In order to invest the expression of AmGS under cold stress conditions, real-time RT-PCR was carried out in 6-week-old axenic seedlings. As shown in Fig. 3A, the transcripts of AmGS started to increase from 12 h after cold stress, and became obvious 24 h after cold stress, and increased by 7 folds and stop increasing at the 48 h time-point. The result showed that it is a late-responsive gene, as AtGS3 in Arabidopsis ( Taji et al., 2002).