<div><p>F-box protein is a core component of the ubiquitin E3 ligase SCF complex and is involved in the gibberellin (GA) signaling pathway. To elucidate the molecular mechanism of GA signaling in wheat, three homologous <i>GIBBERELLIN-INSENSITIVE DWARF2</i> genes, <i>TaGID2</i>s, were isolated from the Chinese Spring wheat variety. A subcellular localization assay in onion epidermal cells and <i>Arabidopsis</i> mesophyll protoplasts showed that <i>TaGID2</i>s are localized in the nuclei. The expression profiles using quantitative real-time polymerase chain reaction showed that <i>TaGID2</i>s were downregulated by GA<sub>3</sub>. The interaction between TaGID2s and TSK1 (homologous to ASK1) in yeast indicated that TaGID2s might function as a component of an E3 ubiquitin-ligase SCF complex. Yeast two-hybrid assays showed that a GA-independent interaction occurred between three TaGID2s and RHT-A1a, RHT-B1a, and RHT-D1a. Furthermore, TaGID2s interact with most RHT-1s, such as RHT-B1h, RHT-B1i, RHT-D1e, RHT-D1f, etc., but cannot interact with RHT-B1b or RHT-B1e, which have a stop codon in the DELLA motif, resulting in a lack of a GRAS domain. In addition, RHT-B1k has a frame-shift mutation in the VHIID motif leading to loss of the LHRII motif in the GRAS domain and RHT-D1h has a missense mutation in the LHRII motif. These results indicate that TaGID2s, novel positive regulators of the GA response, recognize RHT-1s in the LHRII motif resulting in poly-ubiquitination and degradation of the DELLA protein.</p></div
