Differential expression of a poplar SK₂-type dehydrin gene in response to various stresses

Abstract

Dehydrins are group II, late embryogenesis abundant proteins that act putatively as chaperones in stressed plants. To elucidate the function of dehydrins in poplar, we isolated the SK(2)-type dehydrin gene Podhn from Populus alba x P. tremula var. glandulosa suspension cells and analyzed its expression following treatments of abiotic stress, wounding and plant growth regulator. Sequence homology and phylogenetic analyses indicate Podhn encodes an acidic dehydrin (pI 5.14, 277 amino acids, predicted size 25.6 kDa) containing two lysine-rich "K-segments" and a 7-serine residue "S-segment", both characteristic of SK(2)-type dehydrins. Southern blots show Podhn genes form a small gene family in poplar. Podhn was expressed in all tissues examined under unstressed conditions, but most strongly in cell suspensions (especially in the stationary phase). Drought, salt, cold and exogenous abscisic acid (ABA) treatments enhanced Podhn expression, while wounding and jasmonic acid caused its reduction. Therefore, Podhn might be involved in ABA or stress response.