The Expression Pattern And Functional Analysis Of AtSPX1 Gene In Arabidopsis Thaliana

The SPX domain proteins, which were identified about ten years ago, have been confirmed now to exist in many eukaryotes. While some SPX proteins were proved to be related to phosphorus signaling or iron signaling, the function of most of these proteins remains unknown. Analysis of the AtSPXl expression pattern showed that it is expressed in root, leaf, stem, flower and silique. The expression of AtSPX1 could be greatly induced by phosphorus starvation. Binary vector harboring AtSPX1::GFP fused gene was bombarded into onion epidermal cells. Results show that AtSPXl protein was localized in the nucleus. No significant phenotype change was observed in transgenic plants overexpressing AtSPX1 compared to the wild type plants under either Pi-sufficient or Pi-deficient condition. The transgenic plants, however, show tolerance to iron starvation during early stage of development. Quantitative RT-PCR results indicated that the expression of phosphorus-responsive genes AtACP5, PAP2, RNS1 was enhanced in the AtSPX1 overexpressing lines, as well as the ferritin genes and NRAMP3. Our results suggested that AtSPX1 may play a role in the remobilization of phosphorus and iron transportation during early stage of development. Our research suggests that AtSPX1 may have dual functions.