Functional Analysis Of A Phosphate Transporter Gene OsPht2;1in Rice

Phosphorus (Pi) is one of the three major nutrients in plant growth and is important components of nucleic acids, phospholipids and ATP. The low availability of soil P is a major constraint for crop production in many agricultural systems worldwide though the total P contents is high in soil. In order to adapt to low phosphorus stress, higher plants thus take all kinds of adaptation mechanism such as alter their root architecture, Pi uptake, Pi translocation and distribution. Rice (Oryza sativa) is one of the most important staple food crops and model plant for scientific research. Consequently, research on functional characterization of rice PTs family genes with regard to rice nutrients uptake and translocation is of extreme importance for understanding of the mechanism and utilization of Pi resources in environment.Phosphate (Pi) is taken up by plant roots from the soil and translocated within the plant via phosphate transporters. So far, the isolation and research on PTs focused on Phtl family members in rice more compared with the research on Pht2family members. It is of great significance to research functional characterization of OsPht2;1in Pi uptake and translocation.In this thesis, we report the expression pattern of OsPht2;1and the in planta function of only one Pht2family in rice(Oryza sativa). The main results are summarized as follows:1. We cloned full length cDNA sequence of OsPht2;1from rice cDNA based on mRNA sequence information which codes for a572-amino acid protein. The encoding amino acid and phylogenetic tree analysis showed gene function is conservative of Pht2family.The expression pattern of OsPht2;1in rice was investigated and the results showed its mRNA expressed in leaf mainly and in root little with the using of RT-PCR and Q-PCR. In addition, OsPht2;1induced by phosphate deficiency and light.2. By transforming the construct of overexpression of OsPht2;1into Nipponbare cultivar, we successfully obtained the transgenic lines with overexpression of OsPht2;1. Compared with WT, the Pi concentrations of OsPht2;1-Ox plants increased about20%in roots, about30%in shoots and the biomass increased about28%in Pi-sufficient conditions. The Pi concentrations of OsPht2;1-Ox plants increased about40%in shoots and the biomass increased about30%in Pi-deficient conditions, while the Pi concentrations had no difference in roots.3. The transgenic lines of OsPht2;1show high sensitivity to Pi starvation which have great influence on root architecture. Over-expression of OsPht2;1increased some parts of the following:total root length, total root surface area, root volume and root tips number.4. We also carried out pot experiment with three levels of fertilizer P. The total Pi concentration in leaf3, leaf2, leaf1and panicle axis are higher in transgenic lines compared with WT. In field test, the total Pi concentration in leaf3, leaf2, leaf1and panicle axis is higher of transgenic lines than WT. The yield production also is improved.5. We analyzed the relative gene expression of the Phtl family members in the OsPht2;1overexpression plants by the Real-time PCR. The data shows the overexpression of OsPht2;1could strengthen intensity of Pi translocation and utilization so as to influence the expression degree of Phtl family members.Taken together, all these results indicated that OsPht2;1played very important roles in Pi translocation and utilization at each stage of rice development. Notably, OsPht2;1was also found to be involved to improve the Pi use efficiency in rice.