Silicon alleviates copper (Cu) toxicity in cucumber by increased Cu-binding capacity
- 106 Downloads
Although silicon (Si) is known to increase plant resistance to metal toxicity stress, the mechanisms responsible for alleviation of copper (Cu) toxicity are still insufficiently clear. We investigated the role of Si on Cu-binding processes involved in buffering excessive Cu in cucumber (Cucumis sativus L.) tissues.
Cucumber plants were subjected to moderate Cu toxicity stress (10 μM Cu) without (−Si) or with (+Si) supply of 1.5 mM Si. We analyzed total and cell wall concentrations of Cu and Cu-binding compounds (organic acids and Cu-proteins) along with parameters of oxidative stress (e.g. lipid peroxidation and lignification).
Supply of Si decreased total Cu concentration in both root and leaf tissues, but increased the root cell wall Cu fraction. Also, Si increased superoxide dismutase (SOD) activity in 10 μM Cu-treated plants. Concomitantly, protein levels of Cu/Zn SOD isoforms (CSD1 and CSD2) in root tissues also increased in +Si plants. The leaf Cu-binding compounds, such as aconitate and plastocyanin (including the expression of CsPC gene) were higher in the +Si plants. Consequently, Si supply effectively lowered lipid peroxidation in both roots and leaves of Cu-stressed plants.
Supply of Si enhanced both the accumulation of Cu-binding molecules (Zn/Cu SOD in roots; aconitate and plastocyanin in leaves), and the Cu-binding capacity of the root cell wall.
KeywordsCell wall SOD Copper toxicity Cucumber (Cucumis sativus L.) Plastocyanin Silicon
This work was supported by the Serbian Ministry of Education, Science and Technological Development (ON-173005 and ON-173028) and in part by the grant of bilateral scientific cooperation between Serbia and Slovakia SK-SRB-2013-0021 (451-03-545/2015-09/02). We thank Dr. Nina Nikolic (University of Belgrade, Serbia) for critical reading of the manuscript.
- Choi SM, Suh KH, Kim J-S, Park Y-I (2001) Inactivation of photosystem I in cucumber leaves exposed to paraquat-induced oxidative stress. J Photosci 8:13–17Google Scholar
- Cohu CM, Abdel-Ghany SE, Gogolin Reynolds KA, Onofrio AM, Bodecker JR, Kimbrel JA, Niyogi KK, Pilon M (2009) Copper delivery by the copper chaperone for chloroplast and cytosolic copper/zinc-superoxide dismutases: regulation and unexpected phenotypes in an Arabidopsis mutant. Mol Plant 2:1336–1350CrossRefGoogle Scholar
- Geng A, Wang X, Wu L, Wang F, Wu Z, Yang H, Chen Y, Wen D, Liu X (2018) Silicon improves growth and alleviates oxidative stress in rice seedlings (Oryza sativa L.) by strengthening antioxidant defense and enhancing protein metabolism under arsanilic acid exposure. Ecotoxicol Environ Saf 158:266–273CrossRefGoogle Scholar
- Líška D, Soukup M, Lukačová Z, Bokor B, Vaculík M (2017) Mechanisms of silicon-mediated alleviation of abiotic stress in plants: recent advances and future perspective. In: Tripathi D, Singh V, Ahmad P, Chauhan D, Prasad S (eds) Silicon in plants: advances and future prospects. CRC Press, Taylor & Francis, Boca Raton, pp 1–27Google Scholar
- Lux A, Vaculík M, Kováč J (2015) Improved methods for clearing and staining of plant samples. In: Yeung E, Stasolla C, Sumner M, Huang B (eds) Plant microtechniques and protocols. Springer, pp 167–178Google Scholar
- Marschner H (1995) Mineral nutrition of higher plants. Academic Press, LondonGoogle Scholar
- Moura JCMS, Bonine CAV, de Oliveira Fernandes Viana J, Dornelas MC, Mazzafera P (2010) Abiotic and biotic stresses and changes in the lignin content and composition in plants. J Integr Plant Biol 52: 360–376Google Scholar
- Sagasti S, Bernal M, Sancho D, B. del Castillo M, Picorel R (2014) Regulation of the chloroplastic copper chaperone (CCS) and cuprozinc superoxide dismutase (CSD2) by alternative splicing and copper excess in Glycine max. Funct Plant Biol 41: 144–155Google Scholar