.5. Total RNA extraction and cDNA synthesis 30 L of total RNA with the concentration of 210–320 ng L−1 was extracted from different samples according to the method of Chang et al. (1993), and then digested with RNase-free DNase
(Takara, Japan) to remove the residual genomic DNA. The firststrand cDNA was synthesized from 1 g of DNA-free RNA using a PrimeScript®
RT reagent Kit (Takara, Japan), according to the manufacturer’s instructions