NFS1, NFS2 and ISD11 gene expression in cold-treated plants. Quantitative RT-PCR analysis of NFS1 gene expression in (a) root and (b) leaf, NFS2 gene expression in (c) root and (d) leaf and ISD11 gene expression in (e) root and (f) leaf from cold-treated plants. Relative expression level was measured by performing qPCR in four biological replicates and four technical replicates for each biological replicate per tissue with SE shown. Values were normalized against F-BOX and MET. Letters or numbers indicate difference in transcription level among time-points analyzed. * indicates difference in transcription level between duplicated genes at one point.