The complete peach dehydrin family: characterization of three recently recognized genes

Three genes encoding dehydrins have been previously described from peach. In the course of searching the peach genome, three additional members of this stress-associated family were recognized, PpDhn4-6. PpDhn1 and 6 have no introns, whereas the remaining four genes have a single intron located near the 3′ end of the serine (S) tract. PpDHN2 was the only dehydrin with a predicted basic pI; pI predictions for the other dehydrins ranged from about 5.3 to about 6.3. None of the peach dehydrins have tryptophan residues, but, in contrast to most dehydrins, three (PpDHN1, 3, and 4) have one or more cysteine residues. Phylogenetic analysis indicated a close relationship between PpDhn1 and 6 and PpDhn3 and 4. Expression analysis under low temperature and dehydration confirmed that PpDhn2 is the major responder to drought, while both PpDhn1 and 6 respond exclusively to cold. Comparison of the first 500 base pairs upstream of the translation start site revealed the presence of cis-elements associated with low temperature and drought/osmotic/salt and hormone response regulation.