Silicon Differentially Influences Copper Toxicity Response in Silicon-accumulator and Non-accumulator Species

Abstract

<jats:p>The use of copper (Cu) in agriculture is widespread as a pesticide, and it is present in high concentrations in certain types of manures. As the use of Cu continues and manure management is incorporated into sustainable systems, the likelihood of Cu toxicity increases. Supplemental silicon has been used to successfully counteract potential micronutrient toxicity. There is currently considerable debate regarding the value of including silicon (Si) as a nutrient in fertility programs and as such, it is not part of a typical management practice in floriculture crop production in the United States. We investigated the potential for Si to ameliorate the effects of Cu toxicity in both a Si-accumulating [zinnia (<jats:italic>Zinnia elegans</jats:italic>)] and a Si-non-accumulating [snapdragon (<jats:italic>Antirrhinum majus</jats:italic>)] species. Using visible stress indicators and dry weight analysis, it initially appeared that Si was a significant benefit to only zinnia under Cu toxicity. Enzymatic assays and elemental analysis of leaves, stems, and roots revealed that both species responded to supplemental Si, showing evidence of reduced stress and nutrient concentrations more similar to healthy, control plants than plants exposed to Cu toxicity. Although there appear to be differences in the extent of Si-mediated amelioration of Cu toxicity between these two plants, both responded to supplemental Si. This adds to the growing body of evidence that all plants likely have Si-mediated responses to stress, and its inclusion into fertility programs should be more broadly considered than current practices.</jats:p>

Mechanisms of silicon-mediated alleviation of heavy metal toxicity in plants: A review

“…Silicon application under Al stress increased Mg and Zn concentrations in shoots and roots of rice as compared to Al treatment alone while Si did not affect the Mn concentration in both parts . Moreover, Si influenced mineral nutrient concentrations, either as a main effect or as an interactive effect, in zinnia (Zinnia elegans) and Erica andevalensis plants under Cu stress (Frantz et al, 2011;Oliva et al, 2011). Under Zn toxicity, Si þZn application increased K, P and Fe in maize ad rice seedling as compared to Zn stress alone (Kaya et al, 2009;Mehrabanjoubani et al, 2014).…”

Effects of Silicon in the Nutrient Solution for Three Horticultural Plant Families on the Vegetative Growth, Cuticle, and Protection Against Botrytis cinerea

“…Researching the possible nutritional role of Si has proven to be challenging due to its various beneficial effects on monocotyledons and dicotyledons as well as the subsequent problems that arise in studies focused solely on one genetic model (Richmond and Sussman, 2003). Although there are apparent differences between the beneficial effects caused by Si in high-accumulator and nonaccumulator plants, published enzymatic assays and elemental analysis results show that both groups responded to supplemental Si (Frantz et al, 2011). In addition, these beneficial effects manifest at multiple levels, ranging from physiological changes to altered gene expression (Khandekar and Leisner, 2011;Li et al, 2008), at least in the response of plants to copper toxicity.…”

“…Recent studies have discussed the possibility of including Si as one of the macronutrients necessary for the nutrition of higher plants (Frantz et al, 2011;Kernan and Marx, 2000). Currently, Si is considered to be a beneficial rather than an essential nutrient for plants, and the effects of Si fertigation have frequently been demonstrated in Siaccumulator crops such as rice and sugarcane (Haynes, 2014).…”

Nutrition and Quality in Ornamental Plants

“…zinnia) vs. low (e.g. snapdragon) Si accumulating plants, mitigation of Cu metal toxicity was observed in both plants in response to Si application, but was much more pronounced in the former (FRANTZ et al, 2011).…”