Over-expression of a high-affinity phosphate transporter in transgenic barley plants does not enhance phosphate uptake rates

摘要

Transgenic barley plants that over-express the gene encoding a phosphate transporter were generated and used to test the hypothesis that manipulation of transporters may lead to improved phosphate uptake by plant roots. Replicate T-2 seedlings from a homozygous line with a single locus insertion were grown in dilute flow culture. The phosphate contents and uptake rates of these plants were compared with control transgenic and wild-type plants. When external phosphate concentration was maintained at 10 muM, all plants including the transgenic overexpressing line displayed low rates of phosphate uptake and contained high levels of phosphate in the shoot tissue. When external phosphate concentration was maintained at 2 muM, the uptake rates increased to a similar level in all plant lines. Three transgenic over-expressing lines were then grown in soil at a range of phosphate concentrations and the dry weights and total phosphorus contents of the shoots were measured and compared to a transgenic control line. The results showed that over-expression of the gene encoding a phosphate transporter did not improve the uptake of phosphate under any of the conditions tested. Transporter activity is likely to be influenced by posttranscriptional mechanisms and will require further investigation before this strategy can be applied to improving plant nutrition.