three types of hybrid grapes evaluated in micropropagation showed very similar values of the measured parameters, even having originated from embryos of different developmental stages.

Canopy Management of Table Grapes Cultivar in Tropical Conditions

The production of some seedless table grapes under tropical conditions presents low bud fertility on the main canes and low yield, which leads to the need of pruning in the lateral shoots. The objective of this study was to evaluate the influence of the canopy management for the formation of lateral shoots associated with dellsity of canes on the yield and quality of grapes ＂Sugraone＂ in the Sao Francisco Valley. The experiment was carried out over two growing seasons （2011-2012） in a commercial vineyard of Sugraone in Petrolina, Pernambuco state, Brazil. The treatments consisted of two canopy managements （shoot topping associated to elimination of lateral shoots and shoot topping and formation of lateral shoots） combined with two to three densities of canes after pruning （1.8, 2.8 and 3.8 canes/m^2）. The formation of ＂lateral shoots＂ increased yield and number of clusters per plant during two consecutive growing seasons, besides using 2.8 varas/m^2 resulted in highest yields only in 2011 growing season. The variables mass bunch, mass berry, soluble solids （SS）, soluble sugar, titxatable acidity （TA） and pulp firmness were not affected by treatments, while the attributes related to color, as like brightness and hue angle of the skin, and total extractable polyphenols content were influenced by canopy management, especially in the 2012 growing season. Shoot topping to induce formation of laterals shoots associated with density of 2.8 canes/m2 increased the yield of seedless grapes cultivar Sugraone grown in the Sao Francisco Valley, not significantly affecting the quality of the grape.

Development and application of KASP marker for high throughput detection of the seedless trait in grapevine

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.

Effects of dehydration speed on the metabolism of membrane lipids and its relation to the browning of the Thompson seedless grape

Xinjiang is the main producing area of raisins and the largest green raisins production base in China.The browning of Thompson seedless grape raisin is extremely serious during the drying process,and has become the key issue in the development of Xinjiang raisin industry.Previous studies have shown that dehydration speed has a great impact on the browning of Thompson seedless grape,but few relevant mechanisms have been studied.Here,we demonstrate the effect of dehydration speed on lipid metabolism and its relation to the browning of the Thompson seedless grape during drying.Compared to slow dehydration treatment,rapid dehydration treatment of the Thompson seedless grape exhibited a lower degree of browning and activities of lipoxygenase(LOX),a higher index of unsaturated fatty acids and degree of unsaturated fatty acid.Moreover,the Thompson seedless grape treated with rapid dehydration resulted in a lower rate of superoxide anion production,hydrogen peroxide content,membrane permeability,and malondialdehyde content.These findings demonstrate that rapid dehydration inhibiting the browning of Thompson seedless grapes might be due to the inhibiting activities of LOX and the lower accumulation of reactive oxygen species.These activities can inhibit lipid peroxidation and slow the decomposition of unsaturated fatty acid in the membrane in Thompson seedless grapes,protecting the cellular membrane structural integrity,which may result in less contact of polyphenol oxidase with phenolic substrates and less enzymatic browning during drying.The results provide a theoretical basis for the application of rapid dehydration in drying Thompson seedless grapes.