A genomic DNA fragment containing the
complete LEAFY COTYLEDON1-LIKE (HaL1L) gene was
retrieved by chromosome walking. Its sequence was confirmed
and elongated by screening a sunflower genomic
DNA BAC Library. HaL1L, whose cDNA had already
been sequenced and characterized, encodes a NF-YB subunit
of a CCAAT box-binding factor (NF-Y) involved in
the early stages of zygotic and somatic embryogenesis in
the Helianthus genus. In the HaL1L 50-flanking region,
elements specific to a putative TATA-box promoter and
two ‘‘CG isles’’ were identified. An investigation of the
methylation status of these CG rich DNA regions showed
that differentially methylated cytosines were recognizable
in the DNA of embryos on the fifth day after pollination in
comparison to leaf DNA suggesting that during plant
development epigenetic regulation of HaL1L transcription
was achieved by methylating cytosine residues. We also
searched the HaL1L nucleotide sequence for cis-regulatory
elements able to interact with other transcription factors
(TFs) involved in the HaL1L regulation. Of the elements
identified, one of the most intriguing is WUSATA, the
target sequence for the WUSCHEL (WUS) TF, which may
be part of a complex regulation network controlling
embryo development. In this article, we show that the
WUSATA target site, located in the intron of HaL1L, is
able to bind the TF WUS. Interestingly, we found auxin
and abscisic acid responsive motifs in the HaL1L promoter
region suggesting that this gene may additionally by under
hormonal control. Finally, the presence of a cytoplasmic
polyadenylation signal downstream to the coding region
indicates that this gene may also be controlled at the
translation level by a temporarily making the pre-synthesized
HaL1L mRNA unavailable for protein synthesis