Heat shock‐induced biphasic Ca²⁺ signature and OsCaM1‐1 nuclear localization mediate downstream signalling in acquisition of thermotolerance in rice (Oryza sativa L.)

Abstract

We investigated heat shock (HS)‐triggered Ca2+ signalling transduced by a Ca2+ sensor, calmodulin (CaM), linked to early transcriptome changes of HS‐responsive genes in rice. We observed a biphasic [Ca2+]cyt signature in root cells that was distinct from that in epicotyl and leaf cells, which showed a monophasic response after HS. Treatment with Ca2+ and A23187 generated an intense and sustained increase in [Ca2+]cyt in response to HS. Conversely, treatment with Ca2+ chelator, L‐type Ca2+ channel blocker and CaM antagonist, but not intracellular Ca2+ release inhibitor, strongly inhibited the increased [Ca2+]cyt. HS combined with Ca2+ and A23187 accelerated the expression of OsCaM1‐1 and sHSPC/N genes, which suggests that the HS‐induced apoplastic Ca2+ influx is responsible for the [Ca2+]cyt response and downstream HS signalling. In addition, the biphasic response of OsCaM1‐1 in the nucleus followed the Ca2+ signature, which may provide the information necessary to direct HS‐related gene expression. Overexpression of OsCaM1‐1 induced the expression of Ca2+/HS‐related AtCBK3, AtPP7, AtHSF and AtHSP at a non‐inducing temperature and enhanced intrinsic thermotolerance in transgenic Arabidopsis. Therefore, HS‐triggered rapid increases in [Ca2+]cyt, together with OsCaM1‐1 expression and its nuclear localization, are important in mediating downstream HS‐related gene expression for the acquisition of thermotolerance in rice.

Systems-Wide Analysis of Acclimation Responses to Long-Term Heat Stress and Recovery in the Photosynthetic Model OrganismChlamydomonas reinhardtii

“…Recent work suggested that an unfolded protein response also exists in the chloroplast (Yu et al, 2012;Schmollinger et al, 2013;Ramundo et al, 2014). Plasma membrane fluidity has been identified as an important temperature sensor in land plants that appears to lie upstream of the unfolded protein response (Sangwan et al, 2002;Suri and Dhindsa, 2008;Saidi et al, 2009;Wu et al, 2012). Increased membrane fluidity appears to open calcium channels in the plasma membrane and inflowing calcium to trigger signaling cascades, including an H 2 O 2 burst (Königshofer et al, 2008), leading to the activation of the HS response.…”

Effect of pretreatment with hydrogen sulfide donor sodium hydrosulfide on heat tolerance in relation to antioxidant system in maize (Zea mays) seedlings

“…During the process of evolution, plants have developed the antioxidant system, including antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), guaiacol peroxidase (GPX) and ascor-bate peroxidase (APX), as well as low-molecular weight water-soluble antioxidants ascorbic acid (AsA) and glutathione (GSH), to maintain ROS homeostasis in plant cells (Foyer & Noctor 2009Jaleel et al 2009;Ahmad et al 2010;Szarka et al 2012;Garg & Kaur 2013). Therefore, the balance between ROS and antioxidant system plays crucial role in the acquisition of heat stress in plants (Wahid et al 2007;Ahmad et al 2010;Saidi et al 2011;Mittler et al 2012;Szarka et al 2012;Wu et al 2012). However, the effect of hydrogen sulfide treatment on heat tolerance of maize seedlings in relation to antioxidant system is not fully understood.…”

“…Among these stress factors, high temperature is a major abiotic factor affects metabolism, growth, development, reproduction, yield, and even survival of plants including crop plants like maize (Zea mays L.) (Li & Gong 2011;Saidi et al 2011;Mittler et al 2012;Wu et al 2012;Grover et al 2013;Piterková et al 2013). In crop plants, maize not only is a new model plant, but also the third most important food grain crop after wheat and rice, and heat stress is the principal cause of maize failure worldwide, global warming accentuates this problem (Leipner & Stamp 2009;Strable & Scanlon 2009).…”

“…In crop plants, maize not only is a new model plant, but also the third most important food grain crop after wheat and rice, and heat stress is the principal cause of maize failure worldwide, global warming accentuates this problem (Leipner & Stamp 2009;Strable & Scanlon 2009). Numerous studies have clearly illustrated high temperature stress commonly leads to oxidative stress as result of peroxidation of membrane lipids, degradation of proteins, inactivation of enzymes, DNA damage, etc., (Saidi et al 2011;Mittler et al 2012;Wu et al 2012;Grover et al 2013;Piterková et al 2013;Tari et al 2013). The degree of oxidative stress is determined by the level of reactive oxygen species (ROS) such as superoxide radical (O .…”

“…The degree of oxidative stress is determined by the level of reactive oxygen species (ROS) such as superoxide radical (O . − 2 ), hydrogen peroxide (H 2 O 2 ), hydroxyl radical (OH .− ) (Saidi et al 2011;Mittler et al 2012;Wu et al 2012;Piterková et al 2013). During the process of evolution, plants have developed the antioxidant system, including antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), guaiacol peroxidase (GPX) and ascor-bate peroxidase (APX), as well as low-molecular weight water-soluble antioxidants ascorbic acid (AsA) and glutathione (GSH), to maintain ROS homeostasis in plant cells (Foyer & Noctor 2009Jaleel et al 2009;Ahmad et al 2010;Szarka et al 2012;Garg & Kaur 2013).…”