Establishment Of The System Of Somatic Embryogenesis At High Frequency And The Preliminary Study On Transgenics In Loquat(Eriobotrya Japonica Lindl.)

Three loquat(Eriobotrya japonica Lindl.) cultivars, 'Jiefangzhong' 'Chonghong No.3' 'Zaozhong No.6' were used as initial explants to study the in-vitro culture of immature embryos, mature embryos and radicels. The system of high frequency of somatic embryogenesis and plant regeneration was established in the experiment through relatively comprehensive studies on the somatic embryogenesis and plant regeneration in loquat, and then the preliminary study on the transformation of loquat EC mediated by Agrobacterium was performed. The main results were described as follows:1. Several types of calli were induced from immature embryos culture, such as C1. C2. C3. C4. C5 C6 and C7 types. Embryogenic calli(C8) were selected from the calli of Type C3 derived from 'Zaozhong No.6'. The embryogenic callus could be maintained for over 1 year alternatively cultured on the MS medium supplemented with 1mg/L 2,4-D, 0.25mg/L KT and the other MS mediums containing lmg/L 2,4-D, 0.25mg/L KT and 5mg/LAgNO₃.2. The system of high frequency of somatic embryogenesis and plant regeneration was established. The calli of Type C₈(EC) showed strong embryogenic capacity with 100% frequency of embrygenesis cultured on MS media supplemented with 0.25mg/L KT and 2% sucrose in darkness. Both clustered cotyledonary embryoids touched with calli and cotyledonary embryoids detached from calli germinated into plantlets with roots. shoots and leaves cultured on MS media added with 0.25mg/L KT and 2% sucrose in the light after they had gone through the process of 3-month maturing culture on MS medium containing lmg/L KT and 5% sucrose. More than 90% of clustered cotyledonary embryoids germinated and over 80% of them developed into plantlets. More than 75% of cotyledonary embryoid detached from calli germinated and over 60% of them developed into plantlets.3. The study on the somatic embryogenesis of mature embryos and radicles was performed. Calli were induced from both mature embryos and radicles when they were cultured on MS media added with lmg/L 2,4-D, 0.5mg/L KT or BA, but embryoids only obtained from the calli derived from radicles. Direct induction of somatic embryogenesis of the bases of mature embryos and radicles was observed cultured on MS medium supplemented only with 0.25mg/L KT after they were cultured on MS medium containing lmg/L 2,4-D and 0.5mg/L KT for 15 days in advance. The ratio of induction...