The molecular characterization of a cDNA encoding the putative integral membrane protein, HvSec61α, expressed during early stage of barley kernel development

The Sec61 complex is essential for the translocation of both soluble proteins and integral membrane proteins into the membrane of the endoplasmic reticulum. To study the molecular events that occur during kernel development, the suppression subtractive hybridization (SSH) method was performed using grains of barley (Hordeum vulgare L.) cv. Karl at different developmental stages (14 DAF and 5 DAF). One of the SSH clones showed high homology to cDNA encoding, a Sec61α subunit in wheat, but not to any clones previously registered in barley. The full-length clone was screened and then designated as HvSec61α (Hordeum vulgare Sec61 α subunit). The transcription level of HvSec61α was low in grains at 5 DAF, increased at 8 DAF and was highest at 11 DAF. The transgenic Arabidopsis over expressing HvSec61α grew more vigorously than wild-type plants during drought stress. The expression of HvSec61α was high in grains but low in other tissues, such as the pericarp, stem, and leaf. The expression of HvSec61α increased in vegetative tissues in response to abiotic stresses such as PEG, cold, or salt as well as to hormones such as ABA, MeJA, and cytokinin. We speculate that the physiological function of the Sec61 complex might not only be to translocate secretory proteins, but as well integral membrane proteins in the ER during early kernel development in barley.