Seymour, R.2006-06-192006-06-192004Plant, Cell and Environment, 2004; 27(8):1014-10220140-77911365-3040http://hdl.handle.net/2440/1949The definitive version is available at www.blackwell-synergy.com<jats:title>ABSTRACT</jats:title><jats:p>Inflorescences of the arum lily<jats:italic>Symplocarpus foetidus</jats:italic>are thermogenic and thermoregulatory. The spadix increases respiratory heat production rate as ambient temperature decreases. This study examined the relationships between spadix temperature (<jats:italic>T</jats:italic><jats:sub>s</jats:sub>), respiration rate (<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/PCE_1206_mu1.gif" xlink:title="inline image" />) and ambient temperature (<jats:italic>T</jats:italic><jats:sub>a</jats:sub>) at equilibrium and during transient responses to step changes in<jats:italic>T</jats:italic><jats:sub>a</jats:sub>. Intact inflorescences inside a miniature constant temperature cabinet in the field showed the most precise temperature regulation yet recorded; over a 37.4 °C range in<jats:italic>T</jats:italic><jats:sub>a</jats:sub>(−10.3 to 27.1 °C),<jats:italic>T</jats:italic><jats:sub>s</jats:sub>changed only 3.5 °C (22.7 to 26.2 °C). Regulated temperatures were not related to spadix size (1.9–7.3 g) or circadian cycle. Dynamic responses to step changes in<jats:italic>T</jats:italic><jats:sub>a</jats:sub>involved a phasic change in<jats:italic>T</jats:italic><jats:sub>s</jats:sub>, first in the same direction as<jats:italic>T</jats:italic><jats:sub>a</jats:sub>, then reversing at 38.3 min, and finally approaching equilibrium at 87.6 min, on average. Meanwhile<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/PCE_1206_mu1.gif" xlink:title="inline image" />changed in a monotonic curve toward equilibrium. Models revealed that the dynamics of temperature change were inconsistent with simply a physical lag in the system, but involved some form of biochemical regulation, possibly by changes in activity of a rate‐limiting functional protein.</jats:p>enJournal article002004175710.1111/j.1365-3040.2004.01206.x0002230644000062-s2.0-384305339456066Seymour, R. [0000-0002-3395-0059]