Stock of chromosome-types and tissue cultured shoot primordium

Abstract

1. From the necessity for long-term preservation of the chromosome-types found in annual Haplopappus gracilis (2n=4), studies on the cloning of this plant were carried out by some vegetative treatments including tissue culture. Hence a tissue cultured block named as shoot primordium was found in 1983. Botanical properties observed in the shoot primordium and its applications were summarized in this paper. 2. A shoot primordium is a dome-shaped tissue which occurs on the way to an adventitious shoot from tissue cultured cells of an explant in somatic life cycle. The shoot primordium proliferates self-propagating and forms a small mass of shoot primordia. 3. Properties observed in shoot primordia were described in the following way : external and anatomical morphology, cells, pattern of proliferation, somatic life cycle, superior stability in chromosome number, high ability to regenerate, ability of rapid proliferation, production of secondary metabolites and application to cryopreservation. 4. Applicative techniques developed up to the presents for the shoot primordia were outlined on the following subject : induction of shoot primordium, subculture and regeneration, induction of artificial mutation, isolation of free single cells, induction of somatic embryos, induction of shoot primordia from callus, and cryopreservation. 5. Shoot primordia could be induced successfully in 66 higher plants among 89 plants examined. It is found that the shoot primordia can be induced easily in most of the annual plants and in the perennial plants examined. It is also able to induce shoot primordia in some woody plants.