Plant-Derived Smoke Ameliorates Salt Stress in Wheat by Enhancing Expressions of Stress-Responsive Genes and Antioxidant Enzymatic Activity

Abstract

Abiotic stresses are the biggest threat to the increasing population worldwide. Salt stress is one of the most significant abiotic stresses, affecting 20% of the crop production around the world. Plant-derived smoke (PDS) has been reported as a biologically active plant product in stimulating seed germination, seedling growth and physiological characteristics of crops under abiotic stress conditions. Nevertheless, studies showing how PDS alleviates salt stress are largely unknown. Here, we report the molecular mechanism of how PDS could alleviate salt stress in wheat. Initially, PDS at 2000 ppm enhanced seed germination, root/shoot length and seedling fresh weight. However, PDS at 1000 and 500 ppm did not show any significant effect. Salt stress at 150 and 200 mM significantly reduced seed germination rate, root/shoot length and fresh weight of the wheat seedlings. Interestingly, PDS supplementation at 2000 ppm concentration was sufficient to restore seed germination under salt stress condition. Moreover, PDS improved root/shoot length and seedling biomass under 150 and 200 mM salt stress, suggesting that PDS is a potent plant product, capable of abiotic stress alleviation in crops. In comparison to the control, PDS-treated seedlings displayed increased activity of major antioxidative enzymes such as superoxide dismutase, peroxidase and ascorbate peroxidase under salt stress, resulting in reduced levels of hydrogen peroxide and lipid peroxidase, showing that PDS can possibly help in salt stress amelioration by regulating redox homeostasis. Importantly, salt stress altered the expression of germination marker genes, such as TaSAM, TaPHY, TaBGU (germination positive effectors), TaLEA and TaGARS34 (germination negative effectors), suggesting the potential role of PDS in the germination pathway under salt stress. Further, PDS modulated the transcript levels of several salt stress stress-responsive genes, including TaSOS4, TaBADH and TaHKT2. In conclusion, this study provides a molecular and physiological basis for elucidating the mechanism of how PDS functions in stress induction in wheat, as well as demonstrates the importance of PDS in agricultural practices, laying the groundwork for future research into the role of PDS in the amelioration of abiotic stresses in various plants.

Plant-Derived Smoke Solution Alleviates Cellular Oxidative Stress Caused by Arsenic and Mercury by Modulating the Cellular Antioxidative Defense System in Wheat

“…Likewise, the majority of biochemical and physiological processes also get disturbed because of toxicity [ 48 , 49 , 50 , 51 ]. Recently, various concentrations of PDS have been used to restore plant growth under salt stresses; however, of these concentrations, PDS (2000 ppm) was found to most significantly alleviate the negative effect of salt stress [ 43 ]. Looking at the previous findings with PDS 2000 ppm, in the present study, we used PDS 2000 ppm to counteract the inhibitory effects of As and Hg stress, which is considered an ultimatum to the environment.…”

“…A detailed study regarding the mitigatory role of PDS on the alleviation of negative effects of abiotic and heavy metal stress indicated that PDS plays a significant role in enhancing plant growth under heavy metal stress (Shabbir and Ilyas 2019, book chapter). Recently, PDS has been reported to mitigate the toxic effects of salt stress in wheat germination, seedling growth, and seedling fresh biomass [ 43 ]. Another study determined the well-proven alleviation effects of PDS on salt stress and improved the seed germination rate in maize [ 27 ].…”

“…These results are in line with those that found that As, Hg, and Ni toxicity increased H 2 O 2 and MDA contents in Glycine max , maize, and Allium species [ 70 , 71 , 72 ]. A recent study showed high levels of H 2 O 2 and TBARS under salt stress, while the application of PDS reduced the levels of H 2 O 2 and TBARS under salt stress [ 43 ]. These findings conclude that PDS has the capability of ameliorating As and Hg stress by reducing the oxidative stress in plant cells.…”

“…C. jwarancusa plants were thoroughly washed with water and shade dried for 15 days. PDS solution was prepared by weighing 333 gm of the semi-shade-dried leaves of C. jwarancusa which were burned in a locally constructed furnace on an electric heater [ 42 , 43 ]. The furnace’s window was sealed with aluminum foil to reduce the possibility of smoke leakage.…”

“…The resulting solution was called a stock solution which was further diluted to 2000 ppm for further use in the experiment. Previously, we screened several PDS dilutions such as 500, 1000 and 2000 ppm for the alleviation of salt stress [ 43 ]. PDS 2000 ppm significantly alleviated the salt stress and during present experiments, PDS 2000 ppm performed better.…”