Salicylic acid-mediated alleviation of cadmium toxicity in hemp plants in relation to cadmium uptake, photosynthesis, and antioxidant enzymes

Abstract

To assess the role of salicylic acid (SA) in alleviating cadmium (Cd) toxicity in hemp (Cannabis sativa L.) plants, the growth parameters, Cd accumulation, photosynthetic performance and activities of major antioxidant enzymes were investigated in hemp seedlings treated with 500 lM SA, under 0, 25, 50, and 100 mg Cd kg -1 sands (DW) conditions, respectively. Cd exposure resulted in a small reduction in biomass (12.0-26.9% for root, and 8.7-29.4% for shoot, respectively), indicating hemp plants have innate capacity to tolerant Cd stress. This was illustrated by little inhibition in photosynthetic performance, unchanged malondialdehyde content, and enhancement of superoxide dismutase (SOD) and peroxidases (POD) activities in hemp plants. Cd content in root is 25.0-29.5 times' higher than that in shoot, suggesting the plant can be classified as a Cd excluder. It is concluded that SA pretreatment counteracted the Cd-induced inhibition in plant growth. The beneficial effects of SA in alleviating Cd toxicity can be attributed to the SA-induced reduction of Cd uptake, improvement of photosynthetic capacity, and enhancement of SOD and POD activities.

Cadmium Bioavailability, Uptake, Toxicity and Detoxification in Soil-Plant System

“…Later, Belkadhi et al 2015 further reported that exogenous SA also protected phospholipids of L. usitatissimum by decreasing the percentages of monogalactosyldiacylglycerol, phosphatidylcholine, phosphatidylethanolamine and phosphatidylglycerol. The net result of exogenous SA application is the alleviation of Cd-induced root growth inhibition and overall attenuation of Cd toxicity-the latter of which has been reported for a variety of plants (e.g., V. faba (Popova et al 2009), O. sativa ), B. juncea (Ahmad et al 2011), G. max (Drazic andMihailovic 2005), L. usitatissimum (Belkhadi et al 2010), H. vulgare (Tamás et al 2015), Cannabis sativa (Shi et al 2009), Z. mays (Krantev et al 2008), T. aestivum (Agami and Mohamed 2013) and Pisum sativum (Popova et al 2009)). Salicylic acid is reported to reduce Cd toxicity to plants not only at the level of antioxidant defense but also by altering other mechanisms of Cd detoxification which are not yet well known (Gallego et al 2012).…”

Salicylic Acid Improves Root Antioxidant Defense System and Total Antioxidant Capacities of Flax Subjected to Cadmium

“…Furthermore, SA application has been reported to alleviate the symptoms of Cd toxicity observed in plants (Zawoznik et al, 2007;Zhang and Chen, 2011). Previous studies have shown that SA treatment mitigates the oxidative stress generated by Cd in different plant species such as barley (Metwally et al, 2003), soybean (Drazic and Mihailovic, 2005), rice (Guo et al, 2007), maize (Krantev et al, 2008), pea (Popova et al, 2009), and hemp (Shi et al, 2009). However, little has been reported about the role of SA in the increase of total antioxidant capacities under Cd stress.…”

Salicylic acid and nitric oxide alleviate osmotic stress in wheat (Triticum aestivum L.) seedlings

“…Signaling compounds such as SA or NO have dual functions as potent oxidant or effective antioxidant mostly depends on their concentrations and on the status of the environments (Shi et al 2009). When applied at appropriate low concentrations, they are able to reduce the severity of stresses in many species (Horvath et al 2007), by inducing transient oxidative stress in plants, which acts as a hardening process, increasing antioxidant capacity of plants (Horvath et al 2007).…”

“…SA is an important signal involved in the activation of plant defense responses against abiotic and biotic stresses and plays a crucial role for the regulation of physiological and biochemical processes (Saruhan et al 2012). Effects of SA on plants are concentration dependent, treatment duration, plant species, age at treatment, and plant organ examined used for pretreatment (Shi et al 2009).…”