RNA extraction and qRT-PCR assays
RNAprep pure plant kit (TIANGEN, China) was used to extracted total RNA and then using the PrimeScript™ RT reagent kit (TaKaRa, China) to reverse-transcribed RNA to cDNA. SYBR Premix Ex Taq II Kit (Takara, China) was used to performed a real-time PCR system (Bio-Rad CFX96, USA). The SmActin gene was selected as endogenous control (Yanget al. , 2010). 2-△△ct method was used to calculate the relative expression levels. All the qRT-PCR analysis primers are listed in Supplemental Table S1. Three independent biological replicates and three technical replicates were used to obtain the data.