Figure 5.
Knockout of SPX4 leads to ectopic PSR gene expression in P-replete shoots but not in roots. Knockout of SPX genes should lead to the release of PHR1-activated gene expression under P-replete and Pi-resupply conditions, as shown here for DEGs in whole seedlings of the spx1 spx2 double mutant (asterisk; Puga et al., 2014). PHR1 knockout primarily affects PSR gene expression in P-limited organs, shown here as the common response to changes in Pi supply of both phr1-1 and phr1-2 alleles (this work; greater than 2-fold change in mutant versus the wild type; false discovery rate [FDR] < 0.05). The spx4-1 mutant shows the expected response in P-replete shoots, but not under Pi resupply. spx4-1 mutant roots show a similar transcript profile to the wild type. See Supplemental Data Sets S1 and S2 for details.