Salicylic acid alleviates arsenic and zinc toxicity in the process of reserve mobilization in germinating fenugreek (Trigonella foenum-graecum L.) seeds

To improve plant growth and increase yield and crop quality, the farmer uses many organic or mineral substances. The presence of extensive mineral substances causes high concentrations of heavy metals. Among these heavy metals we can find arsenic (As) and zinc (Zn). The purpose of this study was to evaluate the physiological parameters (the growth, nutrient elements, soluble sugars contents, etc.) and the enzymatic and nonenzymatic antioxidative systems in radicles and cotyledons of Trigonella foenum-graecum L. after treatment with 0, 3 of Na2HAsO4 center dot 7H(2)O and 5 mM of ZnSO4 for 72 h of germination. As and Zn treatment caused a significant reduction of radicle and cotyledon growth, chlorophyll and carotenoid contents, the accumulation of mineral nutrients (K, Ca, and Cu), soluble proteins and free amino acids in cotyledons, as well as the activities of hydrolytic enzymes (amylase and phosphatase). The increasing As and Zn concentration resulted in the stimulation of SOD, CAT, APX, and GR activities. The detrimental effects of As and Zn were reversed after applying 0.2 mM salicylic acid (SA), causing an increase in radicle growth, soluble sugar, protein and free amino acid contents in cotyledons and radicles. Similarly, the activities of hydrolytic enzymes (alpha- and beta-amylase) were enhanced. On the other hand, cell viability declined, even after the addition of SA. These results suggest that SA may improve fenugreek seedling growth by providing protection against the toxic effects of heavy metal stress caused by As and Zn. (C) 2019 SAAB. Published by Elsevier B.V. All rights reserved.