Exogenous cysteine alleviates mercury stress by promoting antioxidant defence in maize (Zea mays L.) seedlings

Authors : Ferhunde AYSİN, Aykut KARAMAN, Asli YİLMAZ, Ozkan AKSAKAL, Ebru GEZGİNCİOGLU, Sakineh Mohammadi KOHNEHSHAHRİ

Pages : 506-516

View : 12 | Download : 6

Publication Date : 2020-10-01

Article Type : Research Paper

Abstract :Mercury insert ignore into journalissuearticles values(Hg); is one of the most important environmental pollutants that negatively affects plant growth and development. Cysteine insert ignore into journalissuearticles values(Cys); plays an important role in plant response to various environmental stress factors. In the present study, the alleviation of Hg stress through exogenous Cys treatment to maize seedlings was evaluated. For this purpose, a hydroponic experiment was set up to investigate the effect of HgCI2 insert ignore into journalissuearticles values(100 μM); and in combination with Cys insert ignore into journalissuearticles values(200 μM); on plant growth, total chlorophyll content, reactive oxygen species, antioxidant enzyme activities, and mRNA expression levels of some antioxidant genes in maize seedlings. The results showed that HgCI2 treatment significantly decreased both root and shoot growth and total chlorophyll content, also increased the malondialdehyde insert ignore into journalissuearticles values(MDA);, hydrogen peroxide insert ignore into journalissuearticles values(H2O2);, and superoxide levels insert ignore into journalissuearticles values(O2.–); in maize seedlings. After treatment with 200 μM exogenous Cys combined with 100 μM HgCl2, root and shoot growth and total chlorophyll content increased and the concentration of MDA, H2O2, O2 .– in seedlings notably decreased and catalase insert ignore into journalissuearticles values(CAT);, glutathione reductase insert ignore into journalissuearticles values(GR);, superoxide dismutase insert ignore into journalissuearticles values(SOD);, and peroxidase insert ignore into journalissuearticles values(POD); activities in seedlings increased significantly. In addition, HgCI2 treatment alone or combination with Cys markedly increased the root and leaf Hg content. The higher amounts of Hg accumulated in the roots of the seedlings. Furthermore, qRT-PCR results showed that the mRNA levels of CAT, GR, and SOD genes were up-regulated at HgCI2 + Cys treatment groups compared to the HgCI2 treatment alone. The results of the study indicated that exogenous Cys improved resistance to Hg-stress in maize seedlings by activating antioxidant defence system.
Keywords : Antioxidant, cysteine, gene expression, glutathione, mercury