2.8 qRT-PCR
Total RNA samples were isolated with a SuperPure Plantpoly RNA Kit (Gene Answer) following the manufacturer’s instructions. RNase-free DNAse I (New England Biolabs) was used to remove any trace genomic DNA. First-strand complementary DNA (cDNA) was synthesized with Reverse Transcriptase M-MLV (Takara) and oligo (dT) 12-18 as a primer. The PCR reactions were performed with SYBR Green kit (Roche) on a LightCycler® 96 SW 1.1 cycler (Roche). TheNtL25 gene was chosen as the internal reference control (Schmidt & Delaney, 2010), and the realtive expression levels of the target genes were calculated as described previously (Livak & Schmittgen, 2001). All the gene-specific primers for qRT-PCR were listed in Supplemental Table S3.