Strigolactones Modulate Cellular Antioxidant Defense Mechanisms to Mitigate Arsenate Toxicity in Rice Shoots

Abstract

Metalloid contamination, such as arsenic poisoning, poses a significant environmental problem, reducing plant productivity and putting human health at risk. Phytohormones are known to regulate arsenic stress; however, the function of strigolactones (SLs) in arsenic stress tolerance in rice is rarely investigated. Here, we investigated shoot responses of wild-type (WT) and SL-deficient d10 and d17 rice mutants under arsenate stress to elucidate SLs’ roles in rice adaptation to arsenic. Under arsenate stress, the d10 and d17 mutants displayed severe growth abnormalities, including phenotypic aberrations, chlorosis and biomass loss, relative to WT. Arsenate stress activated the SL-biosynthetic pathway by enhancing the expression of SL-biosynthetic genes D10 and D17 in WT shoots. No differences in arsenic levels between WT and SL-biosynthetic mutants were found from Inductively Coupled Plasma-Mass Spectrometry analysis, demonstrating that the greater growth defects of mutant plants did not result from accumulated arsenic in shoots. The d10 and d17 plants had higher levels of reactive oxygen species, water loss, electrolyte leakage and membrane damage but lower activities of superoxide dismutase, ascorbate peroxidase, glutathione peroxidase and glutathione S-transferase than did the WT, implying that arsenate caused substantial oxidative stress in the SL mutants. Furthermore, WT plants had higher glutathione (GSH) contents and transcript levels of OsGSH1, OsGSH2, OsPCS1 and OsABCC1 in their shoots, indicating an upregulation of GSH-assisted arsenic sequestration into vacuoles. We conclude that arsenate stress activated SL biosynthesis, which led to enhanced arsenate tolerance through the stimulation of cellular antioxidant defense systems and vacuolar sequestration of arsenic, suggesting a novel role for SLs in rice adaptation to arsenic stress. Our findings have significant implications in the development of arsenic-resistant rice varieties for safe and sustainable rice production in arsenic-polluted soils.

Silicon and Strigolecton Application Alleviates the Adversities of Cadmium Toxicity in Maize by Modulating Morpho-Physiological and Antioxidants Defense Mechanisms

“…The defense mechanism of stressed plants was found to be more efficient in terms of antioxidant enzymes and osmo-protectant (proline, total soluble sugars, soluble protein, and total phenolics) accumulation when Cd-stressed plants experienced SL and Si + SL (with Si + SL being more pronounced). These findings are also supported by Qiu et al [63] and Mostafa et al [64]. As reported by Mostafa et al [64], SL biosynthesis in response to heavy metal stress stimulates the antioxidant system at the cell level and the sequestration of arsenic in vacuole.…”

“…These findings are also supported by Qiu et al [63] and Mostafa et al [64]. As reported by Mostafa et al [64], SL biosynthesis in response to heavy metal stress stimulates the antioxidant system at the cell level and the sequestration of arsenic in vacuole. This stress-related response from SL can also account for improvement of antioxidant efficiency in Cd-stressed maize plants and osmolyte accumulation, resulting in enhanced plant performance.…”

Strigolactones as a hormonal hub for the acclimation and priming to environmental stress in plants

“…Consistently, a trove of findings with potential application impact has been building up, especially in connection with the use of GR24 treatment before or during stress to improve crop performances. The stresses covered by this kind of studies range from heat and cold (Chi et al, 2021 ; Omoarelojie et al, 2020 , 2021 , X. Zhang et al, 2020 ); low light, and related senescence and growth inhibition (Lu et al, 2019 ; Mayzlish‐Gati et al, 2010 ; Tian et al, 2018 ; Zhou et al, 2022 ); high light (Thula et al, 2022 ); to heavy metals such as cadmium (Chen et al, 2007 ; Niu et al, 2021 ; Qiu et al, 2021 ; Tai et al, 2017 ) and the metalloid arsenic (Mostofa, Ha, et al, 2021 ; Mostofa, Rahman, et al, 2021 ). We will focus here mostly on the connections between strigolactones and responses to osmotic stress, while the results exploring protection from other abiotic stresses are summarized in Table 1 .…”

“…In a further example, cadmium stress is both better tolerated in GR24treated plants, and in part avoided, since it appears that treatment helps the plant exclude the toxic metal, reducing its uptake (Qiu et al, 2021;Tai et al, 2017). A similar situation is reported for arsenate (Mostofa, Ha, et al, 2021;. Finally, rac-GR24 triggers a more efficient water-saving phenotype (and thus, drought avoidance) in leaves of grapevine (Vitis vinifera L.) under PEG-induced osmotic stress, by allowing to maintain net carbon assimilation rates in the presence of lower stomatal conductance.…”

Halotolerant Pseudomonas koreensisS4T10 mitigate salt and drought stress in Arabidopsis thaliana

“…Plants protect themselves by enhancing enzymatic and non‐enzymatic antioxidants, whereas superoxide dismutase (SOD) is a key enzyme that neutralizes O 2 •− by converting it into O 2 and H 2 O 2 (Bowler et al, 1992, Rahman et al, 2021). Moreover, GSH‐dependent enzymes, such as glutathione peroxidase (GPX) and glutathione S‐transferase (GST), neutralize toxic aldehydes produced as by‐products of ROS‐triggered lipid oxidation (Csiszár et al, 2016, Mostofa et al, 2021). Polyphenol oxidase (PPO) is responsible for breaking down the phenol group into o ‐quinones, which play a role in reducing various ROS (Thipyapong et al, 2004, Boeckx et al, 2015).…”