title: Two rice phosphate transporters, OsPht1;2 and OsPht1;6, have different functions and kinetic properties in uptake and translocation.
abstract: Plant phosphate (Pi) transporters mediate the uptake and translocation of this nutrient within plants. A total of 13 sequences in the rice (Oryza sativa) genome can be identified as belonging to the Pi transporter (Pht1) family. Here, we report on the expression patterns, biological properties and the physiological roles of two members of the family: OsPht1;2 (OsPT2) and OsPht1;6 (OsPT6). Expression of both genes increased significantly under Pi deprivation in roots and shoots. By using transgenic rice plants expressing the GUS reporter gene, driven by their promoters, we detected that OsPT2 was localized exclusively in the stele of primary and lateral roots, whereas OsPT6 was expressed in both epidermal and cortical cells of the younger primary and lateral roots. OsPT6, but not OsPT2, was able to complement a yeast Pi uptake mutant in the high-affinity concentration range. Xenopus oocytes injected with OsPT2 mRNA showed increased Pi accumulation and a Pi-elicited depolarization of the cell membrane electrical potential, when supplied with mM external concentrations. Both results show that OsPT2 mediated the uptake of Pi in oocytes. In transgenic rice, the knock-down of either OsPT2 or OsPT6 expression by RNA interference significantly decreased both the uptake and the long-distance transport of Pi from roots to shoots. Taken together, these data suggest OsPT6 plays a broad role in Pi uptake and translocation throughout the plant, whereas OsPT2 is a low-affinity Pi transporter, and functions in translocation of the stored Pi in the plant.
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, China.
authors.forename: Penghui
authors.initials: P
authors.lastname: Ai
authors.forename: Shubin
authors.initials: S
authors.lastname: Sun
authors.forename: Jianning
authors.initials: J
authors.lastname: Zhao
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Fan
authors.forename: Weijie
authors.initials: W
authors.lastname: Xin
authors.forename: Qiang
authors.initials: Q
authors.lastname: Guo
authors.forename: Ling
authors.initials: L
authors.lastname: Yu
authors.forename: Qirong
authors.initials: Q
authors.lastname: Shen
authors.forename: Ping
authors.initials: P
authors.lastname: Wu
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Miller
authors.forename: Guohua
authors.initials: G
authors.lastname: Xu
mesh_terms: D000818:Animals; D001692:Biological Transport; D018506:Gene Expression Regulation, Plant; D055785:Gene Knockdown Techniques; D007700:Kinetics; D009865:Oocytes; D012275:Oryza / Q000235:genetics* / Q000378:metabolism; D028061:Phosphate Transport Proteins / Q000235:genetics / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D018749:RNA, Plant / Q000378:metabolism; D014981:Xenopus
chemical_list: D028061:Phosphate Transport Proteins; D010710:Phosphates; D010940:Plant Proteins; D012333:RNA, Messenger; D018749:RNA, Plant