Changes in antioxidants are critical in determining cell responses to short‐ and long‐term heat stress

Abstract

Heat stress can have deleterious effects on plant growth by impairing several physiological processes. Plants have several defense mechanisms that enable them to cope with high temperatures. The synthesis and accumulation of heat shock proteins (HSPs), as well as the maintenance of an opportune redox balance play key roles in conferring thermotolerance to plants. In this study changes in redox parameters, the activity and/or expression of reactive oxygen species (ROS) scavenging enzymes and the expression of two HSPs were studied in tobacco Bright Yellow-2 (TBY-2) cells subjected to moderate short-term heat stress (SHS) and long-term heat stress (LHS). The results indicate that TBY-2 cells subjected to SHS suddenly and transiently enhance antioxidant systems, thus maintaining redox homeostasis and avoiding oxidative damage. The simultaneous increase in HSPs overcomes the SHS and maintains the metabolic functionality of cells. In contrast the exposure of cells to LHS significantly reduces cell growth and increases cell death. In the first phase of LHS, cells enhance antioxidant systems to prevent the formation of an oxidizing environment. Under prolonged heat stress, the antioxidant systems, and particularly the enzymatic ones, are inactivated. As a consequence, an increase in H2 O2 , lipid peroxidation and protein oxidation occurs. This establishment of oxidative stress could be responsible for the increased cell death. The rescue of cell growth and cell viability, observed when TBY-2 cells were pretreated with galactone-γ-lactone, the last precursor of ascorbate, and glutathione before exposure to LHS, highlights the crucial role of antioxidants in the acquisition of basal thermotolerance.

Foliar application of methyl jasmonate induced physio-hormonal changes in Pisum sativum under diverse temperature regimes

“…Simulations of current and future anthropogenic activity predict that average global air temperature will further increase by 1e4.5 C, at rate of 0.2 C per decade, by the end of the 21st century, which may reduce global crop yields (IPCC, 2007;Rienth et al, 2014;Sgobba et al, 2015). Although increase of 2e6 C has dramatic effects on growth (hypocotyls elongation) and flowering time depending on the light conditions (Thines et al, 2014;Bours et al, 2015).…”

“…Although increase of 2e6 C has dramatic effects on growth (hypocotyls elongation) and flowering time depending on the light conditions (Thines et al, 2014;Bours et al, 2015). However, even brief exposures of tropical or temperate crops to high temperatures (40 C) at sensitive life stages can bring about irreparable agricultural losses (Sgobba et al, 2015;Wang et al, 2015). Heat stress negatively influences the physiological functions of plants, affecting cellular homeostasis, plant-soil-water relations, photosynthesis, and respiration; causing cell membrane injury and leaf chlorosis and necrosis; and lowering plant biomass and yield .…”

Mutualistic fungal endophytes produce phytohormones and organic acids that promote japonica rice plant growth under prolonged heat stress

“…These plant-microbe interactions can provide regulatory dynamics towards plant growth in biotic and abiotic stresses. One of the major, currently encountered abiotic stresses, is heat stress (Sgobba et al, 2015). Higher temperatures resulting from global climate change have already had drastic effects on crop growth, and global temperatures are predicted to rise by 2-5 °C by the end of this century.…”

“…The occurrence of heat-shock waves will further affect agricultural production (Fragkostefanakis et al, 2014). Overall, heat stress interrupts plant growth by impairing important physiological and morphological processes such as reductions in seed germination, net assimilation rate-dependent relative growth rate, plant height, photosynthesis, and flowering, along with premature cell death (Hasanuzzaman et al, 2013;Sgobba et al, 2015). Rice is perhaps the most important staple food crop for the majority of the world's population (Lin et al, 2014).…”

Temperature experienced during incubation affects antioxidant capacity but not oxidative damage in hatchling red-eared slider turtles (Trachemys scripta elegans)

“…Following extended cold exposure, similar increases in some antioxidant enzymes have been observed in mammals (Spasićet al, 1993;Selman et al, 2000;Kaushik and Kaur, 2003) and zebrafish (Danio rerio) (Malek et al, 2004). In contrast, although antioxidant enzymes increased in response to acute heat stress in tobacco plant seeds, antioxidant systems were negatively affected by long-term heat stress and high indices of oxidative stress were observed (Sgobba et al, 2015). Thus, associations between environmental temperature and oxidative stress will vary over different temporal scales.…”