Alleviation of Copper Toxicity in Arabidopsis thaliana by Silicon Addition to Hydroponic Solutions

Abstract

<jats:p>Copper (Cu) is an essential micronutrient for plants and is the a.i. in pesticides for some pathogens and algae. Elevated doses of Cu can cause toxicity in plants. While silicon (Si) is reported to alleviate the toxicity of some heavy metals, its role in reducing the symptoms induced by excess Cu is unclear. Therefore, the role of Si in plant response to Cu stress was investigated in arabidopsis [<jats:italic>Arabidopsis thaliana</jats:italic> (L.) Heyn.]. Based on plant symptoms (a reduction of leaf chlorosis as well as increased shoot and root biomass) and a reduction of phenylalanine ammonia lyase [PAL (EC 4.3.1.5), a stress-induced enzyme] activity in the shoot, Si was found to alleviate copper stress. Real-time reverse transcriptase-polymerase chain reaction analyses indicated that the RNA levels of two arabidopsis copper transporter genes, <jats:italic>copper transporter 1</jats:italic> (<jats:italic>COPT1</jats:italic>) and <jats:italic>heavy metal ATPase subunit 5</jats:italic> (<jats:italic>HMA5</jats:italic>) were induced by high levels of Cu, but were significantly decreased when Si levels were also elevated. Taken together, our findings indicate that Si addition can improve the resistance of arabidopsis to Cu stress, and this improvement operates on multiple levels, ranging from physiological changes to alterations of gene expression.</jats:p>

Citric acid assisted phytoremediation of copper by Brassica napus L.

“…2) and, as a result, plants growth and biomass was decreased in B. napus. Earlier studies showed that 30 mM Cu in hydroponic decreased root growth and caused leaf chlorosis in Arabidopsis thaliana (Li et al, 2008) while, 7.5 mM Cu can cause upto 50% reduction in root of biomass maize (Ouzounidou et al, 1995). However, the degree of damage to the growth of B. napus as observed in the present study is relatively low, which indicated a level of Cu stress tolerance in this plant.…”

Silicon delays Tobacco ringspot virus systemic symptoms in Nicotiana tabacum

“…TMV was resuspended in sodium phosphate buffer (pH 7.0), mixed with washed celite and used for inoculum. N. tabacum seeds were germinated hydroponically in nutrient solution containing 0.1 mM soluble K 2 SiO 3 as described by Li et al (2008). Plants were hydroponically propagated in a growth chamber at 20 • C under a 16 h light: 8 h dark photoperiod at a light intensity of 70 mol m −2 s −1 of photosynthetically active radiation.…”

Distribution and variability of silicon, copper and zinc in different bamboo species

“…These authors suggested that the formation of Zn-silicate compounds in the cytoplasm may be responsible for the alleviation of the Zn toxicity. In Arabidopsis thaliana, Li et al (2008) have shown that Si improves the resistance to Cu stress. A recent study has shown that Si modulates the expression of various genes involved in Cu tolerance in A. thaliana (Khandekar and Leisner 2011).…”