Effect of lead on physiological and antioxidant responses in two Vigna unguiculata cultivars differing in Pb-accumulation

Abstract

Lead (Pb) is one of the most toxic anthropogenic pollutants, occurring widely in both terrestrial and aquatic ecosystems, where it impairs plant growth and development. In this work, the effect of 0.5 mM EDTA-Pb was evaluated in two Vigna unguiculata cultivars (SV and SET), with the aim of detecting genotype/cultivar dependent changes in the physiological and anti-oxidant responses (CAT and APX) of a leguminous plant. The data showed that SV accumulated more Pb in roots while SET accumulated more in leaves, indicating differential regulation in Pb-translocation/accumulation. Lead affected the growth of SV less severely than SET, mainly associated with reduced inhibition in photosynthetic parameters. Furthermore, CAT and APX activities increased or were sustained at elevated levels in both cultivars in response to lead. However, gene expression analyses revealed that CAT1 was the main lead responsive gene in SET while CAT2 was more responsive in SV. APX1 was higher expressed in tissues with higher Pb-accumulation while APX2 was ubiquitously responsive to lead in both cultivars. Taken together, these results reveal differential ability of V. unguiculata cultivars in Pb-accumulation in different tissues affecting distinctly physiological and anti-oxidant responses. In addition, the existence of cultivars with predominant Pb-accumulation in aerial tissues invokes a need for studies to identify pollution-safe cultivars of leguminous plants to ensure food safety.

Foliar application of salicylic acid improves growth and yield attributes by upregulating the antioxidant defense system in Brassica campestris plants grown in lead-amended soils

“…Consequently, increased H 2 O 2 generation caused greater lipid peroxidation indicated by higher MDA contents. Lead-induced oxidative stress changes in morphology and structural properties of roots in different crops, resulting in a reduction of resistance, has also been demonstrated in other crop plants, e.g., Vigna unguiculata [45], O. sativa [39], B. napus [46], Zea mays [47], Vicia faba [48], Zygophyllum fabago [49], Triticum aestivum [50], and Medicago sativa [51]. Although some plants have developed an efficient antioxidant defense system to resist Pb-induced oxidative stress [51,52], excessive ROS generation results in disruption of the antioxidant defense mechanism, which is the major consequence of Pb toxicity [45].…”

“…CAT activity may vary depending on the plant species and severity of a stress. It has been documented that CAT activity elevated in leguminous crops, while it was reduced in rice under heavy metal stress conditions [45,68,69]. Moreover, CAT activity increased with a minor stress but decreased in severe conditions [50].…”

Response of photosynthesis to different concentrations of heavy metals in Davidia involucrata

“…After 90 days, the whole plants were harvested, after which the roots and leaves were separated and dried at 65˚C for 72 h to a constant weight to measure metal concentrations. The root, stem and leaf samples were digested in HNO 3 -HClO 4 , and the concentrations of Pb and Cd were determined via an atomic absorption spectrophotometer (AA-7000, Shimadzu, Japan) [6,38]. To explore the accumulation and transformation of Pb and Cd in the roots, stems and leaves, the bioaccumulation factor (BCF) and the translocation factor (TF) were calculated as follows [3]:…”

“…They are highly toxic and pose a threat to plants and animals (including humans) by affecting their normal growth and health [4,5]. Heavy metals are absorbed mainly through the roots of plants and either remain there or are translocated to the shoots and into cells [6]. For most plant species, roots represent a barrier for metals.…”

Acid Rain Increases Impact of Rice Blast on Crop Health via Inhibition of Resistance Enzymes

“…Acid rain pollution could have effects on plant diseases by altering physiological metabolism and/or disease resistance systems of the host [ 17 , 18 ]. The antioxidant system appears especially sensitive to acid rain [ 10 , 19 , 20 ]. Previous studies have shown that P. oryzae combined with acid rain can induce rice plants to activate the defense system, improve the activity of plant peroxidases (POD) and phenylalanine ammonia-lyase (PAL), and stimulate the production of polyphenolic compounds, thus improving the plant resistance to stress [ 21 , 22 ].…”