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Title: TAPROOT-SPECIFIC EXPRESSION OF A CYTOKININ BIOSYNTHESIS GENE (IPT) IN TRANSGENIC SUGARBEET.

Author
item Smigocki, Anna
item McCanna, Iris
item IVIC, SNEZANA - UNIV BELGRADE, YUGOSLAVIA
item SNYDER, GORDON - VOLUNTEER, USDA/ARS/BA
item Sicher Jr, Richard
item OWENS, LOWELL - COLLABORATOR, USDA/ARS/BA

Submitted to: American Society of Plant Physiologists Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 6/27/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Transport of assimilates towards site of cytokinin application has been demonstrated in many plant organs. In the developing sugarbeet taproots increased cytokinin levels have been correlated with cambial initiation and rapid cell division periods. To increase endogenous cytokinin concentrations in the sugarbeet taproot, we fused a bacterial cytokinin biosynthesis gene (ipt) with a tuber-specific promoter from the patatin gene of potato. Agrobacterium-mediated gene transfer was used to introduce the reconstructed ipt and a kanamycin- selectable marker gene into cultured sugarbeet cotyledons. Shoots that regenerated on kanamycin-containing medium were difficult to root. To compensate for the presumably elevated cytokinin levels, transformants were cultured on media with high auxin concentrations (3 mg IBA and 2 mg NAA per liter). One rooted transformant appeared normal except for a slight increase in adventitious shoot development. Another transformant that was more difficult to root and exhibited other characteristic cytokinin effects, namely reduced apical dominance and dark green leaves. Genomic Southern blot analysis confirmed the presence of the ipt and NPTII genes in these two transformants. Transgenic plants are being analyzed for expression of the cytokinin gene and carbohydrate content.