Dehydrins, PpDHNA and PpDHNB from Physcomitrium patens provide drought and cold tolerance while PpDHNC shows antimicrobial property suggesting different dehydrins perform separate functions in P. patens. The moss Physcomitrium patens can withstand extremes of environmental condition including abiotic stress such as dehydration, salinity, low temperature and biotic stress such as pathogen attack. Osmotic stress is inflicted under both cold and drought stress conditions where dehydrins have been found to play a significant protective role. In this study, a comparative analysis was drawn for the three dehydrins PpDHNA, PpDHNB and PpDHNC from P. patens. Our data shows that PpDHNA and PpDHNB play a major role in cellular protection during osmotic stress. PpDHNB showed several fold upregulation of the gene when P. patens was subjected to cold and osmotic stress in combination. PpDHNA and PpDHNB provide protection to enzyme lactate dehydrogenase under osmotic as well as freezing conditions. PpDHNC possesses antibacterial activity and thus may have a role in biotic stress response. PpDHNC shows antimicrobial activity against Rhodococcus fascians and Bacillus subtilis. The K segments of PpDHNC are probably associated with the antimicrobial activity. Further investigations involve the use of K segments of PpDHNC alongwith PpDHNA and PpDHNB to form a supra molecule of dehydrin that may show protective properties under multi-stress conditions.