Study On The Cloning And Expression Of OrLPT1, A Gene Encoding Phosphate Transporter In Rice (Oryza Sativa L.)

Phosphorus (Pi) is one of the essential macronutrients required by the roots ofplants. Rice is a major crop that feeds about one half of the world's population.Phosphorus deficiency is a major limiting factor for rice production of the agricultureof world. Pi uptake systems consist of low-affinity and high-affinity transportcomponents. Under Pi deficiency, the high-affinity transport system is considered tobe the major mechanism for Pi uptake by roots. Genes encoding high affinity Pitransporters have been isolated from many plant species including Lycopersiconesculentum, Arabidopsis thaliana and so on. But there are little study on the genes andfunction of rice Pi transporters. In this paper, OrLPT1, a novel Pi transporter from ricewas cloned and its expression under both Pi sufficiency and deficiency was analyzed.The main results as following:1. A full-length cDNA clone, OrLPT1, encoding rice phosphate transporter was isolated from the total RNA of phosphate-starved leaves. The open reading frame of OrLPT1 is 1605 bp in length (Genbank accession number:AF335588).2. OrLPT1 ORF encods a polypeptide with 535 amino acid residues (molecular mass of 57.6KDaltons), which shares more than 64% amino acid identity with some other high-affinity Pi transporters of plants. Hydropathy analysis of the deduced polypeptides showed that the OrLPT1 is highly hydrophobic and contains 12 putative membrane-spanning regions. The phosphorylation sites for protein kinase C(TAR), casein kinase II(SLEE) and the N-glycosylation site(NATT) are conserved among high affinity Pi transporters from other eukaryotes.3. Southern blot with rice genomic DNA digested by different restriction enzymes was performed by using a fluorescein labeled probe of the 459bp cDNA region of OrLPT1. The probe hybridized with three bands indicating the existence of more related sequences in the rice genome.4. To estimate the phylogenetic relationship between OrLPT1 and other Pi transporters in plants, we used MEGA software (version 2.01) and bootstrap...