Four different G. elata tissues (epidermis, cortex, parenchymal cell A and B) were collected from three mature tuber samples. Total RNAs were extracted using TRIzol® Reagent (Thermo Fisher Scientific, USA) according to the manufacturer’s instructions. The concentrations and purities of the total RNAs were assessed by a spectrophotometric analysis at 260 and 280 nm. One μg of total RNA was reverse transcribed at 42 °C using TransScript® Reverse Transcriptase (TransBionovo Co, China) and Oligo(dT)18 according to the manufacturer’s recommendations. Prior to use in qPCR, cDNA was diluted 1:5 with H2O.