Evidence has been provided that the plant uncoupling proteins (pUCP) play b
asic physiological roles similar to the other uncoupling protein subfamily
members (mammalian UCP1,2,3,4 and BMCP) and are effective in the situations
of slight uncoupling that leads to: (1) accelerated respiration and metabo
lic rates that are beneficial to plant growth and development; (2) decrease
d formation of reactive oxygen species in mitochondria; and, (3) mild therm
ogenesis, inevitably accompanying the previous two phenomena. Hypotheticall
y, specific physiological roles of pUCP such as cut off of ATP synthesis co
uld be manifested in connection with climacteric respiratory rise during fr
uit ripening, seed dormancy, and plant senescence. pUCP might also facilita
te growth under low temperatures, e.g., during seed germination or in roots
. The existence of these specific roles is suggested by the immunochemical
and functional localization of pUCP in mitochondria of fruits, seeds and ro
ots of various plant species.