Direct embryogenesis in the genus Helianthus and RAPD analysis of obtainedclones

摘要

A rapid and efficient regeneration system via somatic embryogenesis from leaf discs and stem segments has been developed for four sunflowers species (Helianthus spp.). The effect of different combinations of growth regulators, explant source and genotype on the embryogenic response of five wild sunflower species was evaluated. Maximum frequency of somatic embryogenesis was achieved in the presence of 5.5 mu M indolacetic acid (IAA) and 5.3 mu M zeatine (ZA) irrespective of the genotype. Leaf explants performed superior to stem segments. The species showed a marked difference in their re,regeneration potential with the highest percentage of 62% embryogenic explants in the case of H. giganteus followed by H. maximiliani (15%). From H. nuttallii and H. tuberosus 8% embryogenic explants were obtained while only callus or root formation was observed with H, grosesserratus. Shoots rooted spontaneously while embryogenic structures had to be treated with naphtylacetic acid (NAA). Thirty five randomly selected regenerated clones were analyzed with eleven 10-mer primers to verify genomic stability using RAPD-PCR on an average of 114 markers per clone. No polymorphisms could be detected between the clones and their parents. This regeneration system may be of value for application in genetic transformation with Agrobacterium tumefaciens or microparticle gun of the wild sunflower species.