<div><p>Production and secretion of acid phosphatases (APases) is a hallmark adaptive response of plants to phosphate (Pi) deprivation. Researchers have long hypothesized that Pi starvation-induced APases are involved in internal Pi recycling and remobilization as well as in external Pi utilization. Two phosphatase under-producer (<i>pup</i>) mutants, <i>pup1</i> and <i>pup3</i>, were previously isolated in <i>Arabidopsis</i>. Characterization of these 2 <i>pup</i> mutants provided the first genetic evidence for the above hypothesis. To date, however, the molecular lesions in these 2 <i>pup</i> mutants remain unknown. In this work, we demonstrate that <i>pup1</i> and <i>pup3</i> contain point mutations in the <i>Arabidopsis</i> purple acid phosphatase gene <i>AtPAP10</i> and <i>AtPAP26</i>, respectively. Our results answer a long-standing question about the molecular identity of the <i>PUP1</i> and <i>PUP3</i> genes and corroborate the conclusions from previous studies regarding the function of AtPAP10 and AtPAP26 in plant acclimation to Pi deprivation.</p></div
