Verification of tiling array detected differentially expressed genes. (a) RT-PCR analysis of the transcript abundance in six organ types for six selected soybean genes that are preferentially expressed in the nodule. Total RNA (5 μg) was reverse transcribed and 5% of the product used as template for PCR, which was carried out for 35 cycles. (b) Organ type-specific variation of the expression level of the gene Gm_121, as determined by median-polishing of the tiling array data. Dashed lines indicate the deviation value at p = 0.001.