For semi-quantitative polymerase chain reaction (PCR), half a microliter of the first strand cDNA products were used for each gene amplification. PCR conditions were as follows: denaturation at 94°C for 30 s, annealing at 60°C for 30 s, and an extension step at 72°C for 1 min. Linearity between the amount of input RNA and the final PCR products was verified. The transcriptional level of b-actin was used as an internal control. Specific primers (Supplementary Table S1) were designed according to gene sequences of MALDI-TOF-MS-identified proteins and the local transcriptomic database of sweet potato. The realtime PCR was performed by the IQ5 real-time PCR system (BIO-RAD, California, USA) in a total volume of 20 lL containing 100 ng of cDNA template, 19 SYBR Ò Premix Ex Taq TM II (Perfect Real Time, TaKaRa), and a 400 nM concentration of each primer. Serial dilutions of each cDNA were used to generate a quantitative PCR standard curve to calculate the corresponding PCR efficiencies. After initial denaturation at 95°C for 30 s, the amplification was carried out through 40 cycles, each consisting of denaturation at 95°C for 5 s, primer annealing at 60°C for 30 s, and DNA extension at 72°C for 30 s. Melting curves were obtained, and quantitative analysis of the **data** was performed using the BIO-RAD IQ5 standard edition optical System software (version 2.1) in a normalized expression (ddCt) model. Transcriptional levels of Ib-RCAs and Ib-RCAl were normalized to b-actin gene. Specific primers of Ib-RCAs, Ib-RCAl and b-actin for real-time PCR were list in Supplementary Table S1. Results were obtained from three biological replicates.