Chlorophyll degradation by tetracycline and cadmium in spinach (Spinacia oleracea L.) leaves

Abstract

Degradation of chlorophyll was studied in leaves of spinach grown in soil containing cadmium and tetracycline, based on spectroscopic measurements and biochemical analyses of plant extracts. It was shown that plant exposure to the highest levels of tetracycline and cadmium resulted in 64% and 68%, respectively, reduction in chlorophyll content. The chlorophyll degradation rate constants were determined, and they were found to increase with increasing doses of tetracycline and cadmium. The rate constant of chlorophyll degradation by tetracycline ranged from k = 960 M −1 day −1 to k = 2180 M −1 day −1 , and the rate constant of chlorophyll degradation by cadmium ranged from k = 1130 M −1 day −1 to k = 2580 M −1 day −1 , depending on dose. Plant stress responses to tetracycline are much stronger than to cadmium, as is visible from the activity of guaiacol peroxidase and catalase. However, phytotoxicity of cadmium, measured by the rate of chlorophyll degradation and enzyme activities, is much higher compared to tetracycline. The spectroscopic measurements were taken 10 days after tetracycline and cadmium were added to the reagent grade chlorophyll which was used at the concentration of chlorophyll in plants. Changes in absorption and fluorescence spectra are likely to result from removal of magnesium from the chlorophyll molecule, and thus they indicate the formation of pheophytin. Cadmium, on the other hand, is probably bound into the chlorophyll molecule, substituting its magnesium.

Overexpression of tomato RING E3 ubiquitin ligase gene SlRING1 confers cadmium tolerance by attenuating cadmium accumulation and oxidative stress

“…Phenotypically, Cd‐stressed plants show severe leaf yellowing, stunted shoot growth, and reduced root elongation (Hasan et al, 2019; Zhang et al, 2020; Zhao & Wang, 2019). Cd‐induced leaf chlorosis is attributed to both reduction in chlorophyll synthesis and enhancement of its degradation (Rydzyński et al, 2018; Zhang et al, 2020). Nonetheless, Cd‐induced damages to the structure of the chloroplast also result in the reduction of the chlorophyll content under Cd stress (Hasan et al, 2019).…”

Salicylic Acid Priming Regulates Stomatal Conductance, Trichome Density and Improves Cadmium Stress Tolerance in Mentha arvensis L.

“…The values of photosynthetic pigments (Chl a, b, total Chl, and Caro contents) and leaf gas exchange attributes (P N , gs, Ci, and WUE) progressively declined with increasing levels of soil-applied Cd, relative to the control plants ( Table 2 ; Figure 1 ). The Cd-induced inhibition of chlorophyll biosynthesis is due to the retention of Cd 2+ ions in the thylakoids and stroma of the chloroplasts ( Lysenko et al, 2018 ), and the substitution of Mg 2+ bound into the chlorophyll molecule ( Rydzyński et al, 2018 ). The reduction in leaf gas exchange attributes at both levels of Cd stress was due to stomatal inhibition ( Figure 5A ) that restricted gas exchange between the environment and menthol mint plants, and these results are in line with those of Zaid and Mohammad (2018) .…”

Physiological and Biochemical Parameters of Common Duckweed Lemna minor after the Exposure to Tetracycline and the Recovery from This Stress

“…After centrifugation at 1700× g for 15 min, the pellets were washed with the solvent five times, and the ethanol solutions from all extraction stages were combined. The supernatants were diluted five times; then, they were subjected to analyses of absorption spectra using a Carry 300 UV-Visible Spectrophotometer (Varian, Inc., Victoria, Australia) according to Rydzy ński et al [72].…”