| Walnut(Juglans regia L.),Juglans of Juglandaceae,is an important economic forest tree species,its fruit nutrient-rich,durable wood.Walnut has strong adaptability and is widely planted in China.There are some problems in walnut production,such as low application rate of improved varieties,serious damage of diseases and pests,so it is important to speed up the breeding of improved varieties and strengthen the breeding of stress-resistant varieties.Somatic embryogenesis is characterized by rapid propagation,complete structure and high rate of plant regeneration.It is important to study the somatic embryogenesis of walnut.In this study,’xiangling’ walnut was used as experimental material.To explore the influencing factors of somatic embryogenesis of ’xiangling’ walnut,and to select the suitable explants and the best culture conditions in vitro for somatic embryogenesis of ’xiangling’ walnut,the proliferation and mature culture of somatic embryos were also discussed.The main results were as follows:1.The best disinfection method for stem and fruit of walnut explant was 70%alcohol 30s+0.1%Hgcl2 for 10 min.The suitable disinfection method of anthers was 70%alcohol 30s+5%NaClO(effective chlorine 8%)for 8 min+0.1%Hgcl2 for 3 min.2.Immature embryos were the best explants for somatic embryogenesis in ’xiangling’walnut.The rate of embryogenic callus induction was 66.67%at the 8th week after anthesis.The induction rate of embryogenic callus of ovule was 53.33%.3.The optimal ratio of exogenous hormones for callus induction from immature embryos of ’xiangling’ walnut was DKW medium supplemented with 2.0 mg/L 6-BA+1.0 mg/L 2,4-D,the induction rate was 96.67%,the somatic embryogenesis was indirect,the induction rate of DKW medium supplemented with 1.0 mg/L TDZ was 80.00%,somatic embryogenesis is the direct route.4.The rate of embryogenic callus induction was 66.67%when 0.5 g/L L-Glutamine medium was added,and 65.6%when 30 g/L sucrose was added.The rate of embryogenic callus induction in dark culture was 63.33%,which was higher than that in light treatment.5.The culture medium of somatic embryos was DKW liquid medium supplemented with 1.0 mg/L 6-BA+0.25 mg/L NAA+0.5 g/L Gln+30 g/L sucrose.The culture medium of somatic embryos was liquid suspension culture,and the rate of proliferation was 315.60%.6.The maturation of somatic embryos:adding 45 g/L Sucrose+2.0 mg/L ABA+7 g/L agar to DKW medium could effectively promote the maturation of somatic embryos. |
