Integrative effects of zinc and temperature on germination in Dimorphandra wilsonii rizz.: Implications of climate changes

Abstract

The integrative effects of zinc (Zn; 0 mg L , 75 mg L , 150 mg L , and 200 mg L ) and temperature (25 °C, 30 °C, and 35 °C) on seed germination of the threatened Brazilian species Dimorphandra wilsonii were evaluated. Zinc effects on seed germination were only observed at 30 °C and 35 °C. By stimulating respiration rates, rising temperatures accentuate hydrogen peroxide (H O ) formation in germinating seeds in the presence of Zn. Seed Zn tolerance was related to the activation of enzymatic antioxidants, and ascorbate peroxidase (APX) activity had a central role in H O scavenging under the highest temperatures tested. Increased APX activity allowed successful germination, whereas decreasing APX activity was accompanied by decreasing germination rates in Zn-treated seeds at 35 °C. Within a scenario of future climate change, it will be extremely important to avoid increasing Zn concentrations in natural habitats that would threaten conservation efforts directed toward this endangered plant species. Environ Toxicol Chem 2017;36:2036-2042. © 2017 SETAC.

Integrative signaling of hydrogen peroxide and gibberellin on Zn‐mediated alleviation of thermodormancy in sorghum seeds

“…Similarly, seeds transferred from 40 to 30°C showed greater germinability and H 2 O 2 levels, and the activities of antioxidant enzymes were lower in Zn‐treated seeds than in controls (Figures 1 and 2B,C). Zn is known to increase seed mitochondrial activity and the natural generation of the H 2 O 2 and ATP required for seed germination (Bicalho et al, 2017) as observed in our study (Table 3). Zn was also observed to decrease APX and CAT activity in Dimorphandra wilsonii seeds at high temperatures, leading to ROS accumulation and signaling (Bicalho et al, 2017).…”

“…Zn is known to increase seed mitochondrial activity and the natural generation of the H 2 O 2 and ATP required for seed germination (Bicalho et al, 2017) as observed in our study (Table 3). Zn was also observed to decrease APX and CAT activity in Dimorphandra wilsonii seeds at high temperatures, leading to ROS accumulation and signaling (Bicalho et al, 2017). H 2 O 2 mediates the regulation of ABA catabolism and GA biosynthesis in Arabidopsis seeds (Liu et al, 2010).…”

“…Therefore, any factor affecting mitochondrial respiration may affect seed germination by interfering with energy production and ROS signaling. Rising temperatures will stimulate respiratory activity and energy production during early seed germination—but the overproduction of ROS due to temperature‐induction of mitochondrial metabolism and any resulting oxidative stress can prevent seed germination (radicle protrusion) if the antioxidant systems fail to prevent ROS accumulations (Bicalho et al, 2017). Supra‐optimal temperatures can also affect seed germination by increasing the expression of ABA biosynthesis and ABA signaling genes, as well as genes that negatively regulate GA signaling (Izydorczyk et al, 2018), leading to an increase in embryonic ABA levels and ABA sensitivity, as well as decreased embryo GA sensitivity (Izydorczyk et al, 2018).…”

“…However, we hypothesize that by interfering with primary metabolism (i.e. respiration) (Bicalho et al, 2017), metals may induce ROS production that can:…”

Temperature and Light Modulation of Herbicide Toxicity on Algal and Cyanobacterial Physiology

“…Temperature modulates the enzymatic activities involved in repair processes (including the activation, synthesis, or repair of damaged molecules) (Sobrino and Neale, 2007) needed to counteract the damages induced by exposure to pollutants. Temperature can also interact additively or synergistically with pollutants, accentuating their detrimental effects on cellular mechanisms (Bicalho et al, 2017).…”