Toward functional characterization of Triticum aestivum WFCA-coding sequences

Abstract

Flowering is a critical step in the plant life cycle. If flowering occurs too early or too late, seed production suffers. Flowering is regulated through numerous flowering repressors. As long as these repressors persist, the plant will remain in a vegetative growth stage. Some plants possess two separate genetic pathways, the autonomous pathway and the vernalization pathway, that promote the transition to flowering through stable downregulation of flowering repressors. Once the plant achieves floral competence, it will flower under inductive environmental conditions. In Arabidopsis, FCA is a key autonomous pathway gene, acting with FY to promote the floral transition. Recently, gene sequences resembling FCA were cloned from hexaploid wheat (Triticum aestivum) and designated as WFCA. WFCA shows numerous similarities to the FCA peptide, especially regarding three key regions: two RNA Recognition Motifs and the WW domain. This study seeks to determine if WFCA genes function similar to FCA by determining if they are able to complement the fca-1 mutant of Arabidopsis thaliana. T1 progeny from an Arabidopsis fca-1 plant transformed with WFCA were grown without vernalization and assayed for the final leaf number (FLN). The late flowering fca-1 control plants bolted with an average FLN of 14.8 while the T1 population had an average FLN of 14.3. Although the numerical difference is slight, the results are statistically significant, and suggest that WFCA genes may have some degree of flowering promotion activity in Arabidopsis. The lack of strong complementation may be due to divergence of the WFCA genes from their Arabidopsis counterparts. With increasing evidence for divergence in flowering promotion between monocot and dicot species, the development of a robust monocot model system appears to be critical to provide a good framework to assist studies of the particular nuances of the monocot flowering process.