Germplasm and Physiologic Effects on Induction of High-Frequency Hormone Autonomous Callus and Subsequent Shoot Regeneration in Sugarbeet1
- J. W. Saunders and
- K. Shin2
The availability of adapted germplasm capable of regenerating shoots from callus may affect the speed with which tissue culture-mediated genetic improvements can be brought to commercial usage. To assess the shoot regeneration capability in Beta vulgaris L., 17 germplasm sources including sugarbeet, table beet, fodder beet and leaf beet were screened for callus-forming ability and shoot regeneration. Petiole and blade explants from in vitro shoot cultures grown with 6-benzyladenine (BA) as the only growth regulator were challenged to initiate callus on a Murashige-Skoog basal medium (MS) with 0.25 or 1.0 mg L−1 BA. Bud regeneration was scored on the callus induction medium or after transfer of primary callus to MS + 1.0 mg L−1 BA + 0.3 mg L−1 3-indoleacetic acid. Some individual genotypes from each of the 17 germplasm sources produced callus, and bud regeneration from callus was seen in 14 of the 17 germplasm sources, indicating that this ability is widespread in the species. Direct adventitious budding on petioles was also found within all germplasm sources. Use of BA as the sole growth regulator induced buds on callus within the range 0.1 to 3.0 mg L−1. Kinetin and tzeatin alone induced buds, but at the higher concentrations of 30 and 10 mg L−1, respectively. Environmental conditions and leaf part affected callus induction frequency on explants. Leaf blade segments were considerably more responsive than petiole segments. Explants cultured at 31°C initiated callus at least five times more frequently than those at 23°C. Highest frequency of callus induction with one genotype occurred in the dark, and no callusing occurred in 200 μmol ml−2 S −1C light from fluorescent lamps. An uncomplicated procedure for shoot regeneration evolved through these experiments, permitting lone explants to initiate callus and subsequently regenerate shoots on MS + 1.0 mg L−1 BA without transfer. This system is applicable to a wtde range of B. vulgaris L. germplasm.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © . .