Document Type



Cytokinins play important roles in regulating plant growth and development. A new genetic construct for regulating cytokinin content in plant cells was cloned and tested. The gene coding for isopentenyl transferase (ipt) was placed under the control of a 0.821 kb fragment of the 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase gene promoter from Lycopersicon esculentum (LEACO1) and introduced into Nicotiana tabacum (cv. Havana). Some LEACO1(0.821) (kb)-ipt transgenic plant lines displayed normal shoot morphology but with a dramatic increase in the number of flower buds compared to nontransgenic plants. Other transgenic lines produced excessive lateral branch development but no change in flower bud number. Isolated leaves of transgenic tobacco plants showed a significantly prolonged retention of chlorophyll under dark incubation (25 degrees C for 20 days). Leaves of nontransformed plants senesced gradually under the same conditions. Experiments with LEACO1(0.821) (kb)-gus transgenic tobacco plants suggested auxin and ethylene involvement in induction of LEACO1(0.821) (kb) promoter activity. Multiple copies of nucleotide base sequences associated with either ethylene or auxin response elements were identified in the LEACO1(0.821) (kb) promoter fragment. The LEACO1(0.821) (kb)-ipt fusion gene appears to have potential utility for improving certain ornamental and agricultural crop species by increasing flower bud initiation and altering branching habit.


Published in Plant Cell Reports, Vol. 25, pp.1181-1192 (June 20, 2006).
The original publication is available at

Figure 1-new.ppt (28 kB)
Figure 1

figure 2.tif (620 kB)
Figure 2

figure 3.tif (363 kB)
Figure 3

figure 4.tif (331 kB)
Figure 4

figure 5.tif (522 kB)
Figure 5

figure 6.tif (151 kB)
Figure 6