Arabidopsis purple acid phosphatase 10 is a component of plant adaptive mechanism to phosphate limitation

Abstract

When grown with inadequate quantities of inorganic phosphate (Pi), plants synthesize and secret acid phosphatases into the rhizosphere. These secreted acid phosphatases are thought to release the Pi group from organophosphates present in the surrounding environment and to thereby increase Pi availability to plants. So far, however, the genetic evidence to support this hypothesis is still lacking. Previously, we showed that overexpression of Arabidopsis purple acid phosphatase 10 (AtPAP10) improved the growth of plants on Pi-deficient medium (P⁻ medium) supplemented with the organophosphate compound ADP; in contrast, the growth of atpap10 mutant lines was reduced on the same medium. In the current research, we determined the growth performance of these lines on P⁻ medium supplemented with four other organophosphates. The results showed that AtPAP10 could utilize rhizosphere organophosphates other than ADP for plant growth but with different utilization efficiencies. This work provides further genetic evidence that AtPAP10 phosphatase is a component of plant adaptive mechanism to Pi limitation.

Figure 1. Shoot and root fresh weights of the four atpap10 mutant lines and the WT when grown for 14 d on the P^- medium supplemented with different quantities of Fru-6-P (A), PEP (B), phytate (C) and P-Ser (D). The quantities of organophosphates added to the P^- medium are indicated at the bottom. The experiments were repeated three times with similar results. Values represent means with SE of three replicates (40 seedlings per replicate). Asterisks indicate significant differences compared with the WT (p < 0.05, t-test).

Figure 2. Shoot and root fresh weights of the three AtPAP10 overexpressing lines (lines 5, 10 and 17) and the WT when grown for 14 d on the P^- medium supplemented with different quantities of Fru-6-P (A), PEP (B), phytate (C) and P-Ser (D). The quantities of organophosphates added to the P^- medium are indicated at the bottom. The experiment were repeated three times with similar results. Values represent means with SE of three replicates (40 seedlings per replicate). Asterisks indicate significant differences compared with the WT (p < 0.05, t-test).