Figure 4.

PHT1;3 is involved in root-to-shoot Pi translocation under extremely low Pi supply. A, Cellular Pi concentration in roots and shoots of wild-type and pht1;3 mutant plants. Four-leaf-old seedlings were grown in nutrient solution containing four different Pi concentration levels until the seventh leaf blades were fully expanded (two weeks). Values represent means ± sd of biological replicates (n = 5). Different letters indicate significant differences (P < 0.05, one-way analysis of variance, Duncan’s test). B, RT-qPCR analysis of PHT1;3 expression in response to different Pi concentration treatments. Seeds of the wild-type plants were germinated in deionized H₂O and then transferred to nutrient solution supplied with five different Pi concentrations, respectively. The roots, leaf sheaths, and four leaf blades (the fourth to the seventh) were sampled for RNA extraction. OsActin (LOC_Os03g50885) was used as an internal standard. Values represent means ± sd of biological replicates (n = 3). FW, fresh weight.