Different molecular bases underlie the mitochondrial respiratory activity in the homoeothermic spadices of Symplocarpus renifolius and the transiently thermogenic appendices of Arum maculatum

Abstract

Symplocarpus renifolius and Arum maculatum are known to produce significant heat during the course of their floral development, but they use different regulatory mechanisms, i.e. homoeothermic compared with transient thermogenesis. To further clarify the molecular basis of species-specific thermogenesis in plants, in the present study we have analysed the native structures and expression patterns of the mitochondrial respiratory components in S. renifolius and A. maculatum. Our comparative analysis using Blue native PAGE combined with nano LC (liquid chromatography)-MS/MS (tandem MS) has revealed that the constituents of the respiratory complexes in both plants were basically similar, but that several mitochondrial components appeared to be differently expressed in their thermogenic organs. Namely, complex II in S. renifolius was detected as a 340 kDa product, suggesting an oligomeric or supramolecular structure in vivo. Moreover, the expression of an external NAD(P)H dehydrogenase was found to be higher in A. maculatum than in S. renifolius, whereas an internal NAD(P)H dehydrogenase was expressed at a similar level in both species. Alternative oxidase was detected as smear-like signals that were elongated on the first dimension with a peak at around 200 kDa in both species. The significance and implication of these data are discussed in terms of thermoregulation in plants.

The biochemical basis for thermoregulation in heat-producing flowers

“…COX capacities were also determined as KCN-sensitive (0.5 mM) and n -propyl gallate-insensitive (0.1 mM) respiration. Protein concentrations of purified mitochondria were determined as in our previous report 24 . Mitochondria were stored at −80 °C and used for enzyme assays.…”

Metabolic interplay between cytosolic phosphoenolpyruvate carboxylase and mitochondrial alternative oxidase in thermogenic skunk cabbage, Symplocarpus renifolius

“…Real-time qPCR was performed using a Thermal Cycler Dice (TP800; Takara Bio) instrument as described previously 13,31 . Gene-specific primers (Supplementary Table 2) were designed from identified cDNAs and the housekeeping gene EF1 α was used as a normalization control 31 …”

Changes in the OXPHOS system in leaf and root mitochondria of Arabidopsis thaliana subjected to long-term sulphur deficiency

“…Similarly, S deficiency in bean plants does not increase protein levels or AOX capacity, and COX capacity is decreased (Juszczuk and Ostaszewska 2011). Alternative oxidase does not form a part of OXPHOS system in A. thaliana under normal conditions (Eubel et al 2003;Kakizaki et al 2012). In S-deficient plants, the apparent lack of association of AOX with any of complexes (Fig.…”