Submitted to: Journal of Sugarbeet Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/12/1996
Publication Date: N/A
Interpretive Summary: Sugarbeet seed could be produced more economically, and beneficial genes from other crops added more efficiently into sugarbeet, if a laboratory method for very rapid multiplication of seeds could be devised. Using a sugarbeet plant previously developed for laboratory research, a method was found for producing artificial embryos, the tiny preformed plant contained in seeds, as the first step in development of mass production of laborator seeds. These results are important to sugarbeet farmers and processors, as well as to seed producers, because of the reduced costs to produce sugar in each part of the chain in the sugarbeet industry.
Technical Abstract: Somatic embryos could be used for proliferative propagation or for gene transfer procedures in sugarbeets if adequate methods for initiation and development could be devised. With sugarbeet model clone REL-1, plating of fresh suspension culture cells grown with hormone-free Murashige-Skoog (MS) medium onto semi-solid hormone-free elicited a low frequency of somatic embryogenesis, about one embryo per ml of suspension used. The inclusion of 0.1 or 0.3 mg/l abscisic acid (ABA) in the semi-solid medium increased the number of somatic embryos up to eight-fold. A combination of alpha-naphthylacetic acid (NAA, 1 mg/l) and ABA (o.1 mg/l) gave the highest somatic embryo yield, 15 embryos per ml of suspension. After 22 to 40 days, embryos at various stages were present at the callus surface. These ranged from globular, heart and torpedo shaped embryos to mature opaque white embryos with cotyledons and radicles. The external morphology of several somatic embryos was examined by scanning electron microscopy. The somatic embryos developed into normal plants, exhibiting betalain pigmentation on hypocotyls after being transferred onto hormone-free MS medium. The conversion rate of somatic embryos of different lengths (1, 2, 3 mm) into complete plants was similar (78, 81, and 85% respectively). Secondary embryogenesis, which would be useful in providing embryoids for gene transfer purposes, was not observed in this study.