Modified responses of root growth and reactive oxygen species-scavenging system to combined salt and heat stress in transgenic rice

Impact of Combined Heat and Salt Stresses on Tomato Plants—Insights into Nutrient Uptake and Redox Homeostasis

“…Moreover, APX activation did not result in an insufficient AsA pool, as both DHAR and GR remained unaffected, with efficient AsA regeneration possibly being ascribed to monodehydroascorbate (MDHAR, EC 1.6.5.4) action [12]. Contrarily to what was observed in roots, in shoots, no ROS were overaccumulated, and APX was not while SOD and CAT were actually inhibited, effects also documented by Liu and Huang [89] and Djanaguiraman et al [92] When plants were exposed to the combination of stressors, O 2 − levels in roots were unaffected, which seems to agree with the maintenance of SOD activity also reported in this organ, an effect that opposes the activation of this AOX enzyme documented by Zhao et al [22] in rice roots. Moreover, and though there was an activation of both H 2 O 2scavenging enzymes, APX and CAT, the AOX system did not fully detoxify this ROS, since H 2 O 2 content was still higher than in CTL plants, but not at high enough levels to induce noticeable oxidative damage.…”

“…AsA, a powerful AOX involved in ROS scavenging via direct or indirect pathways [74], was not affected by either stress (individual or combined), in either its synthesis or its regeneration levels (Tables 2 and 3). In fact, and although the opposite is frequently found [22,75,76], these results fall in accordance with the similar pattern of activity between the enzymes mediating AsA oxidation (APX) and its reduction (DHAR). Curiously, in heat-treated plants, especially in combination with salt, a slight tendency towards a higher oxidation of AsA was observed, this being in line with higher APX activity.…”

“…This might be related to a SOD-mediated reaction, and while no changes in its activity were reported, high basal SOD levels could be sufficient to deal with mild stress conditions. Nonetheless, a tendency for SOD to possess higher activity in this treatment and organ can be noticed, as supported by Zhao et al [22] and Liu and Huang [89]. Unsurprisingly, due to ROS accumulation, CAT and APX activities were enhanced in an effort to detoxify H 2 O 2 and prevent oxidative damage.…”

“…However, and despite the knowledge regarding the effects of different abiotic stressors, in a real environmental context, crops are exposed to a multitude of factors whose impacts on the plants' physiological performance are not always easily extrapolated from what occurs in the presence of an individual stressor [13][14][15][16][17]. Despite that, very few authors have tackled the impacts of a consistently warmer and more saline environment (either through soil salinization or poor water quality) on plant species [18][19][20][21][22].…”

Salt and Heat Stress Trigger Morpho-Physiological Changes, Antioxidant Enzyme and Secondary Metabolites Gene Expression in Rice (Oryza sativa L.)

“…Salt and heat stress are two of the most common environmental stressors in rice cultivation (Zhao et al 2010). This stress combination can lead to increased reactive oxygen species (ROS) production, which causes oxidative damage in plants (Mittler 2006;Mishra et al 2018).…”