Isolation and partial characterisation of PHT1;5, a putative high affinity phosphate transporter from Arabidopsis thaliana

[摘要] ENGLISH ABSTRACT: Inorganic Phosphate (Pi) is one of the key nutrients required by all living organisms on earth. This nutrient is of vital importance to higher plants but it is not readily available for uptake from the soil, implying constant stress on plants. During photosynthetic dark and light reactions, phosphate is a prerequisite for all reactions to occur and to ensure plant survival. This statement implies that a careful homeostatic control of this nutrient is necessary in order to maintain a balanced carbon flow in all sub-cellular plant compartments.Phosphate limitation is a threat to plant survival and one way of addressing this nutritional hurdle is by feeding plants with fertilizer. This method of crop development and general plant maintenance by humans has a devastating effect on the environment, as phosphate causes eutrophication and various other consequences which are detrimental to animal life. Plants, however, are naturally equipped with Pi transporters which are activated conditionally depending on the external Pi availability. These transporters are present in most sub-cellular compartments and some of them have been identified and characterised, while others remain to be a prediction. If these transporters are characterised accordingly it might eventually mean that the use of fertilizers may no longer be necessary. In order to contribute to successful Pi-efficient crop development, a clearer understanding of P-dynamics in the soil and its recycling ability inside the plant itself is necessary.During this study it was attempted to characterise a putative high affinity Pi transporter, PHT1;5, from Arabidopsis thaliana via a Escherichia coli and yeast heterologous expression system and its Km value predicted in order to verify/hypothesise whether it is a high or low affinity transporter. This transporter is expressed in leaves and could be a promising tool for future carbon partitioning studies during phosphate limitation.

[发布机构] Stellenbosch University