Identification and functional analysis of soybean GmSBH1 gene promoter conferring high temperature- and humidity-induced expression

Abstract

Soybean homeobox gene GmSBH1 has previously been proven to be involved in response to high temperature and humidity (HTH) stress. To investigate its expression patterns and active cis-elements, a 2040-bp 5'-upstream genomic DNA fragment of GmSBH1,named GmSBH1P, was isolated by PCR walking and characterized. Sequence analysis revealed that the fragment contains a series of cis-acting elements related to stress responses. The transient expression assay in the leaves of Nicotiana benthamiana and in the cotyledonary nodes of soybean indicated that the GmSBH1P strongly and rapidly mediates the induction of GUS expression under HTH stress. Deletion and mutation analysis of the promoter indicated that the cis-acting HSE (GAACTTTC) in GmSBH1P is essential for the promoter in response to HTH stress. In addition, 82 different proteins were identified to bind the cis-element by a yeast one-hybrid system. These results indicated that the cloned promoter GmSBH1P could be applied to enhance the resistance to HTH stress, and the HSE would be an ideal candidate for mediating the expression of HTH-responsive genes in plants.