ABSTRACT
In a hydroponic culture, experiments were performed to study the influence of potassium (K) supplementation (0, 20, 40, 60, 80, and 100 mg L(-1)) on the arsenic (As; 0, 8, and 10 mg L(-1))-accrued changes in growth traits (plant biomass, root-shoot length) and the contents of lepidine, As and K, in garden cress (Lepidium sativum Linn.) at 10 days after treatment. The changes in these traits were correlated with shoot proline content, protein profile, and the activities of antioxidant enzymes namely superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), glutathione reductase (GR, EC 1.8.1.7), and ascorbate peroxidase (APX, EC 1.11.1.11). In general, As-alone treatments significantly decreased the growth traits but lead to significant enhancements in shoot proline and enzyme activities. K-supplementation to As-treated L. sativum seedlings decreased shoot-As content, reduced As-induced decreases in growth traits but enhanced the content of shoot proline, and the activities of the studied enzymes maximally with K100 + As8 and As10 mg L(-1). Both 8 and 10 mg L(-1) of As drastically downregulated the shoot proteins ranging from 43-65 kDa. With As10 mg L(-1), there was a total depletion of protein bands below 23 kDa; however, K80 mg L(-1) maximally recovered and upregulated the protein bands. Additionally, protein bands were downregulated (at par with As-alone treatment) above K80 mg L(-1) level. Interestingly, As-stress increased lepidine content in a dose-dependent manner which was further augmented with the K-supplementation. It is suggested that K protects L. sativum against As-toxicity by decreasing its accumulation and strengthening antioxidant defense system and protein stability.
Subject(s)
Arsenic/toxicity , Lepidium sativum/drug effects , Potassium/metabolism , Soil Pollutants/toxicity , Arsenic/chemistry , Dose-Response Relationship, Drug , Lepidium sativum/growth & development , Lepidium sativum/metabolism , Plant Proteins/metabolism , Potassium/administration & dosage , Proline/chemistry , Soil Pollutants/chemistryABSTRACT
The effect of mercury (Hg) on the biochemical parameters of Lycopersicon esculentum Mill leaf was studied. Application of mercuric chloride in varying concentrations (0.5, 1.0, 1.5 and 2.0 mM HgCl2 kg(-1) sand) caused significant reduction that went up to 89% and 72% chlorophyll a and chlorophyll b contents respectively (at flowering stage), 69% in carotenoid content, 64% in total soluble protein content and 91% in nitrate reductase activity (all at post-flowering stage). The amounts of nitrate and proline increased maximally (151% and 143% respectively) at the flowering stage, whereas total soluble sugar enhanced by 57% at the post-flowering stage. Changes observed in most of the parameters, were concentration dependent. Such studies seem to be able to discover suitable bioindicators of heavy metal pollution.
