Proceedings of the XLV Italian Society of Agricultural Genetics - SIGA Annual Congress

Salsomaggiore Terme, Italy - 26/29 September, 2001

ISBN 88-900622-1-5

Poster Abstract

GFP IN ORNAMENTALS

MERCURI A.*, SACCHETTI A.**, DE BENEDETTI L.*, SCHIVA T.*, ALBERTI S.**

* Istituto Sperimentale per la Floricoltura, Corso degli Inglesi 508, 18038 Sanremo, Imperia, Italy

istflori@sistel.it

** Department of Cell Biology and Oncology, Istituto di Ricerche Farmacologiche Mario Negri, Consorzio Mario Negri Sud, 66030 Santa Maria Imbaro, Chieti, Italy

green fluorescent protein, flower, transgenic plant, Osteospermum, Eustoma

New flower colors in ornamentals are traditionally obtained through screening of naturally occurring variants. More recently, flower variants have been obtained by genetic engineering of pigment metabolic pathways, e.g. in Gerbera jamesonii hybrida, Dianthus caryophyllus or Eustoma grandiflorum (Lisianthus).

The Green Fluorescent Protein (GFP) from the jellyfish Aequorea victoria is a spontaneously fluorescent protein, that is widely used as a recombinant protein tag in vivo. The wild type gfp is efficiently expressed by several plant species, e.g. in Citrus sinensis and maize. In other cases, e.g. in Arabidopsis, an aberrant splicing of the gfp mRNA prevents an efficient expression. However, this can be restored by using viral vectors (potato virus X or tobacco mosaic virus), that are not subject to the aberrant splicing, or a modified gfp cDNA where the cryptic splice site is removed by mutagenesis.

The use of Green Fluorescent Protein as a flower fluorescent dye is appealing. However, the generation of fluorescent flowers has remained as yet elusive. In this work we demonstrate the generation of green-fluorescent flowers. Non-fluorescent GFP-transgenic flowers were analysed by Western blot and spectrofluorimetry, and were demonstrated to efficiently express GFP. This indicated that the lack of GFP fluorescence could be due to opacity to the exciting light. Thus, flowers that are largely transparent to UV, Eustoma grandiflorum (Lisianthus), or that present a transparent petal cuticle, Osteospermum ecklonis, were selected for gfp transformation. Strikingly, the transformed Eustoma flowers fluoresced brightly upon illumination with UV light. GFP-transgenic Osteospermum flowers also appeared distinctly green upon UV illumination. GFP was expressed in comparable amounts by the fluorescent Osteospermum and by the non-fluorescent Limonium petals, confirming that an efficient excitation of GFP fluorescence is a limiting factor in its detection. These results demonstrate the feasibility of using GFP as a fluorescent dye for flower petals. Chromophores excited at longer, more deeply penetrating wavelengths, e.g. DsRed, may extend the use this technology also to flowers opaque to UV light.