Abstract
We have previously reported finding of AtbHLH106 for salt tolerance by activation-tagging of Arabidopsis calli (JSPP meeting, 2009). We here show the evidences that AtbHLH106 (hereafter bHLH106) plays an important role not only in salt regulation but also in cold and ABA responses. An additional homozygous knock-out line newly generated by self-pollination, has shown sensitivity to salt stress to confirm our previous results. Knock-out lines were also sensitive to cold stress and different concentrations of ABA in a solid medium. Rescue lines have also been developed for bHLH106, showing the phenotype of enhanced tolerance to different levels of salt stress. Knock-out, rescue and over-expression lines were subjected to GeneChip analysis (Affymetrix), resulting in a number of genes up-regulated or down-regulated compared with wild-type with or without salt stress. Electrophoresis mobility shift assay (EMSA) has confirmed the interaction between bHLH106 synthesized in a cell-free system (CFS) and promoter sequences of at least five genes. These results provide proof for involvement of the transcription factor bHLH106 in a network of salt stress regulation in Arabidopsis.
