Real-time RT-PCR reactions were performed with a Mastercycler® ep realplex real-time PCR system (Eppendorf, Hamburg, Germany) using SYBR®Premix Ex Taq™ (TaKaRa, Dalian, China). The cDNA was amplified with the following primers: for SlActin (accession number BT012695), forward 5′-CCACGAGACTACATACAA-3′ and reverse 5′-TACCACCACTGAGCACAA-3′; for SlDES1 (accession number XM_004248001), forward 5′-AAATAACTGGCAATGGGGTT-3′ and reverse 5′-TGGTCTGTTGGCGAGTCTAA-3′; for SlCDKA;1 (accession number Y17225), forward 5′-CACTTGCCTGTCGCCTCCTC-3′ and reverse 5′-ACCCCCTCGTCTTCCTGCTC-3′; for SlCYCA2;1 (accession number AJ243452), forward 5′-CATTAACAAGGGTATGCGAA-3′ and reverse 5′-GTCAGGTAAAGAGTGTCCGG-3′; for SlKRP2 (accession number AJ441250), forward 5′-CTTCACAAACCACCCACCCC-3′ and reverse 5′-TTTCGTCCACCTCCCTCACC-3′. Relative expression levels were presented as values relative to the control samples at the indicated time points, after normalization to SlActin transcript levels.