The Genes Functional Compare Analysis Between The OsPHR2 And AtPHR1

AtPHR1 plays an important role in the Pi signaling system in Arabidopsis. To Compare the function of AtPHR1 and 0sPHR2 ,the homologous gene of AtPHR1 in rice, we developed transgenic plants of Arabidopsis (Col) with over expressions of AtPHR1 and OsPHR2 respectively.Using the transgenic lines and bioinformatics analyses; we found ectopic function of OsPHR2 in Arabidopsis. The results are summarized as follows:1. Bioinformatics analysis indicates that, OsPHR2 is homologous to AtPHR1. They have the similar MYB-CC domain, while there are some differences in the CC domain between them. In the AtPHR1, the 347 amino acid is Tyrosine, which is an important tyrosine kinase phosphorylation site. In the OsPHR2, the corresponding amino acid is Cysteine , consequently there is no tyrosine kinase phosphorylation site. In the AtPHR1, the 372 amino acid is Lysine, which is an important sumoylation site, but the corresponding amino acid is Proline in the OsPHR2. In the super-secondary structure, The CC domain of the AtPHR1 is a longααhelix, but there is a turn in the middle of CC domain of the OsPHR2.2. Under high Pi level(HP: 1000μM Pi), the OsPHR1 over expression Arabidopsis plants showed reduction of plant growth compared to the wild type, including lower plant height, shorter legumes and lower sterility. On the contrary, the AtPHR1 over expression plants showed no significant differences in plant growth compared to the wild type. Under low Pi level(LP: 35μM Pi), however, no significant phenotypic change was found among the wild type, phr1,over expression lines of OsPHR2 and AtPHR1.3. The OsPHR2 over expression plants showed higher anthocyanins accumulation and higher inorganic Pi concentration in shoots under HP level compared to the wild type, but not the total Pi in plants. There is no obvious difference in AtPHR1 over expression plants compared to wild type under HP level. Under low Pi level, there is no distinct difference in anthocyanins accumulation, inorganic Pi concentration, the total Pi among the wild type, 0sPHR2 and AtPHR1 over expression plants.4. The Pi-starvation-inducible genes, such as AtlPS1, At4 and AtPAP2, were induced in 0sPHR2 over expression plants under HP level. These inductions were some degree repressed in AtPHR1 over expression plants. While there is no obvious change for the Pho2 gene. Under LP level, no different transcript levels were observed in AtlPS1, At4 and AtPAP2 among the wild type, OsPHR2 and AtPHR1 over expression plants.