Abstract
BackgroundInorganic phosphate (Pi) is essential for plant growth, and phosphorus deficiency is a main limiting factor in plant development. Its acquisition is largely mediated by Pht1 transporters, a family of plasma membrane-located proteins. Chrysanthemum is one of the most important ornamental plants, its productivity is usually compromised when grown in phosphate deficient soils, but the study of phosphate transporters in chrysanthemum is limited.ResultsWe described the isolation from chrysanthemum of a homolog of the Phosphate Transporter 1 (PT1) family. Its predicted product is a protein with 12 transmembrane domains, highly homologous with other high affinity plant Pi transporters. Real-time quantitative PCR analysis revealed that the gene was transcribed strongly in the root, weakly in the stem and below the level of detection in the leaf of chrysanthemum plants growing in either sufficient or deficient Pi conditions. Transcript abundance was greatly enhanced in Pi-starved roots. A complementation assay in yeast showed that CmPT1 partially compensated for the absence of phosphate transporter activity in yeast strain MB192. The estimated K m of CmPT1 was 35.2 μM. Under both Pi sufficient and deficient conditions, transgenic plants constitutively expressing CmPT1 grew taller than the non-transformed wild type, produced a greater volume of roots, accumulated more biomass and took up more phosphate.ConclusionsCmPT1 encodes a typical, root-expressed, high affinity phosphate transporter, plays an important role in coping Pi deficiency of chrysanthemum plants.
Highlights
Inorganic phosphate (Pi) is essential for plant growth, and phosphorus deficiency is a main limiting factor in plant development
The high affinity route is largely mediated by plasma membrane-localized Pi transporters belonging to the PHOSPHATE TRANSPORTER1 (Pht1) family [8,10]
The peptide sequence shares a high level of homology with known high affinity plant Pht1 proteins: 77.1% with AtPT1 (GenBank accession number AED94948), 78.5% with LePT1 (AAB82146), 71.8% with OsPT8 (Q8H6G8) and 78.9% with MtPT5 (ABM69111) (Figure 1)
Summary
Inorganic phosphate (Pi) is essential for plant growth, and phosphorus deficiency is a main limiting factor in plant development. Its acquisition is largely mediated by Pht transporters, a family of plasma membrane-located proteins. The application of phosphate-based fertilizer can correct deficiency, but even when provided in a highly accessible form, as little as 10% of the phosphorus applied is recovered by plants [3], with the remainder either becoming immobilized or lost through run-off [4]. The concentration of inorganic phosphate (Pi) in plant tissues lies in the range 5–20 mM [6], whereas the level available in a typical soil is three orders of magnitude lower than this [7]. The high affinity route is largely mediated by plasma membrane-localized Pi transporters belonging to the PHOSPHATE TRANSPORTER1 (Pht1) family [8,10]. Following the identification of Pi transporters in Arabidopsis thaliana [10], a large number of PT genes have been identified and characterized in a wide range of species such as Arabidopsis thaliana [3,11,12], rice [13,14,15], tomato [16], tobacco [17,18], maize [19], barley [20], Medicago truncatula [21], Populus trichocarpa [22], and soybean [23]
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