Cloning And Functional Analysis Of TSK1, A SKP1 Homologue From Wheat

SKP1, S-phase kinase-associated-protein 1, was shown to be a component of a SCF (SKP1-Cullin-F-box) complex, which is necessary for ubiquitin-mediated protein degradation in eukaryotes. The SCF complex is composed of 4 major subunits: Cullin (CDC53 in yeast), SKP1, a RING finger protein (RBX1/HRT1/ROC1) and an F-box protein. Among them, SKP1 acts as an adaptor to link Cullin1 (Cul1) to F-box protein, which specifically recognizes different target proteins via a variable C-terminal domain and interacts with SKP1 through an N-terminal structural motif. A number of SKP1-like genes are found in plants, but only ASK1 (Arabidopsis SKP1-like 1) and ASK2 have been characterized genetically. In Arabidopsis, many F-box proteins were found to interact with ASK1 or ASK2, which suggests that they could form various SCF complexes, and evidence indicated that SCF complexes regulate plant development by affecting the signal pathways of auxin, gibberellin, and ethylene. Until now, little is known about the SKP1 genes in monocots and the relationship between SKP1 protein and ABA signaling.Here, we report on a SKP1-like gene from winter wheat named TSK1 (Triticum aestivum SKP1-Like 1). Expression analysis revealed that it was expressed predominantly in young roots and floral buds but repressed by abscisic acid (ABA) treatment. RNA in situ hybridization showed it is expressed in shoot apical meristems (SAMs) and anthers, especially the tapetum and microsporocytes at the meiosis stage.