Mitochondrial alternative pathway is associated with development of freezing tolerance in common wheat

Abstract

Cold acclimation is an adaptive process for acquiring cold/freezing tolerance in wheat. To clarify the cultivar difference of freezing tolerance, we compared mitochondrial respiration activity and the expression profile of alternative oxidase (AOX) genes under low-temperature conditions using two common wheat cultivars differing in freezing tolerance. During cold acclimation, the respiration capacity of the alternative pathway significantly increased in a freezing-tolerant cultivar compared with a freezing-sensitive cultivar. More abundant accumulation of the AOX and uncoupling protein gene transcripts was also observed under the low-temperature conditions in the tolerant cultivar than in the sensitive cultivar. These results suggest that the mitochondrial alternative pathway might be partly associated with the cold acclimation and freezing tolerance in wheat.

An analytical model of non‐photorespiratory CO2 release in the light and dark in leaves of C3 species based on stoichiometric flux balance

“…There is evidence that AOX activity is strongly enhanced by stress (Finnegan, Soole & Umbach 2004), including water stress (Bartoli et al 2005;Ribas-Carbo et al 2005), low temperatures (Matos et al 2007;Mizuno et al 2007) and excess light (Noguchi et al 2005;Yoshida, Terashima & Noguchi 2007), and that it serves as a supplementary electron sink, probably to regenerate NAD + and/or to prevent generation of reactive oxygen species (Amirsadeghi et al 2006). A core hypothesis of our model is that po is downregulated to maintain flux balance, first by reducing TCA cycle activity, and then by downregulation of po.…”

Salt stress-induced expression of rice AOX1a is mediated through an accumulation of hydrogen peroxide

“…Much works have shown that the AOX pathway, AOX transcript abundance, and AOX protein amount are increased under various stressful conditions, including chilling (Mizuno et al 2008), drought (Ribas-Carbo et al 2005;Bartoli et al 2005), phosphate limitation (González-Meler et al 2001), and plant diseases (Simons et al 1999). Recent work reported that treatment of Citrus cell suspensions with high concentration of NaCl led to a stimulation of the capacity of the AOX pathway and an increase in AOX protein amount (Ferreira et al 2008).…”

Post-transcriptional Regulation in Mitochondria of Rice and Wheat at Low Temperatures

“…A temporal difference exists between developmental-and cold-induced increases, in that the accumulation of intron-containing transcripts is maximized half to one day after imbibition, whereas 3 to 7 days are required after cold treatment. However, mitochondrial responses are shared by germinating seeds and cold-treated plants, such as increased O 2 uptake capacity, differential fluxes between cyanide-sensitive (mainly, cytochrome) and -insensitive respiratory (AOX) pathways, and the activation of some mitochondrial genes encoded in the nuclear genome 3,42,52,62 . It is possible that one or more of these responses is directly associated with the accumulation of intron-containing transcripts and will shed light on the physiological significance of the phenomenon.…”