Flower development of Lilium longiflorum - The Lilium information ...

SUMMARY
Summary
Lily (Lilium spp.) is among the most traditional and beloved ornamental
flowers worldwide. The genus Lilium comprises almost one hundred species, among
which is the primary subject of our research, described in this thesis, the species Lilium
longiflorum (Thunb.), known as trumpet lily or Easter lily.
Despite the great economic importance of ornamental lily species, little is
known about its biology at the molecular level so far. In a time when two genomes are
fully sequenced, Arabidopsis thaliana and Oryza sativa, only a few genes have been
characterized in Lilium spp. yet. Possible reasons for this are discussed throughout this
thesis.
This work intends to be a contribution to bridging the fundamental research
concerning transcription factors involved in development of flower morphology in
model species and the applied objectives of molecular breeding for manipulating
flower morphology, endeavouring to create new cultivars with specific and novel
features, more specifically in Lilium spp.
The ABC model for floral development was proposed more than 10 years ago
and since then many studies have been performed in model species, such as
Arabidopsis thaliana, Antirrhinum majus, petunia and many other species in order to
confirm this model. This investigation has led to additional information on flower
development and to more complex molecular models.
In the first chapter of this thesis, notions of molecular floral development, the
difficulties of working with molecular biology of lily, the state-of-the-art in lily
transformation are introduced, as well as general overviews of transcription factors,
MADS-box genes, the ABCDE model for flower development and functional
characterization of genes in heterologous systems. These concepts will guide the
reader throughout the work we present here.
AGAMOUS (AG) is the only C type gene found in Arabidopsis and it is
responsible for stamen and carpel development as well as floral determinacy. In the
second chapter, we describe the isolation of LLAG1, a putative AG orthologue from
lily (L. longiflorum) by screening a cDNA library derived from developing floral buds.
The deduced amino acid sequence of LLAG1 revealed the MIKC structure and a high
homology in the MADS-box among AG and other orthologues. Phylogenetic analysis
indicated close relationship between LLAG1 and AG orthologues from monocot
species. Spatial expression data showed LLAG1 transcripts exclusively in stamens and
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