Characterization of the FaVRT-2 gene encoding a MADS-box transcription factor responsive to vernalization in tall fescue (Festucaarundinacea)

Abstract

Delay of floral transition is a valuable trait in commercially important turfgrass species. It has been reported that short vegetative phase (SVP)-like proteins, potential repressors of the floral inductive pathway, control the transition from vegetative to reproductive phase. A homolog of SVP-like genes was isolated from tall fescue (Festuca arundinacea) by 5′-rapid amplification of cDNA ends (RACE) and 3′-RACE and designated as F. arundinacea VEGETATIVE TO REPRODUCTIVE TRANSITION gene-2 (FaVRT-2). It encodes a putative protein of 226 amino acids with a conserved MADS (M) domain, a Keratin-like (K) domain, and a C-terminal (C) domain. Phylogenetic analysis showed that FaVRT-2 is most closely related to VRT-2 proteins from ryegrass, barley, and wheat and belongs to the StMADS11 subfamily of MADS-box transcription factors. Subcellular localization showed that the FaVRT-2 protein accumulates in the nucleus suggesting a role as trans acting factor. FaVRT-2 transcripts accumulate abundantly in roots and stems and is moderately present in leaves under normal conditions (without non-vernalization treatment). Real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) showed similar transcriptional patterns of FaVRT-2 under both vernalization and non-vernalization conditions. However, the peak of FaVRT-2 transcripts under vernalization condition occurred 14 days earlier than that found under non-vernalization condition. These results support the hypothesis that FaVRT-2, a putative repressor of floral transition, is regulated by vernalization in tall fescue.

Keywords:

• MADS-box
• induction kinetics
• subcellular localization
• tall fescue
• vernalization

Acknowledgments

This research was financially supported by the Graduate Scientific Innovation Foundation of Guizhou Academy of Agricultural Sciences, China (09007). We are grateful to Dr. R. A. McIntosh (Plant Breeding Institute, University of Sydney) for critically reading the manuscript.