Combined ability of salicylic acid and spermidine to mitigate the individual and interactive effects of drought and chromium stress in maize (Zea mays L.).
Application of the growth regulator salicylic acid (SA) and the polyamine spermidine (Spd) can be used to manage various plant abiotic stresses. We aimed to evaluate the sole and combined effects of SA and Spd on maize (Zea mays) under individual and combined drought and chromium (Cr) stress. Drought, Cr, and drought + Cr treatments caused oxidative stress by inducing higher production of reactive oxygen species (H2O2, O2-), enhanced malondialdehyde content and increased relative membrane permeability. Increased oxidative stress and higher Cr uptake in the host plant reduced the content of carotenoids, other photosynthetic pigments and protein, and changed carbohydrate metabolism. Combined drought + Cr stress was more damaging for the growth of maize plants than the individual stresses. Exogenous treatments of SA and Spd alleviated the adverse effects of drought and Cr toxicity, reflected by accumulations of osmolytes, antioxidants and endogenous polyamines. Single applications of Spd (0.1 mM) increased plant height, shoot fresh weight, leaf area, above-ground dry matter accumulation and polyamine content under drought, Cr, and drought + Cr stress conditions. However, the combined treatment SA + Spd (0.25 mM + 0.05 mM) was more effective in increasing protein and water contents, photosynthetic pigments, and carotenoids. The same treatment increased Cr tolerance in the maize plants by decreasing uptake of this heavy metal from root to shoot. The SA + Spd treatment also decreased oxidative stress by promoting antioxidant enzyme activities, and enhanced levels of proline, soluble sugars, and carbohydrate contents under individual and combined stress conditions. Results indicate that the combined half-dose application of SA + Spd may be utilized to boost the tolerance in maize under individual as well as combined drought and Cr stress conditions.
Naz R
，Sarfraz A
，Anwar Z
，Yasmin H
，Nosheen A
，Keyani R
，Roberts TH
... -
《-》
Responses to exogenous elicitor treatment in lead-stressed Oryza sativa L.
Heavy metal toxicity adversely affects plants by changing physiological, biochemical, and molecular mechanisms. Lead (Pb) is one of the most common heavy metal pollutants. Hence this study investigated changes caused by exogenous methyl jasmonate (MeJA; 20 and 100 µM) and salicylic acid (SA; 2 and 20 mM) elicitors in local Karacadağ rice exposed to Pb stress (0, 100, and 400 ppm). The effects of elicitors on photosynthetic pigment content (chlorophyll a, chlorophyll b, and total carotenoid), proline, malondialdehyde (MDA), total phenolic and flavonoid, Pb, and total protein contents in stressed plants were evaluated. All parameters studied increased and decreased at varying rates in the treatment groups compared to the Pb-free group (control), indicating that rice plants were affected by Pb stress. The elicitors (MeJA, SA, and MeJA + SA) were applied by foliar spraying. The elicitor treatments increased photosynthetic pigment content, total protein, proline, total flavonoid, and phenolic contents depending on the elicitor type and concentration. MDA and Pb contents, increasing with Pb toxicity, decreased with elicitor treatments, and the stress degree was reduced. When the elicitors were compared, SA was more effective than MeJA in total flavonoid content at 400 ppm Pb toxicity. However, MeJA was more effective in photosynthetic pigment contents, MDA, total protein, Pb, total phenolic, and proline contents. The best results for all parameters examined in rice plants exposed to Pb toxicity were obtained from the 400 ppm Pb + 2 mM SA + 20 µM MeJA treatment group. In conclusion, this study showed that the combined application of MeJA + SA alleviated the harmful effects of Pb by reducing MDA and increasing photosynthetic pigments, total protein, proline, and secondary metabolites, especially at high Pb concentrations. Consequently, this study demonstrated that the combined use of MeJA and SA in rice plants eliminated the negative effects of stress quite effectively, even at high Pb concentrations. Therefore, future studies should focus on the synergistic application of different elicitors to better understand the effects of heavy metal toxicity on plant growth and development.
Altun H
，Orcan P
《BMC PLANT BIOLOGY》
Role of exogenous-applied salicylic acid, zinc and glycine betaine to improve drought-tolerance in wheat during reproductive growth stages.
Drought has become a dangerous threat to reduce crop productivity throughout the world. Exogenous applications of regulators, micronutrients, and/or osmoprotectants for inducing drought-tolerance in field crops have been effectively adopted. A controlled pot study was performed to investigate the relative efficacy of salicylic acid (SA), zinc (Zn), and glycine betaine (GB) as foliar applications on the growth, tissues pigments content, relative water content (RWC), leaf gas-exchange, antioxidant enzymes activity, reactive oxygen species (ROS) accumulation, osmolytes contents, and the yield parameters of wheat plants subjected to two soil water conditions (85% field capacity: well-watered, 50% field capacity: water-deficient) during reproductive growth stages.
Water deficient conditions significantly decreased the growth, yield parameters, RWC, photosynthesis pigment, and gas-exchange attributes except for intercellular CO2 concentration. However, foliar applications remarkably improved the growth and yield parameters under water deficit conditions. Under drought condition, exogenous applications of SA, Zn, and GB increased the grain yield pot- 1 by 27.99, 15.23 and 37.36%, respectively, as compared to the control treatment. Drought stress statistically increased the contents of hydrogen peroxide (H2O2), superoxide anion radical (O2 •-), and malonaldehyde (MDA), and elevated the harmful oxidation to cell lipids in plants, however, they were considerably reduced by foliar applications. Foliar applications of SA, Zn, and GB decreased MDA content by 29.09, 16.64 and 26.51% under drought stress, respectively, as compared to the control treatment. Activities of all antioxidant enzymes, proline content, and soluble sugar were increased in response to foliar applications under water deficit conditions.
Overall, foliar application of GB, SA, and Zn compounds improved the drought-tolerance in wheat by decreasing the ROS accumulation, promoting enzymatic antioxidants, and increasing osmolytes accumulation. Finally, GB treatment was most effective in thoroughly assessed parameters of wheat followed by SA and Zn applications to alleviate the adverse effects of drought stress.
Shemi R
，Wang R
，Gheith EMS
，Hussain HA
，Cholidah L
，Zhang K
，Zhang S
，Wang L
... -
《BMC PLANT BIOLOGY》
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