| Popis: |
Somatic embryo maturation is a critical step in somatic embryogenesis. Quality and viability of somatic embryos determine their germination and healthy plantlet production. Embryo maturation of conifers depends on nutritive medium composition, particularly on type and concentration of sucrose, and abscisic acid (ABA) concentration. Here, the role of different sugars and different concentrations of ABA on embryo maturation of two phenotypic different tissues of omorika spruce were examined. Embryogenic tissue in mature zygotic embryos was induced on modified LP medium supplemented with 1% sucrose, 10 uM 2,4-D and 5 uM BAP. During maintenance of cultures on 1/2xLP with 1% sucrose, 5 uM 2,4-D and 2.5 uM BAP two types of embryogenic tissue (B and W) were distinguished on their morphogenic and anatomic characteristics. On maturation medium (1/2xLP with 3% sucrose and 20 uM ABA) B tissue had significantly higher capacity of maturation than tissue W. Embryo maturation depended on sugar molarity that is on osmotic pressure of medium as well as on the sugar concentration expressed in percentage. Optimal embryo maturation in lines of B type tissue was achieved on 3% glucose (with higher osmotic pressure than 3% sucrose). Maturation in lines W was not improved on any tested media. Higher concentration of sugar (6%) inhibited embryo maturation in the both types of tissue. Combination of two sugars (sucrose + maltose, glucose + maltose) was more suitable than single ones. The highest number of mature somatic embryos were obtained on media with 40 uM ABA, while 60 uM ABA inhibited maturation. |
