An Arabidopsis mutant missing one acid phosphatase isoform

Plant response to phosphorus starvation includes the increased production and secretion of acid phosphatase. We have isolated a mutant of Arabidopsis thaliana (L.) Heynh., phosphatase-underproducer 1 (pup1), that has reduced histochemical staining for acid phosphatase activity in roots of plants grown under phosphorus-starvation conditions. Although pup1 is defective in the production of one inducible acid phosphatase isoform, the most abundant inducible isoform is present. The pup I mutants are able to respond to phosphorus-deficient conditions by an increase in overall levels of acid phosphatase activity, accumulation of anthocyanins, an increase of the root-to-shoot ratio, and changes in the partitioning of phosphorus between roots and shoots. The gross morphology of the mutants appears normal, except that a small difference in the root to shoot ratio was observed in plants grown under nonstressed conditions. The pup1 gene is incompletely dominant and it is located between 40.2 (+/-6.2) and 44.9 (+/-9.9) cM on chromosome 2. This mutant will be useful For determining the role of this acid phosphatase isoform in plant response to phosphorus starvation.