Relative Genetic Stability of Embryogenic Cultures of the Gramineae and Uniformity of Regenerated Plants

Abstract

Presence of cytologically abnormal cells and regeneration of variant plants from tissue cultures of many plant species, including members of the Gramineae, is now well documented. However, in none of these reports has any attempt been made to correlate the presence or absence of such genetic variability to the nature of cell cultures used or the method of plant regeneration. It is proposed that in gramineous species such variability exists largely in those instances where the cell cultures contain large, relatively vacuolated and non-starch containing cells and where plants are formed by the organization of shoot meristems. Owing to the multicellular origin of such plants, the occurence of chimeras is not uncommon. Conversely, it is shown that embryogenic cell cultures of the Gramineae, which contain small, richly cytoplasmic and starch-containing meristematic cells — described as embryogenic cells — show relative cytological stability in culture and give rise to plants that show neither any evidence of morphological anomalies nor changes in the number or structure of chromosomes. Furthermore, there is a strong selection in favor of normal cells during the process of somatic embryogenesis. Since somatic embryos are derived from single cells no chimeras are formed.