Abstract
pst2 (photoautotrophic salt tolerance 2) mutant was screened at our laboratory. Higher expression of bHLH19 (At2g22760; bHLH, basic helix-loop-helix) was found by DNA microarray analysis in pst2 without salt stress. Under salt stress conditions, another species of mRNA was produced by alternative splicing in addition to the completely-spliced one. The transient expression of bHLH19 fused to sGFP, revealed its restrictive presence in the nucleus. Transgenic plants over-expressing the completely- and incompletely-spliced mRNA species exhibited more tolerant to salt than wild-type ones did. In order to clarify a role of AtbHLH19 in salt tolerance, microarray analysis was performed for the transgenic and wild-type plants to figure out candidate genes regulated by AtbHLH19. We are performing gel mobility shift assay to determine the consensus sequences of promoters recognized by AtbHLH19, in focusing on binding ability of heterodimer formed with one of three homologs of AtbHLH19.
