IDENTIFICATION OF HIGHLY REGENERATIVE GENOTYPES WITHIN ELITE LINES OF SUGAR BEET FOR USE IN MOLECULAR BREEDING

Authors: IVIC-HAYMES, SNEZANA - TOWSON UNIVERSITY; Smigocki, Anna

Submitted to: In Vitro Cellular and Developmental Biology - Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/23/2004
Publication Date: 1/1/2005
Citation: Ivic-Haymes, S.D., Smigocki, A.C. 2005. Identification of highly regenerative genotypes within elite lines of sugar beet for use in molecular breeding. In Vitro Cellular and Developmental Biology - Plants. 41(4):483-488.

Interpretive Summary: Disease and pest problems are responsible for decreases in production of sugar from sugar beet, an economically important crop that provides more than 35% of the world's sugar supply. Conventional breeding has had little success in improving disease resistance in sugar beet. Biotechnology holds more promise for improving disease resistance in sugar beet, but because breeding cultivars are recalcitrant to regrowth of whole plants (regeneration) in the laboratory, progress has been limited. To identify plants with high regeneration potential, we tested individual plants from seven sugar beet breeding lines for their ability to form plantlets from unorganized leaf cells (callus). We showed that rates of regenerative callus formation varied significantly between breeding lines and between individual plants of the same line. We identified highly regenerative plants in five of the tested breeding lines and showed that regenerated plants looked normal and had regeneration capacity similar to that of the parent plant. The progress described in this report will be of benefit to scientists interested in employing biotechnology for increasing sugar yields from sugar beet.

Technical Abstract: Development of an efficient transformation method for recalcitrant crops such as sugar beet (Beta vulgaris L.) depends on identification of germplasm with relatively high regeneration potential. Individual plants of seven sugar beet breeding lines were screened for their ability to form somatic embryos and/or adventitious shoots on leaf disk callus. Disks were excised from partially expanded leaves and cultured on medium with 1 mg/l BAP for 7 wk. At 5 wk of culture, friable calluses began to appear, some of which regenerated embryos and shoots. Rates of regenerative callus formation varied significantly between breeding lines and between individual plants of the same line. Line FC607 exhibited the highest frequency of plants whose explants produced shoots (60%). Among the plants with a positive shoot regeneration response, line FC607 also had the highest frequency of explants that produced regenerative callus (56%). The range of regeneration frequencies for individual sugar beet plants of each breeding line was very wide. In five of the lines, plants with relatively high shoot regeneration ability were identified. No loss of regeneration potential was observed on selected FC607 plants maintained in the greenhouse for more than 4 years. Regenerated plants exhibited normal phenotypes and regeneration abilities comparable to the respective source genotypes.