Study On Influencing Factors Of Embryo Rescue Of Seedless Grape And Marker Assisted Selection

Seedless is an important trait of table grape,and seedless grape varieties selection is one of major targets of grape breeding.In conventional cross breeding,seedless grape is selected from seed × seedless,but the breeding efficiency is low.Embryo rescue technology can use stenospermocarpic seedless grape as mother parent for hybridization,which greatly improve the seedless rate of offsprings and shorten the breeding period,so this technology is widely used in seedless grape breeding.However,there is still a low success rate of embryo rescue,and it is necessary to further study and optimize the technology system.Here,eight cross combinations were executed using five seedless cultivars as female parents,and two cultivar or hybrid with cold resistance as male parents,respectively.Hybrid ovules were harvested and cultured in solid or solid-liquid biphase MM3 medium.Then the developed embryos were stripped out and cultured in solid phase WPM medium.The effect of medium forms,parent genotype and ovule culture time on embryo rescue was investigated.The purpose of this study was to optimize the technology system of seedless grapes embryo rescue,and created a batch of new seedless grape germplasm,and then execute markers assisted selection for hybrid seedlings obtained using the seedless molecular marker SCF27-200,thus,lay a foundation for further breeding new seedless varieties.The main results obtained are as follows:1.A total of 8 204 ovules from eight hybrid combinations were inoculated,and 1 722 embryos were developed and 1 415 embryos were germinated.Finally,894 normal seedlings were obtained.2.The effects of medium forms on embryo rescue were varied in different hybrid combinations.The embryo development rate of ‘Qinxiu’ × ‘Beichun’,‘Crimson Seedless’ בBeichun’ and ‘Qinhong No.1’ × ‘Venus Seedless’ in solid-liquid biphase MM3 medium was significantly higher than that in solid medium,while that of ‘Jupiter’ × ‘Beichun’ and‘Qinhong No.1’ × ‘Beichun’ in solid MM3 medium was significantly higher than that in solid-liquid MM3 biphase medium.3.Parental genotype had significant effect on embryo rescue efficiency.When ‘Beichun’was used as the male parent,‘Perlette’ had the highest embryo development rate,germination rate and seedling rate(46.31%,41.74% and 17.95%,respectively),followed by‘Qinhong No.1’(29.24%,23.71% and 15.95%,respectively),and the lowest volumes presented in ‘Crimson Seedless’(2.52%,1.96% and 0.84%,respectively).When ‘Venus Seedless’ was used as the male parent,‘Perlette’ still had the highest embryo development rate(37.08%,25.41% and 24.17%,respectively),indicating that ‘Perlette’ and ‘Qinhong No.1’ are suitable for embryo rescue as maternal parents.4.When ovules were cultured in dark for 7-10 weeks,the seedling rate of ‘Perlette’ בVenus seedless’ increased with the extension of culture time.The embryo development rate,embryo germination rate and seedling rate of ‘Perlette’ × ‘Venus Seedless’ and ‘Qinhong No.1’ × ‘Venus Seedless’ reached the maximum value when cultured in solid-liquid biphase MM3 medium for 10 weeks,which were 46.67%,36.67% and 36.17%,and 16.43%,10%and 7.68%,respectively.5.A total of 894 hybrid progenies obtained by embryo rescue were selected by using seedless molecular marker SCF27-2000,of which 559 lines had this marker and were preliminarily identified as seedless lines.