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Localization, physiological role and functional analysis of Anion Transporter-3 (Arabidopsis thaliana)

Abstract

Inorganic phosphate (Pi) is one of the most important components of fertilizers because of its importance in many biochemical activities during plant growth and development. They are cycled and recycled all over the plant from floral buds to root tips. Even though the Pi concentration in soil is way less, plants have devised many ways to increase its concentration inside the plant body; one of them being phosphate transporters.

In this project, the maintenance of dynamic cycling of inorganic phosphate was discussed in terms of a phosphate transporter, Anion Transporter-3 (ANTR3). Reverse genetics were applied with the help of bioinformatics and other web based tools which provided valuable initial information. The model organism Arabidopsis thaliana, both wild-type and mutants was cultivated hydroponically. Screening for homozygotes proceeded standardization of a protocol for isolation of plastids from the roots of these plants. Presence and absence of protein in root plastids was confirmed by anti-body specific western blotting in wild-type and mutants respectively. This was followed by functional and biochemical analysis of the protein by radioactive transport assays with radioactively tagging phosphate.

The development of a protocol for isolation of root plastids from roots of Arabidopsis thaliana with high yields has been successful. In-vitro studies by radioactive phosphate transport experiments were possible with the help of knock out mutants. It has been concluded that transport of Pi via ANTR3 is dependent on a gradient either from proton concentration or cations (Na+). Back exchange experiments have aided us in establishing its activity in export and import of Pi. Last but not the least, phenotypic analysis have observed larger biomass in mutants leading to the conclusion that even thought other transporters are present, the sink (roots) – source (leaves) balance is disturbed.


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Last updated: 05/20/09