The effect of explant type on somatic embryogenesis induction in Pisum sativum (cv. Oskar and an unregistered line HM-6) was studied. Shoot apices, leaf primordia, and epicotyl fragments of axenically grown, etiolated seedlings, as well as embryonic axes and cotyledon fragments isolated from zygotic embryos at different stages of development, were used as explants. Somatic embryogenesis was induced essentially as described by Griga in 1998 – MS salts and sucrose, B5 Gamborg vitamins, picloram (2.5 μM). After induction period (14 days) all cultures were transferred to the differentiation medium (basal medium as above, auxin omitted). Both in Oskar and HM-6, only shoot apices developed somatic embryos and (with significantly lower frequency) adventitious shoots.
Modified versions of the Cry3A gene of Bacillus thuringiensis (Bt) were transferred into Norway spruce (Picea abies). Both the biolistic approach and Agrobacterium tumefaciens mediated procedure were employed for transformation of embryogenic tissue (ET) cultures. The latter method proved to be more efficient yielding 70 transgenic embryogenic tissue lines compared with 18 lines obtained by biolistics. The modified Cry3A genes were driven by a 35S promoter and the nptII screenable selection marker gene was used in all vectors. The transgenic ETs were molecularly characterized and converted into mature somatic embryos. Germinating embryos formed plantlets which were finally planted into perlite and their Cry3A gene transcription activities were demonstrated by RT-PCR.
The research was conducted on explants of silver fir (Abies alba Mill.) deriving from several forest districts in southern Poland. The study encompassed the influence of the origin of plant material, type of explants, kind of substances used for explants sterilization, PPM and the type of medium on the ability to form embryogenic callus and to develop somatic embryos in silver fir explants. From the plant material collected in three sites, 57 clones were obtained from mature zygotic embryos; this produced an embryogenesis frequency of 6%. Embryogenic callus was obtained with a diameter of 65–70 mm depending on the material origin. The best medium for development of callus inducted on embryos isolated from mature silver fir seeds was the SH medium. Somatic embryos were formed in a globular stadium (24 pieces) on this medium. The 10% solution of NaOCl (used for 15 minutes) turned out to be the most effective substance for seed sterilization.
Somatic embryos were induced from immature zygotic embryos of Arabidopsis thaliana cultured on Gamborg basal medium (B5) supplemented with dichlorophenoxyacetic acid (2,4-D) at 5 µM l-1. The somatic embryos were of unicellular origin. The sequence of divisions and the orientation of newly formed walls resembled the Onagrad pattern of early embryogenesis. Histological studies revealed no connection between the somatic embryos and explant tissue. In contrast to zygotic embryos, in late heart-shaped somatic embryos both sieve and tracheary elements were present. The sieve elements that formed in somatic embryos were characterized by larger plates than normal sieve elements observed in seedlings. Typical features of the tracheary elements in somatic embryos were irregular shape and thickening of the secondary walls.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.