Mechanisms of thermoregulation in plants

Abstract

Endothermic heating of floral tissues and even thermoregulation is known to occur in a number of plant species across a wide taxonomic range. The mechanisms by which flowers heat, however, are only just beginning to be understood, and even less is known about how heating is regulated in response to changes in ambient temperature. We have recently demonstrated that the alternative pathway of respiration, in which the alternative oxidase (AOX) rather than cytochrome C (COX) acts as terminal electron acceptor, is responsible for heat generation in one thermoregulating species, the sacred lotus (Nelumbo nucifera). In the March issue of the Journal of Experimental Botany we further demonstrated that AOX-mediated heat production in this species is regulated at both the level of gene expression and also post-translationally. Similarly, AOX has also been implicated in heat production in other thermogenic species. In this addendum we discuss the central role of AOX in heat production and how post-translational mechanisms may provide the fine control necessary for thermoregulation.

Keywords: Nelumbo nucifera; alternative oxidase; thermogenic plants; uncoupling proteins.

Figure 1

Changes in air temperature (dotted line) and receptacle temperature (solid line) for sacred lotus, Nelumbo nucifera, over the 2–3 d thermoregulatory phase of floral development. Floral development occurs over 4–5 d and during the thermoregulatory phase receptacle temperature is maintained at close to 32°C, while air temperature can vary from 8–45°C.,