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Title: TRANSGENIC SUGARBEETS ENGINEERED FOR PRDUCTION OF HIGH CYTOKININ LEVELS IN THE TAPROOT.

Author
item Smigocki, Anna
item SNYDER, GORDON - UNIV OF MD COLLEGE PARK
item McCanna, Iris
item OWENS, LOWELL - COLLABORATOR, USDA

Submitted to: American Society of Sugarbeet Technologists
Publication Type: Abstract Only
Publication Acceptance Date: 3/2/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Cambial initiation and rapid cell division periods in the developing sugarbeet taproot are known to be correlated with increased cytokinin levels. To evaluate the effect of increased endogenous cytokinin concentrations on vascular ring development and assimiliate transport to the taproot, a bacterial cytokinin biosynthesis gene (ipt) was introduced into sugarbeets. To target expression of the ipt gene to the taproot, it was fused with a promoter from the patatin gene of potato. Particle bombardment was used to introduce the reconstructed ipt and a NPTII selectrable marker gene into embryogenic hypocotyl callus. Shoots regenerated on kanamycin-containing selective media required high auxin concentrations (3 mg IBA and 2 mg NAA per liter) for root initiation, presumably to compensate for the elevated cytokinin levels. One rooted transformant appeared normal except for a slight increase in adventitious shoot development. Another transformant was more difficult to root and exhibited other characteristic cytokinin effects of reduced apical dominance and dark green leaves. Southern blots of restriction enzyme digested PCR products confirmed the presence of the ipt and NPTII genes in these two transformants. Transgenic plants are in the process of further analysis for expression of the cytokinin gene and sucrose content.