BSMVγ constructs selected for relative stability also produce successful gene silencing in barley roots. A RT-PCR analysis of the stability of BSMVγ constructs in barley roots. Expected lengths for the PCR products are presented in brackets. Lanes 1, 2: BSMV-IPS1 (493 bp); 3, 4: BSMV-Pht1;1 (610 bp); 5, 6: BSMV-Pht1;4 (616 bp); 7, 8: BSMV-Pht1;7 (623 bp); 9, 10: BSMV-PHR1 (495 bp); 11, 12: BSMV-PHO2247 (511 bp); 13, 14: BSMV-PHO2387 (651 bp); 15, 16: GFP250 (492 bp); 17: control plasmid carrying BSMVγ-GFP375 (617 bp); 18: control plasmid carrying BSMVγ-IPS1 (493 bp); M4: GeneRuler 50 bp DNA Ladder (Fermentas); M5: O'GeneRuler 50bp DNA Ladder (Fermentas). White arrow represents DNA fragment of 500 bp; bands below are 400, 300, and 250 bp. B and C HvPHR1 expression levels in root tissue determined by qRT-PCR, normalization to 18 S rRNA. BSMV-PHR1 (black bars), BSMV-GFP250 (white bars). Samples in B are identical to those shown in A, lanes 9, 10 and 15,16. In C, each bar represents five independent samples. AU - arbitrary units; error bars denote standard deviations. D HvPHO2 expression levels in root and leaf tissue determined by qRT-PCR, normalization to 18 S rRNA. BSMV-PHO2247 (black bars), BSMV-GFP250 (white bars). E As D, but bars represent Pi content in inoculated plants (in μmol Pi/g of fresh weight).