Combined effect of ultraviolet‐B radiation and cadmium contamination on nutrient uptake and photosynthetic pigments in Brassica campestris L. seedlings

Abstract

Environmental and industrial pollution along with increase in ground level UV-B radiation, because of stratospheric ozone depletion, present multiple stresses, which may affect crop photosynthesis and productivity. The present study was undertaken to see interactive effects of heavy metal contamination (Cd(2+)) and UV-B exposure on essential nutrient (Ca(2+), Mg(2+), K(+)) uptake, biomass, and chlorophyll content in mustard (Brassica campestris L.) seedlings. Plants grown in 0.5, 1.0, 2.5, and 5.0 mg L(-1) Cd(2+) supplemented medium were exposed to UV-B for 30 min (0.4 mW cm(-2)) per day. The interactive effect of two stresses measured after 5 and 10 days showed an overall decline in biomass. Under dual stress (5 mg Cd(2+) L(-1)) significant (P < 0.001) decrease in chlorophyll a (43%), chlorophyll b (23%), and carotenoid (53%) was observed. Ca(2+) uptake was reduced by 51% in roots under high doses of Cd(2+) (5 mg L(-1)) and simultaneous exposure to 0.4 mW cm(-2) UV-B for 10 days. Mg(2+) content was reduced by 48% and K(+) by 62% under similar exposure conditions. Decline in nutrient uptake in Brassica campestris L. seedlings was observed both in root and shoot leaf in the initial growth period under controlled lab conditions. Cadmium ion (Cd(2+)) uptake was significantly enhanced by 33% (P < 0.001) in the presence of UV-B. The findings are significant as multiple stress conditions prevalent in the environment play an important role during the early growth period, a period critical for crop yield.

Changes of photosynthetic activities of maize (Zea mays L.) seedlings in response to cadmium stress

“…It inhibits the synthesis of chlorophylls (Chl) (Padmaja et al 1990, Burzyński and Kłobus 2004, Azevedo et al 2005, Shukla et al 2008 and their stable binding to proteins (Horváth et al 1996), thereby decreasing the accumulation of pigment-lipoprotein complexes, particularly photosystem (PS) I (Krupa et al 1987, Sárvári 2005. Ahmed and Tajmir-Riahi (1993) reported that Cd interacted with the protein subunits of light harvesting complex II.…”

Elodea nuttallii exposure to mercury exposure under enhanced ultraviolet radiation: Effects on bioaccumulation, transcriptome, pigment content and oxidative stress

“…Nevertheless, nothing is known about the influence of UV radiation on Hg accumulation and toxicity in aquatic plants, and very few studies have been conducted on the interactive effects of UV and metals in general. UV radiation has been shown to promote metal accumulation, notably for Ni and Cd in Cucumis sativus, Pisum sativum, seedlings of Glycine max, and seedlings of Brassica campestris (Agrawal & Mishra, 2009, Mishra et al, 2010, Prasad, 2005, Shukla et al, 2008. Furthermore, the accumulation of Cu by E. nuttallii was strongly promoted by UV, resulting in more than twice higher ratio between Cu concentrations in shoots and those in the medium under combined UV + Cu exposure as compared to Cu alone (Regier et al, 2015).…”

“…Furthermore, the accumulation of Cu by E. nuttallii was strongly promoted by UV, resulting in more than twice higher ratio between Cu concentrations in shoots and those in the medium under combined UV + Cu exposure as compared to Cu alone (Regier et al, 2015). Moreover, UV and metals seemed to have additive effects on physiological processes, such as photosynthetic efficiency, oxidative stress and nutrition (Agrawal & Mishra, 2009, Mishra et al, 2010, Prasad, 2005, Regier et al, 2015, Shukla et al, 2008. To our knowledge, no studies dealing with the combined exposure of aquatic plants to Hg and UV exist.…”

Structural and functional alterations in photosynthetic apparatus of plants under cadmium stress

“…Figure 1 illustrates the effects of Cd as a potent inhibitor of photosynthesis. Photosynthesis inhibition may be attributed to diminished chlorophyll biosynthesis (Shukla et al 2008), interrupted O 2 - evolving reactions of PSII and altered electron flow around PSI and PSII (Mallick and Mohn 2003). Cd hampers Calvin cycle by slowing down activity of various enzymes hence resulting in decreased photosynthesis (Ying et al 2010).…”