Involvement of soluble sugars in reactive oxygen species balance and responses to oxidative stress in plants

Abstract

Soluble sugars, especially sucrose, glucose, and fructose, play an obviously central role in plant structure and metabolism at the cellular and whole-organism levels. They are involved in the responses to a number of stresses, and they act as nutrient and metabolite signalling molecules that activate specific or hormone-crosstalk transduction pathways, thus resulting in important modifications of gene expression and proteomic patterns. Various metabolic reactions and regulations directly link soluble sugars with the production rates of reactive oxygen species, such as mitochondrial respiration or photosynthesis regulation, and, conversely, with anti-oxidative processes, such as the oxidative pentose-phosphate pathway and carotenoid biosynthesis. Moreover, stress situations where soluble sugars are involved, such as chilling, herbicide injury, or pathogen attack, are related to important changes in reactive oxygen species balance. These converging or antagonistic relationships between soluble sugars, reactive oxygen species production, and anti-oxidant processes are generally confirmed by current transcriptome analyses, and suggest that sugar signalling and sugar-modulated gene expression are related to the control of oxidative stress. All these links place soluble carbohydrates in a pivotal role in the pro-oxidant and antioxidant balance, and must have constrained the selection of adaptive mechanisms involving soluble sugars and preventing de-regulation of reactive oxygen species production. Finally, in line with the specific role of sucrose in oxygenic photosynthetic organisms, this role of soluble sugars in oxidative stress regulation seems to entail differential effects of glucose and sucrose, which emphasizes the unresolved issue of characterizing sucrose-specific signalling pathways.

Regulation of Leaf Starch Degradation by Abscisic Acid Is Important for Osmotic Stress Tolerance in Plants

“…Furthermore, the maltose levels in the starch-less Arabidopsis mutant pgm remained unchanged in response to osmotic stress (Supplemental Figure 2). Concomitantly with the induction of starch degradation, wild-type plants responded to the osmotic stress by accumulating high levels of sugars and proline in the leaves (Supplemental Figure 7), presumably for osmotic adjustment and energy supply to maintain cell survival and metabolic activity (Couée et al, 2006;Verslues and Sharma, 2011). Our data suggest that most of these osmolytes derived from photosynthetic carbon assimilation and only partly from starch hydrolysis.…”

“…Sugars and proline can also help stabilize proteins and cell structures, particularly when the stress becomes severe or persists for longer periods (Hoekstra et al, 2001). These compounds can also act as free radical scavengers, protecting against oxidation by removing excess reactive oxygen species, reestablishing the cellular redox balance (Couée et al, 2006;Miller et al, 2010). Thus, the ability to adjust patterns of assimilation, storage, and utilization of carbon in response to changes in the environment may determine not only biomass production but also plant fitness in terms of survival under stressful environmental conditions.…”

Impacts of leaf age and heat stress duration on photosynthetic gas exchange and foliar nonstructural carbohydrates in Coffea arabica

“…The sink demand in this treatment was also low due to the inhibition of reproduction. In contrast to the other NSC constituents that did not change with time in the 90‐min treatment, the transient increase in sucrose content at day 2 may reflect an initial repair or defense response to the substantial damage caused by the 90‐min treatment because sucrose has been linked to defense against ROS (Bita & Gerats, 2013), antioxidant production (Couée et al., 2006), osmotic adjustment (Cavatte et al., 2012), and stress response signaling (El Sayed, Rafudeen, & Golldack, 2014; Secchi & Zwieniecki, 2011, 2016; Sugio et al., 2009; Wang & Ruan, 2016). Also, soluble sugars such as sucrose are among the primary metabolites and osmolytes known to accumulate in response to heat stress (Wahid et al., 2007) and are necessary for protection from elevated temperature and maintaining water balance and membrane stability (Bita & Gerats, 2013; Farooq et al., 2008).…”

Morphological and physiological alterations induced by lactofen in soybean leaves are reduced with nitric oxide

“…Soluble Morphological and physiological alterations induced by ... sugars can have defense signals and responses useful to plants for controlling not only the photosynthetic activity but also the ROS level. Consequently, soluble sugars can regulate the defense against several ROS-producing stresses, such as those caused by xenobiotics (Couée et al, 2006). Besides, glucose, a reducing soluble sugar, is the main initial carbonic precursor for carotenoid (Pallet & Young, 1993) and ascorbate (Smirnoff et al, 2001) biosynthesis, as well as for amino acid carbonic skeletons, including cysteine, glutamate, and glycine, which are glutathione components (Noctor & Foyer, 1998).…”

“…Besides, glucose, a reducing soluble sugar, is the main initial carbonic precursor for carotenoid (Pallet & Young, 1993) and ascorbate (Smirnoff et al, 2001) biosynthesis, as well as for amino acid carbonic skeletons, including cysteine, glutamate, and glycine, which are glutathione components (Noctor & Foyer, 1998). All these compounds are involved in defenses against oxidative stress through ascorbateglutathione cycles, as well as in redox reaction homeostasis and peroxide detoxification (Couée et al, 2006). In addition, specific amino acids such as histidine, methionine, and tryptophan can be oxidized by O 2 - (van Breusegem et al, 2001).…”