Gene expression analysis for candidate genes present within the PUE locus on chromosome 1 (7.24–7.34 Mb).

Genotypes belong to two haplotype groups contrasting for PUE: HT1-6 with low PUE represented by IR64 and Taichung Native, and HT1-7 (high PUE) with representative Yodanya and Mudgo. RNA was sampled from P deficient plants (Low P) and P sufficient plants (High P). (a) Semiquantitative RT-PCR of all 14 genes within the locus. The known P-responsive gene SQD-2 was included as a control, as were two housekeeping genes. Gene expression was compared in old leaves (OL, beginning to senesce) and young leaves (YL, >50% developed). (b—e) qPCR for SQD2 and the three most promising canditate genes. In addition to old and young leaves expression was determined in intermediate leaves (ML, typically the two leaves below the youngest fully expanded). Fold change for Fig 7b is expressed on a log scale.