Plant Process and Function

en Pretreatment with salicylic acid and nitric oxide alleviates silver nanoparticles toxicity in medicinal Hypericum perforatum plants Pretreatment with salicylic acid and nitric oxide alleviates silver nanoparticles toxicity in medicinal Hypericum perforatum plants تنش فلزات سنگین Toxic ions stress پژوهشي Research <div style="text-align: left;">Since the use of seed priming agents to reduce the potential toxicity of AgNPs has not been explored, we evaluated the combined effects of 0.1 mM salicylic acid (SA) and 0.1 mM nitric oxide (NO) on responses of Hypericum perforatum plants to Ag-induced stress. The results of growth parameters together with measurement of malondialdehyde (MDA) revealed that exposure to AgNPs or AgNO3 caused more toxicity, which was closely associated with the over–accumulation of ROS. However, SNP (NO) and SA addition successfully mitigated adverse impact of AgNPs on H. perforatum seedlings, which was associated with the higher synthesis of chlorophyll b pigments and proline. In addition, a further increase in antioxidants (phenolic compounds) was observed in NO-primed plants under AgNPs-induced stress, which was concomitant with the high level of SOD activity. We concluded that NO minimized the inhibitory effects of AgNPs stress by increasing the phenolic compounds as well as by regulating accumulation of Ag, ROS and antioxidants. To sum up, exogenous NO plays a key role in enhancing its resistance to Ag stress in physiological base, thereby improving the growth and phenolic compounds production (chlorogenic acid, quercetin and rutin) of H. perforatum plant. </div> Since the use of seed priming agents to reduce the potential toxicity of AgNPs has not been explored, we evaluated the combined effects of 0.1 mM salicylic acid (SA) and 0.1 mM nitric oxide (NO) on responses of Hypericum perforatum plants to Ag-induced stress. The results of growth parameters together with measurement of malondialdehyde (MDA) revealed that exposure to AgNPs or AgNO3 caused more toxicity, which was closely associated with the over–accumulation of ROS. However, SNP (NO) and SA addition successfully mitigated adverse impact of AgNPs on H. perforatum seedlings, which was associated with the higher synthesis of chlorophyll b pigments and proline. In addition, a further increase in antioxidants (phenolic compounds) was observed in NO-primed plants under AgNPs-induced stress, which was concomitant with the high level of SOD activity. We concluded that NO minimized the inhibitory effects of AgNPs stress by increasing the phenolic compounds as well as by regulating accumulation of Ag, ROS and antioxidants. To sum up, exogenous NO plays a key role in enhancing its resistance to Ag stress in physiological base, thereby improving the growth and phenolic compounds production (chlorogenic acid, quercetin and rutin) of H. perforatum plant. Chlorogenic acid, Exogenous nitric oxide, Hypericum perforatum, Salicylic acid, Silver nanoparticle, Toxicity Chlorogenic acid, Exogenous nitric oxide, Hypericum perforatum, Salicylic acid, Silver nanoparticle, Toxicity 83 93 http://jispp.iut.ac.ir/browse.php?a_code=A-10-737-7&slc_lang=en&sid=1 Elham Ghasemifar Elham Ghasemifar 100319475328460030354 100319475328460030354 No Department of Biology, Payame Noor University (PNU), PO BOX 19395-3697 Tehran, Iran Department of Biology, Payame Noor University (PNU), PO BOX 19395-3697 Tehran, Iran Ghader Habibi Ghader Habibi gader.habibi@gmail.com 100319475328460030355 100319475328460030355 Yes Department of Biology, Payame Noor University (PNU), PO BOX 19395-3697 Tehran, Iran Department of Biology, Payame Noor University (PNU), PO BOX 19395-3697 Tehran, Iran Golamreza Bakhshi-Khaniki Golamreza Bakhshi-Khaniki 100319475328460030356 100319475328460030356 No Department of Biology, Payame Noor University (PNU), PO BOX 19395-3697 Tehran, Iran Department of Biology, Payame Noor University (PNU), PO BOX 19395-3697 Tehran, Iran