Zaccai, M., Institutes for Applied Research, Ben Gurion University of the Negev, Beersheva 84105, Israel
Lewinsohn, E., Newe Ya'ar Research Center, ARO, Ramat Yishay 30095, Israel
Pichersky, E., Department of Biology, University of Michigan, Ann Arbor, MI, United States

The control of flowering time is an essential issue for most ornamentals. The molecular basis of this trait has been extensively studied in model plants, yielding useful information on the role of various genes which could potentially be used in heterologous systems. For instance, overexpression of the meristem-identity gene LEAFY (LFY) from Arabidopsis has previously been shown to be sufficient to reduce flowering time in plants as diverse as Arabidopsis itself, tobacco and aspen. We tested the effect of LFY overexpression on flower development in lisianthus plants transformed with LFY cDNA under constitutive control of the 35S CaMV promoter (35S::LFY, provided by Dr. Weigel). F1 progenies from two different transformed plants flowered in average one to two weeks earlier than control plants at two consecutive years. The number of nodes to the first flower as well as the number of flowers per inflorescence were reduced in the early-flowering plants, suggesting a faster flower development. Normal fertile flowers were obtained from all plants. These results indicate that flowering time can me manipulated by transgenic means. Lisianthus transformations with genes acting upstream to LFY are currently being made. The possibility of introducing a fragrance to lisianthus flowers by genetic engineering is being investigated using genes from the scented plant Clarkia breweri: Acetyl CoA benzyl alcohol acetyl transferase (BEAT) and S-linalool synthase (LIS). These two genes code for key enzymes in the synthesis of the aroma compounds benzyl acetate and S-linalool respectively. Aroma modification of the fruit of transgenic tomato plants carrying a LIS construct has already been demonstrated. The effect of BEAT and LIS transgenes on tobacco and lisianthus fragrance is under investigation.