Responses of the Mitochondrial Respiratory System to Low Temperature in Plants

<p>Low-temperature (LT) stress induces significant changes to plant cells including perturbations of various physio-biochemical and metabolic processes, which impact primary metabolism, respiratory rate, and the ATP production for biosynthesis and growth. Mitochondria from LT-tolerant species respond to LT through remodeling their composition that changes the structural and functional properties of the organelles. In this review, we discuss physiological aspects of mitochondrial respiration rate that are affected by LT, as well as, changes in the abundance of respiratory components under LT. The latter includes components of the phosphorylating and non-phosphorylating pathways and adjustments of mitochondrial membrane composition. Our objective is to provide a detailed overview of the often-contrasting reports of mitochondrial-specific changes and responses to LT and look for consensus themes to explain changes and draw more generally applicable observations about the LT response of plant respiration.</p

Influence of frost damage on the sugars and sugar alcohol composition in quince (Cydonia oblonga Mill.) floral nectar

Cold stress adversely affects growth and productivity, and triggers a series of morphological, physiological, biochemical and molecular changes in plants. Since sugars are present in all floral nectars in greater amounts than any other constituent, the aim of this study was to examine how frost exposure changes sugar metabolism and how it affects on the content of sugar components in the nectar of quince. Three quince cultivars ('Vranjska', 'Triumph' and 'Leskovac. ka') were investigated in this study. The contents of sugars (glucose, fructose, sucrose, trehalose, maltose, isomaltose, rhamnose, arabinose, ribose, melezitose, raffinose, and panose) and sugar alcohols (sorbitol, erythritol, mannitol and galactitol) were analyzed by high performance anion exchange chromatography (HPAEC) with amperometric detection. The results showed that after late spring frosts and irreversible damage of flower parts, the nectar of the three quince cultivars contained elevated levels of fructose, trehalose, arabinose, ribose, rhamnose, raffinose, galactitol and mannitol, indicating an impairment of central carbohydrate metabolism. The ratios between individual sugars, such as the glucose/fructose ratio, were changed in the nectar of damaged flowers in all three quince cultivars. The examined cultivars showed similar sugar response to cold stress. The only exception was 'Leskovac. ka' for the glucose and melezitose pathway, which means that composition of those two sugars changed significantly according to the genotype. The larger are the carbohydrates reserves in different parts of a fruit tree, the higher is the tolerance to any form of frost damage, the results of this study could help in the understanding of how different quince cultivars react to this kind of stress and how they modulate their sugar metabolism