qRT-PCR analysis of the expression of HvPHO2, HvIPS1 and HvIPS2 in P-deficient (−P) and P-sufficient (+P) shoots of barley (cv. Pallas). The primers and conditions for the qRT-PCR were as previously described (Huang et al., 2011). A: qRT-PCR of HvPHO2; B: qRT-PCR of HvIPS1; C: qRT-PCR of HvIPS2. * means p < 0.003 versus the expression of the same gene under sufficient P.