Identification of the UPSTREAM OF FLOWERING LOCUS C (UFC) gene in gladiolus as a marker for the flowering control gene FLOWERING LOCUS C (FLC)

Jaser A. Aljaser is Ph.D. candidate in Applied Plant Science in Horticulture at the University of Minnesota Twin Cities, USA. He received his M.Sc. in Horticulture and Agronomy from the University of California Davis (UCD), USA, in 2015, and received his B.Sc. in Botany from Kuwait University (KU), Kuwait, in 2008. His Ph.D. research topic is gladiolus breeding for rapid generation cycling to produce seed propagated “annual” gladiolus from original perennial species and identification of flowering genes. He is currently Teaching Assistant at KU and pursuing his Ph.D. Upon graduation, he will be appointed as an Assistant Professor in Horticulture with emphasis on floriculture at KU. The objectives of the poster presented at the XIII International Symposium on Flower Bulbs and Herbaceous Perennials were to identify the presence of the UPSTREAM OF FLOWERING LOCUS C (UFC) gene in gladiolus and to test the possibility of identifying FLOWERING LOCUS C (FLC) from the generated scaffolds. Gladiolus (Gladiolus × hybridus) is a geophytic ornamental garden plant as well as a cut flower. It is ranked in the top 10 of cut flowers for floral design. In ornamental plants, flowering is a crucial step for the success of cut flower production. Therefore, understanding the flowering pathway and gene expression is important for efficient selective breeding. In this geophyte, the flowering pathway is poorly understood. FLC is a major flowering repressor found in Arabidopsis and many dicot species. FLC plays a vital role in the control of flower initiation. However, in monocot species FLC was not identified. The lack of identifying FLC in monocot species and discovery of another mechanism of flowering in monocots, such as vernalization in wheat and plant age in both maize and rice, led to our hypothesis that monocot geophytes may also be FLC-independent for flower initiation. To determine if FLC is present in gladiolus, we searched for genes linked with FLC. In Arabidopsis, FLC is closely linked to two genes, UFC and DOWNSTREAM of the FLOWERING LOCUS C (DFC). The genes are hypothesized to be associated with FLC, as UFC expression is downregulated upon vernalization similar to FLC, although the clear function of UFC has not been determined. Designing UFC primer, sequencing and analyzing the sequences in multialignment showed two exons of the UFC gene with over 80% pairwise of monocot species such as date palm and asparagus. Also, exon gene prediction and protein BLASTs confirmed the presence of the UFC gene. The results also confirmed the presence of another exon for FLOWERING LOCUS C EXPRESSOR (FLX) that upregulates FRIDGA (FRI) and mediates FLC expression. In conclusion, the identification of UFC in gladiolus is a crucial step to test if FLC is present. The identification of UFC will help as a marker to locate FLC exons. In addition, the discovery of FLX exons, which is FRI-mediated for the FLC activation gene, supports the hypothesis that monocots evolved away from the FLC dependent pathway into being FLC-independent species, and the FLC gene may not be found as a whole gene but rather a remnant exon.

Jaser A. Aljaser won an ISHS Young Minds Award for the best poster presentation at the the XIII International Symposium on Flower Bulbs and Herbaceous Perennials in Korea in May 2019.

Jaser A. Aljaser, Department of Horticultural Science, University of Minnesota, 320 Alderman Hall, 1970 Folwell Avenue, St. Paul, MN 55108, USA, e-mail: Aljas008@umn.edu

The article is available in Chronica Horticulturae