A Flexible In Vitro Shoot Culture Propagation System for Sugarbeet that Includes Rapid Floral Induction of Ramets1, 2

Abstract

In vitro shoot cultures of sugarbeet (Beta vulgaris L.) were established from lateral buds of flowering plants, providing a flexible vegetative propagation system for a polycross breeding scheme. Monthly transfers of cultures on Murashige‐Skoog medium with 1.1 µM benzyladenine had a shoot multiplication rate of 3 to 5 per month, with higher rates at more frequent transfers. Shoots were rooted on Murashige‐Skoog medium with 16 µM α‐naphthalene‐acetic acid or in Jiffy‐7 peat pots. Shoots of most genotypes multiplied in vitro by axillary shoot growth as well as by adventitious shoot regeneration from petiole surfaces. Shoot regeneration from petioles increased with greater benzyladenine concentration in the range 0–11 µM, but was less in the presence of 0.38 or 3.8 µM ± cistrans abscisic acid. One genotype failed to regenerate shoots from petioles. Shoot cultures also returned to vigorous growth after 56 weeks storage at 4 C in the dark. Shoot culture ramets from most genotypes tested flowered in as little as 26 days in continuous incandescent light in a growth chamber at 14/10 hours fluorescent light/dark at 20/14 C, without the cold treatment usually employed with sugarbeets.