Abstract
Cadmium (Cd) contamination, which poses a serious threat to human health, has been recognized as a major threat to the agricultural system and crop production. Salicylic acid (SA) is a signaling molecule that plays an important role in against Cd toxicity. Previously, we found that spraying rice with SA could reduce the Cd accumulation in rice grains grown in Cd-contaminated soil. In this study, we studied the specific mechanism of SA spray on reducing Cd accumulation in rice grain. The results showed that treatment with SA could alleviate Cd toxicity in rice by increasing the activities of antioxidant enzymes that reduce hydrogen peroxide (H2O2) accumulation, but not by changing the pH, or total or available Cd of the soil. The key factor by which SA treatment reduced Cd accumulation in rice grains was by decreasing the Cd content in rice leaves at the flowering stage. This indicated that SA could modulate the Cd accumulation in shoots, reducing the Cd translocation to rice grains. Furthermore, SA could increase the H2O2 content, activating the SA-signaling pathway and modulating the expression levels of Cd transporters (OsLCT1 and OsLCD) in rice leaves to increase Cd tolerance and reduce Cd accumulation in the rice grain. Thus, spraying rice with SA may be effective measure to cope with Cd contamination in paddy soils.
Highlights
Growing population and fast industrialization coincide together, results in the generation and dissemination of huge amount of toxic metals in the environment (Hasanuzzaman et al, 2012)
In the previous field experiments, we found that Salicylic acid (SA) spraying could reduce the Cd accumulation of rice grain grown in Cd-contaminated soil
SA application could relieve the Cd toxicity obviously, increased the plant height and shoot Dw plant-1 of the Cd-exposed rice plants, but there was no significant difference between Cd and AOPP+Cd groups (Table 2 and 3), the same trends were observed at all the three stages of rice plants
Summary
Growing population and fast industrialization coincide together, results in the generation and dissemination of huge amount of toxic metals in the environment (Hasanuzzaman et al, 2012). Cd is one of the most phytotoxic heavy metals which have no biological role in plants, and its contamination in agricultural soil has become a great problem for crop production in recent decades. As a common soil pollutant, Cd can accumulate in plant tissues to cause toxicity and enter human through the food chain and drinking water to cause diseases in kidney, bone and respiratory system and cancers (Zhou et al, 2017). Rice is an important staple food for nearly half of the world’s population (Valipour et al 2015) and is a major source of Cd uptake for people. Cd-contaminated rice has occurred in China, which poses important public health risks (Liu et al, 2016b). It is essential to produce low-Cd rice to reduce the potential risks that Cd poses to human health
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