Expression differences for genes involved in lignin, glutathione and sulphate metabolism in response to cadmium in Arabidopsis thaliana and the related Zn/Cd‐hyperaccumulator Thlaspi caerulescens

Abstract

Cadmium (Cd) is a widespread, naturally occurring element present in soil, rock, water, plants and animals. Cd is a non-essential element for plants and is toxic at higher concentrations. Transcript profiles of roots of Arabidopsis thaliana (Arabidopsis) and Thlaspi caerulescens plants exposed to Cd and zinc (Zn) are examined, with the main aim to determine the differences in gene expression between the Cd-tolerant Zn-hyperaccumulator T. caerulescens and the Cd-sensitive non-accumulator Arabidopsis. This comparative transcriptional analysis emphasized the role of genes involved in lignin, glutathione and sulphate metabolism. Furthermore the transcription factors MYB72 and bHLH100 were studied for their involvement in metal homeostasis, as they showed an altered expression after exposure to Cd. The Arabidopsis myb72 knockout mutant was more sensitive to excess Zn or iron (Fe) deficiency than wild type, while Arabidopsis transformants overexpressing bHLH100 showed increased tolerance to high Zn and nickel (Ni) compared to wild-type plants, confirming their role in metal homeostasis in Arabidopsis.

MYB72 Is Required in Early Signaling Steps of Rhizobacteria-Induced Systemic Resistance in Arabidopsis

“…Analysis of the Arabidopsis transcriptome using the Arabidopsis microarray database and analysis toolbox GENEVESTIGATOR (Zimmermann et al, 2004) confirmed that MYB72 is not activated in response to any of the hormones or biological agents tested (data not shown), suggesting that the induction of MYB72 in the roots upon colonization by nonpathogenic rhizobacteria is highly specific. However, low iron conditions or treatment of Arabidopsis roots with an excess amount of zinc do induce the expression of MYB72 in the roots (Colangelo and Guerinot, 2004;Van de Mortel et al, 2008). Studies by Thomine et al (2003) and Van A, RNA gel-blot analysis of MYB72 transcript levels in roots and shoots of 5-week-old wildtype Col-0 plants and the mutant and transgenic lines EV (EV control), myb72-1, and 35S:MYB72-OX1 to -OX7.…”

Response to metal stress of Nicotiana langsdorffii plants wild-type and transgenic for the rat glucocorticoid receptor gene

“…Response processes are specific for each different stress conditions as shown by the lack of any uniform transcriptome profile of plants subjected to different types of stress such as heat or cold, drought or salinity, strong light, mechanical and heavy metal stress (Cheong et al, 2002;Debnath et al, 2011;Kreps et al, 2002;Mantri et al, 2012;Marco et al, 2011;Rizhsky et al, 2004;Shen et al, 2012;Van de Mortel et al, 2008;Yang and Chu, 2011). Integrated responses to different biotic and abiotic stress conditions are regulated by the hormonal network of the plants, including auxins, cytokinins, abscisic acid (ABA), 3-indole acetic acid (IAA) and brassinosteroids (Bajguz and Hayat, 2009), which combined with many metabolites (i.e., jasmonic acid and ethylene) and secondary messengers (i.e., Ca 2+ ) play a pleiotropic regulatory key role.…”

Structural changes in leaves and roots are anatomical markers of aluminum sensitivity in sunflower1

“…The Al-sensitive IAC-Uruguai plants showed an increase in the number of root cells with highly lignified cell walls. In some cases, lignification may be beneficial, forming a physical barrier against toxic metals (Van de Mortel et al 2008). Alternatively, in a number of plant species, increased lignification occurs in response to mechanical damage in tissues, such as rupture of epidermal cell layer (Moura et al 2010).…”

“…Absolute integrity percentage, estimated based on electrolyte leakage (Vásquez-Tello et al 1990), and relative water content were measured in the youngest fully expanded leaf at 1, 5, 10 and 15 days after the AlCl 3 application. Leaf discs were placed in closed tubes containing 10 mL of deionized water and incubated in the dark for 24 h, at 8 ºC.…”

“…It has been observed that metal stress induces the lignification of root tissues (Moura et al 2010). This anatomical change is a barrier against toxic metals, decreasing the influx into the central cylinder (Van de Mortel et al 2008, Shu et al 2012. On the other hand, increased root lignin levels may reduce the water uptake (Emam & Bijanzadeh 2012), affecting cell elongation (Sasaki et al 1996).…”